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Increasing Frequency of Extreme El Nino Events due to Greenhouse Warming
Abstract
El Niño events are a prominent feature of climate variability with global climatic impacts. The 1997/98 episode, often referred to as `the climate event of the twentieth century', and the 1982/83 extreme El Niño, featured a pronounced eastward extension of the west Pacific warm pool and development of atmospheric convection, and hence a huge rainfall increase, in the usually cold and dry equatorial eastern Pacific. Such a massive reorganization of atmospheric convection, which we define as an extreme El Niño, severely disrupted global weather patterns, affecting ecosystems, agriculture, tropical cyclones, drought, bushfires, floods and other extreme weather events worldwide. Potential future changes in such extreme El Niño occurrences could have profound socio-economic consequences. Here we present climate modelling evidence for a doubling in the occurrences in the future in response to greenhouse warming. We estimate the change by aggregating results from climate models in the Coupled Model Intercomparison Project phases 3 (CMIP3; ref. ) and 5 (CMIP5; ref. ) multi-model databases, and a perturbed physics ensemble. The increased frequency arises from a projected surface warming over the eastern equatorial Pacific that occurs faster than in the surrounding ocean waters, facilitating more occurrences of atmospheric convection in the eastern equatorial region.
... Por su alta influencia que tiene a lo largo del Pacífico central el ENOS tiene cuatro regiones bien definidas, la 1+2, 3, 3.4, y 4 (Wang et al., 2017;Wang y Lui, 2021). Si bien ENOS ha sido extensamente estudiado durante décadas, su comportamiento aún no se comprende en su totalidad y persiste incertidumbre sobre cómo este fenómeno podría modularse en el futuro ante el cambio climático global (Misra, 2023;Cai et al., 2014). En particular, se requiere investigar con mayor profundidad cómo ENOS impacta en el crecimiento, productividad y distribución de las especies forestales en diferentes áreas tropicales y subtropicales (Lara et al., 2020, Feeley et al., 2012. ...
... Por otra parte, el cambio climático global (CC) también está modificando los patrones espaciales y temporales de ENOS en las últimas décadas, a través de alteraciones en los gradientes de temperatura superficial marina y en los flujos de circulación atmosférica tropical (Cai et al., 2014;Collins et al., 2010). A su vez, el CC está afectando la distribución, composición, funcionalidad y resiliencia de numerosos ecosistemas y especies forestales alrededor del mundo, particularmente su crecimiento anual, el cual puede registrarse en los anillos de crecimiento de los árboles (Guan et al., 2012;Wu et al., 2015. ...
... Finalmente, a medida que el cambio climático altera los patrones de ENOS y otros fenómenos (Cai et al., 2014), es esencial desarrollar modelos predictivos del crecimiento arbóreo ante distintos escenarios climáticos futuros. Esto permitirá generar estrategias de adaptación y conservación de los bosques tropicales frente al calentamiento global (Sánchez y Reyes, 2015). ...
Este libro, resultado de la colaboración entre la Universidad Politécnica Salesiana de Ecuador y la Friedrich Alexander Universität de Erlangen-Nürnberg, ofrece una visión integral y multidisciplinar del cambio climático en la región andina. Abarca desde los ecosistemas únicos hasta las dinámicas sociales y políticas que afectan a las comunidades, invitando a reflexionar sobre cómo esta crisis global transforma una de las zonas más diversas del mundo. Basado en investigaciones presentadas en una conferencia internacional en Alemania, y en estudios recientes, el texto no solo explica el impacto del calentamiento global en los ecosistemas, como los bosques secos y las zonas costeras, sino que también aborda custiones humanas clave: ¿cómo perciben y enfrentan las comunidades indígenas y urbanas los cambios climáticos? ¿Qué papel juegan el género, la etnicidad y la política en las estrategias de adaptación? Con un enfoque científico sólido, pero accesible, este libro busca responder a esas preguntas desde una perspectiva interdisciplinar. Además, explora las tendencias actuales en los países andinos, reflexionar sobre los desafíos del colapso climático y considerar soluciones transformadoras basadas en la resiliencia y la cooperación.
... Por su alta influencia que tiene a lo largo del Pacífico central el ENOS tiene cuatro regiones bien definidas, la 1+2, 3, 3.4, y 4 (Wang et al., 2017;Wang y Lui, 2021). Si bien ENOS ha sido extensamente estudiado durante décadas, su comportamiento aún no se comprende en su totalidad y persiste incertidumbre sobre cómo este fenómeno podría modularse en el futuro ante el cambio climático global (Misra, 2023;Cai et al., 2014). En particular, se requiere investigar con mayor profundidad cómo ENOS impacta en el crecimiento, productividad y distribución de las especies forestales en diferentes áreas tropicales y subtropicales (Lara et al., 2020, Feeley et al., 2012. ...
... Por otra parte, el cambio climático global (CC) también está modificando los patrones espaciales y temporales de ENOS en las últimas décadas, a través de alteraciones en los gradientes de temperatura superficial marina y en los flujos de circulación atmosférica tropical (Cai et al., 2014;Collins et al., 2010). A su vez, el CC está afectando la distribución, composición, funcionalidad y resiliencia de numerosos ecosistemas y especies forestales alrededor del mundo, particularmente su crecimiento anual, el cual puede registrarse en los anillos de crecimiento de los árboles (Guan et al., 2012;Wu et al., 2015, Pucha et al., 2015. ...
... Finalmente, a medida que el cambio climático altera los patrones de ENOS y otros fenómenos (Cai et al., 2014), es esencial desarrollar modelos predictivos del crecimiento arbóreo ante distintos escenarios climáticos futuros. Esto permitirá generar estrategias de adaptación y conservación de los bosques tropicales frente al calentamiento global (Sánchez y Reyes, 2015). ...
Este libro, resultado de la colaboración entre la Universidad Politécnica Salesiana de Ecuador y la Friedrich Alexander Universität de Erlangen-Nürnberg, ofrece una visión integral y multidisciplinar del cambio climático en la región andina. Abarca desde los ecosistemas únicos hasta las dinámicas sociales y políticas que afectan a las comunidades, invitando a reflexionar sobre cómo esta crisis global transforma una de las zonas más diversas del mundo. Basado en investigaciones presentadas en una conferencia internacional en Alemania, y en estudios recientes, el texto no solo explica el impacto del calentamiento global en los ecosistemas, como los bosques secos y las zonas costeras, sino que también aborda cuestiones humanas clave: ¿Cómo perciben y enfrentan las comunidades indígenas y urbanas los cambios climáticos? ¿Qué papel juegan el género, la etnicidad y la política en las estrategias de adaptación? Con un enfoque científico sólido, pero accesible, este libro busca responder a esas preguntas desde una perspectiva interdisciplinar. Además, explora las tendencias actuales en los países andinos, reflexionar sobre los desafíos del colapso climático y considerar soluciones transformadoras basadas en la resiliencia y la cooperación.
... The most recent widespread CLR outbreak of 2012 -2013 resulted in harvest losses of up to 30% in Colombia (Cristancho et al., 2012) and 50% loss in Costa Rica (Cressey, 2013). El Niño events are expected to double in frequency and cause dry conditions that last longer in South America (Cai et al., 2014(Cai et al., , 2020. Given the opposing effects of warmer and drier conditions on fungal diseases, the net effect of expected future climate scenarios on CLR is ambiguous. ...
... We use an existing mechanistic model of temperature and humidity dependent CLR germination and infection risk under historical climate in the coffee region of Colombia (Bebber et al., 2016). To simulate projected disease dynamics, we modify the temperature and humidity-related parameters in that CLR risk model to reflect the climate projections of warmer temperatures and prolonged droughts reported in (Cai et al., 2014(Cai et al., , 2020. ...
... to our sun-grown coffee scenario.Cai et al. (2014) projected that the occurrence of El Niño cycles will be doubled under future climate change scenario. In Colombia, El Niño cycles lead to periods our climate change simulations. For instance, the first El Niño cycle runs from January to June 1995. In the climate change scenario, this cycle begins from January until December 1995. ...
The indirect impact of climate change on agriculture through diseases and pests is understudied. However, estimating the direct and indirect impacts separately is necessary for selecting adaptation strategies based on the direction and magnitude of each impact channel. We investigate the relative contribution of the indirect climate impact in the context of coffee and coffee leaf rust, the crop's most damaging disease. We construct a farm-level bioeconomic model and assess the impact of projected warmer temperatures and more prolonged droughts on the expected net present values of four farm types in Colombia: sun and shade-grown farms at low and high altitudes. We find that sun-grown farms at both altitudes and shade-grown farms at low altitudes benefit from a warmer and drier climate. The relative magnitudes and directions of the direct and indirect climatic impacts suggest different adaptation priorities at different altitudes for each system: resilience to the disease is a priority for sun-grown systems at high altitudes whereas heat tolerance is most important for sun and shade-grown coffee farms at low altitudes. Our results indicate that, while shade-grown coffee is optimal under historical climate, its advantage over sun-grown coffee is lost under the projected climate. We identify climate-adjusted, altitude-specific price premiums for shade-grown coffee that can avoid a transition from shade to sun-grown systems and prevent the associated potential loss of ecosystem services.
... The combined effects of remote forcing from the equatorial CEP and local air-sea interaction in the tropical WNP are supported by numerical experiments [22][23][24] . Besides, from the perspective of large-scale zonal circulation adjustment, enhanced convection in the equatorial CEP shift the Walker circulation eastward, resulting in reduced precipitation anomalies over the tropical WNP 22,[25][26][27][28][29][30][31] , and thereby influencing the WNPAC. Even under global warming scenario, the precipitation anomalies in the equatorial CEP and the tropical WNP still dominate the variations of the WNPAC during El Niño mature winter 32 . ...
... Similarly, equatorial CEP precipitation anomalies show a strong association with WNPAC intensity in the MME results (Fig. 1c), with that six models exhibit a significant correlation exceeding the 90% confidence level (Fig. S6). These equatorial CEP precipitation anomalies could influence tropical WNP precipitation anomalies through atmospheric teleconnections 8,21 or the Walker circulation 22,[25][26][27][28][29][30][31] , thereby affecting the strength of the anomalous anticyclone. While ENSO plays a significant role in influencing WNPAC, its SST variability does not seem to directly affect the intensity of the anticyclone. ...
... Predicted changes in ENSO-driven precipitation anomalies during the CO 2 RD relative to the RU period exhibit intensified negative anomalies in the tropical WNP and positive anomalies in the equatorial CEP (Figs. 1b and 2a). These precipitation anomalies are similar to those observed under global warming scenarios, as reported in previous studies [29][30][31][68][69][70][71][72] . Based on the two-layer approximated moisture budget equation 31 , the variation in precipitation anomalies (ΔP 0 ) can be decomposed into the thermodynamic (ÀΔ q Á ω 0 ) and dynamic (À q Á Δω 0 ) components. ...
... The rise of global average temperatures as well as mean state changes associated with human-induced climate change are believed to trigger more extreme El Niño and La Niña events in the future (Cai et al., 2014(Cai et al., , 2015, more consecutive positive Indian Ocean Dipole (IOD) events (Cai et al., 2009), and weaker, more frequent Pacific Decadal Oscillation (PDO) phases (Zhang and Delworth, 2016). The worldwide scale of climate change consequences (Glynn and de Weerdt, 1991;Vos and Velasco, 1999;Aronson et al., 2000;Vincent et al., 2011;Cai et al., 2012) as well as the extent of the damage make studying past variations of climate phenomena's impacts on specific regions, such as the Maritime Continent (MC), necessary in order to understand possible future variations for regional climates. ...
... However, the relationship of Anemone and Eve δ 18 O sw records with western central Pacific salinity switched from positive to negative during recent time periods. This is consistent with increasingly stronger and more frequent El Niño events (Cai et al., 2014) where precipitation in the western central Pacific increases and precipitation in the Maritime Continent decreases compared to in-phase precipitations in the MC and western central Pacific during La Niña events (Yuan and Yan, 2013). ...
... Indeed, results from a 2014 study showed that warmer PDO phases enhance the impact of El Niño and reduce the impact of La Niña on monsoonal precipitation during the South Asian monsoon (Krishnamurthy and Krishnamurthy, 2014). The switch from PDO and IPO phases with the three strongest recorded La Niña events on record (1955-1956, 1973-1974, and 1975-1976) to warm PDO and IPO phases in the late 1970s with the presence of the three strongest El Niño events on record (1982-1983, 1997-1998, and 2015-2016) are indicators of a shift (Yeh et al., 2009;Cai et al., 2014). Such a shift towards more frequent (positive trend in the NINO3.4 ...
The El Niño Southern Oscillation (ENSO) is a worldwide climate phenomenon impacting temperatures and precipitation regimes across the globe. Previous studies have shown this climate phenomenon to influence Malaysian Borneo's hydroclimate. In the context of a changing climate and increasingly strong extreme ENSO events, understanding the influence of ENSO on this region, and its evolution through time, is essential to better constrain the future impacts it will have on the Maritime Continent's hydroclimate. Here, we used coupled δ18O and Sr/Ca records from massive corals' carbonate calcium skeletons to build a proxy for past hydroclimate: δ18Oseawater (δ18Osw) and compensate for the limited dependable instrumental data in most of the 20th century. We assessed our two 90 and 60-year-long δ18Osw records' quality as proxies for regional hydroclimate by correlating them with different instrumental salinity datasets before performing moving windowed correlations with the NINO3.4 index, an indicator of ENSO state.
Results show that agreement between geochemical proxies and instrumental data highly depends on the chosen dataset, study site location, period, and monsoon season, with stronger agreement with more recent data, pointing towards insufficient data quality when going far back in time. More importantly, when correlated against the NINO3.4 index, our δ18Osw records showed a growing correlation for most of their respective lengths. From the 1980s, we found an increasing influence of ENSO on the local hydroclimate with correlation coefficients r >0.8 during the wet monsoon season. Our findings highlight the differences in results depending on the chosen observational dataset, time scale, or period of the year, and stress the importance of such geochemical archives to better understand the impacts of ENSO across periods predating reliable instrumental data. More importantly, our findings show how the concurrent evolution of the IOD, and the PDV affect ENSO and ultimately, northwestern Borneo's hydroclimate through their teleconnections.
... According to the characteristics of climate, we found that 1997 was the drought year and the abrupt point of precipitation change in the NQL, which is consistent with the time point of climate change in the twentieth century (Cai et al., 2014;Zhang et al., 2017). And the increase in heavy precipitation events of NQL in recent years may be related to ENSO events (Cai et al., 2014). ...
... According to the characteristics of climate, we found that 1997 was the drought year and the abrupt point of precipitation change in the NQL, which is consistent with the time point of climate change in the twentieth century (Cai et al., 2014;Zhang et al., 2017). And the increase in heavy precipitation events of NQL in recent years may be related to ENSO events (Cai et al., 2014). From the perspective of the spatial pattern of vegetation change, we found that the vegetation area and NDVI had increased in mountain areas. ...
... The relationship between ENSO and GMST is of particular interest to scientists, as fluctuations in ENSO can have a significant impact on global climate (Niedzielski, 2014;Trenberth et al., 2002;Vecchi & Wittenberg, 2010). When an El Niño event occurs, the central and eastern Pacific Ocean's Sea surface temperatures exceed the average, resulting in altered atmospheric circulation patterns (Cai et al., 2014;Latif & Keenlyside, 2008). This may lead to precipitation increases in certain regions, such as the western coast of South America, and drought conditions in others, including Australia and Indonesia. ...
... El Niño's contribution to long-term warming trends is one of its most significant effects on GMST. While the duration of individual El Niño events may vary from a few months to a year, the elevated temperatures that accompany these events can contribute to the broader trend of increasing global temperatures (Cai et al., 2014;Yeh et al., 2009). This is because El Niño events discharge heat stored in the oceans into the atmosphere, which in turn contributes to an increase in the GMST. ...
Global mean surface temperature serves as a crucial metric in understanding the Earth’s climate dynamics, providing insights into long-term climate trends and variability. Over the course of a million years, the trajectory of global temperatures has been shaped by a multitude of factors, including natural climatic cycles, human activities, and external influences. By examining the historical trends and drivers influencing global mean surface temperature, researchers can gain valuable insights into the past, present, and future climate scenarios. This article delves into the intricate interplay of these factors and explores the lessons we can learn from studying the temperature trajectory over a million-year span.
... In marine environments, instead of reacting to changes in long-term mean conditions, responses to extreme climatic events may be more overarching (Frolicher and Laufkotter 2018;Wernberg et al. 2012). The biggest source and control of yearly fluctuations in the climate is the El Niño Southern Oscillation (ENSO) (Cai et al. 2014;Santoso et al. 2017;Wang et al. 1999). Though characterized by recurring (2 to 7-year) oscillations between a warming and a cooling phase in tropical Pacific sea surface temperatures (SST), it is a "global pattern of anomalies" (Cane 1986) that has strong impacts on global and regional marine ecosystems. ...
... Ontogeny influenced the element pattern of S. niphonius, leading to significant differences of elemental concentrations among different life stages (Pan et al. 2020a, b). ENSO is the source of year-to-year variations in global climate and its impacts continued all the year round through winter (Cai et al. 2014;Santoso et al. 2017;Wang et al. 1999). Thus, we used the mean elemental concentration of the whole otolith (covered a span of 1 year) to extract the spatial and temporal variations in element pattern. ...
... We note that CESM1 projections exhibit an El Niño-like warming pattern ( Supplementary Fig. 9a), which is often found in multi-model projections [30][31][32][33] . However, observational results show less pronounced changes in past El Niño-like SST patterns 34 . ...
... • C), strong EI Niño (ONI = 1.5-1.9 • C), very strong EI Niño (ONI ≥ 2 • C), weak La Niña (ONI = −0.5 to −0.9 • C), moderate La Niña (ONI = −1 to −1.4 • C), strong La Niña (ONI = −1.5 to −1.9 • C), very strong La Niña (ONI ≤ −2 • C) [59][60][61][62][63]. We characterized the pCO 2 sw and FCO 2 dynamics during these ENSO events in the four representative regions including warm pool, cold tongue, as well as the tropical North and South Pacific (Boxes 1-4 in Figure 1), and we also analyzed the data series specifically in Niño 3, Niño 3.4, and Niño 4. It should be noted that regions of Niño 3 and Niño 3.4 fall entirely in the cold tongue region, while Niño 4 partially covered both the warm pool and cold tongue region. ...
The equatorial Pacific serves as the world’s largest oceanic source of CO2. The contrasting ocean environment in the eastern (i.e., upwelling) and western (i.e., warm pool) regions makes it difficult to fully characterize its CO2 dynamics with limited in situ observations. In this study, we addressed this challenge using monthly surface partial pressure of CO2 (pCO2sw) and air-sea CO2 fluxes (FCO2) data products reconstructed from satellite and reanalysis data at a spatial resolution of 1° × 1° in the period of 1982–2021. We found that during the very strong El Niño events (1997/1998, 2015/2016), both pCO2sw and FCO2 showed a significant decrease of 41–58 μatm and 0.5–0.8 mol·m⁻²·yr⁻¹ in the eastern equatorial Pacific, yet they remained at normal levels in the western equatorial Pacific. In contrast, during the very strong La Niña events (1999/2000, 2007/2008, and 2010/2011), both pCO2sw and FCO2 showed a strong increase of 40–48 μatm and 1.0–1.4 mol·m⁻²·yr⁻¹ in the western equatorial Pacific, yet with little change in the eastern equatorial Pacific. In the past 40 years, pCO2sw in the eastern equatorial Pacific was increasing at a higher rate (2.32–2.51 μatm·yr⁻¹) than that in the western equatorial Pacific (1.75 μatm·yr⁻¹), resulting in an accelerating CO2 outgassing (at a rate of 0.03 mol·m⁻²·yr⁻²) in the eastern equatorial Pacific. We comprehensively analyzed the potential effects of different factors, such as sea surface temperature, sea surface wind speed, and ΔpCO2 in driving CO2 fluxes in the equatorial Pacific, and found that ΔpCO2 had the highest correlation (R ≥ 0.80, at p ≤ 0.05), highlighting the importance of accurate estimates of pCO2sw from satellites. Further studies are needed to constrain the retrieval accuracy of pCO2sw in the equatorial Pacific from satellite remote sensing.
... Moreover, since this asymmetry can be different across seasons, better simulation of asymmetry can also significantly improve seasonal predictability of precipitation and can play a pivotal role in the improvement of regional drought and flood planning. In a warming climate, changes in ENSO strength and frequency (Bayr & Latif, 2023;Cai et al., 2014;Cai, Santoso, et al., 2015;Cai, Wang, et al., 2015;Heede & Fedorov, 2023) are likely to make the impacts of ENSO on regional climates more severe Maher et al., 2023;McGregor et al., 2022;Perry et al., 2020;Yeh et al., 2018). Better future projections of ENSO-precipitation teleconnections and associated asymmetry/ nonlinearity may assist better resource management and reduce the adverse impacts of hydrological extremes (Glantz, 2001;Lee et al., 2018;McPhaden et al., 2006;Ren et al., 2022;Santoso et al., 2015). ...
El Niño–Southern Oscillation (ENSO) is a prominent climate phenomenon affecting precipitation patterns across much of the world. Regional ENSO‐precipitation teleconnections are often asymmetric such that the precipitation response to El Niño is stronger or weaker than the response to La Niña. Better understanding of asymmetry in teleconnections can improve the predictability of climate extremes during ENSO events. In this study, we assess the capability of 50 state‐of‐the‐art climate models and a reanalysis against observational data in simulating seasonal differences in asymmetric response of precipitation to ENSO. The analysis is performed across 46 sub‐continental scale regions, using a precipitation composite technique for deriving the asymmetric component of precipitation response. Significant regional and seasonal diversity is found in the asymmetric response to ENSO, both in observations and models. Model performance in simulating the nature of teleconnections is higher than the performance in simulating the associated asymmetry. Model performance in capturing the regional diversity of asymmetry is highest in austral spring. The model biases in asymmetry are related to the inability of the models to accurately simulate the skewness of the heavy tailed local precipitation distributions and Niño3.4 SST distributions. In regions outside the Pacific and Indian Ocean basins, model bias in the skewness of local precipitation variability plays a larger role in model asymmetry bias. This analysis contributes to better understanding the fidelity of CMIP6 models in capturing asymmetry in teleconnections across different seasons and regions which are critical for making skillful projections of floods and droughts in a warming climate.
... Therefore, the Tillandsiales might also be considered a very sensitive system reacting to global climate change. Indeed, since the last few decades, there has been a major decline and dieback of T. landbeckii lomas in the Chilean Atacama Desert (Cai et al., 2014;Cereceda et al., 2008;Muñoz et al., 2016;Schulz, 2009;Schulz et al., 2011), which highlights the need for research to understand the ecological and evolutionary principles of this unique ecosystem. ...
... This can be identified as the This suggests a persistent potential for errors in the seasonal forecasting of the AAC associated with El Niño events in GloSea6, with the possibility of significant prediction errors during extreme events due to slight differences in the longitudinal positioning of the equatorial Pacific SST. Moreover, as it is expected that strong El Niño events will occur more frequently in the warmer world than in the present climate (Cai et al. 2014), accurate model simulations for Pacific SST cores during the decaying periods are expected to become increasingly important. This perspective also suggests the importance of interbasin sensitivity during the decaying El Niño in climate models, as differences in the sensitivity can lead to inapplicable forecasts for catastrophic climate events in our world. ...
In this study, GloSea6 hindcast (HCST) from the UK Met Office is used to investigate the model prediction skill for the impacts on the East Asian summer associated with two extreme El Niño cases (1997/1998 and 2015/2016). For the 1998 case, we found that GloSea6 model is able to predict the ocean–atmosphere circulations one to two seasons ahead, including the anomalously positive sea surface temperature (SST) in the Tropical Indian Ocean (TIO) and the anomalous anticyclone (AAC) in the Western North Pacific during the spring and summer seasons. However, for the 2016 case it fails to capture the observed fast cooling of the spring TIO SST and the rapid decaying of the summer AAC, due to an overestimated linkage between the summer TIO and the precedent winter El Niño. Physically, the exaggerated model SST warming over both the eastern and western Indian Ocean suppresses the development of the surface westerly wind that enhances the summer monsoon flow in the TIO and cools the warmed SST as in the real world. According to further analysis, the sensitivity of the TIO is linked to the formation of the spring AAC, which is influenced by the longitudinal position of warm Pacific SST, causing the HCST to display a more idealized El Niño-TIO-AAC teleconnection than the observations. Thus, simulating the decaying El Niño and its teleconnection to the TIO is crucial for reliable seasonal forecasts of East Asian climate during post-El Niño summers.
... In this study, annual flood intensity does not consider seasonal factors or other disturbances that influence changes in patterns due to El Niño-Southern Oscillation (ENSO). ENSO is a global climate phenomenon that can modulate flood patterns in various regions Cai et al. [36]. By considering ENSO, the accuracy of flood intensity predictions can be improved. ...
... The response of ENSO precipitation to anthropogenic warming has been extensively studied over the past decade [10][11][12][13][14][15][16][17][18] . Most climate models suggest that future ENSO precipitation will intensify and move eastward with an El Niño-like mean state warming 17,19 . ...
El Niño-Southern Oscillation-induced tropical Pacific precipitation anomalies have global impacts and will intensify under greenhouse warming, but the potential for mitigating these changes is less understood. Here, we identify distinct hysteresis features in the precipitation-sea surface temperature sensitivity between strong El Niño and La Niña phases using a large ensemble carbon removal numerical simulation. The strong El Niño precipitation sensitivity exhibits a century-scale hysteretic enhancement and eastward shift, mainly due to modulated deep convection anomalies by the Intertropical Convergence Zone via cloud-longwave feedback. Instead, the strong La Niña counterpart is concentrated toward the equator, mostly in the central-western Pacific, with a shorter hysteresis period of a few decades. This primarily involves changes in shallow convection and surface thermal structures during La Niña, shaped by global warming-induced upper-ocean circulation changes. The distinct climate change regimes of strong El Niño and La Niña precipitation sensitivity hold important implications for assessing mitigation consequences.
... Particularly, the suppression of fire has resulted in woody encroachment in Thailand (Chankhao et al. 2022) whereas research in DDF in Viet Nam has shown that fires that are too frequent can limit tree recruitment (Nguyen et al. 2019). Without a deeper understanding of the distribution of savannas in south-east Asia, it is impossible to effectively manage the remaining savannas of the region, especially in the context of the increasing frequency of extreme El Niño events due to climate change that heighten global fire risks (Timmermann et al. 1999;Goldammer and Wanthongchai 2008;Cai et al. 2014;Wang et al. 2017) and the need to manage savannas to maximise carbon emission reductions, biodiversity conservation and local livelihoods. ...
Savannas, characterised by a continuous grass layer and discontinuous tree layer, are widespread globally and highly flammable during dry seasons, contributing to 90% of annual global burned areas and significant emissions. Asian savannas, often mismanaged owing to structural variability and misclassification as ‘poor forests’, face excessive or insufficient fire regimes. Addressing trans-boundary haze and climate mitigation requires improved understanding and sustainable management. This paper addresses savanna management challenges, particularly misclassified dry dipterocarp forests in the Lower Mekong, by synthesising knowledge on their distribution and the role of fire use by local communities, and recommends holistic, community-based fire management, integrated planning and incentives.
... El Niño-Southern Oscillation (ENSO) is the most significant interannual climate variability on Earth (Philander 1983;Neelin et al. 1998;McPhaden et al. 2006). It impacts global climate and weather through air-sea interactions, occasionally leading to extreme disaster events (Alexander et al. 2002;Cai et al. 2014). Consequently, the accuracy of ENSO forecasting is of paramount importance. ...
During the mature phases of two types of El Niño, the patterns of sea surface temperature anomalies (SSTA) are obviously different, with the centers near eastern Pacific (EP) for the EP El Niño and near the dateline (180° of longitude) for the central Pacific (CP) El Niño. However, contradicting with the observation, in the Community Earth System Model version 2 (CESM2), the SSTA centers of both types of El Niño are close to the CP area, which makes them difficult to be separated, i.e., the CESM2 shows a relatively poor depiction of the realistic El Niño diversity. To explore the possible reasons for this deficiency, a meticulous comparison of the dominant mechanisms for the equatorial Pacific SSTA evolution, i.e., the thermocline feedback (TH) and the zonal advective feedback (ZA), between the model and observation is conducted in this study. The results suggest that comparing with the observation, the weak intensity of TH and the westward shift of the dominant ZA position in the model are the primary causes that induce such proximity of SSTA centers of the two types of El Niño. The deeper thermocline depth, which induce smaller amplitude of thermocline depth variation, cause the deviation of the TH in CESM2. Furthermore, the deviation of the ZA comes from the pronounced westward bias in simulating the background zonal gradient of sea surface temperature, along with the weak zonal current anomalies in the EP area.
... However, the impact of climate change on insect population dynamics is less well understood. Global warming is expected to increase the frequency and intensity of extreme climatic events and alter large-scale climate patterns, such as El Niño Southern Oscillation (ENSO), which affects seasonal rain and temperature patterns [6,7]. Tropical insects are thought to be living at or near their thermal optima and have narrower thermal tolerances than those at higher latitudes, suggesting that such changes in the intensity and frequency of ENSO events are likely to impact their populations significantly. ...
Recent reports of insect decline have raised concerns regarding population responses of ecologically important groups, such as insect pollinators. Additionally, how population trends vary across pollinator taxonomic groups and degree of specialization is unclear. Here, we analyse 14 years of abundance data (2009–2022) for 38 species of native insect pollinators, including a range of Coleoptera, Lepidoptera and Hymenoptera specialists and generalists from the tropical rainforest of Barro Colorado Island, Panama. We estimated population trends across taxonomic groups to determine whether specialist species with a narrower range of interacting mutualistic partners are experiencing steeper population declines under environmental change. We also examined the relationship between climate variables and pollinator abundance over time to determine whether differences in sensitivity to climate predict differences in population trends among pollinator species. Our analyses indicated that most pollinator populations were stable or increasing, with few species showing evidence of decline, regardless of their degree of specialization. Differences in climate sensitivity varied among pollinator species but were not associated with population trends, suggesting other environmental factors at play for tropical insect pollinators. These results highlight the need for long-term population data from diverse tropical taxa to better assess the environmental determinants of insect pollinator trends.
... As the dominant mode of interannual variability in the tropical climate system, El Niño-Southern Oscillation (ENSO) exerts a substantial influence on global weather and climate. Under global warming, there has been an increase in the frequency of extreme El Niño events and variability in the eastern Pacific El Niño (Cai et al 2014(Cai et al , 2018. Additionally, an increased frequency of multi-year La Niña events has occurred in recent decades and is projected to be more common in the future (Geng et al 2023, Wang et al 2023a. ...
The Indonesian Throughflow (ITF) serves as the only tropical branch of the Great Ocean Conveyer Belt, and plays an important role in Indo-Pacific Basin interactions. By calculating the heat budget during single and triple La Niña events (1973–1976, 1998–2000, 2020–2023), we quantified the contribution of enhanced ITF heat transport to prolonging the recharge process during triple La Niña events. During triple La Niña events, the accumulated heat transported by the ITF is about −15.01 ZJ (more than twice that for single events), nearly offsetting the positive contribution of net heat flux from the atmosphere over the Pacific Ocean. Single La Niña events are confined to thermal processes within the Pacific Ocean, while triple events are products of basin interactions, and the ITF serves as a crucial oceanic link between the tropical Indian and Pacific Oceans. The enhanced heat transport of the ITF is concentrated in the subsurface layer (100–200 m), significantly during the second year of a triple La Niña event. The accumulation of enhanced ITF heat transport in the subsurface layer effectively expands the recharge–discharge area from the western Pacific to the eastern Indian Ocean, with the ensuing discharge process of the tropical Indian Ocean along with sustained La Niña conditions in the Pacific Ocean.
... Long-term data on tropical tree regeneration are also vital for predicting and managing effects of climate change on tropical forests (Comita and Engelbrecht, 2014). In the tropics, global climate change is expected to result in altered precipitation patterns, with predicted shifts in total annual rainfall and dry season length, as well as increases in extreme weather events, such as droughts (Cai et al., 2014;Chadwick et al., 2016). Predicting how these changes will affect tropical forests requires data on tropical tree species responses to water availability (Comita and Engelbrecht, 2014). ...
Dynamics at early life stages play a critical role in shaping the composition and diversity of tropical tree communities. To better understand spatial and temporal patterns of recruitment, growth, and survival at early life stages, we established a long-term census of woody seedlings and small saplings in the Barro Colorado Island 50-ha Forest Dynamics Plot. Individuals ≥20 cm tall and <1cm diameter at breast height (dbh) were censused in 18,434 1-m 2 seedling plots every one to two years between 2001 and 2018, resulting in a dataset of 1,002,400 observations of 185,693 individuals of more than 400 tree, shrub, and liana species. Here, we present patterns of seedling density and diversity from this long-term census and review the main findings of published studies that have used this dataset.
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... From 1981 (when NOAA dataset starts) sudden H W E drops are observed, which tend to correlate to El Niño/La Niña events and can be interpreted as due to the spatial structures formed by the uneven warming/cooling of the region during these events, 80 which accentuate due to global warming (Cai et al., 2014;Xie et al., 2010); however, H W E also decreases during other periods and further analysis is needed to understand the mechanisms underlying these variations. ...
Efficient data analysis techniques are urgently needed due to the large amount of data continuously generated by Earth modeling and monitoring systems. We show that the spatial permutation entropy (SPE) is a valuable technique to characterize spatio-temporal geophysical data, allowing detailed analysis at different scales. Specifically, we show that SPE is able to uncover differences in two sea surface temperature (SST) products, in two relevant geographical regions: the equatorial Pacific (Niño3.4) and the Gulf Stream. SPE is calculated as the entropy of the probabilities of occurrences of symbols that are defined along two orientations, west-east (WE) or north-south (NS), and either in consecutive grid points, or separated by a lag, δ. We find substantial differences between the analyzed datasets, for the WE orientation with δ = 1, that gradually disappear as δ increases. We also identify two transitions, one in year 2007 when ERA5 changed its sea–surface boundary condition to OSTIA, and the second one in 2021 when NOAA changed satellite, from MeteOp–A to MeteOp–C. These transitions were not detected when using conventional data analysis tools, which demonstrates that SPE is a valuable tool for the analysis of 2D geophysical data.
... In the future scenario, the SST horizontal gradient in the Equatorial Pacific will decrease, and the predicted future development of the ENSO will turn to more El Niño events, while the frequency of La Nina events will not change significantly [75]. In addition, the frequency of extreme ENSO events will increase as a result of climate change-induced increases in sea surface temperatures [76,77]. ...
The El Niño-Southern Oscillation (ENSO) alters ocean–atmosphere carbon exchange, but the mechanisms by which it affects the air–sea carbon flux (FCO2) remain unclear. Here, we used gridded FCO2 data from 2003 to 2021 to elucidate the control processes and regional differences in the influence of the ENSO on FCO2 in the mid–low latitude Pacific Ocean. Overall, the mid–low latitude Pacific Ocean region was a net sink for CO2, with an average uptake rate of −0.39 molC·m⁻²·year⁻¹. Specifically, during the La Niña period in 2010–2012, the absorption rate decreased by 15.38%, while during the El Niño period in 2015–2016, it increased by 30.77%. El Niño (La Niña) suppressed (promoted) biological primary production in the North Pacific, leading to reduced (enhanced) carbon uptake. El Niño (La Niña) also inhibited (promoted) physical vertical mixing in the Equatorial Pacific, leading to reduced (enhanced) carbon emissions. In the South Pacific, however, El Niño increased carbon uptake and La Niña decreased carbon uptake; although, not by these two processes. More frequent El Niño in the future will further reduce carbon absorption in the North Pacific and carbon emission in the Equatorial Pacific but increase carbon absorption in the South Pacific.
... El Niño is associated with milder and wetter conditions, while La Niña tends to bring colder and drier weather. These ENSO-related changes can impact European regions, affecting precipitation, temperature, and even extreme events (Brönnimann, 2007;Cai et al., 2010). Variations in the cloud cover show similarities with the variability modes of the ENSO, NAO, and QBO. ...
Norway spruce (Picea abies [L.] Karst.) is the most important economic tree species in Central Europe. It has been affected by extensive windstorms and bark beetle disturbances, which have intensified in recent years. Spruce stands are subject to regular reoccurring disturbances with different intensities. This study examines timber harvests in the Czech Republic and the tree-ring series of Norway spruce from six permanent research plots across the country. The timber harvest shows a cyclical connection with the sunspot number, and of these, the percentage of spruce logging shows a substantial link with the sunspot number while the percentage of salvage logging indicates a relation with Total Solar Irradiance (TSI) and seasonal temperature. The seasonal North Atlantic Oscillation (NAO) indicated a link with logging types as well. However, the connection between TSI and SunSpot Number (SSN) with logging types was statistically significant, while the tree rings were more related to seasonal NAO than timber harvests. The tree Ring Width Index (RWI) series shows reduced growth, which precedes the peak in the timber harvests by 1 year. Timber harvests peak one year after minimum RWI, and they coincide with solar minimum years. In summary, average tree ring series reach predominantly their lowest values one year before the solar minimum, coinciding with increased spruce and salvage logging. Conversely, during the solar maximum, harvests are lower, and tree ring series remain relatively stable. In the spectral analysis, tree-ring series and all types of timber harvests show a quasi-11-year cycle. Spruce trees indicate higher tree-ring growth and lower timber harvests during solar maximum compared to solar minimum and this may be associated with specific meteorological conditions that may be affected by solar variability. European forestry is unfamiliar with the effects of the solar cycle; nevertheless, this phenomenon is present in both spruce tree rings and the aggregate of timber harvests. Further research on this issue will be necessary, but it is already apparent that regularly recurring calamities in spruce stands are likely to be reflected in all of Central Europe.
... Precipitation is a critical component of the Earth's water cycle, directly impacting the accessibility of water resources. Alterations in the frequency, duration, and intensity of climate events resulting from changes in precipitation create environmental stress and pose threats to the global ecosystem (Allan et al. 2021;Cai et al. 2014;IPCC 2022). With the escalation of global climate change, there is an anticipation of shifts in the pattern, amount, and intensity of precipitation, leading to an increased occurrence of hydro-meteorological disasters like floods and droughts, which cause significant societal and environmental damage (Sahu et al. 2020a;Treut et al. 2020;Zhang et al. 2011). ...
Nepal has a unique physiographical heterogeneity inducing high precipitation variability. In the context of changing climate, a better understanding of such variability of precipitation poses considerable significance. This study investigates the spatio-temporal variation of precipitation and Precipitation Concentration Index (PCI) by analyzing monthly data from 79 meteorological stations across Nepal from 1990 to 2020. Mann–Kendall (MK) and Sen’s slope tests were applied to determine the trends of precipitation and PCI. The influence of large atmospheric circulation patterns on precipitation and PCI was also evaluated using Pearson’s correlation coefficient. Additionally, the study examined the relationship of five geographical factors, namely, longitude, latitude, elevation, slope, and aspect with PCI. Results show that the annual PCI values range from 14.06 (moderate) to 25.34 (strongly irregular). Notably, lowland regions exhibit higher precipitation irregularity compared to the hilly and mountainous areas. Annual precipitation is declining at an average rate of 4.98 mm per year, while annual PCI is increasing at 0.53 per decade across the country. The correlation between precipitation and Niño 3.4 index is found significantly (p < 0.05) negative over most parts of Nepal. Additionally, PCI and the absolute Niño 3.4 index were seen to have a significant negative correlation. This study further demonstrates a strong positive association between the PCI and sea surface temperature across maritime continents. Likewise, there is a significant negative correlation between elevation (-0.59) and slope (-0.29) with PCI. These valuable insights hold practical significance for disaster preparedness, water resource management, and agriculture planning in Nepal.
... Many investigations into long-term ENSO strength examine a moving multidecadal standard deviation (e.g. Cai et al., 2014) effectively ignoring shifts in the background mean. Another strategy involves metrics based on temperature differences, such as equatorial versus tropical Pacific SST anomalies (Oldenborgh et al., 2021), which effectively filter out part of the global warming signal. ...
Marine heatwaves (MHWs), prolonged periods of unusually high ocean temperatures, significantly impact global ecosystems. However, there is ongoing debate regarding the definition of these extreme events, which is crucial for effective research and communication among marine scientists, decision-makers, and the broader public. Fundamental to all MHW analyses is a clearly defined background oceanic climate – i.e., a temperature ‘baseline’ against which the MHW is defined. While a single approach to implementing a baseline may not be suitable for all MHW research applications, the choice of a baseline for analysing MHWs must be intentional as it affects research outcomes. This perspective examines baseline choices and discusses their implications for marine organism and ecosystem risks, and their relevance in communicating MHW characteristics and metrics to stakeholders, policymakers, and the public. In particular we analyse five different baseline approaches for computing MHW statistics, assess their technical differences, and discuss their ecological implications. Different baselines suggest widely different trends in MHW characteristics in a warming world. This would, for example, imply differences in future risk, reflective of marine organisms with different adaptive potential, thereby affecting recommendations for management strategies. We also examine the consequences of different baseline choices on ease of implementation and communication with wider audiences. Our analyses highlight the need to clearly specify a chosen baseline in MHW studies, and to be mindful of its implications for MHW statistics, practical considerations, and interpretations concerning the adaptive capacities of marine organisms, ecosystems and human systems. The challenges and implications of different MHW baselines highlighted here have similar relevance in research and communication for other branches of climate extremes.
... Most studies that are typically driven by model inter-comparison project phase five (CMIP5) or six (CMIP6) simulations of the 2000 to 2099 period, find a connection between anthropogenic climate change and increased Niño 3.4 variability. Doubling of the Niño 3.4 variability represents a moderately large increase within the context of this literature, though several authors have suggested this represents the difficulty of representing changes in ENSO dynamics using single index (Cai et al., 2014;Fredriksen et al., 2020;Yun et al., 2021). More generally, a consensus is building that supports the idea that ENSO-driven interannual variability will increase, leading to more extreme El Niño/La Niña events (Cai et al., 2021). ...
The threat that climate change poses to water resource systems has led to a substantial and growing number of impact studies. These studies follow two approaches: (a) top‐down studies are driven by projections of future climate change provided by downscaled general circulation models (GCMs); and (b) bottom‐up studies are driven by the systematic evaluation of exploratory scenarios. Top‐down approaches produce realistic scenarios rooted in the simulation of thermodynamic and dynamic processes represented in GCMs, but the internal resolution of these processes make it difficult to link vulnerabilities to discrete components of change. Bottom‐up approaches link vulnerabilities to discrete components of change through the structured evaluation of exploratory scenarios, but the lack of insight rooted in climate change processes can lead to the development of implausible scenarios. This paper evaluates exploratory scenarios developed through thermodynamic and dynamical guided perturbations motivated by GCM‐bound insights. The result is a hybrid approach that bridges a gap between top‐down and bottom‐up approaches. This yields several advantages. First, emerging vulnerabilities are linked to distinct thermodynamic and dynamic processes that are modeled in GCMs with differential likelihoods and plausible ranges of change. Second, the structured evaluation of process‐informed exploratory scenarios link system vulnerabilities to distinct components of climate change. An illustrative case study demonstrates perturbations linked to thermodynamic and dynamical processes have a large impact on stakeholder‐defined flood and drought performance, and the structured evaluation of process‐informed exploratory scenarios find nuanced infrastructure‐specific vulnerabilities that would be difficult to identify using an alternative approach.
... The scientific consensus, supported by studies such as Trenberth (2011), GISTEMP (Gistemp 2018) and Cai et al. (2014), suggests that climate change will disrupt precipitation patterns, increasing the likelihood of droughts or floods while global temperatures rise and sea levels elevate. Developing robust and adaptive rice varieties is essential to effectively addressing the effects of climate change in response to these issues (Zhang et al. 2023). ...
Human society is contending with a substantial environmental issue in the shape of global warming. IPCC’s sixth assessment report indicates that high-emission climate change scenarios are expected to render around 10% of the currently suitable cropland unusable by the middle of this century. Rice, among the food crops, holds paramount significance in the context of global food security. Until now, annual rice production has matched the requirements due to advancements in understanding the crop’s physiological and biochemical processes, the genetics of key traits, and the rapid transition and refinement of breeding tools. Rice production must be sustained in the coming years due to the crop’s increased susceptibility to severe biotic and abiotic challenges, particularly unexpected drought and submergence, caused by changing climatic circumstances. Increased events of drought and submergence, seawater intrusions and inland salinity pose serious threats to rice production. Hence, breeding for climate-resilient rice varieties becomes paramount to ensure future rice demands. In the recent past, mechanisms underlying climate resilience in rice have been unraveled, which accelerate the discovery of several resistant genes/QTL regions against various stresses. Ultimately, marker-assisted breeding programs were intensified by the researchers across the globe. Further, establishing well-informed regulatory frameworks concerning new breeding technologies and enhanced collaboration in sharing genetic resources, genomic data, and bioinformatics proficiency between developed and developing countries will be pivotal in effectively addressing the multifaceted challenges arising from rapidly evolving climatic conditions and escalating food demands. The upcoming obstacles to long-term sustainable rice production in the face of global climate change are covered in this chapter, along with contemporary breeding techniques for climate-resilient rice.
... Obtaining a reliable projection of the tropical Pacific zonal sea surface temperature (SST) gradient change in response to greenhouse gases (GHGs)-induced global warming is one of the most important issues in climate science research, as it exerts crucial impacts on changes in the El Niño-Southern Oscillation (Alizadeh, 2022;Collins et al., 2010) and the global hydrological cycle (Dong et al., 2021;Xie et al., 2010). Most state-of-the-art climate models, such as those participating in Phase 5 or 6 of the Coupled Model Inter-comparison Project (Eyring et al., 2016;Taylor et al., 2012), project an El Niño-like pattern with more SST warming in the eastern equatorial Pacific (EEP) than the western equatorial Pacific (WEP) (Heede & Fedorov, 2021;Watanabe et al., 2020), which has strong implications for changes in ENSO events (Cai et al., 2014;Zheng et al., 2016) and rainfall change patterns (Huang, 2014). ...
Reliable projections of the tropical Pacific sea surface temperature (SST) warming (TPSW) patterns are critically important for exploring the future climate change. However, climate models suffer from long‐standing common biases in simulating the present‐day climate, raising doubts about the model projected TPSW patterns. Here by using outputs from 30 CMIP6 models, we find the projected TPSW patterns are significantly correlated with the simulated present‐day SST in the tropical North Atlantic (TNA), with higher present‐day TNA SSTs tending to project more weakened zonal SST gradients by producing more present‐day low‐level clouds and the resultant positive cloud–shortwave–SST feedbacks over the eastern equatorial Pacific. An emergent constraint using observed TNA SST reveals a consistent El Niño‐like warming pattern in all models with more weakened zonal SST gradient than before in most models, together with a reduction of the inter‐model uncertainty in the zonal SST gradient change by more than 20%.
... As ectothermic animals, fish experience direct impacts on their body temperature, growth, reproduction, and various life activities from the ambient water temperature. In the context of global climate change, cold and hot extreme weather events are becoming increasingly frequent [1,2]. In recent decades, marine organism have been increasingly exposed to unsuitable temperature stressors [3,4]. ...
Background
The leopard coral grouper (Plectropomus leopardus) is a commercially valuable tropical marine fish species known to be sensitive to low temperatures. A comprehensive understanding of the molecular mechanisms governing its response to acute cold stress is of great importance. However, there is a relative scarcity of fundamental research on low-temperature tolerance in the leopard coral grouper.
Methods
In this study, a cooling and rewarming experiment was conducted on 6-month-old leopard coral groupers. Within 24 h, we decreased the ambient temperature from 25 °C to 13 °C and subsequently allowed it to naturally return to 25 °C. During this process, a comprehensive investigation of serum hormone levels, enzyme activity, and brain transcriptome analysis was performed.
Results
P. leopardus displayed a noticeable adaptive response to the initial temperature decrease by temporarily reducing its life activities. Our transcriptome analysis revealed that the differentially expressed genes (DEGs) were primarily concentrated in crucial pathways including the blood-brain barrier (BBB), inflammatory response, and coagulation cascade. In situ hybridization of claudin 15a (cldn15a), a key gene for BBB maintaining, further confirmed that exposure to low temperatures led to the disruption of the blood-brain barrier and stimulated a pronounced inflammatory reaction within the brain. Upon rewarming, there was a recovery of BBB integrity accompanied by the persistence of inflammation within the brain tissue.
Conclusions
Our study reveals the complex interactions between blood-brain barrier function, inflammation, and recovery in P. leopardus during short-term temperature drops and rewarming. These findings provide valuable insights into the physiological responses of this species under cold stress conditions.
... This is made more relevant as basin-wide processes such as the Indian Ocean Dipole (IOD) and Pacific Decadal Oscillation (PDO) are intensifying (Mantua & Hare 2002;Wang et al. 2017) and increasing the variability of climate signals at regional and local scales (Smith & Sardeshmukh 2000;Cai et al. 2005). For example, within decadal shifts of the PDO, increased interannual variability in the El Niño Southern Oscillation (ENSO) (Cai et al. 2014;Pathirana et al. 2023) has likely led to an increased frequency of marine heatwaves (Holbrook et al. 2019;Ryan et al. 2021) and impacted boundary current strength (Ong et al. 2018). These changing conditions in turn impact local-scale sea surface temperatures (SST) and other environmental conditions that affect ectotherm metabolic processes (Pörtner and Knust 2007), fitness, growth (Gillanders et al. 2012), behaviour (Mitchell et al. 2022), and distribution (Gervais et al. 2021). ...
Fish growth underpins individual fitness and population-level metrics, with fluctuations linked to environmental variability. Growth chronologies derived from otolith increment analysis are a powerful proxy to understand population responses to environmental change and productivity. Yet, long-term patterns of growth and their environmental drivers are better understood for shallow-water species compared to deep-water inhabitants. Additionally, focus is largely on adults, disregarding the potential influence of juvenile growth which is critical to size- and age-at-maturity. Here, we investigate the long-term growth patterns of two commercially important snapper species separated by depth in northwestern Australia’s coastal shelf waters, the shallow-water Lutjanus sebae (70 year chronology, 1950–2020) and the deep-water Etelis boweni (41 year chronology, 1973–2013). Annually-resolved otolith growth chronologies revealed distinct environmental sensitivities within (juveniles vs adults) and among (shallow- vs deep-water habitats) species. Within species, juveniles and adults responded differently to shared environmental stimuli, highlighting the importance of understanding the impacts of environmental effects and sensitivities for different life-history stages. Across species, L. sebae exhibited highly variable growth tied to local climate signals such as sea surface temperature and rainfall, while E. boweni displayed more stable growth patterns that only responded to interannual and decadal shifts in the environment (e.g. Pacific Decadal Oscillation). Our results highlight potential vulnerabilities of shallow-water species to future environmental perturbations compared to species residing at depth, as they are likely to encounter more extreme climate variability under future oceanic conditions. This study contributes valuable insights into understanding and managing the impacts of future environmental variability on fisheries sustainability, emphasising the need for continued research across species and habitats.
... The weakened quasi-biennial tendency is associated with the increasing frequency of multi-year El Niño events ( Figure S2a in Supporting Information S1; Ding et al., 2022). Models also project an increase in the frequency of extreme El Niño events ( Figure S2b in Supporting Information S1), which is consistent with Cai et al. (2014). However, the increased frequency of extreme El Niño events does not lead to an enhancement of biennial component of ENSO forcing. ...
Plain Language Summary
A positive Indian Ocean Dipole (pIOD) could induce droughts and floods in the eastern and western Indian Ocean countries, respectively. In consecutive pIOD events, the multi‐year accumulation of precipitation anomalies leads to more severe and prolonged climate anomalies than that in a single pIOD event. Observations show that consecutive pIOD events have become more frequent under global warming. They occurred only twice in the last 50 years of last century and have already occurred three times in the first 20 years of this century. Model outputs suggest that the observed increasing trend of consecutive pIOD frequency will continue in future. The overall frequency of consecutive pIOD will increase by 131.3% over 1950–2100. More than 65% of pIOD will manifest as consecutive pIOD events in the second half of this century. Mixed consecutive pIOD that start with ENSO‐pIOD increases fastest among all types of consecutive pIOD events. The increase in consecutive pIOD is contributed by higher ENSO‐pIOD frequency, weaker biennial component of ENSO forcing, and more active IOD triggers other than ENSO. Climate extremes associated with consecutive pIOD events are likely to occur more often in the Indian Ocean surrounding countries due to more frequent consecutive pIOD events.
Precision farming is an optimized management farming scheme that seeks to link the real-time needs of crops with the nutrients to be administered. Sensing platforms that can monitor the physiological status of crops in situ are key to enabling timely and localized interventions. However, the underdevelopment of plant sensing strategies limits the potential of precision farming. In this Review, we discuss the challenges and advancements in phyto-monitoring, focusing on strategies that are applicable to a wide range of plant species and suitable for field deployment. We explore species-agnostic sensors, including optical and electrochemical sensors, whose operation is based on principles that are widely applicable to all plant species. These platforms enable real-time monitoring of the physiological state of crops by assessing key biomarkers, such as plant hormones, and metabolites such as salicylic acid and reactive oxygen species. Evaluating these systems, we conclude that an integrative sensing approach is necessary to compensate for the limitations of the individual methods and can provide a holistic view of crop health. Cost-effective species-agnostic sensors are thus needed to provide information that can be used to minimize the resource footprint of farming and meet the growing global demand.
Climate change is increasing the frequency of large-scale, extreme environmental events and flattening environmental gradients. Whether such changes will cause spatially synchronous, large-scale population declines depends on mechanisms that limit metapopulation synchrony, thereby promoting rescue effects and stability. Using long-term data and empirical dynamic models, we quantified spatial heterogeneity in density dependence, spatial heterogeneity in environmental responses, and environmental gradients to assess their role in inhibiting synchrony across 36 marine fish and invertebrate species. Overall, spatial heterogeneity in population dynamics was as important as environmental drivers in explaining population variation. This heterogeneity leads to weak synchrony in the California Current Ecosystem, where populations exhibit diverse responses to shared, large-scale environmental change. In contrast, in the Northeast U.S. Shelf Ecosystem, gradients in average environmental conditions among locations, filtered through nonlinear environmental response curves, limit synchrony. Simulations predict that environmental gradients and response diversity will continue to inhibit synchrony even if large-scale environmental extremes become common. However, if environmental gradients weaken, synchrony and periods of large-scale population decline may rise sharply among commercially important species on the Northeast Shelf. Our approach thus allows ecologists to 1) quantify how differences among local communities underpin landscape-scale resilience and 2) identify the kinds of future climatic changes most likely to amplify synchrony and erode species stability.
Seed priming technology (SP) is a practice (conducted prior to sowing) where seeds are treated with a wide range of seed priming agents (SPA) for a set time period followed by withdrawal. The efficacy of SP has been widely examined against various abiotic and biotic stressors with various crops in controlled field environmental conditions. Among the abiotic stressors, heavy metals and/or metalloids (HMs) are considered as a serious threat to sustainable agriculture. Compared with other stressors, the efficacy of SP in ameliorating HM-induced phytotoxicity and minimizing HMs content in edible parts are limited. However, there is a lack of a comprehensive study dedicated to HMs stress in wide range of crops. This review article employs a blend of bibliometric-based analysis (to assess global trends) followed by systematic evaluation of traditional (micronutrient, biomolecules, etc.) and nanomaterial (NMs)-based SPAs in ameliorating HMs-induced stress and accumulation in various crops. Our assessment suggests SPs as a suitable means to fill the vacuum that exists among the controlled environment and field condition, cost effective, easy remedial measure for HMs-induced stress. However, the need of in-depth (cellular and molecular level) as well as multi-location trials will definitely add to the current knowledge for development of effective HM stress resilience.
In the late spring to summer season of 2023, Canada witnessed unprecedented wildfires, with an extensive burning area and smoke spreading as far as the East Coast of the United States and Europe. Here, using multisource data analysis and climate model simulations, we show that an abnormally warm North Atlantic, as well as an abnormally low Barents Sea ice concentration (SIC), are likely key climate drivers of this Canadian fire season, contributing to ~80% of the fire weather anomaly over Canada from June to August 2023. Specifically, the warm North Atlantic forms an anomalous regional zonal cell with ascending air over the Atlantic and descending air encircling Canada, creating hot and dry local conditions. Meanwhile, reduced Barents SIC leads to a high-pressure center and reinforces the dry northern winds in Canada through Rossby wave dynamics. These exacerbated dry and hot conditions create a favorable environment for the ignition and spread of fires, thus contributing to the prolonged and extreme fire season in Canada. These teleconnections can extend to decadal scales and have important implications for understanding and predicting decadal fire activity in Canada and the surrounding regions.
Amid escalating global marine heat waves, the Arabian Gulf is critical due to its shallow depths, high temperatures, and vulnerability to climate change impacts. This study provides a detailed spatio-temporal analysis of marine heatwave events from 1982 to 2022 across the Arabian Gulf and the adjacent Gulf of Oman. The study delineates regions of heightened vulnerability within these water bodies by comprehensively analyzing seasonal and annual variabilities and trend assessments. Moreover, an exploration of prevailing surface circulation patterns, underpinned by an extensive study of global circulation model outputs, elucidates the oceanographic mechanisms contributing to temperature dynamics. Identifying 25 significant heat wave events, with a focused examination of the six most protracted episodes, is noteworthy among the findings. Strikingly, the analysis reveals that the Gulf of Oman surpasses the Arabian Gulf in heatwave intensity. Looking forward, the investigation extends to future surface water temperature projections up to the close of the current century. The collective results underscore the region's acute susceptibility to the climate change perturbations of climate change, emphasizing the urgency of targeted interventions to mitigate these effects and address concurrent local stressors.
This study investigates the changes in rainfall dynamics in Tanzania, focusing specifically on the onset and precipitation probability of rainy seasons. The research stems from growing concerns about climate variability in East Africa, which has significant implications for agriculture, water resources, and food security. Despite Tanzania's heavy reliance on rain-fed agriculture, there is a lack of understanding regarding how rainfall patterns are shifting, impacting both local farmers and national policies. Utilizing time series analysis and the Instat Climatic tool for the assessment of rainfall onset dates, Mann-Kendall (MK) test, Sen’s slope estimator (Q 2 ) for onset dates trend analysis and Markov chain model for precipitation probability, we analysed historical rainfall data from 27 weather stations (regions) across Tanzania. Our findings indicate a noticeable shift in the onset of the rainy seasons, with variability in the trends of rainfall onset across different regions. Furthermore, a consistent pattern wherein southern and central regions tend to witness prolonged waiting times for the start of the rainy season and increase in the probability of rain following a rainy day (rr), while the probability following a dry day (rd) remains relatively stable. These results highlight critical adaptations necessary for agriculture and water management strategies in Tanzania. Late rainfall onset could hinder crop growth, particularly for maize and other staple foods, leading to potential food shortages and economic instability if no adaptive measures are implemented. The findings underscore the need for interdisciplinary collaboration to develop robust frameworks that integrate climatic forecasts into agricultural planning. Understanding the shifting dynamics of rainfall is essential not only for Tanzania but also for other regions facing similar climate challenges, emphasizing the interconnectedness of climate change impacts on food systems and livelihoods around the world.
The objective of this study was to verify and test the association between concern and negative emotions about climate change and depression, anxiety, and stress in students in Rio Grande, Brazil, before and after the 2024 extreme climate event. This is a quantitative study, with before and after measurements, with a single group. The questions measured the outcome: “Are you concerned about climate change?” and “Do you have negative emotions about climate change or thoughts and feelings that bad things could happen to the planet because of climate change?” The DASS-21 measured mental health. Adjusted analyses were conducted using linear regression, with results presented in beta coefficient and 95% CI. We observed an increasing concern (p=0.004) and negative emotions about the climate (p=0.019), depression (p=0.047), anxiety (p=0.043), and stress (p=0.010) symptoms from pre- to post-event. The depression score increased significantly in those who were concerned about climate change before and after the event (b=4.64, 95%CI=1.91; 7.38; p=0.006), as did depression and anxiety scores in those with negative emotions about the climate (b=5.11, 95%CI=1.59; 8.62; p=0.015; (b=4.43, 95%CI=1.28; 7.78; p=0.028, respectively). It is concluded that the students assessed increased their concern and negative emotions about the climate and deteriorated mental health after an extreme event.
The El Niño–Southern Oscillation (ENSO), originating in the central and eastern equatorial Pacific, is a defining mode of interannual climate variability with profound impact on global climate and ecosystems. However, an understanding of how the ENSO might have evolved over geological timescales is still lacking, despite a well-accepted recognition that such an understanding has direct implications for constraining human-induced future ENSO changes. Here, using climate simulations, we show that ENSO has been a leading mode of tropical sea surface temperature (SST) variability in the past 250 My but with substantial variations in amplitude across geological periods. We show this result by performing and analyzing a series of coupled time-slice climate simulations forced by paleogeography, atmospheric CO 2 concentrations, and solar radiation for the past 250 My, in 10-My intervals. The variations in ENSO amplitude across geological periods are little related to mean equatorial zonal SST gradient or global mean surface temperature of the respective periods but are primarily determined by interperiod difference in the background thermocline depth, according to a linear stability analysis. In addition, variations in atmospheric noise serve as an independent contributing factor to ENSO variations across intergeological periods. The two factors together explain about 76% of the interperiod variations in ENSO amplitude over the past 250 My. Our findings support the importance of changing ocean vertical thermal structure and atmospheric noise in influencing projected future ENSO change and its uncertainty.
El Nino events, characterized by anomalous warming in the eastern equatorial Pacific Ocean, have global climatic teleconnections and are the most dominant feature of cyclic climate variability on subdecadal timescales. Understanding changes in the frequency or characteristics of El Nino events in a changing climate is therefore of broad scientific and socioeconomic interest. Recent studies(1-5) show that the canonical El Nino has become less frequent and that a different kind of El Nino has become more common during the late twentieth century, in which warm sea surface temperatures (SSTs) in the central Pacific are flanked on the east and west by cooler SSTs. This type of El Nino, termed the central Pacific El Nino (CP-El Nino; also termed the dateline El Nino(2), El Nino Modoki(3) or warm pool El Nino(5)), differs from the canonical eastern Pacific El Nino (EP-El Nino) in both the location of maximum SST anomalies and tropical-midlatitude teleconnections. Here we show changes in the ratio of CP-El Nino to EP-El Nino under projected global warming scenarios from the Coupled Model Intercomparison Project phase 3 multi-model data set(6). Using calculations based on historical El Nino indices, we find that projections of anthropogenic climate change are associated with an increased frequency of the CP-El Nino compared to the EP-El Nino. When restricted to the six climate models with the best representation of the twentieth-century ratio of CP-El Nino to EP-El Nino, the occurrence ratio of CP-El Nino/EP-El Nino is projected to increase as much as five times under global warming. The change is related to a flattening of the thermocline in the equatorial Pacific.
The interannual variability of the South Pacific Convergence Zone (SPCZ) and its influence on tropical cyclone (TC) genesis in the South Pacific are investigated using observations and ERA40 reanalysis over the 1979–2002 period. In austral summer, the SPCZ displays four typical structures at interannual timescales. The first three are characterized by a diagonal orientation of the SPCZ and account for 85% of the summer seasons. One is close to climatology and the other two exhibit a 3° northward or southward departure from the SPCZ climatological position. In contrast, the fourth one, that only encompasses three austral summer seasons (the extreme 1982/1983 and 1997/1998 El Niño events and the moderate 1991/1992 El Niño event), displays very peculiar behaviour where the SPCZ largely departs from its climatological position and is zonally oriented. Variability of the western/central Pacific equatorial sea surface temperature (SST) is shown to modulate moisture transport south of the equator, thereby strongly constraining the location of the SPCZ. The SPCZ location is also shown to strongly modulate the atmospheric circulation variability in the South Pacific with specific patterns for each class. However, independently of its wide year-to-year excursions, the SPCZ is always collocated with the zero relative vorticity at low levels while the maximum vorticity axis lies 6° to the south of the SPCZ position. This coherent atmospheric organisation in the SPCZ region is shown to constrain tropical cyclogenesis to occur preferentially within 10° south of the SPCZ location as this region combines all the large-scale atmospheric conditions that favour the breeding of TCs. This analysis also reveals that cyclogenesis in the central Pacific (in the vicinity of French Polynesia) only occurs when the SPCZ displays a zonal orientation while this observation was previously attributed to El Niño years in general. Different characteristics of El Niño Southern Oscillation (ENSO)-related Pacific equatorial warming are shown to impact differently on the SPCZ position, suggesting that for regional scales, such as the South Pacific, the SPCZ classification is more appropriate than a simple ENSO index to characterize TC interannual variability. These findings suggest that forecasting the strength of El Niño through SST variations in the eastern Pacific may not be sufficient to accurately predict cyclogenesis in the South Pacific, especially east of the dateline.
Natural disasters like the “El Niño” phenomenon often hit hardest on the poor. Yet, it is often difficult to separate the effects on living conditions resulting from inclement weather from general inadequacies in infrastructure and lack of economic development. This study proposes methodologies to identify different types of risks associated with natural disasters and to establish degrees of vulnerability to such risks by geographical areas and population groups. It finds that most economic costs in Ecuador relate to losses of agricultural production and damages to infrastructure. Increased health risks are also critical. Outcomes suggest that most of the agricultural income losses are borne by small farmers in the production of rice, corn, coffee and cocoa, and to a lesser extent by agricultural workers in the sugar cane industry and banana plantations. The overall impact on the already high poverty incidence in the affected areas could be as large as 10 percentage points. For some, El Niño was not a disaster but a boon. Wealthy shrimp producers, in particular, saw productivity increase by over 25%, while banana exporters can compensate for produc-tion losses through higher export quotas and prices. Health risks are greatest in areas with poor sanitary infrastructure and poor overall social conditions.
A series of 200 year long integrations is performed using the
Geophysical Fluid Dynamics Laboratory CM2.1 by varying the Tokioka
parameter, a minimum entrainment rate threshold in the cumulus
parameterization. Changing the threshold alters both the tropical
Pacific mean state and the El Niño-Southern Oscillation (ENSO)
variability. Increasing the Tokioka parameter causes a basin-wide
cooling in the tropical Pacific with the reduction of high clouds. The
degree of cooling in the western part of the basin is bigger than that
in the east. As a result, the east-west asymmetry in the tropical
Pacific sea surface temperature (SST) decreases with increasing the
Tokioka parameter. Accompanied with the reduced east-west SST asymmetry
are the increase of mean precipitation over the eastern Pacific and the
eastward shift of the atmospheric responses to the ENSO-related SST
forcing. The eastward shifted wind stress anomaly associated with ENSO
leads to the stronger ENSO variability. In this way the magnitude of
ENSO simulated in this model increases with the Tokioka parameter.
Implication of our results on the relationship between the tropical
Pacific mean state and ENSO is discussed.
We present the Met Office Hadley Centre's sea ice and sea surface temperature (SST) data set, HadISST1, and the nighttime marine air temperature (NMAT) data set, HadMAT1. HadISST1 replaces the global sea ice and sea surface temperature (GISST) data sets and is a unique combination of monthly globally complete fields of SST and sea ice concentration on a 1° latitude-longitude grid from 1871. The companion HadMAT1 runs monthly from 1856 on a 5° latitude-longitude grid and incorporates new corrections for the effect on NMAT of increasing deck (and hence measurement) heights. HadISST1 and HadMAT1 temperatures are reconstructed using a two-stage reduced-space optimal interpolation procedure, followed by superposition of quality-improved gridded observations onto the reconstructions to restore local detail. The sea ice fields are made more homogeneous by compensating satellite microwave-based sea ice concentrations for the impact of surface melt effects on retrievals in the Arctic and for algorithm deficiencies in the Antarctic and by making the historical in situ concentrations consistent with the satellite data. SSTs near sea ice are estimated using statistical relationships between SST and sea ice concentration. HadISST1 compares well with other published analyses, capturing trends in global, hemispheric, and regional SST well, containing SST fields with more uniform variance through time and better month-to-month persistence than those in GISST. HadMAT1 is more consistent with SST and with collocated land surface air temperatures than previous NMAT data sets.
El Niño events, characterized by anomalous warming in the eastern equatorial Pacific Ocean, have global climatic teleconnections and are the most dominant feature of cyclic climate variability on sub-decadal timescales. Understanding changes in the frequency or characteristics of El Niños in a changing climate is therefore of broad scientific and socioeconomic interest. Recent studies show that the canonical El Niño has become less frequent and that a different El Niño "flavor" has become more common during the late twentieth century in which warm sea surface temperature (SST) in the central Pacific is flanked on the east and west by cooler SST. This flavor, termed the central Pacific El Niño (CP-El Niño; also termed the dateline El Niño or El Niño Modoki or Warm pool El Nino), differs from the canonical eastern Pacific El Niño (EP-El Niño) in both the location of maximum SST anomalies and tropical-midlatitude teleconnections. Here we show changes in the ratio of CP-El Niño to EP-El Niño under projected global warming scenarios from the Coupled Model Intercomparison Project phase 3 multi-model dataset.Using calculations based on historical El Niño indices, we find that projections of anthropogenic climate change are associated with an increased frequency of the CP-El Niño compared to the EP-El Niño. When restricted to the six climate models with the best representation of the twentieth century ratio of CP-El Niño to EP-El Niño, the occurrence ratio of CP-El Niño/EP-El Niño is projected to increase as much as five times under global warming. The change is related to a flattening of the thermocline in the equatorial Pacific.
The Global Precipitation Climatology Project (GPCP) Version-2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5 8 latitude 3 2.58 longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit satellite microwave data, geosynchronous-orbit satellite infrared data, and surface rain gauge obser- vations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The dataset is extended back into the prem- icrowave era (before mid-1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the rain gauge analysis. The dataset archive also contains the individual input fields, a combined satellite estimate, and error estimates for each field. This monthly analysis is the foundation for the GPCP suite of products, including those at finer temporal resolution. The 23-yr GPCP climatology is characterized, along with time and space variations of precipitation.
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.
Using observed data sets mainly for the period 1979–2005, we find that anomalous warming events different from conventional El Niño events occur in the central equatorial Pacific. This unique warming in the central equatorial Pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly (SSTA) on both sides along the equator. empirical orthogonal function (EOF) analysis of monthly tropical Pacific SSTA shows that these events are represented by the second mode that explains 12% of the variance. Since a majority of such events are not part of El Niño evolution, the phenomenon is named as El Niño Modoki (pseudo-El Niño) (“Modoki” is a classical Japanese word, which means “a similar but different thing”). The El Niño Modoki involves ocean-atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution, analogous to the Southern Oscillation in the case of El Niño. Hence the total entity is named as El Niño–Southern Oscillation (ENSO) Modoki. The ENSO Modoki events significantly influence the temperature and precipitation over many parts of the globe. Depending on the season, the impacts over regions such as the Far East including Japan, New Zealand, western coast of United States, etc., are opposite to those of the conventional ENSO. The difference maps between the two periods of 1979–2004 and 1958–1978 for various oceanic/atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline. This appears to be a cause of more frequent and persistent occurrence of the ENSO Modoki event during recent decades.
The El Niño–Southern Oscillation (ENSO) is a naturally occurring fluctuation that originates in the tropical Pacific region and affects ecosystems, agriculture, freshwater supplies, hurricanes and other severe weather events worldwide. Under the influence of global warming, the mean climate of the Pacific region will probably undergo significant changes. The tropical easterly trade winds are expected to weaken; surface ocean temperatures are expected to warm fastest near the equator and more slowly farther away; the equatorial thermocline that marks the transition between the wind-mixed upper ocean and deeper layers is expected to shoal; and the temperature gradients across the thermocline are expected to become steeper. Year-to-year ENSO variability is controlled by a delicate balance of amplifying and damping feedbacks, and one or more of the physical processes that are responsible for determining the characteristics of ENSO will probably be modified by climate change. Therefore, despite considerable progress in our understanding of the impact of climate change on many of the processes that contribute to El Niño variability, it is not yet possible to say whether ENSO activity will be enhanced or damped, or if the frequency of events will change.
The South Pacific convergence zone (SPCZ) is the Southern Hemisphere's most expansive and persistent rain band, extending from the equatorial western Pacific Ocean southeastward towards French Polynesia. Owing to its strong rainfall gradient, a small displacement in the position of the SPCZ causes drastic changes to hydroclimatic conditions and the frequency of extreme weather events--such as droughts, floods and tropical cyclones--experienced by vulnerable island countries in the region. The SPCZ position varies from its climatological mean location with the El Niño/Southern Oscillation (ENSO), moving a few degrees northward during moderate El Niño events and southward during La Niña events. During strong El Niño events, however, the SPCZ undergoes an extreme swing--by up to ten degrees of latitude toward the Equator--and collapses to a more zonally oriented structure with commensurately severe weather impacts. Understanding changes in the characteristics of the SPCZ in a changing climate is therefore of broad scientific and socioeconomic interest. Here we present climate modelling evidence for a near doubling in the occurrences of zonal SPCZ events between the periods 1891-1990 and 1991-2090 in response to greenhouse warming, even in the absence of a consensus on how ENSO will change. We estimate the increase in zonal SPCZ events from an aggregation of the climate models in the Coupled Model Intercomparison Project phases 3 and 5 (CMIP3 and CMIP5) multi-model database that are able to simulate such events. The change is caused by a projected enhanced equatorial warming in the Pacific and may lead to more frequent occurrences of extreme events across the Pacific island nations most affected by zonal SPCZ events.
Spatial variations in sea surface temperature (SST) and rainfall changes over the tropics are investigated based on ensemble simulations for the first half of the 21st century under the greenhouse gas (GHG) emission scenario A1B with coupled ocean-atmosphere general circulation models at the Geophysical Fluid Dynamics Laboratory (GFDL) and National Center for Atmospheric Research (NCAR). Despite a GHG increase that is nearly uniform in space, pronounced patterns emerge in both SST and precipitation. Regional differences in SST warming can be as large as the tropical mean warming. Specifically, the tropical Pacific warming features a conspicuous maximum along the equator and a minimum in the southeast subtropics. The former is associated with westerly wind anomalies while the latter is linked to intensified southeast trade winds, suggestive of wind-evaporation-SST feedback. There is a tendency for a greater warming in the northern than southern subtropics in accordance with asymmetries in trade wind changes. Over the equatorial Indian Ocean, surface wind anomalies are easterly, the thermocline shoals and the warming is reduced in the east, indicative of Bjerknes feedback. In the midlatitudes, ocean circulation changes generate narrow banded structures in SST warming. The warming is negatively correlated with wind speed change over the tropics, and positively correlated with ocean heat transport change in the northern extratropics. Tropical precipitation changes are positively correlated with spatial deviations of SST warming from the tropical mean. In particular, the equatorial maximum in SST warming over the Pacific anchors a band of pronounced rainfall increase. The gross moist instability follows closely relative SST change as equatorial wave adjustments flatten upper tropospheric warming. The comparison with atmospheric simulations in response to a spatially uniform SST warming illustrates the importance of SST patterns for rainfall change, an effect overlooked in current discussion of precipitation response to global warming. Implications for global and regional response of tropical cyclones are discussed.
This study examines the response of the tropical atmospheric and oceanic circulation to increasing greenhouse gases using a coordinated set of twenty-first-century climate model experiments performed for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). The strength of the atmospheric overturning circulation decreases as the climate warms in all IPCC AR4 models, in a manner consistent with the thermodynamic scaling arguments of Held and Soden. The weakening occurs preferentially in the zonally asymmetric (i.e., Walker) rather than zonal-mean (i.e., Hadley) component of the tropical circulation and is shown to induce substantial changes to the thermal structure and circulation of the tropical oceans. Evidence suggests that the overall circulation weakens by decreasing the frequency of strong updrafts and increasing the frequency of weak updrafts, although the robustness of this behavior across all models cannot be confirmed because of the lack of data. As the climate warms, changes in both the atmospheric and ocean circulation over the tropical Pacific Ocean resemble "El Niño–like" conditions; however, the mechanisms are shown to be distinct from those of El Niño and are reproduced in both mixed layer and full ocean dynamics coupled climate models. The character of the Indian Ocean response to global warming resembles that of Indian Ocean dipole mode events. The consensus of model results presented here is also consistent with recently detected changes in sea level pressure since the mid–nineteenth century.
The change in the teleconnections of both El Niño and La Niña over the North Pacific and American regions due to a future
greenhouse warming has been analyzed herein by means of diagnostics of the Intergovernmental Panel on Climate Change-Fourth
Assessment Report (IPCC-AR4) coupled general circulation models (CGCMs). Among the IPCC-AR4 CGCM simulations, the composites
of the eight-member multimodel ensemble are analyzed. In most CGCMs, the tropical Pacific warming due to the increase of CO2 concentration in the atmosphere promotes the main convection centers in the equatorial Pacific associated with both El Niño
and La Niña to the east. The eastward shift of the convection center causes a systematic eastward shift of not only El Niño
but also La Niña teleconnection patterns over the North Pacific and America, which is demonstrated in the composite maps of
500hPa circulation, surface temperature, and the precipitation against El Niño and La Niña, as observed in a comparison between
the pre-industrial and CO2 doubling experiments. Thus, a systematic eastward migration of convection centers in the tropical Pacific associated with
both El Niño and La Niña due to a future global warming commonly causes the eastward shift of the atmospheric teleconnection
patterns over the Northern Hemisphere.
As in the observed record, the termination of El Niño in the coupled IPCC-AR4 climate models involves meridional processes
tied to the seasonal cycle. These meridional processes both precondition the termination of El Niño events in general and
lead to a peculiar termination of extreme El Niño events (such as those of 1982–83 and 1997–98), in which the eastern equatorial
Pacific warm sea surface temperature anomalies (SSTA) persist well into boreal spring/early-summer. The mechanisms controlling
the peculiar termination of extreme El Niño events, which involves to the development of an equatorially centred intertropical
convergence zone, are consistent across the four models that exhibit extreme El Niños and observational record, suggesting
that this peculiar termination represents a general feature of extreme El Niños. Further, due to their unusual termination,
extreme El Niños exhibit an apparent eastward propagation of their SSTA, which can strongly influence estimates of the apparent
propagation of ENSO over multi-decadal periods. Interpreting these propagation changes as evidence of changes in the underlying
dynamical feedbacks behind El Niño could therefore be misleading, given the strong influence of a single extreme event.
KeywordsEl Niño/Southern Oscillation (ENSO)-Extreme events-IPCC-AR4 climate models-Coupled ocean–atmosphere mechanisms-Validation
The interannual variability of the South Pacific Convergence Zone (SPCZ) and its influence on tropical cyclone (TC) genesis
in the South Pacific are investigated using observations and ERA40 reanalysis over the 1979–2002 period. In austral summer,
the SPCZ displays four typical structures at interannual timescales. The first three are characterized by a diagonal orientation
of the SPCZ and account for 85% of the summer seasons. One is close to climatology and the other two exhibit a 3° northward
or southward departure from the SPCZ climatological position. In contrast, the fourth one, that only encompasses three austral
summer seasons (the extreme 1982/1983 and 1997/1998 El Niño events and the moderate 1991/1992 El Niño event), displays very
peculiar behaviour where the SPCZ largely departs from its climatological position and is zonally oriented. Variability of
the western/central Pacific equatorial sea surface temperature (SST) is shown to modulate moisture transport south of the
equator, thereby strongly constraining the location of the SPCZ. The SPCZ location is also shown to strongly modulate the
atmospheric circulation variability in the South Pacific with specific patterns for each class. However, independently of
its wide year-to-year excursions, the SPCZ is always collocated with the zero relative vorticity at low levels while the maximum
vorticity axis lies 6° to the south of the SPCZ position. This coherent atmospheric organisation in the SPCZ region is shown
to constrain tropical cyclogenesis to occur preferentially within 10° south of the SPCZ location as this region combines all
the large-scale atmospheric conditions that favour the breeding of TCs. This analysis also reveals that cyclogenesis in the
central Pacific (in the vicinity of French Polynesia) only occurs when the SPCZ displays a zonal orientation while this observation
was previously attributed to El Niño years in general. Different characteristics of El Niño Southern Oscillation (ENSO)-related
Pacific equatorial warming are shown to impact differently on the SPCZ position, suggesting that for regional scales, such
as the South Pacific, the SPCZ classification is more appropriate than a simple ENSO index to characterize TC interannual
variability. These findings suggest that forecasting the strength of El Niño through SST variations in the eastern Pacific
may not be sufficient to accurately predict cyclogenesis in the South Pacific, especially east of the dateline.
KeywordsSouth Pacific Convergence Zone–Interannual variability–Tropical cyclone–El Niño Southern Oscillation
A coordinated set of global coupled climate model [atmosphere-ocean general circulation model (AOGCM)] experiments for twentieth- and twenty-first-century climate, as well as several climate change commitment and other experiments, was run by 16 modeling groups from 11 countries with 23 models for assessment in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). Since the assessment was completed, output from another model has been added to the dataset, so the participation is now 17 groups from 12 countries with 24 models. This effort, as well as the subsequent analysis phase, was organized by the World Climate Research Programme (WCRP) Climate Variability and Predictability (CLIVAR) Working Group on Coupled Models (WGCM) Climate Simulation Panel, and constitutes the third phase of the Coupled Model Intercomparison Project (CMIP3). The dataset is called the WCRP CMIP3 multimodel dataset, and represents the largest and most comprehensive international global coupled climate model experiment and multimodel analysis effort ever attempted. As of March 2007, the Program for Climate Model Diagnostics and Intercomparison (PCMDI) has collected, archived, and served roughly 32 TB of model data. With oversight from the panel, the multimodel data were made openly available from PCMDI for analysis and academic applications. Over 171 TB of data had been downloaded among the more than 1000 registered users to date. Over 200 journal articles, based in part on the dataset, have been published so far. Though initially aimed at the IPCC AR4, this unique and valuable resource will continue to be maintained for at least the next several years. Never before has such an extensive set of climate model simulations been made available to the international climate science community for study. The ready access to the multimodel dataset opens up these types of model analyses to researchers, including students, who previously could not obtain state-of-the-art climate model output, and thus represents a new era in climate change research. As a direct consequence, these ongoing studies are increasing the body of knowledge regarding the understanding of how the climate system currently works, and how it may change in the future.
Deep convection over tropical oceans is observed generally above a threshold for sea surface temperatures, which falls in the vicinity of 26-28°C. High-resolution models suggest that the related sea surface temperature threshold for tropical cyclones rises in a warming climate. Some observations for the past few decades, however, show that tropical tropospheric warming has been nearly uniform vertically, suggesting that the troposphere may have become less stable and casting doubts on the possibility that the sea surface temperature threshold increases substantially with global warming. Here we turn to satellite observations of rainfall for the past 30 years. We detect significant covariability between tropical mean sea surface temperatures and the convective threshold on interannual and longer timescales. In addition, we find a parallel upward trend of approximately 0.1°C/decade over the past 30 years in both the convective threshold and tropical mean sea surface temperatures. We conclude that, in contrast with some observational indications, the tropical troposphere has warmed in a way that is consistent with moist-adiabatic adjustment, in agreement with global climate model simulations.
El Niño events, characterized by anomalous warming in the eastern equatorial Pacific Ocean, have global climatic teleconnections and are the most dominant feature of cyclic climate variability on subdecadal timescales. Understanding changes in the frequency or characteristics of El Niño events in a changing climate is therefore of broad scientific and socioeconomic interest. Recent studies show that the canonical El Niño has become less frequent and that a different kind of El Niño has become more common during the late twentieth century, in which warm sea surface temperatures (SSTs) in the central Pacific are flanked on the east and west by cooler SSTs. This type of El Niño, termed the central Pacific El Niño (CP-El Niño also termed the dateline El Niño, El Niño Modoki or warm pool El Niño), differs from the canonical eastern Pacific El Niño (EP-El Niño) in both the location of maximum SST anomalies and tropical-midlatitude teleconnections. Here we show changes in the ratio of CP-El Niño to EP-El Niño under projected global warming scenarios from the Coupled Model Intercomparison Project phase 3 multi-model data set. Using calculations based on historical El Niño indices, we find that projections of anthropogenic climate change are associated with an increased frequency of the CP-El Niño compared to the EP-El Niño. When restricted to the six climate models with the best representation of the twentieth-century ratio of CP-El Niño to EP-El Niño, the occurrence ratio of CP-El Niño/EP-El Niño is projected to increase as much as five times under global warming. The change is related to a flattening of the thermocline in the equatorial Pacific.
During the second phase of the EFEDA experiment (ECHIVAL Field Experiment in a Desertification Threatened Area), the spatial variability of the soil water retention and hydraulic conductivity characteristics of layers 2-12 and 17-27 cm depth was characterized. A simplified method, based on particle size distribution and simple infiltration tests was used. It provided these characteristics at the nodes of a 1 km grid over 10x10 km2 around the town of Tomelloso (Castilla- La Mancha, Spain). A total number of 78 sample points were used to address the problem of soil surface properties variability and its consequences on the monthly and annual water balance. The SiSPAT (Simple Soil Plant Atmosphere Transfer model) 1-D Soil-Vegetation-Atmosphere Transfer (SVAT) model was run with a one-year climatic forcing for the 78 soil profiles until equilibrium was reached. As no runoff was generated, the spatial variability of the water budget components only concerned soil evaporation, transpiration and deep drainage. It was found that i) the choice of the type of boundary condition at the bottom of the soil profile was greatly influencing the final variability, ii) the variability of transpiration was the largest in situations of water stress for the vegetation, iii) soil evaporation was the most sensitive component when plants were well supplied with water. Various aggregation methods of soil surface parameters (use of the arithmetic mean, median of the parameters or parameters associated to the average soil texture of the Clapp and Hornberger (1978) classification) were assessed. The use of median parameters in a single 1-D simulation was found to provide the best agreement with the average of the 78 simulations performed for each grid cell using locally measured soil properties. The use of average soil texture parameters led to a significant bias, especially in the case of water stress.
The highest sea surface temperatures ever recorded, related both to the
1997–98 El Niño/Southern Oscillation and to global warming1, caused severe bleaching of corals worldwide in 1998 (ref. 2). This thermal anomaly induced mass mortality of scleractinian
corals on lagoonal reefs in Belize, the first time that a coral population
in the Caribbean has collapsed completely from bleaching. Cores extracted
from the Belizean reefs showed that these events were unprecedented over at
least the past 3,000 years.
One probable extinction and one range reduction of eastern Pacific reef-building hydrocoral (Millepora) species mark the first documented cases of species eliminations resulting from the worldwide 1980s coral reef bleaching
events. Two of 12 Panamanian coral species were eliminated suddenly from their former ranges by prolonged high sea temperatures
during the 1982-83 El Niño-Southern Oscillation event. Three conditions contributed to their demise: high sensitivity to sea
warming, populations confined to a small geographic area, and bathymetric restriction to the euphotic zone (≤20 meters depth)
where El Niño sea warming had its greatest effect
This study finds that economic and social costs of "El Nino" in Ecuador have been substantial. Most economic costs relate to losses of agricultural production and damages to infrastructure. Increased health risks are most critical in the social sectors.
Summarizes the meteorological and oceanographic aspects of this El Nino, which created extreme disturbance in the islands and seas of the central tropical Pacific. -after Author
Researchers frequently use automated model selection methods such as backwards elimination to identify variables that are independent predictors of an outcome under consideration. We propose using bootstrap resampling in conjunction with automated variable selection methods to develop parsimonious prediction models. Using data on patients admitted to hospitals with a heart attack, we demonstrate that selecting those variables that were identified as independent predictors of mortality in at least 60% of the bootstrap samples resulted in a parsimonious model with excellent predictive ability.
We show that space-time smoothed outgoing longwave radiation (OLR)
indices of equatorial Pacific seasonal variability can give an
interestingly different perspective on El Nino than is obtained from sea
surface temperature (SST) indices or the Southern Oscillation index
(SOI.) In particular, the index defined by averaging over an eastern
central region exhibits strongly event-like character; more so than in
any other El Nino- Southern Oscillation (ENSO) warm-phase index known to
the authors. We suggest that the years identified as events by this OLR
index deserve particular recognition, and it is noteworthy that they are
all conventionally agreed to be "El Nino" years. Although the historical
record for OLR is much shorter than for SST or SOI, OLR offers a direct
connection to anomalous atmospheric heating. Results presented suggest
that anomalous tropical atmospheric heating drives substantial
mid-latitude atmospheric anomalies in the years with these OLR events.
Other years, whose ENSO-status differs depending upon the index favored,
are not particularly distinctive from an OLR perspective and the
evidence for tropically driven mid-latitude atmospheric anomalies in
these years is less clear. Thus, a case could be made that either they
do not deserve special classification or that they should be identified
as different from the distinctive conventional El Nino years.
The warm event, El Niño, that struck the eastern equatorial Pacific in 1982–83 was the strongest recorded in the last 100 years. Coastal people suffered floods, crop losses and failure of fish catches as the ocean waters grew warmer and the rainfall increased more than tenfold. Wildlife was affected in many different ways. The author has been working as a Naturalist Guide within the Galápagos National Park for the past three and a half years and he is particularly interested in the interactions of seabirds with their environment.
October 1982 through July 1983, the Galapagos Islands experienced the strongest El Niño-Southern Oscillation (ENSO) event yet recorded, with heavy rains and a warm, unproductive ocean. During this period most seabirds did not breed, and many left the archipelago altogether. Dark-rumped petrels which did breed during the event demonstrated low growth rate of chicks. Censuses and observations demonstrated substantial population decreases of other seabirds during the ENSO. Magnificent frigate birds suffered decreased nesting success, while blue-footed boobies abandoned all nesting attempts. Total censuses of Galapagos penguins and flightless cormorants taken before and after the ENSO demonstrated declines of 77% and 49%, respectively. We discuss the seabird population declines during ENSO and their subsequent recovery.
The El Niño/Southern Oscillation (ENSO) phenomenon is the
strongest natural interannual climate fluctuation. ENSO originates in
the tropical Pacific Ocean and has large effects on the ecology of the
region, but it also influences the entire global climate system and
affects the societies and economies of manycountries. ENSO can be
understood as an irregular low-frequency oscillation between a warm (El
Niño) and a cold (La Niña) state. The strong El
Niños of 1982/1983 and 1997/1998, along with the more frequent
occurrences of El Niños during the past few decades, raise the
question of whether human-induced `greenhouse' warming affects, or will
affect, ENSO. Several global climate models have been applied to
transient greenhouse-gas-induced warming simulations to address this
question, but the results have been debated owing to the inability of
the models to fully simulate ENSO (because of their coarse equatorial
resolution). Here we present results from a global climate model with
sufficient resolution in the tropics to adequately represent the narrow
equatorial upwelling and low-frequency waves. When the model is forced
by a realistic future scenario of increasing greenhouse-gas
concentrations, more frequent El-Niño-like conditions and
stronger cold events in the tropical Pacific Ocean result.
Global mean sea surface temperature (SST) has risen steadily over the past century, but the overall pattern contains extensive and often uncertain spatial variations, with potentially important effects on regional precipitation. Observations suggest a slowdown of the zonal atmospheric overturning circulation above the tropical Pacific Ocean (the Walker circulation) over the twentieth century. Although this change has been attributed to a muted hydrological cycle forced by global warming, the effect of SST warming patterns has not been explored and quantified. Here we perform experiments using an atmospheric model, and find that SST warming patterns are the main cause of the weakened Walker circulation over the past six decades (1950-2009). The SST trend reconstructed from bucket-sampled SST and night-time marine surface air temperature features a reduced zonal gradient in the tropical Indo-Pacific Ocean, a change consistent with subsurface temperature observations. Model experiments with this trend pattern robustly simulate the observed changes, including the Walker circulation slowdown and the eastward shift of atmospheric convection from the Indonesian maritime continent to the central tropical Pacific. Our results cannot establish whether the observed changes are due to natural variability or anthropogenic global warming, but they do show that the observed slowdown in the Walker circulation is presumably driven by oceanic rather than atmospheric processes.
Ensembles of climate model simulations are required for input into probabilistic assessments of the risk of future climate
change in which uncertainties are quantified. Here we document and compare aspects of climate model ensembles from the multi-model
archive and from perturbed physics ensembles generated using the third version of the Hadley Centre climate model (HadCM3).
Model-error characteristics derived from time-averaged two-dimensional fields of observed climate variables indicate that
the perturbed physics approach is capable of sampling a relatively wide range of different mean climate states, consistent
with simple estimates of observational uncertainty and comparable to the range of mean states sampled by the multi-model ensemble.
The perturbed physics approach is also capable of sampling a relatively wide range of climate forcings and climate feedbacks
under enhanced levels of greenhouse gases, again comparable with the multi-model ensemble. By examining correlations between
global time-averaged measures of model error and global measures of climate change feedback strengths, we conclude that there
are no simple emergent relationships between climate model errors and the magnitude of future global temperature change. Algorithms
for quantifying uncertainty require the use of complex multivariate metrics for constraining projections.
KeywordsEnsembles–Uncertainty–Model errors–Climate feedbacks–Observational constraints
Researchers frequently use automated model selection methods such as backwards elimination to identify variables that are independent predictors of an outcome under consideration. We propose using bootstrap resampling in conjunction with automated variable selection methods to develop parsimonious prediction models. Using data on patients admitted to hospital with a heart attack, we demonstrate that selecting those variables that were identified as independent predictors of mortality in at least 60% of the bootstrap samples resulted in a parsimonious model with excellent predictive ability.
Compendium of Climatological Impacts
- K Sponberg
Sponberg, K. Compendium of Climatological Impacts, University
Corporation for Atmospheric Research Vol. 1 (National Oceanic and
Atmospheric Administration, Office of Global Programs, 1999);
The Climate Event of the Century
- S A Changnon
- Niño