No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Food security and climate change: the case of rainfed maize production in Mexico
Abstract
Climate change has altered global rainfall amounts and seasonality. Rainfed crops are particularly dependent on foreseeable rainfall, thus yields of maize, wheat and sorghum have decreased globally. Rainfed maize is the cornerstone of the agriculture in Mexico and the nutrition base of as many as twenty million people. Despite its relevance, the risk that climate change represents for this economic activity has not been studied in our country. We evaluated the link between rainfall variability and maize yields in Mexico across three different time periods: the present, the past 30 years and the remainder of this century (future) with RCPs scenarios. We found that rainfed agriculture was distributed as a function of the dry-season length, occurring in areas with a 4–9 months dry season, thus climate change may alter not only agricultural yields, but also the spatial distribution of land uses. There was a linear correlation (r = 0.45) between mean annual precipitation and rainfed maize production nationally for the period 1980–2012. The correlation was stronger (r = 0.91) during 2005–2012 when high-resolution data were available for the analysis. Correlation values were not homogeneously distributed within the country, although the minimum correlation was 0.35. In the future scenarios, yields were predicted to either not change or to decrease by as much as 10%. The strongest negative impacts were predicted across the Northeast and the South of the country, where yields declined by up to 30% in all scenarios.
... Moreover, global warming and the irrational use of natural resources has an impact on food security (Saccon, 2018;Azadi et al., 2018). For example, one problem associated with global warming is drought, which affects agricultural production systems and, consequently, food-bearing plants for human consumption (Ali et al., 2020;Murray-Tortarolo et al., 2018;Mardero et al., 2018). Likewise, water stress promoted by drought in plants leads to reactive oxygen species (ROS) production, generating wilting in leaves, oxidative damage to proteins and cell membrane instability . ...
... Also, climate change has generated alterations in hydrological patterns, which has led to a higher incidence of droughts and flooding which has affected the production of temporary crops (Ali et al., 2020;Arreguin et al., 2019;Murray-Tortarolo et al., 2018). Furthermore, the climatic phenomenon has generated changes in the behaviour of the agricultural system, which are manifesting themselves in the form of erosion, salinization, and a general decline in soil quality, leading to the abandonment of farmland. ...
... At present, Mexico is experiencing changes in temperature and precipitation, resulting in a 25% decrease in crop yields such as corn production. Comparable data have reported a decrease (100 mm year -1 ) and an increase (2000 mm/year), in precipitation in the north and south of the country respectively, during the period of 1901-2009(Murray-Tortarolo et al., 2018. Additionally, significant losses of 45 and 83 mln t of corn and soybeans have also been reported in the United States due to severe drought during 2012 (Rodríguez-Calzada et al., 2019). ...
Drought stress has serious repercussions for agriculture, affecting crop growth with low yield effects concerning food production and food security. The main objective of this
research is to conduct a scientific literature review of the physical methods used to generate tolerance to water stress in crops. (i) The most widely applied physical method to counteract the effects of drought stress is UV radiation, magnetic field application (18%), He-Ne and CO2 laser (18%), gamma radiation (9%) and plasma (6%). (ii) Treatments with ultraviolet light and magnetic fields have been applied mainly in cereals, vegetables, legumes, medicinal plants, and trees. Also, He-Ne, CO2 laser, and plasma in seeds in cereals and medicinal plants in the pre-sowing stage to seed level. Finally, gamma radiation has been applied to plants and seeds (grass, flowers, sugar plant). (iii) The reported physical methods can increase or decrease the biochemical variables under water stress depending on the physical method and radiation parameters applied, as well as the crop, level of drought and the environment in which the plants develop. Thus, UV radiation, magnetic fields, gamma radiation, and He-Ne and CO2 lasers are physical methods that produce seed and plant improvement effects
... Moreover, global warming and the irrational use of natural resources has an impact on food security (Saccon, 2018;Azadi et al., 2018). For example, one problem associated with global warming is drought, which affects agricultural production systems and, consequently, food-bearing plants for human consumption (Ali et al., 2020;Murray-Tortarolo et al., 2018;Mardero et al., 2018). Likewise, water stress promoted by drought in plants leads to reactive oxygen species (ROS) production, generating wilting in leaves, oxidative damage to proteins and cell membrane instability . ...
... Also, climate change has generated alterations in hydrological patterns, which has led to a higher incidence of droughts and flooding which has affected the production of temporary crops (Ali et al., 2020;Arreguin et al., 2019;Murray-Tortarolo et al., 2018). Furthermore, the climatic phenomenon has generated changes in the behaviour of the agricultural system, which are manifesting themselves in the form of erosion, salinization, and a general decline in soil quality, leading to the abandonment of farmland. ...
... At present, Mexico is experiencing changes in temperature and precipitation, resulting in a 25% decrease in crop yields such as corn production. Comparable data have reported a decrease (100 mm year -1 ) and an increase (2000 mm/year), in precipitation in the north and south of the country respectively, during the period of 1901-2009(Murray-Tortarolo et al., 2018. Additionally, significant losses of 45 and 83 mln t of corn and soybeans have also been reported in the United States due to severe drought during 2012 (Rodríguez-Calzada et al., 2019). ...
A b s t r a c t. Drought stress has serious repercussions for agriculture, affecting crop growth with low yield effects concerning food production and food security. The main objective of this research is to conduct a scientific literature review of the physical methods used to generate tolerance to water stress in crops. (i) The most widely applied physical method to counteract the effects of drought stress is UV radiation, magnetic field application (18%), He-Ne and CO2 laser (18%), gamma radiation (9%) and plasma (6%). (ii) Treatments with ultraviolet light and magnetic fields have been applied mainly in cereals, vegetables, legumes, medicinal plants, and trees. Also, He-Ne, CO2 laser, and plasma in seeds in cereals and medicinal plants in the pre-sowing stage to seed level. Finally, gamma radiation has been applied to plants and seeds (grass, flowers, sugar plant). (iii) The reported physical methods can increase or decrease the biochemical variables under water stress depending on the physical method and radiation parameters applied, as well as the crop, level of drought and the environment in which the plants develop. Thus, UV radiation, magnetic fields, gamma radiation, and He-Ne and CO2 lasers are physical methods that produce seed and plant improvement effects.
... In the last six-year period (2013-2018) with the MasAgro program, national production increased through the use of native maize varieties (MAGR, 3.07%) with small-scale producers [32]. Despite all these efforts, grain maize production in Mexico is insufficient to guarantee food security of a population in continuous growth [33]. The agrifood policy in Mexico in the six-year period of 1983-1988 caused the MAGR of this period to be negative (−3.59%), since imports were prioritized over the programs to strengthen the farmland [30]. ...
... In the last six-year period (2013-2018) with the MasAgro program, national production increased through the use of native maize varieties (MAGR, 3.07%) with small-scale producers [32]. Despite all these efforts, grain maize production in Mexico is insufficient to guarantee food security of a population in continuous growth [33]. ...
... The growing trend in the production of grain maize for the SS-Rainfed cycle can be reverted in the short term, as consequence of the reduction of the surface planted since the year 2000 and a null growth of field yields in the same cycle ( Figure 2). In this regard, [33] considers that the constant production of grain maize that Mexico has maintained in the last decade is due to the increase in productive efficiency, particularly in the irrigation areas, which compensates the low productivity per surface planted in the rainfed areas. ...
Mexico depends on maize imports to satisfy its national demand. The use of native maize varieties among subsistence farmers can help to reduce the cereal’s imports. However, the agricultural policy in Mexico to improve the productivity per hectare has centered on the use of improved varieties; among them, the transgenic variety. In this study, the maize productivity in Mexico from 1983 to 2018 was analyzed to determine the influence of agricultural policies in the sector, and the factors that condition the adoption of transgenic maize. It was found that the agricultural policy improved the productivity of those regions with irrigation; however, for rainfed regions, the expected technological changes were not achieved because the ancestral tradition in cultivation, associated with the greater variety of native maize and to a larger indigenous population, was stronger. The adoption of transgenic maize also had low significance in the rainfed regions, since the increase in field yields is not economically profitable with regards to the increase in production costs. Therefore, the agricultural policy to increase productivity ought to be directed at the protection of subsistence farmers, revaluing the use of native varieties that have shown higher resilience to technological and environmental changes.
... Such studies use biophysical crop models that provide gross estimates of changing yields (Howden et al., 2007;De Salvo et al., 2013;Rosenzweig et al., 2014). Climate change scientists have analyzed the impacts of climatic variables over rainfed maize in Mexico (Murray-Tortarolo et al., 2018;Ureta et al., 2020), while others have explored the linkage between institutions, climate risk, and vulnerability of maize production (Eakin et al., 2018). Although these studies are useful to identify coarse trends and impacts of climate change on maize production, they do not consider the diversity of the socio-ecological contexts which can affect their risk. ...
... The general overall climatic ranges for maize included 0 to 2,900 m altitude, 11.3 • to 26.6 • C annual mean temperature, 12.0 • to 29.1 • C growing season mean temperature, and 426-4245 mm annual rainfall (Ruiz-Corral et al., 2008). However, it seems that rainfed maize are strongly correlated to annual precipitation and precipitation seasonality (Challenger, 1998;Murray-Tortarolo et al., 2018). The RF models identified that annual precipitation was the second most important predictor in rainfed maize yields (Supplementary Figure 3). ...
... low yields (<3.0 ton/ha) which will reduce by climate change (Murray-Tortarolo et al., 2018). To overcome the climatic challenges for the agricultural sector in the north of Mexico, farmers have implemented irrigation management to grow animal feed crops such as sorghum and wheat, leaving staple foods production to the southern and central Mexico (Eakin et al., 2014b). ...
Evidence suggests that climate change could drastically reduce Mexico's agricultural productivity with severe socio-ecological consequences. Population growth and the increasing demand of resources will exacerbate these impacts. Focusing on rainfed maize production, we evaluate the socio-ecological risk that municipalities currently face and how climate change could modify it. Municipalities were classified based on their biophysical and socioeconomic traits like temperature, precipitation, population, gross domestic product, marginalization, and agricultural subsidies. The study identifies municipalities that would face higher risk under climate change conditions, and it evaluates whether increases in agricultural subsidies could be effective for reducing the farmers' future risk. Our results show that during the 2010's, 36.8% of the municipalities and 15% of the population were at very high and high risk, respectively. By 2070, under a high-warming scenario these figures increase to 56.5 and 18.5%. We find that a generalized augment in agricultural subsidies is not enough to compensate for the effects of climate change on the socio-ecological risk of rainfed maize producers. We suggest that transformative adaptation is required for managing the agricultural risk that socio-ecological systems experience under climate change conditions. Such adaptation strategies should include poverty alleviation, promotion of resistant and native varieties of crops, capacity building to improve management and water use, sustainable technification, and soil restoration.
... Such studies use biophysical crop models that provide gross estimates of changing yields (Howden et al., 2007;De Salvo et al., 2013;Rosenzweig et al., 2014). Climate change scientists have analyzed the impacts of climatic variables over rainfed maize in Mexico (Murray-Tortarolo et al., 2018;Ureta et al., 2020), while others have explored the linkage between institutions, climate risk, and vulnerability of maize production (Eakin et al., 2018). Although these studies are useful to identify coarse trends and impacts of climate change on maize production, they do not consider the diversity of the socio-ecological contexts which can affect their risk. ...
... The general overall climatic ranges for maize included 0 to 2,900 m altitude, 11.3 • to 26.6 • C annual mean temperature, 12.0 • to 29.1 • C growing season mean temperature, and 426-4245 mm annual rainfall (Ruiz-Corral et al., 2008). However, it seems that rainfed maize are strongly correlated to annual precipitation and precipitation seasonality (Challenger, 1998;Murray-Tortarolo et al., 2018). The RF models identified that annual precipitation was the second most important predictor in rainfed maize yields (Supplementary Figure 3). ...
... low yields (<3.0 ton/ha) which will reduce by climate change (Murray-Tortarolo et al., 2018). To overcome the climatic challenges for the agricultural sector in the north of Mexico, farmers have implemented irrigation management to grow animal feed crops such as sorghum and wheat, leaving staple foods production to the southern and central Mexico (Eakin et al., 2014b). ...
Evidence suggests that climate change could drastically reduce Mexico's agricultural productivity with severe socio-ecological consequences. Population growth and the increasing demand of resources will exacerbate these impacts. Focusing on rainfed maize production, we evaluate the socio-ecological risk that municipalities currently face and how climate change could modify it. Municipalities were classified based on their biophysical and socioeconomic traits like temperature, precipitation, population, gross domestic product, marginalization, and agricultural subsidies. The study identifies municipalities that would face higher risk under climate change conditions, and it evaluates whether increases in agricultural subsidies could be effective for reducing the farmers' future risk. Our results show that during the 2010's, 36.8% of the municipalities and 15% of the population were at very high and high risk, respectively. By 2070, under a high-warming scenario these figures increase to 56.5 and 18.5%. We find that a generalized augment in agricultural subsidies is not enough to compensate for the effects of climate change on the socio-ecological risk of rainfed maize producers. We suggest that transformative adaptation is required for managing the agricultural risk that socio-ecological systems experience under climate change conditions. Such adaptation strategies should include poverty alleviation, promotion of resistant and native varieties of crops, capacity building to improve management and water use, sustainable technification, and soil restoration.
... Warming will alter the length of growing seasons of coldseason crops (e.g., broccoli, lettuce) and will shift suitability ranges of warm-season California crops (e.g., tomatoes) (medium confidence) (Marklein et al., 2020). Increasing atmospheric CO 2 will enhance yields yet reduce nutrient content of many crops (high confidence); a CO 2 concentration of 541 ppm (seen by 2050 in RCP8.5 (Polley et al., 2013;Reeves et al., 2014;Cooley, 2016;Bradford et al., 2020) and transforms grasslands into woody shrublands (Briske et al., 2015;Murray-Tortarolo et al., 2018), while warmer and wetter conditions in the northern regions (CA-PR, US-NW, US-NP) may enhance rangeland production by extending growing seasons (high confidence) (Hufkens et al., 2016;Derner et al., 2018;Zhang et al., 2019a). Increased CO 2 will enhance production (medium confidence) but reduce forage quality (high confidence) in US-NP and US-NW (Table SM14. ...
... Crop pest and pathogen outbreaks are expected to worsen under climate change (high confidence)(Deutsch et al., 2018;Wolfe et al., 2018;Zhang et al., 2019a).Climate change is anticipated to cause declines in livestock production across North America (high confidence)(Table 14.4;SM14.6;Havstad et al., 2018;Murray-Tortarolo et al., 2018). Increases in extreme temperature raise the risk of livestock heat stress, disease and pest impacts(Rojas-Downing et al., 2017). ...
Since AR5, climate-change impacts have become more frequent, intense and have affected many millions of people from every region and sector across North America (Canada, USA and Mexico). Accelerating climate-change hazards pose significant risks to the well-being of North American populations and the natural, managed and human systems on which they depend (high confidence1). Addressing these risks has been made more urgent by delays due to misinformation about climate science that has sowed uncertainty and impeded recognition of risk (high confidence). {14.2, 14.3}
Without limiting warming to 1.5°C, key risks to North America are expected to intensify rapidly by mid-century (high confidence). These risks will result in irreversible changes to ecosystems, mounting damages to infrastructure and housing, stress on economic sectors, disruption of livelihoods, and issues with mental and physical health, leisure and safety. Immediate, widespread and coordinated implementation of adaptation measures aimed at reducing risks and focused on equity have the greatest potential to maintain and improve the quality of life for North Americans, ensure sustainable livelihoods and protect the long-term biodiversity, and ecological and economic productivity, in North America (high confidence). Enhanced sharing of resources and tools for adaptation across economic, social, cultural and national entities enables more effective short- and long-term responses to climate change. {14.2, 14.4, 14.5, 14.6, 14.7}
... First studies on maize reported an increment of 18.0% of the unsuitable area for maize with an increase in temperature of 2.0 °C and − 20% in precipitation (Conde et al. 1998). Other researchers projected a nationwide maize yield reduction of up to 10%, with regional decreases of up to 80% in RCP 8.5 (Murray-Tortarolo et al. 2018) and an average maize yield of 0.25 to 0.5 t/ha for rainfed maize under the same RCP (Ureta et al. 2020). Some papers also have analyzed diverse crops which include sugarcane (Guerrero-Carrera et al. 2015;Baez-Gonzalez et al. 2018) and wheat (Hernandez-Ochoa et al. 2018). ...
... In Mexico, this has been supported by Ureta et al. (2020), who found that temperature is a determinant factor for rainfed maize. Contrastingly, Murray-Tortarolo et al. (2018) suggested that negative impacts on maize yield are mainly associated with water availability and dry season length for rainfed management. Their results are supported by ours in which the same critical regions (northeast and south) of the country are the most affected for rainfed maize under the RCP8.5 scenario. ...
This study quantifies the impacts of climate change on yields and the corresponding economic losses in six relevant crops that account for 65% of the harvested area in Mexico and are highly relevant in terms of consumption and economic value. The results show that crop yields could decrease considerably during this century, especially in the rainfed management system. Under a high-emission scenario, large reductions in yields are expected by the end of this century for both rainfed and irrigated management systems of maize (42%, 31.4%), rice (51.4%, 41.3%), sorghum (41.1%, 36.6%), soybean (59.1%, 44.9%), wheat (23.3%, 20.0%), and rainfed sugarcane (11.7%). At the national level, the present value of losses in the selected crops amounts to $37,934 million dollars, which represents about twice the current total national agricultural production of Mexico. Rainfed agriculture represents about 69% of these losses and reductions in maize yields account for almost 70% of the total losses. States such as Veracruz, Sinaloa, Tamaulipas, and Jalisco represent half of the total economic losses. However, about 16% of the aggregated losses occur in states with high levels of poverty and subsistence farming like Chiapas, Oaxaca, and Guerrero. Climate change will significantly increase the risks that already vulnerable subsistence farmers’ face in the present. Although ambitious mitigation efforts can reduce the estimated impacts in most of the crops, residual damages are considerable, and the prompt implementation adaptation strategies is required.
... Una constante en los resultados es considerar el maíz como recurso indispensable para la seguridad alimentaria mexicana (Donnet, Becerril, Black, & Hellin, 2017;Langner et al., 2019;Murray-Tortarolo, Jaramillo, & Larsen, 2018;Novotny et al., 2021). Mientras que otros se enfocan en la producción pecuaria como solución a la falta de seguridad alimentaria en el país (Ibarra, Sánchez Vargas, & Martínez López, 2013;Nicholson et al., 2021;Velázquez, 2017). ...
... Así mismo, considerar el cambio climático en temas de seguridad alimentaria es indispensable, ya que gran parte de la producción de alimentos depende enteramente de los cultivos de secano, que a su vez dependen de la variabilidad de las precipitaciones y cambios en las temperaturas (Bee, 2014;González-Marín, Moreno-Casasola, Castro-Luna, & Castillo, 2017;Murray-Tortarolo et al., 2018); Munang, Thiaw, & Rivington, 2011). ...
Se describe la relevancia de la medición de la seguridad alimentaria en México. Se aborda su complejidad desde las dimensiones (disponibilidad, acceso, uso y estabilidad), metodologías y métodos. Se realizó un meta-análisis manejando tres importantes repositorios de datos: Science Direct, Scopus y Google Scholar, para el período 2000-2021 haciendo énfasis en el país. Además, se incluyó un análisis bibliométrico y la visualización en red de las relaciones co-ocurrencia entre palabras clave empleadas en 55 artículos científicos. Los resultados muestran un aumento en el estudio de la seguridad alimentaria desde el año 2009 y hasta la fecha. Resalta el empleo de las cuatro dimensiones propuestas por FAO para el estudio de la seguridad alimentaria de diferentes maneras. Sin embargo, también es común estudiarla desde enfoque único o adimensional. Las metodologías más destacadas se centran en el uso de indicadores, índices y encuestas como Ensanut. También diferentes análisis estadísticos como el método de componentes principales y diversos modelos líneas o lineales mixtos. Ha sido común encontrar estudios que no siguen algún método específico, sin embargo, algunos de ellos se basan en las definiciones propuestas por FAO o escalas de medición como la Escala Mexicana de Seguridad Alimentaria o la Escala Latinoamericana y Caribeña de Seguridad Alimentaria. Si bien se ha estudiado de diferentes formas la seguridad alimentaria mexicana, aún quedan vacíos por resolver, siendo evidente que es necesario continuar con la medición incorporando análisis más completos y a escalas más pequeñas.
... The findings of lower consumption of unprocessed foods associated with decreases in rainfall may be driven at least in part by lower production of grains at lower precipitations. Rainfall is one of the most important factors for the growth of cereals, as already observed in studies in Mexico and other countries (25)(26)(27)(28)(29). Specifically, rainfed corn is a fundamental component of agriculture in Mexico and a staple food among Mexicans (11,28,30); corn tortilla, a minimally processed food, represented 20% of TEI among adults in 2012 (11). ...
... The findings of lower consumption of unprocessed foods associated with decreases in rainfall may be driven at least in part by lower production of grains at lower precipitations. Rainfall is one of the most important factors for the growth of cereals, as already observed in studies in Mexico and other countries (25)(26)(27)(28)(29). Specifically, rainfed corn is a fundamental component of agriculture in Mexico and a staple food among Mexicans (11,28,30); corn tortilla, a minimally processed food, represented 20% of TEI among adults in 2012 (11). Lower production of grains, such as corn, can, in turn, lead to lower availability and higher food prices and, therefore, lower consumption of these types of unprocessed or minimally processed foods (31,32). ...
Background: Little is known about the potential impact of climate change on food systems and diet. We aimed to estimate the association of changes in rainfall and temperatures with consumption of unprocessed and processed foods among residents of Mexican cities by climate region.
Methods: We analyzed 3,312 participants of the 2012 Mexican National Health and Nutrition Survey with dietary intake and sociodemographic information linked to historical rainfall and temperature data collected by the Mexican National Weather Service. We classified foods as unprocessed, processed, or ultra-processed. We performed multilevel linear regression to estimate the association of annual change in rainfalls (for each 0.5 mm decrease) and temperatures (for each 0.1°C increase) at municipality level over the past 5 years with consumption of processed and unprocessed foods measured as the contribution to total energy intake. We investigated whether associations differed by climate region (tropical, temperate, and arid).
Results: Each 0.5 mm annual decrease in precipitation was associated with lower consumption of unprocessed foods and higher consumption of ultra-processed foods [mean differences in percent contribution to total energy intake −0.009% (95% CI: −0.019, < −0.001) and 0.011% (95% CI: 0.001, 0.021), respectively]. Each 0.1 degree Celsius annual increase in temperature was also associated with lower consumption of unprocessed and higher consumption of ultra-processed foods [mean differences in percent contribution to total energy intake was −0.03 (95% CI: −0.05, −0.01) and 0.03% (95% CI: <0.01, 0.05)]. When stratified by climate region these associations were only observed in tropical regions.
Conclusions: Decreases in rainfalls and increases in temperature were associated with lower consumption of unprocessed foods but higher consumption of ultra-processed foods, especially in tropical regions. Previous studies have established how food production affects the climate, our study suggests that climate change could, in turn, reinforce modern food production, closing a vicious circle with clear negative implications for planetary health.
... This is particularly the case in Mexico and Mesoamerica, where maize is the basis of human nutrition, and approximately 78.4 % of maize cropping depends on rainfall as the main source of water (SIAP 2019). Cropping practices may mitigate the impact of climate change on food security, however, few studies have analysed how variations in agricultural practices influence microclimate within the crop area, and thereby the physiological performance of the maize plant (Murray-Tortarolo et al. 2018). Such studies are necessary for a better understanding of the ecological and functional dynamics within regional maize crop systems. ...
... There is therefore scope for a better understanding of the physiological response of maize to microclimatic variations as a result of different agricultural management systems. Studies in this regard are useful for designing strategies that contribute to reducing the negative effects of climate change on maize yield (Xu et al. 2017) in small-scale management systems, particularly in rainfed conditions, and whose food security is severely threatened by climate modifications (Nigh & Diemont 2013, Murray-Tortarolo et al. 2018. ...
Background: Maize is cultivated under different agricultural management systems, which influence the ecological dynamics of the crop, and
therefore the physiology of the plant.
Questions: What is the effect of different agricultural management on the microclimate and the physiology of maize plants?
Studied species: Zea mays L.
Study site and dates: Nacajuca, Tabasco, Mexico; January to April 2017.
Methods: Physiological performance of maize plants and microclimatic variation in the crop area was characterized under three management systems: maize monoculture, maize-bean, and maize-bean-squash intercropping. Each treatment was established in three 100 m2 plots (300 m2 per treatment). Four measurements were taken between days 33 and 99 after maize sowing, to characterize five microclimatic parameters (relative air humidity, air and soil temperature, vapor-pressure deficit and soil volumetric water content) and nine physiological parameters (photosynthesis, transpiration, water use efficiency, stomatal conductance, electron transport rate, quantum efficiency of photosystem II, non- photochemical quenching, foliar water potential and chlorophyll content).
Results: Maximum soil temperature was up to 4.4 ºC less in the maize-bean system than in the monoculture at 15:00 h; soil in the maize-bean-squash intercropping retained up to 45 % more water than the monoculture throughout the day. Photosynthesis and electron transport rate in the maize-bean intercropping was up to 32 % higher than in the monoculture. The highest non-photochemical quenching and transpiration rate were observed in the maize-bean-squash system.
Conclusions: The maize-bean and maize-bean-squash combination provides maize plants with lower soil temperature and higher water availability, allowing them better physiological performance compared to monoculture.
... This is particularly the case in Mexico and Mesoamerica, where maize is the basis of human nutrition, and approximately 78.4 % of maize cropping depends on rainfall as the main source of water (SIAP 2019). Cropping practices may mitigate the impact of climate change on food security, however, few studies have analysed how variations in agricultural practices influence microclimate within the crop area, and thereby the physiological performance of the maize plant (Murray-Tortarolo et al. 2018). Such studies are necessary for a better understanding of the ecological and functional dynamics within regional maize crop systems. ...
... There is therefore scope for a better understanding of the physiological response of maize to microclimatic variations as a result of different agricultural management systems. Studies in this regard are useful for designing strategies that contribute to reducing the negative effects of climate change on maize yield (Xu et al. 2017) in small-scale management systems, particularly in rainfed conditions, and whose food security is severely threatened by climate modifications (Nigh & Diemont 2013, Murray-Tortarolo et al. 2018. ...
Background: Maize is cultivated under different agricultural management systems, which influence the ecological dynamics of the crop, and therefore the physiology of the plant. Questions: What is the effect of different agricultural management on the microclimate and the physiology of maize plants? Studied species: Zea mays L. Study site and dates: Nacajuca, Tabasco, Mexico; January to April 2017. Methods: Physiological performance of maize plants and microclimatic variation in the crop area was characterized under three management systems: maize monoculture, maize-bean, and maize-bean-squash intercropping. Each treatment was established in three 100 m2 plots (300 m2 per treatment). Four measurements were taken between days 33 and 99 after maize sowing, to characterize five microclimatic parameters (relative air humidity, air and soil temperature, vapor-pressure deficit and soil volumetric water content) and nine physiological parameters (photosynthesis, transpiration, water use efficiency, stomatal conductance, electron transport rate, quantum efficiency of photosystem II, non-photochemical quenching, foliar water potential and chlorophyll content). Results: Maximum soil temperature was up to 4.4 ºC less in the maize-bean system than in the monoculture at 15:00 h; soil in the maize-bean-squash intercropping retained up to 45 % more water than the monoculture throughout the day. Photosynthesis and electron transport rate in the maize-bean intercropping was up to 32 % higher than in the monoculture. The highest non-photochemical quenching and transpiration rate were observed in the maize-bean-squash system. Conclusions: The maize-bean and maize-bean-squash combination provides maize plants with lower soil temperature and higher water availability, allowing them better physiological performance compared to monoculture.
... The lateral acceleration can be expressed using Newton's second law in terms of the lateral tire forces: = 1 ( , ( , , ) + , ( , )) (8) Lateral force can be defined using the well-known magic formula [30]: ...
... Lateral force can be defined using the well-known magic formula [30]: ...
In this study, a low-cost proposed platform for training dynamics (PPTD) is proposed based on operational amplifiers to understand the dynamics and variables of the agricultural tractor John Deere tractor model 4430 to gain autonomy and analyze the behavior of control algorithms proposed in real time by state feedback. The proposed platform uses commercial sensors and interacts with the Arduino Uno and/or Daq-6009 board from National Instruments. A mobile application (APP) was also developed for real-time monitoring of autonomous control signals, the local reference system, and physical and dynamic variables in the tractor; this platform can be used as a mobile alternative applied to a tractor in physically installed form. In the presented case, the PPTD was mounted on a John Deere tractor to test its behavior; moreover, it may be used on other tractor models similarly as established here. The established results of this platform were compared with models established in MATLAB, validating the proposal. All simulations and developments are shared through a web-link as open-source files so that anyone with basic knowledge of electronics and modeling of vehicles can reproduce the proposed platform.
... The impact of droughts will have a disproportionate impact on low-income, marginalized groups, who also have limited capacity to fund climate adaptation initiatives. For example, maize, a staple crop for small farms in Central America, is generally grown under rain-fed conditions and is therefore highly vulnerable to changes in precipitation ; rainfed maize production is closely correlated with precipitation (Murray-Tortarolo et al., 2018). In northeast Mexico, agricultural yield is predicted to decrease by 30% under some emissions scenarios (Murray-Tortarolo et al., 2018). ...
... For example, maize, a staple crop for small farms in Central America, is generally grown under rain-fed conditions and is therefore highly vulnerable to changes in precipitation ; rainfed maize production is closely correlated with precipitation (Murray-Tortarolo et al., 2018). In northeast Mexico, agricultural yield is predicted to decrease by 30% under some emissions scenarios (Murray-Tortarolo et al., 2018). It is important to prepare for droughts and prevent land degradation, which is more cost-effective than responding to extreme events and restoring land after it has degraded (Mirzabaev et al., 2019). ...
... Although the contribution of agricultural activities accounts for 3.4% of the Mexican GDP (INEGI, 2020), there are~6 million people who depend directly on this sector (SIAP, 2019) and up to 26.9 million people considering their relatives (INEGI, 2021). Farmers in Mexico have been cataloged as of the most vulnerable to climate change because of a mosaic of conditions (Monterroso et al., 2014;Murray-Tortarolo et al., 2018;Donatti et al., 2019), and their incomes are highly dependent on crop yields. The vast majority of agricultural land is rainfed (69.7%) (SIAP, 2021), and conducted in small patches of land (usually <2ha) (Ibarrola-Rivas et al., 2020), with traditional management practices (e.g., milpa). ...
The collection of publicly available databases about climate change and its impacts on natural and human systems is unprecedented and ever-growing. However, the requirements of information can vary widely among users depending on their region, socioenvironmental context, and interests. Moreover, in the current era of active mitigation and adaptation policies, information needs are frequently not satisfied even by these massive and variated collections of databases. The development and use of emulators can help closing this information gap by allowing users to approximate the output from complex models and create user-defined experiments, without being technically or computational demanding on the user. Here, a simple emulator of the EPIC biophysical crop model is presented which is able to adequately reproduce the changes in rainfed maize and to create projections for user-defined scenarios. Moreover, it allows to produce risk measures that are not available with the original model. The proposed methodology is illustrated with a case study of rainfed maize production in Mexico for a reference emissions scenario (SSP370) and two user-defined international mitigation policy scenarios. These scenarios represent 1) current international mitigation commitments and 2) a scenario in which China withdraws from international mitigation efforts. Results showed that, under the reference scenario, climate change could have widespread consequences on rainfed production all over the country with decreases in yields reaching up to 80% in the southeast and northeast of the country. These impacts can be partially modulated by the moderately ambitious mitigation commitments assumed in recent international agreements if all countries comply. However, a potential withdraw of China from these efforts would significantly reduce any benefits from international mitigation. Under all scenarios, changes in productivity impose increasing risks for already vulnerable populations and considerable economic costs at the state and national levels. These results suggest the urgent need for critical planning for adaptation in the agricultural sector of the country.
... On the other hand, in terms of negative effects, climate change could cause a reduction in the level of crop production because of temperature rise; rising soil erosion; and land quality degradation ( Kim et al., 2009 ). However, a number of some recent studies conclude that climate change adversely affects food production ( Murray-Tortarolo et al., 2018 ;Fanzo et al., 2018 ;Arora, 2019 ;and Kehrberger and Holzschuh, 2019 ). In addition, different approaches were adopted in the literature to examine the relationship between climate change and food production such as mathematical programming by Adams et al. (1990) , the Ricardian approach by Gbetibouo and Hassan (2005) ; Fezzi and Bateman (2015) , and static and dynamic panel data analyses by Gedik and Güne (2021) . ...
Climate change is profoundly affecting many activities in the agricultural sector in almost all regions of the
world. To adapt to the prevailing climatic conditions has translated into a cascade of risks for agro-ecosystems and
agricultural production, ultimately impacting food security and nutrition. Hence, the study examines the effect
of climate change on food production in 32 sub-Saharan African (SSA) countries between 2005 and 2019 using
Fixed Effects (FE) and Two-Step System-Generalized Method of Moments (GMM) estimation. Findings help better
understand the link resulting from climate change to adverse impacts on food production, as empirical analyses
indicate that an increase in climate change (CO2 emissions) will result in a significant reduction in food production
in SSA. This implies that climate change seems to have significantly contributed to the challenges associated with
food insecurity in the region. Via changes in average temperature and rainfall patterns, climate change could be
exacerbating existing threats and issues related to food production in the SSA region. It is therefore suggested that
to mitigate the negative impacts of climate change on food production, policy makers should aim at encouraging
and adopting good adaptation approach, primarily at the production stage of food supply.
... The development of hybrid maize is one of the alternative strategies utilized for the improvement of yield traits in extreme environments (Lunduka et al., 2019;Meseka et al., 2018;Zhao et al., 2018). In maize crops, drought or water deficit stress has been reported as major abiotic constraint, especially in arid and semi-arid rainfed regions of the world, where lack of irrigation system negatively impacts water uptake, translocation, and water use efficiency of crop species (Lu et al., 2017;Murray-Tortarolo et al., 2018;Žalud et al., 2017). In drought-prone species, physiological strategies like osmotic adjustment, stay-green, and water status of maize plants have been well established as means of survival and maintenance of crop productivity (Makore et al., 2021;Wossen et al., 2017). ...
Normalized Difference Red Edge Index), and NDVI (Normalized Difference Vegetation Index)) derived from UAV multi-sensors did not vary. At the reproductive stage, CWSI in drought-sensitive genotype (S7328) under WD increased by 1.92-fold over WW. All the vegetation indices (EVI2, OSAVI, GNDVI, NDRE, and NDVI) of Pac339 and S7328 under WD decreased when compared with those of Suwan4452. NDVI derived from GreenSeeker ® handheld and NDVI from UAV data was closely related (R 2 = 0.5924). An increase in leaf temperature (T leaf) and reduction in NDVI of WD stressed maize plants was observed (R 2 = 0.5829) leading to yield loss (R 2 = 0.5198). In summary, a close correlation was observed between the physiological data of individual plants and vegetation indices of canopy level (collected using a UAV platform) in drought-sensitive genotypes of maize crops under WD conditions, thus indicating its effectiveness in the classification of drought-tolerant genotypes.
... As the world's most widely cultivated cereal, maize plays a pivotal role in sustaining global food security. Maize provides up to 20% of food calories in Africa and Meso America, while constituting a prime fodder crop for livestock across the globe (Murray-Tortarolo et al., 2018;Shiferaw et al., 2011). China is the world's second largest maize producer and consumer, cultivating 43.3 million hectares of maize (equivalent to 273 million tons of harvested grain) in 2021 (Wu et al., 2021a). ...
China is the world's second largest maize producer and consumer. In recent years, the invasive fall armyworm Spodoptera frugiperda (J.E. Smith) has adversely affected maize productivity and compromised food security. To mitigate pest-inflicted food shortages, China's Government issued biosafety certificates for two genetically modified (GM) Bt maize hybrids, Bt-Cry1Ab DBN9936 and Bt-Cry1Ab/Cry2Aj Ruifeng125, in 2019. Here, we quantitatively assess the impact of both Bt maize hybrids on pest feeding damage, crop yield and food safety throughout China's maize belt. Without a need to resort to synthetic insecticides, Bt maize could mitigate lepidopteran pest pressure by 61.9 ~ 97.3%, avoid yield loss by 16.4 ~ 21.3% (range -11.9 ~ 99.2%) and lower mycotoxin contamination by 85.5 ~ 95.5% as compared to the prevailing non-Bt hybrids. Yield loss avoidance varied considerably between experimental sites and years, as mediated by on-site infestation pressure and pest identity. For either seed mixtures or block refuge arrangements, pest pressure was kept below established thresholds at 90% Bt maize coverage in Yunnan (where S. frugiperda was the dominant species) and 70% Bt maize coverage in other sites dominated by Helicoverpa armigera (Hübner) and Ostrinia furnacalis (Guenée). Drawing on experiences from other crop/pest systems, Bt maize in se can provide area-wide pest management and thus contribute to a progressive phase-down of chemical pesticide use. Hence, when consciously paired with agroecological and biodiversity-based measures, GM insecticidal crops can ensure food and nutrition security, contribute to the sustainable intensification of China's agriculture and reduce food systems' environmental footprint.
... While most studies have focused on the role of crop diversity as a response to climatic change or instability in terms of stabilizing production (output) or productivity (yield), this study extends the analysis to include diversity effects on revenue stability. Furthermore, the finding that precipitation instability was an especially strong negative predictor of revenue stability highlights the importance of water resources availability and management in southern Mexico, where rainfed cultivation is especially sensitive to climatic variability [72,73], a finding also broadly consistent with the above studies. ...
Stabilizing farm revenues is a goal of agricultural policies around the world, especially in vulnerable regions with limited access to crop insurance. One potential pathway to revenue stability follows the agricultural “insurance hypothesis”, which holds that crop diversification has stabilizing effects on productivity that mitigate risks from environmental stressors and market shocks, thereby producing a form of natural insurance against crop loss. While substantial support for the hypothesis exists, most studies testing the hypothesis have occurred at the farm or landscape levels and have controlled for a limited range of socioeconomic and environmental factors. This study tests the insurance hypothesis by examining the effects of crop species production diversity on revenue stability in low-income regions of southern Mexico. Here, rural farms experience chronic vulnerability to climatic shocks and market forces. Using parametric and non-parametric approaches, three groups of models are used to examine the effects of socio-environmental factors and farm structural and functional characteristics on the crop diversity-revenue stability relationship. Additionally factored in the relationship are the effects of cropping portfolios: statistical groupings of different crop species (n = 304) that characterize distinct farming areas (1340 municipalities). Findings support the insurance hypothesis and underscore the importance of crop diversification in the region. However, findings also show that irrigation plays an even stronger role than crop diversification in stabilizing farm revenues. Furthermore, some crop portfolios negatively impact revenue stability, including some portfolios with high crop diversity. In sum, a better understanding of farm contexts—contributing factors and cropping portfolios—is key to designing policies that help stabilize farm revenues through crop diversification.
... The reduction of the yield parameters is well correlated with the increase of the abiotic variables ( Figure 6B). Our results are in concordance with [3,10,44,45], who stated that under climate change, the temperature is expected to increase, and maize production could be heavily and negatively impacted by climate change [46]. The negative impact of the related effects of climate change on maize in Mexico has been largely studied [20,[47][48][49][50]. Abiotic stresses have also been related to the effects of climate change in Mexico and will negatively affect maize germination, seedlings, growth and reproduction, and yield [49,51]. ...
Warmer temperatures predicted as a result of climate change will have an impact on milpa. An experiment was carried out with induced passive heat with the objective of simulating the increase in temperature on the physiological, morphological, and yield parameters of milpa from different climates of San Luis Potosí, Mexico. Two different environments, Open-top chambers (OTC) and control, and three milpas, from warm–dry, temperate, and hot and humid climates, were studied. A total of 12 experimental units of 13.13 m2 were used in the random design, with a factorial arrangement of 2 × 3 and two replications. Abiotic variables (minimum, maximum, and mean daily temperatures and accumulated heat units) were determined and compared between the two environments and confirmed that the OTC increased the abiotic variables. The growth and development parameters increased under the warming effect. Furthermore, the milpa from hot and humid climate was the least affected. In contrast, the warming considerably delayed yield parameters. The squash suffered the most, while the bean benefited the most. The warming affected the chlorophyll fluorescence and gas exchange differently for each crop. However, at an early stage, the maximum photochemical efficiency (Fv/Fm) and non-photochemical quenching (qN) for bean and maize were reduced, while at a late stage, they were Fv/Fm, photochemical quenching (qP), and qN for maize; stomatal conductance and transpiration rate of the squash were improved under the warming treatments. In conclusion, the warming delayed the yield and photosynthetic parameters, while growth and development benefited. The milpa systems were differently affected by warming.
... Climate change is a global challenge to food security; it is also problematic for sustainable food and nutritional security during the scarcity of resources (Murray-Tortarolo et al., 2018). For example, during extreme climatic events, the availability and accessibility of food get significantly affected, adversely impacting the local community's dietary habits (Guyot et al., 2006). ...
Climate change is the new normal of modern times, complicating the assurance of food security to the vulnerable peoples, especially the local communities with deep-rooted customary beliefs associated with the dietary habits of the Himalayan region. Nevertheless, the magnitude of the climate-induced impacts on traditional communities is not yet fully understood for evidence-based policy formation. Hence, this study aims (i) to analyze the perception of local people towards climate change, (ii) to investigate the perception of local communities toward traditional dietary habits, and (iii) to explore the changes observed in socio-cultural beliefs system due to dietary shift. A cross-sectional study was conducted with 75 in-depth qualitative interviews. The results of the grounded theory approach show that climate change has a localized meaning. Further, environmental change has significantly affected local food choices, which have an implication on the customary belief system attached to the local communities, irrespective of the socio-demography of the communities. The current study concludes that traditional knowledge is significant in addressing the issue of climate change. Therefore, the local society's socio-ecological beliefs must be integrated for effective food security and climate change adaptation strategies. ARTICLE HISTORY
... In our study, the highest net income was generated from the sale of the understory crops: squash and husk tomato (Table 3). However, the maize crop is the cornerstone of agriculture and food in the central region of Mexico (Murray-Tortarolo et al., 2018). For this reason, another form of analysing the potential of polyculture was through calculating the maize equivalent yield (MEY) and the real food security index (RFSI) ( Table 3). ...
The historical milpa has contributed to food security of small farmer families due to its biodiversity. The objective was to evaluate indicators of food access [basic food baskets (BFB), minimum wages (MW) and real food security index (RFSI)], Land Equivalent Ratio (LER), and maximum net income (NI) obtained from the polyculture of native maize-husk tomato-squash in two farm plots in the State of Mexico. The experiment was set up in San Pedro del Rosal (SPR) and San Juan Coajomulco (SJC), irrigated and rainfed, respectively, in the spring-summer cycle 2020. An experimental design in divided plots was used to evaluate two topological patterns: two rows of maize intercalated with one row of tomato and one of squash (MMTS) and one row of maize intercropped with one of husk tomato, one of maize and one of squash (MTMS). Five levels of fertilization with nitrogen, phosphorus and manure were tested. LER was evaluated with the yields of the three species in MMTS, MTMS and in monocropping at the same levels of inputs. BFB, MW, and RFSI were estimated using the regression equation that resulted in the maximum NI. In the two localities, the intercalated crops had higher LER than the monocrops. Comparing the two topological intercropping patterns, the maximum NI was obtained with MTMS in SJC and SPR (MXN $ 113 686.30 and MXN $ 204 649.70 ha-1 y-1). With the NI of the MTMS pattern in SJC and SPR, seven and 14 people, respectively, can be provided with BFB for a year. The highest daily MW were obtained with MTMS. In terms of land equivalent ratio, the highest LER were obtained with the MMTS pattern in SJC (2.78) and SPR (1.64). In economic terms, the better topological pattern is MTMS, and in function of LER, MMTS was better.
... Tradeoffs as a result of adaptation responses appear in the form of maladaptation and limitations, which potentially increase risks in the adaptation of another sector or exacerbate vulnerabilities. In Africa, Asia, and Latin America, maladaptation associated with the FEW nexus has been reported in response to climate-induced droughts resulting in intensive cultivation of marginal lands for food (Afriyie et al., 2018;Hummel et al., 2018;Olivares et al., 2017;Singh et al., 2018), decreased yields from rainfed-dependent agriculture (Murray-Tortarolo et al., 2018;Singh et al., 2018), poor irrigation schemes (Ticehurst & Curtis, 2018), and risks to the loss of livelihoods (Bele et al., 2014;Kronik & Verner, 2010;Villamayor-Tomas & García-López, 2017). On the other hand, adaptation synergies include co-benefits or opportunities that aid risk reduction in other areas or even address multiple vulnerabilities at once. ...
Food-energy-water (FEW) systems are increasingly vulnerable to natural hazards and climate change risks, yet humans depend on these systems for their daily needs, wellbeing, and survival. We investigate how adaptations related to food, energy, and water vulnerabilities are occurring and what the global community can learn about the interactions across these adaptations. We conducted a global analysis of a dataset derived from scientific literature to present the first large scale assessment (n=1,204) of evidence-based FEW-related climate adaptations. We found that the most frequently reported adaptation to FEW vulnerabilities by continent occurred in Africa (n=495) and Asia (n=492). Adaptations targeting food security are more robustly documented than those relevant to water and energy security, suggesting a greater global demand to address food security. Determining statistically significant associations, we found a network of connections between variables characterizing FEW-related adaptations and showed interconnectedness between a variety of natural hazards, exposures, sectors, actors, cross-cutting topics and geographic locations. Connectivity was found between the vulnerabilities food security, water, community sustainability and response to sea-level rise across cities, settlements, & key infrastructure sectors. Additionally, generalized linear regression models revealed potential synergies and tradeoffs among FEW adaptations, such as a necessity to synergistically adapt systems to protect food and water security and tradeoffs when simultaneously addressing exposures to consumption & production versus poverty. Results from qualitative thematic coding showcased that adaptations documented as targeting multiple exposures are still limited in considering interconnectivity of systems or applying a nexus approach in their response. These results suggest that adopting a nexus approach to future FEW-related adaptations can have profound benefits in the management of scarce resources and with financial constraints.
... In Tamazulapam in 2017 or Teopoxco in 2019, the trees bore fruit in spring whereas the main crop failed in summer. Climate change is likely to increase the frequency of such growing seasons, especially in the south of Mexico maize yields are expected to decline under most climate change scenarios (Murray-Tortarolo et al., 2018;Ureta et al., 2020). Crop diversification would improve resilience of smallholder production under climate change and reduce the risk of overall crop failure (Donatti et al., 2019). ...
Maize ( Zea mays L.), the staple crop of Mexico, is often produced by smallholder farmers on sloping terrains. Historically, little agronomic research has been performed under the conditions of these farmers to support them in the sustainable intensification of their production systems. We set up trials at two locations in the state of Oaxaca to evaluate conservation agriculture and agroforestry in collaboration with local farmers. Crop diversification through crop rotations, multicropping, relay cropping or agroforestry increased system yields the most, by up to 1.4 t ha ⁻¹ in Teopoxco and 1.7 t ha ⁻¹ in Tamazulapam. Increased input use through increased fertilization or liming did not increase profitability enough to justify their use. Zero tillage and residue retention increased yields and reduced production costs. Conservation agriculture with agroforestry was a high-yielding, profitable system that also reduced farmers' risk by providing several harvests per year. The most profitable combinations of agroforestry and conservation agriculture could produce up to $4,854 USD ha ⁻¹ in Teopoxco and $2,143 USD ha ⁻¹ in Tamazulapam, while the control treatments in the same sites and years produced $175 USD ha ⁻¹ and $92 USD ha ⁻¹ respectively. In several years the main crop failed, while the trees were able to produce due to their different growing season compared to maize. Through adaptive investigation under farmers' conditions, sustainable intensification of traditional production system is possible with low-cost changes that are locally adapted and within farmers' possibilities.
... Between May and December, maize (Zea mays L.) is generally grown, and this may receive 1 or 2 furrow irrigations depending on the amount of rainfall in the particular growing season. Precipitation is projected to decrease under all climate change scenarios, which will increase the need for irrigation to maize production in the region (Murray-Tortarolo et al., 2018). There are several options for reducing water use in this barley-maize production system. ...
The Mexican Bajío region is the country's main barley ( Hordeum vulgare ) producing area. Barley is commonly produced during the dry autumn–winter season using furrow irrigation with ground water, following which rainfed maize ( Zea mays ) is grown in the spring–summer season using supplementary irrigation. Ground water levels in the region are steadily dropping, and the introduction of water-saving technologies in agriculture is urgently required. Drip irrigation can reduce water use but is costly. Conservation agriculture—the combination of minimal tillage, permanent soil cover and crop diversification—might reduce water use, but studies in irrigated systems are scarce. We compared water use and grain yield in tillage-based conventional agriculture and conservation agriculture, both with furrow irrigation and drip irrigation, in a 3-year (six growing seasons) barley-maize field experiment. Additionally, side-by-side demonstrations of conventional and conservation agriculture were installed simultaneously in farmers' fields and yields, water use and fuel use were recorded. In the field experiment, yields did not differ significantly between production systems, but irrigation water use was on average 17% lower in conservation agriculture than in conventional agriculture, ~36% lower with drip irrigation compared with furrow irrigation in conventional tillage, and 40% lower with drip irrigation and conservation agriculture combined compared with conventional agriculture with furrow irrigation. Water use reductions differed strongly between years, depending on weather. The water saving through conservation agriculture in farmers' fields was similar to the water saving in the controlled experiment with about 17%. Additionally, in farmer's fields conservation agriculture reduced greenhouse gas emissions by 192 kg CO 2 ha ⁻¹ and improved soil health. The implementation of conservation agriculture would be a cost-effective method to reduce water use in the barley-maize production system in the Mexican Bajío, while simultaneously reducing greenhouse gas emissions.
... From the group of conical landraces of maize from the highlands of central Mexico, characterized by conical or pyramidal ears, the "conical cobs'' landrace, with semi-floury grains of reddish to purple or black coloration, has been used by generations for the preparation of traditional dishes and production of pigments (Jiménez-Pérez et al. 2015;Mora-Rochin et al. 2016). Frequently the production of maize in Mexico is affected by biotic and abiotic factors, such as, annual precipitation, frosts, use of agrochemicals (poor nutrient soils), pests and pathogen microorganisms (Murray-Tortarolo et al. 2018). ...
Mexican maize landraces, produced for local consumption, are adapted to different environmental conditions, and their yield is affected by abiotic and biotic factors, including the use of agrochemicals. The search for sustainable alternatives to agrochemicals includes the study of the culturable microbial communities. In this study, the fungal communities associated with 2 Mexican maize landraces reddish and bluish "conical cobs" were found to be comprised of Ascomycota fungi, represented by 89 strains within 6 orders (Pleosporales, Hypocreales, Onygenales, Capnodiales, Helotiales, and Eurotiales) and 16 genera. Cellulases and metallophores production were the primary enzymatic products and plant growth-promoting activities were detected among the isolates. Penicillium, Didymella, and Fusarium strains had the most active enzymatic and plant growth promoting activities, however, Aspergillus sp. HES2-2.2, Talaromyces sp. RS1-7, and Penicillium sp. HFS3-3 showed antagonistic activity against the four phytopathogenic Fusarium strains Fusarium oxysporum, Fusarium sambucinum, Fusarium fujikuroi and Fusarium incarnatum-equiseti and also a high and diverse production of enzymatic and plant growth promoting activities; here we identified fungal strains as candidates to promote maize growth.
... Furthermore, studies have revealed that farmers in the neighbouring south Asian countries largely depend on monsoon rain for meeting their irrigation water requirements (Prasanna 2014;Bhatta and Aggarwal 2015). Apart from Asia (Singh et al. 2014;Lassa et al. 2015;Loo et al. 2015), farmers in sub-Saharan Africa (Shimeles et al. 2018) and Latin America (Prager et al. 2016;Murray-Tortarolo et al. 2018) are also quite dependent on monsoon rains for farming. It has been reported that farmers in the developing countries of South Asia and Latin America are particularly vulnerable to the impacts of climate change due to their heavy reliance on agriculture for livelihood (Jat et al. 2016). ...
Variability of rainfall pattern and its resulting issue of water shortage is a growing concern in Bhutan’s agricultural system. To assess the rainfall anomalies and the extent of farmers’ dependency on rainwater for farming, a semi-structured questionnaire survey was conducted in six districts of the country, covering low-, mid- and high-altitude agro-ecosystems. A point score analysis showed that most farmers (50% or more) depended on rainwater for farming activities. The extent of farmers’ dependency on rainfall across the districts was as high as 51%, except for Paro which had a lower dependency level of 10–20%. However, an overwhelming 40–80% of respondents had perception of decreased rain over the years, and the rainfall data for 20 years (1997–2017) showed a decreasing trend, reinforcing the survey findings. Moreover, up to 75% of respondents had perceptions of rain being untimely and unpredictable, including fewer incidences of short spells of high intensity or occasional prolonged periods of rains. The consequences of these issues were perceived to have caused (1) drying of water sources; (2) delay in planting; (3) erosion and infrastructure damage; and (4) work disruption. To overcome these issues, there is a need to overhaul Bhutan’s irrigation system, in terms of both infrastructure development and methods as aspired by farmers. The need of the hour for Bhutan is to reduce dependency on rains with state-of-the-art irrigation technologies to buffer against the changing patterns of rain and to improve farmers’ resilience to the impact of climate change.
... Maize production in the rainfed regions of the world is projected to decline by 33.3% under drought conditions . Based on the global climate change scenario, many researchers are working on to validate the crop model and find out the suitable land for maize production (Ramirez-Cabral et al. 2017;Murray-Tortarolo et al. 2018). On drought escape, manipulation of planting date is a low-cost solution to address this issue depending on the precipitation forecasting during the rainy season (Kucharik 2008;Moradi et al. 2013;Baum et al. 2020). ...
Drought has been identified as a major factor restricting maize productivity worldwide, especially in the rainfed areas. The objective of the present study was to investigate the physiological adaptation strategies and sugar-related gene expression levels in three maize (Zea mays L.) genotypes with different drought tolerance abilities (Suwan4452, drought tolerant as a positive check; S7328, drought susceptible as a negative check; Pac339, drought susceptible) at the seedling stage. Ten-day old seedlings of maize genotypes were subjected to (i) well-watered (WW) or control and (ii) water-deficit (WD) conditions. Leaf osmotic potential of cv. S7328 under WD was significantly decreased by 1.35–1.45 folds compared with cv. Pac339 under WW, whereas it was retained in cv. Suwan4452, which utilized total soluble sugars as the major osmolytes for maintaining leaf greenness, Fv/Fm, ΦPSII, and stomatal function (Pn, net photosynthetic rate; gs, stomatal conductance; and E, transpiration rate). Interestingly, sucrose degradation (65% over the control) in cv. Pac339 under WD was evident in relation to the downregulation of the ZmSPS1 level, whereas glucose enrichment (1.65 folds over the control) was observed in relation to the upregulation of ZmSPS1 and ZmSUS1. Moreover, CWSI (crop water stress index), calculated from leaf temperature of stressed plants, was negatively correlated with E, gs, and Pn. Overall, growth characteristics, aboveground and belowground parts, in the drought-susceptible cv. Pac339 and cv. S7328, were significantly decreased (> 25% over the control), whereas these parameters in the drought-tolerant cv. Suwan4452 were unaffected. The study validates the use of leaf temperature, CWSI, Pn, gs, and E as sensitive parameters and overall growth characters as effective indices for drought tolerance screening in maize genotypes at the seedling stage. However, further experiments are required to validate the results observed in this study under field conditions.
... Therefore, farmers need to manage upland rice production for both food and different living needs. With rainfed land, agriculture is heavily dependent on rainfall forecasts and runoff [19]. ...
The land is an important factor for people whose lives depend on the agricultural sector. The need for land for various uses has resulted in decreasing agricultural land which could have implications for decreasing food production. Alternative options which are expected to increase the potential for food production are the utilization of marginal land. Farmers with marginal land need to manage their production to meet household needs. So it is important to examine the marketable surplus, the level of commercialization, and the carrying capacity of marginal land. The research area was taken by purposive sampling method in Gunungkidul Yogyakarta. The samples taken were upland rice farmer households with the simple random sampling method. The marketable surplus analysis uses a marketable surplus formula, then the percentage is used to determine the level of farm commercialization. The carrying capacity analysis is carried out using the carrying capacity formula. The results showed that farmer households manage rice production by allocating an average of 59.1% for marketed and 40.9% for household consumption. The allocation of marketable surplus is greater than for household consumption, this shows that gogo rice farming households are towards commercially. The marginal land carrying capacity of 0.641 indicates that the land cannot be developed in an expansive and exploratory manner. The implication is in increasing upland rice production on marginal land, namely by an intensification of farming.
... These physiological traits make these plants particularly vulnerable to suffer significant physiological and structural damages, and even plant mortality, under increasing temperatures and hydric stress [88]. In addition, the Mexical vegetation is highly sensitive to long drought episodes, which are expected to increase in duration and intensity, as documented in Mexico in the last two decades [89][90][91]. This vulnerability becomes especially relevant where the Mexical occupies the top of the mountains, unable to shift its distributional range upwards tracking more favorable conditions. ...
‘Mexical’ scrubland is a sclerophyllous evergreen Mediterranean-like vegetation occurring in the leeward slopes of the main Mexican mountain ranges, under tropical climate. This biome occupies an elevational range approximately from 1900 to 2600 meters above sea level, which frequently is the upper-most part of the mountains range. This puts it at risk of extinction in a scenario of global warming in which an upward retraction of this type of vegetation is expected. The Mexical remains one of the least studied ecosystems in Mexico. For instance, nothing is known about pollinator fauna of this vegetation. Our main objective is to make a first insight into the taxonomic identity of the bee fauna that inhabits this biome, and to study how it is distributed along the elevational gradient that it occupies. Our results highlight that elevation gradient negatively affects bee species richness and that this relationship is strongly mediated by temperature. Bee abundance had no significant pattern along elevational gradient, but shows a significant relationship with flower density. Interestingly, and contrary to previous works, we obtained a different pattern for bee richness and bee abundance. Bee community composition changed strongly along elevation gradient, mainly in relation to temperature and flower density. In a global warming scenario, as temperatures increases, species with cold preferences, occupying the highest part of the elevation gradient, are likely to suffer negative consequences (even extinction risk), if they are not flexible enough to adjust their physiology and/or some life-story traits to warmer conditions. Species occupying mid and lower elevations are likely to extend their range of elevational distribution towards higher ranges. This will foreseeably cause a new composition of species and a new scenario of interactions, the adjustment of which still leaves many unknowns to solve.
... In recent studies, Ray et al. (2019) and Gomez-Zavaglia et al. (2020) have stated that agriculture production is highly sensitive to climate change. Some other research studies have also arrived at the conclusion that climate change affects food production negatively (Fanzo et al. 2018;Murray-Tortarolo et al. 2018;Arora 2019;Aryal et al. 2019;Kehrberger and Holzschuh 2019). ...
Food production as global public goods depends upon many factors. This poses a risk to food safety as well as food prices. One of the most prominent factors that affects food production is climate change, which is mainly caused by carbon emissions. The knowledge of the impact of climate change on food production is important in terms of food policies and awareness regarding the issue. The purpose of this study was to empirically investigate the way in which climate change impacts edible food production in 12 selected countries as they had the highest carbon emissions during the 1995–2014 period. Unlike previous studies in the literature, we employ a food production index as an indicator of food production that does not include products such as coffee and tea, which are not nutritious. Further, we investigate the effects of climate change both statically and dynamically. We also do not focus on any specific country or food, as done by many studies in the literature. The results revealed that climate change adversely affects food production, with the production of edible food decreasing with the increase of climate change/carbon emissions.
... Future climate projections predict a general decrease in precipitation across Mexico (Colorado-Ruiz et al. 2018), which could lead to new migratory peaks over the XXI century (Feng et al. 2010). Drought is expected to increase in intensity and recurrence, which could potentially impact crop yields and livestock populations (Murray-Tortarolo et al. 2018;Murray-Tortarolo and Jaramillo 2019), impoverishing the livelihood of many rural farmers across the country. Particularly, attention should be given to low-income farmers, to create a farming system capable of maintaining-or increasing-their living conditions while dealing with drought. ...
Emigration from Mexico to the USA represents one of the largest current socioeconomic phenomena in the world. Climate, and particularly drought, has been identified as a key driver of peak migratory flows between the two nations. However, current existing studies are constrained by a reduced spatial scale (e.g., a single community or municipality) or a short time-window (e.g. <10 years), which limits our long-term nationwide understanding of the climate-migration relationship. To tackle this, we employed high-resolution (municipal-level) and long-term databases (1970–2009), which included nation-level interviews, border patrol apprehensions, and high-resolution precipitation. Our results showed that the decadal and maximum migratory fluxes in these four decades corresponded to years with low precipitation. In particular, the migration of low-income rural farmers tripled during drought, representing as much as a third of all historical migration. It is very likely that rural people were pushed to leave their lands as the result of strongly diminished rainfed agriculture and pastureland production, their main livelihood. Our results suggest that policy oriented to reduce the negative impacts of drought (such as livestock drought insurances and the provisioning of drought-resistant seeds), particularly to marginal farmers in arid ecosystems, could be an effective way to reduce current and future migratory peaks between Mexico and the USA.
Graphical abstract
... Not surprisingly, according to Appendini and Liverman [89] about 90% of total agricultural losses in the country are related to drought. The sensitivity of crop production to drought in Mexico has been further corroborated by a series of studies that found that rainfall variability is strongly correlated with aggregate production of maize-the most important crop of the country in terms of production and the staple of most rural and urban diets (see [90,91] for national scales, [92] for Oaxaca, and [93] for central Mexico). Although agriculture admittedly accounts for less than five percent of Mexico's Gross National Product, its high susceptibility to drought is a matter of social and political concern since it employs almost a fifth of the national workforce [6,94]. ...
Drought is one of the most disruptive climatic extremes in Mexico. The country is particularly exposed to this phenomenon given its location in the tropics and subtropics. Furthermore, much of the population is highly vulnerable to drought effects. Enhancing drought preparedness in Mexico demands a holistic understanding of this climatic extreme. Here we review the causes, impacts, responses to, and future trends of drought in the country. Our work synthesizes both physical and social perspectives, focusing primarily on climatological and geographical research. Three overarching messages emerge from the existing knowledge: (1) drought has been a recurrent event in Mexico and is predicted to become more severe in coming decades as a consequence of global warming; (2) pervasive socioeconomic inequality in the country has produced a stark differentiation in drought impacts, with the smallholder sector being one of the most affected; and (3) the institutional framework focused on mitigating drought impacts remains highly fragmented and overall prioritizes alleviating rather than preventing disasters. Based on the review, we propose a set of general guidelines to steer public policy towards a more integrated management of drought risk, in which enhancing local adaptive capacities is considered essential.
... The negative associations of temperature (<0.0001) and the slope of the terrain (0.045), as well as the positive association of precipitation (0.001), indicate that lower rainfall, high temperatures, and steep slopes constrain the area planted with maize. Given that under climate change temperature is expected to increase and precipitation to become more erratic, though not necessarily decrease, this indicates that maize production in Mexico could be heavily and negatively impacted by climate change (Murray-Tortarolo et al. 2018;Ureta et al. 2011Ureta et al. , 2020). The capacity of campesinos to adapt to these changes in temperature and precipitation will depend to a great extent on the genetic diversity present in their native varieties and their response to these new conditions (Bellon and van Etten 2014;Mercer and Perales 2010). ...
Mexico is the center of domestication and a center for diversity of maize. Area planted with maize is the country’s largest agricultural land use, mostly planted by smallholder family farmers known as campesinos. They generally plant native varieties, saving and sharing seed by and among themselves, enabling the evolutionary processes that sustain and generate crop genetic diversity to continue today. Campesinos have been viewed as largely subsistence farmers generating limited maize surpluses. Here, we show that subsistence production is insufficient for explaining the quantity of maize they produce and the extent of the area they plant across Mexico. Our hypothesis is that beyond supplying their own consumption needs, campesinos collectively produce maize to respond to the demand of non-maize producing local consumers. We quantify the extent of subsistence versus surplus production among campesinos, showing that they produce more maize than would be needed to feed themselves and generate substantial surpluses. We test statistically the association between the area campesinos plant with maize across the country with socioeconomic variables that link their production to the demand by other consumers, and examine the implications of the results for the supply and conservation of native maize in the country. Our results suggest that maize trading linking campesinos to other consumers may be important and widespread, contributing to create additional incentives beyond self-consumption to plant native varieties from saved seed. We conclude that there are important opportunities for maintaining maize evolution under domestication at large scale by strengthening local maize markets.
... In Mexico, given the high diversity of landraces, many maizes are grown close to their optimum environments. Climate change scenarios anticipate important changes in temperatures and precipitation throughout the country, especially for central Mexico, where the maizes considered in the present study were obtained (Diffenbaugh et al. 2015; de la Barrera and Orozco-Mart ınez 2016; Zhao et al. 2017;Murray-Tortarolo et al. 2018). This is an important threat for the conservation of such unique landraces adapted to specific conditions (Tollenaar et al. 1979). ...
Maize is one of the most important crops in the world, particularly in Mexico where it was domesticated and is central to traditional cultures. The fall armyworm (Spodoptera frugiperda [J.E. Smith]), is a major pest that can greatly reduce production of this crop. Climate change also threatens maize production, as projections estimate an increase of fall armyworm outbreaks. For these reasons, (1) we assessed the changes in the S. frugiperda life cycle along a temperature gradient ranging from 23 °C to 31 °C, and (2) assessed the development of larvae feeding on two Mexican landraces and the responses of each landrace to herbivory under current and predicted climatic conditions; both assessments were conducted under laboratory conditions. Development was faster and each life cycle stage was shorter at higher temperatures. The effect of herbivory differed between the landraces; herbivory was more harmful for White Ranchero than for Yellow. As warmer and drier conditions are expected during this century, sowing appropriate maize landraces that can cope with herbivores under climate change could mitigate potential economic losses.
... In terms of water availability, worldwide climate change generates alterations of global hydrological patterns (Murray-Tortaloro et al. 2018), modifying rainfall amounts, river discharges, drought frequency, and intensity and increasing the dry season length. Hence, Mutiibwa et al. (2018) described that warming air temperature, water availability, and elevated CO 2 emissions are negative projections in current and future yields in agriculture and cattle. ...
Global warming has produced negative effects in all life aspects around the world. Particularly, in terms of agriculture, the rainfall variability causes lower water availability, having unfavorable yield effects in all the crops. Temperature increases and rainfall reduction have resulting decreases in agricultural production and infertility. These issues, combined with the constant population growth, predict a severe food security problem for the next decades. In recent years, natural disasters are more frequent and dangerous as the result of global warming. Droughts, freezing, and flooding are the problems with the highest impact on the food supply chain, particularly in low-income communities, increasing the lack of access to food and undernourished problems, resulting in human casualties. This paper presents a response analysis of the food supply chain network in 14 municipalities of the state of Michoacán in Mexico; these municipalities are the ones with the lowest human development index values, joined to malnutrition problems. Natural disasters such as freezing, flood, and drought were considered and used to measure their impact on the food network through a mathematic optimization model, obtaining food system behavior to these difficulties. In the addressed case study, as a consequence of natural disasters, the total cost of the food network increases fifteen times to obtain a resilient system. The proposed approach is general, and this can be applied to other cases.
... Over extraction of groundwater, which comprises about one-third of all irrigation water, and low irrigation use efficiency is a widespread problem (Sun et al., 2016). Still, while access to irrigation expanded in some areas during the last decade of the twentieth century (Eakin, 2003), most Mexican smallholders lack access to irrigation and depend exclusively on precipitation-based, rainfed systems (Cohen et al., 2014;Murray-Tortarolo et al., 2018;Spring, 2011). At the same time, larger farms in Mexico's extensive northern irrigation districts frequently receive water from both surface and subterranean sources (Lobell et al., 2005;Wilder, 2010). ...
Farmland size is a key factor in debates over agricultural land use, food security, agrochemical pollution, and the future of smallholder systems. This paper examines relationships between farmland size, chemical fertilizers and irrigation management, and maize and wheat yield in Mexico. We used agricultural census data to estimate the mean farmland areas and crop yields of 5.5 million farms and nine million agricultural plots in 2,455 Mexican municipalities. We also derived indices of socio-environmental and management factors to examine relationships with yield. Using multiple regression models, we found that although mean farmland area positively relates to maize and wheat yield, the relationships depend critically on the management contexts of chemical fertilizers and irrigation, which vary widely across farm size gradients. Smallholder yield gaps were associated with deficits in irrigation, rather than chemical inputs. Findings highlight the growing need for expanded irrigation access and/or water management assistance for smaller farms.
... 400). CC will reduce the yields and productions of the main staple crops such as rice (Akinbile et al., 2015;van Oort & Zwart, 2018), wheat (Trnka et al., 2019) and maize (Davenport et al., 2018;Freduah et al., 2019;Murray-Tortarolo et al., 2018;Waha et al., 2013), CC is also predicted to affect livestock productivity (Godber & Wall, 2014;Mare et al., 2018;Naah & Braun, 2019). Ramasamy (2010) put that "Rising temperatures, more intense droughts, floods, and greater weather variability all mean productivity losses to crops and livestock" (p. ...
Climate change is one of the most pressing challenges facing humanity in the Anthropocene era. It is widely admitted that climate change will have far-reaching impacts including on food security. Therefore, this review paper analyses the multifaceted relations between climate change and food security. In particular, the paper explores the impacts of climate change on the four dimensions of food security (i.e. food availability, food access, food utilization, stability). It draws upon a review of scholarly literature indexed in the Web of Science. The analysis of the literature shows that there is a dual relationship between climate change and food security; on the one hand, climate change affects all the dimensions of food security and, on the other hand, the quest for food security has implications in terms of climate change. As for food availability and supply, climate change is widely believed to reduce crop yields and livestock productivity especially in the countries of the Global South. Effects on food production and availability as well as the impacts of extreme climate events affect both food physical and economic accessibility. The changes in production systems induced by climate change may induce changes in dietary patterns and food utilization. Climate change will also affect the stability and resilience of food systems with consequences in terms of long-term food security. Moreover, the quest for food security, through agricultural intensification and agricultural land expansion, increases greenhouse gas emissions from deforestation and land use changes. The intricate relation between climate change and food security makes the case for integrated policies that maximise co-benefits while addressing trade-offs. That is fundamental to make sure that ‘climate action’ will not jeopardize the achievement of ‘zero hunger’ and vice-versa.
... The current literature provides some evidence on the potential impacts that climate change and extreme weather events can have for human populations in Mexico. Climate change has the potential to reduce agricultural production (Conde et al. 2006;Guerrero 2013;Murray-Tortarolo et al. 2018) and land values (Mendelsohn et al. 2010). It could also reduce local employment, increase migration from rural areas (Jessoe et al. 2017), and negatively affect human health (Guerrero 2013). ...
Climate change could increase the frequency and duration of droughts that affect Mexico. This is particularly worrisome because many agricultural communities in the country are poor and with limited capacities for adaptation. This study estimated the impact of droughts on rural households’ wellbeing in Mexico, specifically on per capita earnings, poverty, and children’s school attendance. To do this, we focused our empirical analysis on the effects of the 2011 drought, one of the worst droughts that have affected Mexico in the past 70 years. Our results provide clear evidence that droughts have a negative impact on rural households’ wellbeing. Households that experienced a drought had lower per capita earnings and were almost 5 percentage points more likely to be poor after the drought than their counterparts. Furthermore, droughts reduced female employment and male school attendance in almost three percentage points. Our results also provide indirect evidence showing that households that are less familiar with relative water scarcity are the ones that are hit hardest during droughts. Droughts are poised to become an additional threat to the wellbeing of rural Mexican households.
... Our findings on the negative impact of climate change (assessed based on the dynamics of the representative CWB index and of its constituting parameters P and ETo) on agricultural systems (maize crops) in Romania are consistent with international studies that confirm, either directly or indirectly, the vulnerability of numerous major agricultural crops to climate change across the globe. Thus, there are various specialized studies that addressed the negative impact of climate change (assessed based on a wide series of climatic parameters and indices) on maize agrosystems in various countries around the world, such as Argentina (Verón et al., 2015), Mexico (Murray-Tortarolo et al., 2018), United States (Basche et al., 2016), South Africa (Adisa et al., 2018, Iran (Karandish et al., 2017), India (Tesfaye et al., 2017) or China . In Europe, the impact of climate trends on agriculture indicated, over the past decades, a large heterogeneity across the countries of the continent, with yields reduction (maize and other major crops) in the Mediterranean area and increased yields in northern areas (Moore and Lobell, 2015). ...
... In spite of the contribution to the environment, this way of farming has the disadvantage of being completely dependent on consistent rainfall, temperate weather, and predictable season cycles (Henderson, 2019). For this reason, since 1981 (the first report of CLR), coffee growers along with the government have been working together with the aim to adapt arabica cultivars (Murray-Tortarolo et al., 2018); however, it is becoming increasingly difficult since the optimal germination temperature of HV is above 24°C and the optimal cultivation temperature of Coffee arabica ranges between 18 and 21°C. This rapid adaptability has made useless the efforts to control the epidemic and production losses of at least 30% are becoming more frequent (Medina-Meléndez et al., 2016). ...
Coffee is one of the most important commercial traded commodities in the international market, as well as the most popular beverage around the world. In Mexico, organic coffee cultivation (specifically, Arabica coffee crops) is a highly demanded that generates up to 500,000 employments in 14 federal entities. Among various coffee producers, Chiapas, Veracruz, and Oaxaca are responsible of 80% of the total coffee production in the country. Currently, Mexico is the leading producer of organic coffee in the world. However, there have been a slow recovery due to the large production losses since 2012, caused by earlier and highly aggressive outbreaks of coffee leaf rust (CLR), in the country, where the infectious agent is known as Hemileia vastatrix (HV). This phenomenon is becoming frequent, and climate change effects could be the main contributors. This spontaneous proliferation was generated in Mexico, due to the precipitation and temperature variability, during the last decade. As result, in Mexico, the biological interaction between coffee crops and their environment has been harmed and crucial characteristics, as crop yield and quality, are particularly being affected, directly by the negative effects of the greenhouse phenomenon, and indirectly, through diseases as CLR. Therefore, this review discusses the contribution of climate change effects in the early development of CLR in Mexico. The focus is also given on possible schemes and actions taken around the world as control measures to adapt the vulnerable coffee varieties to tackle this challenging issue.
Maize is a highly important crop, not only because it is a staple crop for humans but also because it is a major source of feed for animals and has immense industrial potential. Existence of vast genetic diversity in maize germplasm makes it an ideal model plant for plant genetic studies. This diversity could play a vital role in maize breeding programmes aimed to enhance its agronomic performance under changing climate. Genome-wide association study takes advantage of such genetic diversity to reveal the genetics underlying a complex phenotypic trait. With the emergence of next-generation sequencing (NGS) and high-throughput phenotyping techniques, the significance of GWAS has been increased. In the last decade, a huge number of GWA studies have been performed in different crops for different phenotypic traits. Extensive natural variations, rapid linkage disequilibrium (LD) decay, wide climatic adaptability and availability of reference genome make maize an ideal crop for GWAS. GWAS in maize identified thousands of genomic regions associated with various phenotypic traits. In general, agronomic traits are polygenic and get affected by different types of stresses, which result in reduced yield and quality. Efforts have been made to improve agronomic traits in maize using traditional breeding and marker-assisted selection breeding. However, due to the low resolution of trait mapping, limited success has been achieved. In this chapter, we discuss how GWAS could take advantage of natural diversity and can play a chief role in improving the agronomic traits in maize. We also shed a light on the importance of functional validation of genes that are found to be associated with a specific trait using GWAS.
Food security can be under threat due to climate change, which has the potential to alter crop yield. Wheat, maize, and rice are major crops contributing to global food security. The impact of climate change on crop yield with different models and techniques has been projected; this reviewed the worldwide impact of climate change on future wheat, rice, and maize production. Wheat and maize crop yields may increase due to climate change in colder regions and may decrease in the countries near the equator. The increase in carbon dioxide concentration in the atmosphere may help wheat and maize crops regarding increased carbon intake in colder regions. The rice crop yield may decrease in almost all major rice-producing countries due to water scarcity, which can be amplified due to climate change. The impact of climate change on crop yield prediction involves uncertainties due to different crop models, global circulation models, and bias correction techniques. It is recommended to use multiple climatic models and more than one bias correction technique for better climatic projections. Adaptation measures could help to reduce the adverse impacts of future climate on agriculture. Shifting the planting calendar, irrigation and nutrient management, improving crop varieties, and expanding the agricultural areas are suggested as the most effective adaptation actions in response to climate change. The findings of this study may help policymakers to achieve Sustainable Development Goal (SDG) 2 (Zero Hunger) and SDG 13 (Climate Action).
En este artículo se expone cómo a pesar de que la ciencia
y la tecnología han permitido aumentar históricamente
la productividad agrícola, hoy día existen grandes retos
derivados del cambio climático y la crisis global de
abastecimiento de agua. Se comentan algunas medidas
de adaptación y manejo del recurso agua, con algunas
referencias a nuestra realidad nacional, y se argumenta
cómo el enfoque de Nexo, que implica la toma de decisiones
sobre el uso del recurso agua de forma transectorial,
representa una alternativa de adaptación al cambio
climático.
Climate change and its impact on agriculture productivity vary among crops and regions. The southeastern United States (SE-US) is agro-ecologically diversified, economically dependent on agriculture, and mostly overlooked by agroclimatic researchers. The objective of this study was to compute the effect of climatic variables; daily maximum temperature (Tmax), daily minimum temperature (Tmin), and rainfall on the yield of major cereal crops i.e., corn (Zea mays L.), rice (Oryza sativa L.), and wheat (Triticum aestivum L.) in SE-US. A fixed-effect model (panel data approach) was used by applying the production function on panel data from 1980 to 2020 from 11 SE-US states. An asymmetrical warming pattern was observed, where nocturnal warming was 105.90%, 106.30%, and 32.14%, higher than the diurnal warming during corn, rice, and wheat growing seasons, respectively. Additionally, a shift in rainfall was noticed ranging from 19.2 to 37.2 mm over different growing seasons. Rainfall significantly reduced wheat yield, while, it had no effect on corn and rice yields. The Tmax and Tmin had no significant effect on wheat yield. A 1 °C rise in Tmax significantly decreased corn (− 34%) and rice (− 8.30%) yield which was offset by a 1 °C increase in Tmin increasing corn (47%) and rice (22.40%) yield. Conclusively, overall temperature change of 1 °C in the SE-US significantly improved corn yield by 13%, rice yield by 14.10%, and had no effect on wheat yield.
In recent years, the impacts of climate change and socio-economic development on the water-energy-food nexus have been a hot topic. Forecasting future food and energy production and water withdrawal trends under a range of climate and socio-economic scenarios is a critical step for formulating agricultural, industrial, and environmental policy. However, published studies are imprecise due to the complexity of the changeable environment and nexus system. Here we conducted a systematic review and meta-analysis based on 97 studies (1253 observations) published before September 2021 to evaluate the effects of climate change factors on food yield and irrigation water, as well as the influence of socioeconomic development on energy production and water withdrawal. The study shows that the most serious impact of climate change on food yield occurred under the RCP8.5 scenario, with an average decrease of 1.73%, 4.17% and 4.56% in the 2020s, 2050s, and 2080s, respectively. Similar to the prediction of food yield, the irrigation water requirement of food production under the influence of climate change in the RCP8.5 scenario (12.22–18.01%) is higher than that in RCP4.5 and RCP2.6. Under the five socio-economic future scenarios, the average energy generation is projected to increase from 77.41 EJ (2010) to 334.11 EJ (2100). Water withdrawals for electricity generation range from 347 km³ (SSP1) to 1263 km³ (SSP5). Population and GDP were significantly and positively correlated with power generation and water withdrawal (P < 0.001). To some extent, increases in CO2 concentration and precipitation could compensate for the negative impact of rising temperatures on food yield. Climate change, as well as economic and social growth, will provide substantial challenges to the future water-energy-food nexus. In particular, the water resource risk at its core will create significant uncertainty in the future water-energy-food nexus. To ensure the security and stability of the nexus, we advocate for quick adoption of innovative technologies as well as a multi-sectoral, coordinated strategy for adaptation. We believe that the findings of this paper will provide effective and reliable data support for future policy formulation.
El estudio del impacto de la sequía en pequeñas comunidades rurales de México (Resumen) La sequía afecta severamente a sociedades campesinas, dedicadas a la agricultura de temporal o pequeña ganadería, en países intertropicales, de economías emergentes. En comparación con otros fenómenos extremos de índole climática, tales como las inundaciones, la sequía es difícil de definir y precisar en cuanto a su ocurrencia en el tiempo y el espacio. Pero la disminución o falta de precipitación impactan de manera decisiva en los calendarios agrícolas de temporal y representan una amenaza a la seguridad alimentaria de familias campesinas. La investigación y las revisiones bibliográficas sobre la sequía han sido numerosas, tanto a nivel disciplinario o interdisciplinario. El tema del impacto de la sequía en pequeñas comunidades campesinas, en cambio, ha recibido menor atención. En este trabajo presentamos una revisión sobre el impacto de la sequía en, y la respuesta de, pequeñas comunidades campesinas en México. Consideramos que existe un acervo de teoría y de experiencias documentadas que demuestran que las comunidades campesinas en México, han tenido, históricamente, una gran capacidad de manejo de las crisis sociales derivadas de los impactos de la variabilidad climática en general y de la sequía en particular. Sugerimos que la investigación sobre estos temas, de manera participativa y a partir del conocimiento ambiental tradicional, es una alternativa importante en el aporte científico para la gestión del riesgo a nivel local.
Objectives
Human responses to climate variation have a rich anthropological history. However, much less is known about how people living in small‐scale societies perceive climate change, and what climate data are useful in predicting food production at a scale that affects daily lives.
Methods
We use longitudinal ethnographic interviews and economic data to first ask what aspects of climate variation affect the agricultural cycle and food production for Yucatec Maya farmers. Sixty years of high‐resolution meteorological data and harvest assessments are then used to detect the scale at which climate data predict good and bad crop yields, and to analyze long‐term changes in climate variables critical to food production.
Results
We find that (a) only local, daily precipitation closely fits the climate pattern described by farmers. Other temporal (annual and monthly) scales miss key information about what farmers find important to successful harvests; (b) at both community‐ and municipal‐levels, heavy late‐season rains associated with tropical storms have the greatest negative impact on crop yields; and (c) in contrast to long‐term patterns from regional and state data, local measures show an increase in rainfall during the late growing season, indicating that fine‐grained data are needed to make accurate inferences about climate trends.
Conclusion
Our findings highlight the importance to define climate variables at scales appropriate to human behavior. Course‐grained annual, monthly, national, and state‐level data tell us little about climate attributes pertinent to farmers and food production. However, high‐resolution daily, local precipitation data do capture how climate variation shapes food production.
Food security and economic welfare strongly depend on agricultural production, and the loss of this production can be a serious challenge for food security and economic welfare. Agricultural production is also influenced by environmental and climatic factors so that the variations of climatic parameters can trigger extensive fluctuations in agricultural production. This study classifies climate changes into four scenarios of normal climate change (scenario 1), climate change (scenario 2), climate variability (scenario 3), and concurrent climate change (scenario 4). Then, economic welfare and food security are studied in each scenario for a 20-year period. We use data on costs and production of three crops-barley, potato, and maize-as three major agronomic plants that influence food security of Iran and the technique of positive mathematical programming. The results reveal the severe loss of acreage, farmer income, and producer and consumer welfare surplus and the increase in crop prices under four scenarios. In all calculation sections, scenarios 4, 2, 3 and 1 had the greatest impact on the studied variables, respectively. In scenarios 1 to 4, average acreage is 372.76, 270.3, 374 and 270 thousand ha and farmers' net revenue is 24238.85, 19156.21, 24304.26 and 19143.11 billion IRR, respectively. The average price of the three studied crops under the four scenarios is 99.7, 125.65, 99.54 and 125.76 billion IRR, respectively. Also, in these scenarios, consumer welfare surplus will be 12286.8, 12072.91, 12277.87 and 12070.19 billion IRR and producer welfare surplus will be 13972.3, 13652.6, 13960.5 and 13648.8 billion IRR, respectively. Changing cropping pattern, using modern irrigation methods, supporting farmers by the government, desert greening, and curbing the emission of greenhouse gases are some practices that can alleviate the consequences of climate change for food security and economic welfare.
One consequence of climate change is the alteration of global water fluxes, both in amount and seasonality. As a result, the seasonal difference between dry- (p < 100 mm/month) and wet-season (p > 100 mm/month) precipitation (p) has increased over land during recent decades (1980–2005). However, our analysis expanding to a 60-year period (1950–2009) showed the opposite trend. This is, dry-season precipitation increased steadily, while wet-season precipitation remained constant, leading to reduced seasonality at a global scale. The decrease in seasonality was not due to a change in dry-season length, but in precipitation rate; thus, the dry season is on average becoming wetter without changes in length. Regionally, wet- and dry-season precipitations are of opposite sign, causing a decrease in the seasonal variation of the precipitation over 62% of the terrestrial ecosystems. Furthermore, we found a high correlation (r = 0.62) between the change in dry-season precipitation and the trend in modelled net primary productivity (NPP), which is explained based on different ecological mechanisms. This trend is not found with wet-season precipitation (r = 0.04), These results build on the argument that seasonal water availability has changed over the course of the last six decades and that the dry-season precipitation is a key driver of vegetation productivity at the global scale.
The effects of climate change on crop and terrestrial food production are evident in several regions of the world (high confidence). Negative impacts of climate trends have been more common than positive ones. {Figures 7-2, 7-7} Positive trends are evident in some highlatitude regions (high confidence). Since AR4, there have been several periods of rapid food and cereal price increases following climate extremes in key producing regions, indicating a sensitivity of current markets to climate extremes, among other factors. {Figure 7-3, Table 18-3} Several of these climate extremes were made more likely as the result of anthropogenic emissions (medium confidence). {Table 18-3}.
We modeled the carbon (C) cycle in Mexico with a process-based approach. We
used different available products (satellite data, field measurements,
models and flux towers) to estimate C stocks and fluxes in the country at
three different time frames: present (defined as the period 2000–2005), the
past century (1901–2000) and the remainder of this century (2010–2100). Our
estimate of the gross primary productivity (GPP) for the country was 2137 ± 1023 TgC yr−1 and a total C stock of 34 506 ± 7483 TgC,
with 20 347 ± 4622 TgC in vegetation and 14 159 ± 3861 in the
soil.Contrary to other current estimates for recent decades, our results showed
that Mexico was a C sink over the period 1990–2009 (+31 TgC yr−1) and
that C accumulation over the last century amounted to 1210 ± 1040 TgC.
We attributed this sink to the CO2 fertilization effect on GPP, which
led to an increase of 3408 ± 1060 TgC, while both climate and land use
reduced the country C stocks by −458 ± 1001 and −1740 ± 878 TgC,
respectively. Under different future scenarios, the C sink will likely
continue over the 21st century, with decreasing C uptake as the climate
forcing becomes more extreme. Our work provides valuable insights on
relevant driving processes of the C cycle such as the role of drought in
drylands (e.g., grasslands and shrublands) and the impact of climate change
on the mean residence time of soil C in tropical ecosystems.
We analyze the impacts of changing dry season length and intensity on vegetation productivity and biomass.. Our results show a wetness asymmetry in dry ecosystems, with dry seasons becoming drier and wet seasons wetter, likely caused by climate change. The increasingly intense dry seasons were consistently correlated with a decreasing trend in NPP and biomass from different products and could potentially mean a reduction of 10-13% in NPP by 2100. We found that annual NPP in dry ecosystems is particularly sensitive to the intensity of the dry season, whereas an increase in precipitation during the wet season has a smaller effect. We conclude that changes in water availability over the dry season affect vegetation throughout the whole year, driving changes in regional NPP. Moreover, these results suggest that usage of seasonal water fluxes is necessary to improve our understanding of the link between water availability and the land carbon cycle.
This study explores the temporal and spatial variability and change in rainfall across southeastern Mexico and the mechanisms by which smallholder farmers adapt to this variability, especially droughts. Members of 150 households in 10 communities were interviewed to investigate adaptation strategies among swidden maize smallholders, linked to their perceptions of climate changes. Precipitation data from seven weather stations were analyzed for the 1973–2012 period. Precipitation anomalies were estimated to evaluate the annual and seasonal stability, deficit, or surplus; and linear regressions were used to evaluate trends. Then, these anomalies were linked to variation in reported agricultural practices. Weather station data show a considerable decline in precipitation in most of the study area, coupled with increased drought frequency and an increase in negative anomalies in recent years. Surveys revealed several mechanisms of adaptation, including adjustment of the agricultural calendar (e.g. delaying planting, combined with planting a greater number of varieties of maize), water storage, and livelihood diversification both within and outside of agriculture. These adaptive mechanisms are responsive to demonstrated climatic change over the past 40 years, though globalization affects Mexico's agrarian economy, and farmers likely respond to a combination of economic and climatic factors. Understanding how resource- and climate-dependent swidden farmers respond to co-occurring climatic and economic changes is essential for effective adaptation policy design.
Low maize (Zea mays L.) yields and the impacts of climate change on maize production highlight the need to improve yields in eastern and southern Africa. Climate projections suggest higher temperatures within drought-prone areas. Research in model species suggests that tolerance to combined drought and heat stress is genetically distinct from tolerance to either stress alone, but this has not been confirmed in maize. In this study we evaluated 300 maize inbred lines testcrossed to CML539. Experiments were conducted under optimal conditions, reproductive stage drought stress, heat stress, and combined drought and heat stress. Lines with high levels of tolerance to drought and combined drought and heat stress were identified. Significant genotype x trial interaction and very large plot residuals were observed; consequently, the repeatability of individual managed stress trials was low. Tolerance to combined drought and heat stress in maize was genetically distinct from tolerance to individual stresses, and tolerance to either stress alone did not confer tolerance to combined drought and heat stress. This finding has major implications for maize drought breeding. Many current drought donors and key inbreds used in widely grown African hybrids were susceptible to drought stress at elevated temperatures. Several donors tolerant to drought and combined drought and heat stress, notably La Posta Sequia C7-F64-2-6-2-2 and DTPYC9-F46-1-2-1-2, need to be incorporated into maize breeding pipelines.
Rainfed areas in Mexico accounts for 14 million hectares where around 23 million people live and are located in places where there is a little climatic information. The severe drought that has im-pacted northern Mexico in the past several years as well as other parts of the country, has forced decision takers to look for improved tools and procedures to prevent and to cope with this natural hazard. For this paper, the methodology of the Food and Agricultural Organization of the United Nations (FAO) for estimating water balance variables was modified to provide crop yield estima-tions under rainfed agriculture in maize producer states of Mexico. The water balance accounts for the daily variation of soil water content having main input rainfall (Pp) and main output crop evapotranspiration (Eta). The algorithm computes crop yield using two distinctive approaches: 1) one based on surplus/deficit functions for each crop considered and 2) yield estimations based on soil water balance and water function productions of the crop being analyzed. For computing wa-ter balance and crop yields, a computer model is built that incorporates the FAO method for water balance (MODEL SICTOD: Computational System for Decision Taking, acronym in Spanish) which stochastically generate precipitation based on wet/dry transition probabilities using a first order Markov chain scheme. Maps of average crop yields were obtained after interpolating model out-comes for the main maize producer states of Mexico: Jalisco, Michoacan, Guerrero, Puebla Oaxaca and Chiapas. Different planting dates were analyzed, early (90 days of length period), interme-diate (120 days of length period) and late (150 days of length period). Crop yield variability cor-relates to the transition probability on having a wet day following a dry day. Results have shown * Corresponding author. I. S. Cohen et al. 1229 high yield variation and probability of crop yield failure and climatic risk follows a distinctive pattern according to planting date and rainfall occurrence. The approach used is of great support for decision taking processes.
Several recently published studies have produced apparently conflicting results of how drought is changing under climate change. The reason is thought to lie in the formulation of the Palmer Drought Severity Index (PDSI) and the data sets used to determine the evapotranspiration component. Here, we make an assessment of the issues with the PDSI in which several other sources of discrepancy emerge, not least how precipitation has changed and is analysed. As well as an improvement in the precipitation data available, accurate attribution of the causes of drought requires accounting for natural variability, especially El Niño/Southern Oscillation effects, owing to the predilection for wetter land during La Niña events. Increased heating from global warming may not cause droughts but it is expected that when droughts occur they are likely to set in quicker and be more intense.
Significance
Agriculture is arguably the sector most affected by climate change, but assessments differ and are thus difficult to compare. We provide a globally consistent, protocol-based, multimodel climate change assessment for major crops with explicit characterization of uncertainty. Results with multimodel agreement indicate strong negative effects from climate change, especially at higher levels of warming and at low latitudes where developing countries are concentrated. Simulations that consider explicit nitrogen stress result in much more severe impacts from climate change, with implications for adaptation planning.
Global temperatures have risen over the past few decades. The water
vapour content of the atmosphere has increased as a result,
strengthening the global hydrological cycle. This, in turn, has led to
wet regions getting wetter, and dry regions drier. Climate model
simulations suggest that a similar intensification of existing patterns
may also apply to the seasonal cycle of rainfall. Here, we analyse
regional and global trends in seasonal precipitation extremes over the
past three decades, using a number of global and land-alone
observational data sets. We show that globally the annual range of
precipitation has increased, largely because wet seasons have become
wetter. Although the magnitude of the shift is uncertain, largely owing
to limitations inherent in the data sets used, the sign of the tendency
is robust. On a regional scale, the tendency for wet seasons to get
wetter occurs over climatologically rainier regions. Similarly, the
tendency for dry season to get drier is seen in drier regions. Even if
the total amount of annual rainfall does not change significantly, the
enhancement in the seasonal precipitation cycle could have marked
consequences for the frequency of droughts and floods.
This paper describes the construction of an updated gridded climate dataset (referred to as CRU TS3.10) from monthly observations at meteorological stations across the world's land areas. Station anomalies (from 1961 to 1990 means) were interpolated into 0.5° latitude/longitude grid cells covering the global land surface (excluding Antarctica), and combined with an existing climatology to obtain absolute monthly values. The dataset includes six mostly independent climate variables (mean temperature, diurnal temperature range, precipitation, wet-day frequency, vapour pressure and cloud cover). Maximum and minimum temperatures have been arithmetically derived from these. Secondary variables (frost day frequency and potential evapotranspiration) have been estimated from the six primary variables using well-known formulae. Time series for hemispheric averages and 20 large sub-continental scale regions were calculated (for mean, maximum and minimum temperature and precipitation totals) and compared to a number of similar gridded products. The new dataset compares very favourably, with the major deviations mostly in regions and/or time periods with sparser observational data. CRU TS3.10 includes diagnostics associated with each interpolated value that indicates the number of stations used in the interpolation, allowing determination of the reliability of values in an objective way. This gridded product will be publicly available, including the input station series (http://www.cru.uea.ac.uk/ and http://badc.nerc.ac.uk/data/cru/). © 2013 Royal Meteorological Society
The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades and the future to year 2035. These “decadal predictions” are initialized based on observations and will be used to explore the predictability of climate and to assess the forecast system's predictive skill. The CMIP5 experiment design also allows for participation of stand-alone atmospheric models and includes a variety of idealized experiments that will improve understanding of the range of model responses found in the more complex and realistic simulations. An exceptionally comprehensive set of model output is being collected and made freely available to researchers through an integrated but distributed data archive. For researchers unfamiliar with climate models, the limitations of the models and experiment design are described.
The largest known economic impact of climate change is upon agriculture because of the size and sensitivity of the sector. Warming causes the greatest harm to agriculture in developing countries primarily because many farms in the low latitudes already endure climates that are too hot. This paper reviews several studies that measure the size of the impact of warming on farms in developing countries. Even though adaptation will blunt some of the worst predicted outcomes, warming is expected to cause large damages to agriculture in developing countries over the next century.
The use of crop wild relatives (CWR) genes to improve crop performance is well established with important examples dating
back more than 60years. In this paper, we review available information on the presence of genes from CWR in released cultivars
of 16 mandate crops of the CGIAR institutes, and some selected additional crops, focusing on the past 20years—the period
since a comprehensive review by Robert and Christine Prescott-Allen in 1986. It appears that there has been a steady increase
in the rate of release of cultivars containing genes from CWR. While there continues to be a strong emphasis on using pest
and disease resistance genes, a wider range of characteristics are being introduced than in the past. Those crops whose wild
relatives have traditionally been used as sources of useful traits (e.g., wheat, tomato) continue to be most likely to include
new genes from their wild relatives. CWR are continually gaining in importance and prevalence, but, we argue, their contributions
to the development of new cultivars remain less than might have been expected given improved procedures for intercrossing
species from different gene pools, advances in molecular methods for managing backcrossing programes, increased numbers of
wild species accessions in gene banks, and the substantial literature on beneficial traits associated with wild relatives.
Maize was domesticated more than 6,000 years ago in central Mexico, and remains a vital staple food and cultural symbol in
Mesoamerica. Maize yield in the central highlands is strongly dependant on adequate rainfall early in the growing season (April–June)
because late maturation of the crop may result in damage from autumn frost. Climate-induced crop failures with profound socioeconomic
impacts have punctuated Mexican history. However, reliable records of maize harvest have not been available until very recently,
and historical records of crop yield and price are discontinuous and can be difficult to interpret. We have developed a continuous,
exactly dated, tree-ring reconstruction of maize yield variability in central Mexico from 1474 to 2001 that provides new insight
into the history of climate and food availability in the heartland of the Mesoamerican cultural province. The reconstruction
indicates that seven of the most severe agricultural crises in Mexican history occurred during decadal-scale episodes of reconstructed
maize shortfalls.
Recent flooding and heavy precipitation events in the US and worldwide have caused great damage to crop production. If the frequency of these weather extremes were to increase in the near future, as recent trends for the US indicate and as projected by global climate models (e.g., US National Assessment, Overview Report, 2001, The Potential Consequences of Climate Variability and Change, National Assesment Synthesis Team, US Global Change Research Program, Washington, DC; Houghton et al., 2001, IPCC Climate Change 2001: The Scientific Basis, Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, 335pp.), the cost of crop losses in the coming decades could rise dramatically. Yet current assessments of the impacts of climate change on agriculture have not quantified the negative effects on crop production from increased heavy precipitation and flooding (Impacts of climate change and variability on agriculture, in: US National Assessment Foundation Document, 2001. National Assessment Synthesis Team, US Global Change Research Program, Washington DC.). In this work, we modify a dynamic crop model in order to simulate one important effect of heavy precipitation on crop growth, plant damage from excess soil moisture. We compute that US corn production losses due to this factor, already significant under current climate, may double during the next thirty years, causing additional damages totaling an estimated $3 billion per year. These costs may either be borne directly by those impacted or transferred to private or governmental insurance and disaster relief programs.
Agricultural activities have dramatically altered our planet's land surface. To understand the extent and spatial distribution of these changes, we have developed a new global data set of croplands and pastures circa 2000 by combining agricultural inventory data and satellite-derived land cover data. The agricultural inventory data, with much greater spatial detail than previously available, is used to train a land cover classification data set obtained by merging two different satellite-derived products (Boston University's MODIS-derived land cover product and the GLC2000 data set). Our data are presented at 5 min (similar to 10 km) spatial resolution in longitude by longitude, have greater accuracy than previously available, and for the first time include statistical confidence intervals on the estimates. According to the data, there were 15.0 (90% confidence range of 12.2-17.1) million km 2 of cropland (12% of the Earth's ice-free land surface) and 28.0 (90% confidence range of 23.6-30.0) million km 2 of pasture (22%) in the year 2000.
New approaches are needed to accelerate understanding of climate impacts on crop yields, particularly in tropical regions. Past studies have relied mainly on crop-simulation models or statistical analyses based on reported harvest data, each with considerable uncertainties and limited applicability to tropical systems. However, a wealth of historical crop-trial data exists in the tropics that has been previously untapped for climate research. Using a data set of more than 20,000 historical maize trials in Africa, combined with daily weather data, we show a nonlinear relationship between warming and yields. Each degree day spent above 30°C reduced the final yield by 1% under optimal rain-fed conditions, and by 1.7% under drought conditions. These results are consistent with studies of temperate maize germplasm in other regions, and indicate the key role of moisture in maize's ability to cope with heat. Roughly 65% of present maize-growing areas in Africa would experience yield losses for 1°C of warming under optimal rain-fed management, with 100% of areas harmed by warming under drought conditions. The results indicate that data generated by international networks of crop experimenters represent a potential boon to research aimed at quantifying climate impacts and prioritizing adaptation responses, especially in regions such as Africa that are typically thought to be data-poor.
To better understand the range of adaptation of maize (Zea mays L.) landraces, climatic adaptation intervals of 42 Mexican maize races were determined. A database of 4161 maize accessions was used to characterize altitudinal and climatic conditions where the 42 maize races grow, yielding ecological descriptors for each race. Using the geographical coordinates of the collection sites of each accession, their climatic conditions were characterized using the geographic information system IDRISI and a national environmental information system. Analyses of variance and cluster analyses of the racial ecological descriptors were performed to determine possible environmental groupings of the races. We found a very high level of variation among and within Mexican maize races for climate adaptation and ecological descriptors. The general overall climatic ranges for maize were 0 to 2900 m of altitude, 11.3 to 26.6°C annual mean temperature, 12.0 to 29.1°C growing season mean temperature, 426 to 4245 mm annual rainfall, 400 to 3555 mm growing season rainfall, and 12.46 to 12.98 h mean growing season daylength. These climatic ranges of maize surpass those from its closest relative, teosinte (Z. mays ssp. parviglumis Iltis and Doebley), indicating that maize has evolved adaptability beyond the environmental range in which ancestral maize was first domesticated.
Climate models suggest that extreme precipitation events will become more common in an anthropogenically warmed climate. However,
observational limitations have hindered a direct evaluation of model-projected changes in extreme precipitation. We used satellite
observations and model simulations to examine the response of tropical precipitation events to naturally driven changes in
surface temperature and atmospheric moisture content. These observations reveal a distinct link between rainfall extremes
and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods. Furthermore, the
observed amplification of rainfall extremes is found to be larger than that predicted by models, implying that projections
of future changes in rainfall extremes in response to anthropogenic global warming may be underestimated.
Dynamic interactions between and within the biogeophysical and human environments lead to the production, processing, distribution, preparation and consumption of food, resulting in food systems that underpin food security. Food systems encompass food availability (production, distribution and exchange), food access (affordability, allocation and preference) and food utilization (nutritional and societal values and safety), so that food security is, therefore, diminished when food systems are stressed. Such stresses may be induced by a range of factors in addition to climate change and/or other agents of environmental change (e.g. conflict, HIV/AIDS) and may be particularly severe when these factors act in combination. Urbanization and globalization are causing rapid changes to food systems.
Climate change may affect food systems in several ways ranging from direct effects on crop production (e.g. changes in rainfall leading to drought or flooding, or warmer or cooler temperatures leading to changes in the length of growing season), to changes in markets, food prices and supply chain infrastructure. The relative importance of climate change for food security differs between regions. For example, in southern Africa, climate is among the most frequently cited drivers of food insecurity because it acts both as an underlying, ongoing issue and as a short-lived shock. The low ability to cope with shocks and to mitigate long-term stresses means that coping strategies that might be available in other regions are unavailable or inappropriate. In other regions, though, such as parts of the Indo-Gangetic Plain of India, other drivers, such as labour issues and the availability and quality of ground water for irrigation, rank higher than the direct effects of climate change as factors influencing food security.
Because of the multiple socio-economic and bio-physical factors affecting food systems and hence food security, the capacity to adapt food systems to reduce their vulnerability to climate change is not uniform. Improved systems of food production, food distribution and economic access may all contribute to food systems adapted to cope with climate change, but in adopting such changes it will be important to ensure that they contribute to sustainability. Agriculture is a major contributor of the greenhouse gases methane (CH 4 ) and nitrous oxide (N 2 O), so that regionally derived policies promoting adapted food systems need to mitigate further climate change.
A comprehensive assessment of the impacts of climate change on agro-ecosystems over this century is developed, up to 2080 and at a global level, albeit with significant regional detail. To this end an integrated ecological-economic modelling framework is employed, encompassing climate scenarios, agro-ecological zoning information, socio-economic drivers, as well as world food trade dynamics. Specifically, global simulations are performed using the FAO/IIASA agro-ecological zone model, in conjunction with IIASAs global food system model, using climate variables from five different general circulation models, under four different socio-economic scenarios from the intergovernmental panel on climate change. First, impacts of different scenarios of climate change on bio-physical soil and crop growth determinants of yield are evaluated on a 5' X 5' latitude/longitude global grid; second, the extent of potential agricultural land and related potential crop production is computed. The detailed bio-physical results are then fed into an economic analysis, to assess how climate impacts may interact with alternative development pathways, and key trends expected over this century for food demand and production, and trade, as well as key composite indices such as risk of hunger and malnutrition, are computed. This modelling approach connects the relevant bio-physical and socio-economic variables within a unified and coherent framework to produce a global assessment of food production and security under climate change. The results from the study suggest that critical impact asymmetries due to both climate and socio-economic structures may deepen current production and consumption gaps between developed and developing world; it is suggested that adaptation of agricultural techniques will be central to limit potential damages under climate change.
Continental runoff has increased through the twentieth century despite more intensive human water consumption. Possible reasons for the increase include: climate change and variability, deforestation, solar dimming, and direct atmospheric carbon dioxide (CO2) effects on plant transpiration. All of these mechanisms have the potential to affect precipitation and/or evaporation and thereby modify runoff. Here we use a mechanistic land-surface model and optimal fingerprinting statistical techniques to attribute observational runoff changes into contributions due to these factors. The model successfully captures the climate-driven inter-annual runoff variability, but twentieth-century climate alone is insufficient to explain the runoff trends. Instead we find that the trends are consistent with a suppression of plant transpiration due to CO2-induced stomatal closure. This result will affect projections of freshwater availability, and also represents the detection of a direct CO2 effect on the functioning of the terrestrial biosphere.
The significant worldwide increase in observed river runoff has been tentatively attributed to the stomatal “antitranspirant” response of plants to rising atmospheric CO2 [Gedney N, Cox PM, Betts RA, Boucher O, Huntingford C, Stott PA (2006) Nature 439: 835–838]. However, CO2 also is a plant fertilizer. When allowing for the increase in foliage area that results from increasing atmospheric CO2 levels in a global vegetation model, we find a decrease in global runoff from 1901 to 1999. This finding highlights the importance of vegetation structure feedback on the water balance of the land surface. Therefore, the elevated atmospheric CO2 concentration does not explain the estimated increase in global runoff over the last century. In contrast, we find that changes in mean climate, as well as its variability, do contribute to the global runoff increase. Using historic land-use data, we show that land-use change plays an additional important role in controlling regional runoff values, particularly in the tropics. Land-use change has been strongest in tropical regions, and its contribution is substantially larger than that of climate change. On average, land-use change has increased global runoff by 0.08 mm/year² and accounts for ≈50% of the reconstructed global runoff trend over the last century. Therefore, we emphasize the importance of land-cover change in forecasting future freshwater availability and climate.
• atmospheric CO2
• water cycle
• climate change
• land cover change