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Climate extremes: The worst heat waves to come

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Abstract

The combination of high temperatures and humidity could, within just a century, result in extreme conditions around the Persian Gulf that are intolerable to humans, if climate change continues unabated.

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... Heat-humidity effects have prompted decades of study in military, athletic, and occupational contexts (8,9). However, consideration of wet-bulb temperature (TW) from the perspectives of climatology and meteorology began more recently (10,11). ...
... S1). In the literature to date, there have been no observational reports of TW exceeding 35°C and few reports exceeding 33°C (9,11,14,15). The awareness of a physiological limit has prompted modeling studies to ask how soon it may be crossed. ...
... Other >31°C hotspots in the weather station record emerge through surveying the globally highest 99.9th TW percentiles: eastern coastal India, Pakistan and northwestern India, and the shores of the Red Sea, Gulf of California, and southern Gulf of Mexico ( Fig. 1). All are situated in the subtropics, along coastlines (typically of a semienclosed gulf or bay of shallow depth, limiting ocean circulation and promoting high SSTs), and in proximity to sources of continental heat, which together with the maritime air comprise the necessary combination for the most exceptional TW (11). That subtropical coastlines are hotspots for heat stress has been noted previously (23,24); our analysis makes clear the broad geographic scope but also the large intraregional variations (Fig. 1). ...
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Article
Humans’ ability to efficiently shed heat has enabled us to range over every continent, but a wet-bulb temperature (TW) of 35°C marks our upper physiological limit, and much lower values have serious health and productivity impacts. Climate models project the first 35°C TW occurrences by the mid-21st century. However, a comprehensive evaluation of weather station data shows that some coastal subtropical locations have already reported a TW of 35°C and that extreme humid heat overall has more than doubled in frequency since 1979. Recent exceedances of 35°C in global maximum sea surface temperature provide further support for the validity of these dangerously high TW values. We find the most extreme humid heat is highly localized in both space and time and is correspondingly substantially underestimated in reanalysis products. Our findings thus underscore the serious challenge posed by humid heat that is more intense than previously reported and increasingly severe.
... In the current climate, T w rarely comes close to the survival threshold, though 35 • C exceedances have been documented (Schär, 2016). As the climate warms, such exceedances are projected to become more frequent (Pal & Eltahir, 2016;Sherwood & Huber, 2010). ...
... Modeling studies (Im et al., 2017) suggest that survival threshold crossings could be commonplace in the region by the end of the 21st century under a "business-as-usual" forcing scenario. ERA-Interim data, 1979-2016. Blue lines show the 800-m elevation contour. Stippling shows areas with population density >250 persons per km 2 , using the Gridded Population of the World Version 4 data set (http://sedac.ciesin.columbia.edu/data/collection/gpw-v4). ...
... We identify T w extremes using data from surface weather stations included in the Hadley Centre Integrated Surface Database (HadISD; version 2.0.1.2016f; Dunn et al., 2012;2016). We select three weather stations that span the LIH ( Figure 1): Shahbaz Airport (Jacobabad; 68.45 • E, 28.28 • N), Padidan (68.13 • E, 26.85 • N), and Nawabshah (68.39 • E, 26.21 • N). ...
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Article
We study extreme wet‐bulb temperature (Tw) events in a regional hot spot of high Tw values in southwest Pakistan's Indus Valley. We focus on the May–June premonsoon months and employ a combination of station data, ERA‐Interim reanalysis, and trajectory calculations to analyze the extreme events. We find that the events are associated with anomalous influx of marine air from the Arabian Sea. The air flows in a shallow layer below 950 hPa and is heated and moistened by diabatic processes over land, arriving at the hot spot region with very high Tw. We surmise that surface evaporation within the strip of well‐irrigated land flanking the Indus River plays a major role in generating these extreme Tw values. Our results imply that studies of extreme Tw events in future, warmer climates must pay close attention to fine‐scale diabatic processes within the boundary layer, especially evaporation over land.
... In this regard, Im et al. (2017), by examining the heat waves of Asian countries, concluded that heatwaves would occur every 10 to 20 days at the end of this century and the coastal cities of southern Iran, Dubai, Abu Dhabi, and Doha are greatly affected by this event. They also showed that the wet-bulb temperature (TW) reached near 35 °C in the summer of 2015 in the port of Mahshahr (Iran), on the coasts of the Persian Gulf and in Saudi Arabia, indicating that the threshold broke earlier than expected (Schär 2016). Confirming the previous research (Schär 2016;Im et al. 2017), the results of our study showed the increase of thermal stress in the southern regions of Iran in the coming decades. ...
... They also showed that the wet-bulb temperature (TW) reached near 35 °C in the summer of 2015 in the port of Mahshahr (Iran), on the coasts of the Persian Gulf and in Saudi Arabia, indicating that the threshold broke earlier than expected (Schär 2016). Confirming the previous research (Schär 2016;Im et al. 2017), the results of our study showed the increase of thermal stress in the southern regions of Iran in the coming decades. ...
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Article
The extreme temperature indices (ETI) are an essential indicator of climate change. The detection of their changes over the next years can play an essential role in the climate action plan (CAP). In this study, four temperature indices (mean of daily minimum temperature (TN), mean of daily maximum temperature (TX), cold-spell duration index (CSDI), and warm-spell duration index (WSDI)) were defined by ETCCDI and two new indices,the maximum number of consecutive frost days (CFD) and the maximum number of consecutive summer days (CSU), were used to examine ETIs in Iran under climate change conditions. We used minimum and maximum daily temperatures of five general circulation models (GCMs), including HadGEM2-ES, IPSL-CM5A-LR, GFDL-ESM2M, MIROC-ESM-CHEM, and NorESM1-M, from the set of CMIP5 bias-correction models. We investigated two representative concentration pathway (RCP) scenarios of RCP4.5 and RCP8.5 during the historical (1965–2005) and future (2021–2060 and 2061–2100) periods. The performance of each model evaluated using the Taylor diagram on a seasonal scale. Among models, GFDL-ESM2M and HadGEM2-ES showed the highest, and NorESM1-M and IPSL-CM5A-LR showed the lowest performance in Iran. Then, an ensemble model was generated using independence weighted mean (IWM) method. The results of multi-model ensembles (MME) showed a higher performance compared to individual CMIP5 models in all seasons. Also, the uncertainty value significantly reduced, and the correlation value of the MME model reached 0.95 in all seasons. Additionally, it is found that WSDI and CSU indices showed positive anomalies in future periods, and CSDI and CFD showed negative anomalies throughout Iran. Also, at the end of the twenty-first century, no cold spells are projected in almost every part of Iran. The CSU index showed that summer days are increasing sharply; according to the results of the RCP8.5 scenario in spring (MAM) and autumn (SON), the CSU will increase by 18.79 and 20.51 days, respectively, at the end of the twenty-first century. It projected that in the future, the spring and autumn seasons will be shorter and summers will be much longer than before.
... Floods and heat waves are some of the most common issues linked to climate change, with current predictions showing an increase in their frequency and intensity in the near future [1][2][3][4]. However, the impacts of our changing climate on human health include not only these dangerous climatic events, but also an increase in zoonotic diseases, such as Lyme disease. ...
... Perceived social norms Responses to the question were used to measure participants' perception of social norms related to the implementation of LDPB: if I adopt behaviors to protect myself against tick bites and therefore Lyme disease in the next year, people who are important to me will support my choice. Participants rated the item on a four-point scale ranging from "strongly agree" (4) to "strongly disagree" (1). ...
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Article
Background: Recent evidence suggests that climate change and other factors are leading to the emergence of Lyme disease in the province of Quebec, where it previously did not exist. As risk areas expand further north, the population can adopt specific preventive behaviors to limit chances of infection. The objectives of this study were to (1) create an index of Lyme disease prevention behaviors (LDPB), and (2) use the theory of planned behavior (TPB) to explain the decision-making process of people who choose to adopt LDPB. Methods: A sample of 1959 adults living in a Lyme disease risk area completed a questionnaire by phone (n = 1003) or on the Web (n = 956). The questionnaire measured whether they did or did not adopt the LDPB proposed by public health officials. It also measured some TPB variables, including their attitude or perceived social norms regarding LDPB. Results: Our findings led to the creation of a Lyme disease prevention index consisting of 10 behaviors, down from the 19 behaviors initially considered for inclusion in the index. Rates of adoption of each behavior varied tremendously, from 4.30 to 83.80%. All variables of the TPB model (attitude, social norms, and perceived control) were significantly associated with intention to adopt preventive behaviors. Intention itself was significantly associated with adoption of LDPB. Likewise, risk perception was positively correlated with the adoption of LDPB. Conclusions: This study led to the creation of a Lyme disease prevention index that can be used by public health agencies, researchers, and professionals to monitor the evolution over time of individuals' LDPB adoption rates. It also showed the usefulness of the TPB in understanding the adoption of LDPB and how intention to adopt such behaviors is formed.
... The past few years have witnessed numerous heatwaves around the world reported as "record breaking," "abnormal," "rare," and "catastrophic" by the media (Ceccherini et al., 2017;Chen & Li, 2017;Coumou & Rahmstorf, 2012;Russo et al., 2015). Under projected future climate warming, the intensity, frequency, and duration of severe heatwaves are likely to increase further (Jones et al., 2015;Lau & Nath, 2014;Mora et al., 2017;Schär, 2016;Schoetter et al., 2015). ...
... A large body of literature has suggested that future GHG increases will very likely enhance the duration, intensity, and frequency of heat extremes across the world (Jones et al., 2015;Lau & Nath, 2014;Meehl & Tebaldi, 2004;Mishra et al., 2017;Mora et al., 2017;Russo et al., 2014;Schär, 2016;Schoetter et al., 2015). However, very little attention has been devoted to contrasting the roles of future GHG increases and aerosol reductions in future heatwave characteristic projections. ...
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Article
Plain Language Summary The past few years have seen record heatwaves worldwide, primarily driven by human activities. We used a state‐of‐the‐art earth system model to investigate future changes in heatwave characteristics under the Representative Concentration Pathway 8.5 scenario and seek to separate the roles of projected changes in anthropogenic greenhouse gases and aerosols. The model shows that there will be more severe heatwaves (in terms of intensity, duration, and frequency) primarily because of global warming, while the internal variability of the climate system does not change much by 2100 and hence has limited influences. Also, these changes are mainly associated with greenhouse gas increases. However, anthropogenic aerosol changes have important influences, through their effects on clouds and radiation, and produce larger impacts comparing to greenhouse gases per unit of warming. Effects of aerosols on clouds such as changes in cloudiness and other rapid adjustments (e.g., changes in vertical temperature profiles), however, are still poorly represented in present generation climate models, leading to large uncertainties in future heatwave projections. Therefore, we call the attention of the community to prioritize efforts into reducing uncertainties involved in aerosol‐cloud interactions, in order to get reliable projections of future climate extremes, as well as effective strategies for climate risk management.
... The thermal environment of tropical cities should be given particular attention because their populations are strongly affected by the UHI, which further increases T a and hence exposure to heat. In combination with anthropogenic global warming, temperatures in some cities may possibly even exceed a threshold for human adaptability (Pal and Eltahir, 2016;Schär, 2016). The situation is made worse by the high humidity levels of the wet Tropics, which present a particularly challenging living environment for residents. ...
Article
The present study examines the temporal and spatial variability of near‐surface air temperature and the canopy layer urban heat island (UHI) in Singapore. Observations collected at 20 locations across the island city‐state and during 6 years make this one of the most extensive studies carried out in a tropical city. Local climate zones (LCZs), defined as urban built and rural land cover types which produce a unique air temperature response, are used to standardize inter‐site comparison. The results show that the choice of the rural reference can affect the nighttime UHI magnitude by up to 2 °C under ‘ideal’ (dry, clear, calm) conditions. The most frequently observed median UHI magnitude increases from 2.8 during all‐weather to 3.7 °C during ‘ideal’ conditions, respectively. A seasonality is present with lowest (highest) mean all‐weather values of ~2.0 (~3.3) °C, observed during the wet (dry) December‐January (April‐October) period. Mean nighttime UHI intensity across seven built type LCZs ranges between 1.8‐3.5 (2.5‐4.3) °C for all‐weather (‘ideal’) conditions. Corresponding daily values are 1.1‐2.3 (1.5‐2.7) °C. The lowest (highest) nighttime magnitudes are associated with open low‐rise LCZ 6 (compact high‐rise LCZ 1) built type. In the middle of the day LCZ 1 can experience a cool island effect. The average UHI values presented here give an indication of the extra warmth experienced in the built‐up spaces of Singapore relative to one possible rural reference land cover type (scattered trees LCZ B). Highest daytime heat exposure is observed in LCZs 3 and 8 which are characterized by low building heights, high impervious surface fraction and lack of vegetation. The present results can be used to support the development and evaluation of urban climate models, develop urban planning policies, improve local weather forecasts and the delivery of integrated urban services.
... Anthropogenic emissions have most likely increased (Schär et al. 2004;Meehl and Tebaldi 2004;Wehner et al. 2016). The likelihood of existing heat waves and the predicted potential warming of the atmosphere is proving to increase the incidence of extreme heatwaves (Hayhoe et al. 2010;Jones et al. 2015;Schär 2016). It has made the intense heat waves and is projected to make heat waves even hotter and more frequent in the future (Vose et al. 2017;Diffenbaugh and Scherer 2013). ...
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Preprint
A cross-sectional online survey was conducted using multiple online channels, where hundreds of responses were recorded from seven different countries, in order to provide a better understanding of the global public opinion about the awareness, perception and attitude about climate change. The results reflected that majority of people believe in the actual happening of Climate Change both by natural as well as anthropogenic causes. While most respondents believed in the anthropogenic causes of climate change, some people still displayed their confidence in the natural causation of climate change and thus affirmed their awareness of its natural causes. There was however, a difference of opinion regarding the mechanism behind the greenhouse effect. The respondents also provided their opinion on the impact of carbon aerosols on the atmospheric temperature. Further, the respondents were optimistic on the issue of climate change reversal and had also preferred some mitigation steps such as the use of geo-engineering over adjusting to the existing impacts of climate change. Although, people confirmed their belief in the human-induced nature of climate change, yet their agreement of having faced bizarre things about climate change like the lack of consensus among the scientists and climate change being a hoax shows their unawareness about the appropriate knowledge and the propaganda against this planetary emergency. Therefore, this study could prove helpful for policy makers and other stakeholders as it shows how much is done and how much more is pending.
... There have been few reports of the TW exceeding 35 • C in the current climate (Schär 2016). Values of TW in regions affected by the deadly 2003 European and 2010 Russian heat waves were limited to 28 • C (Raymond et al 2020). ...
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Article
Changes in heat stress due to climate change affect living and working conditions. The wet-bulb temperature of 35℃ is identified as an upper physiological limit on human survivability. On the basis of CMIP6 model simulations, our evaluations show that the daily maximum wet-bulb temperature is expected to significantly intensify over China and is likely to exceed this critical threshold over some regions by the end of this century, especially under the high emission scenario of SSP5-8.5. The most dangerous hazard from extreme heat-humidity events is concentrated around the most densely populated regions of eastern China as well as Sichuan basin. Under SSP5-8.5, the significant increase of extreme heat-humidity days that daily maximum wet-bulb temperature exceeding 35℃ results in a large fractional population of approximately 81% exposed by the end of this century in China. This is true for different future warming scenarios and the population fraction would be also up to 51% exposed to such extremes even if the early mitigation conducted via SSP1-2.6. Our findings in this study thus have significant implications to the ongoing considerations for the climate change policy in our country.
... While the focus of this study was Australia, it would be of interest to expand out to assess co-occurring heatwaves in different parts of the world. The combination of high heat and humidity in areas such as the Persian Gulf is expected to trigger recordbreaking heat stress levels in the future (Schär, 2016). This could be exacerbated due to co-occurring heatwaves in the coastal areas and hence would be useful to extend this analysis in this region. ...
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Article
Despite numerous studies examining terrestrial or marine heatwaves independently, little work has investigated potential associations between these two types of extreme events. Examination of a limited number of past events suggests that certain co-occurring terrestrial and marine heatwaves have common drivers. Co-occurring events may also interact via local land-sea interactions, thereby altering the likelihood of these events. This study explores possible links between adjacent coastal marine and terrestrial heatwaves around Australia using observation and reanalysis data. We find a significant increase in the number of terrestrial heatwave days in the presence of an adjacent co-occurring marine heatwave along the coastal belt of Australia. In most regions, this increase persists at least 150 km inland. This suggests that processes operating beyond the narrow coastal belt are important in most regions. We also show that synoptic conditions driving a terrestrial heatwave in three locations around Australia are conducive for warming the ocean, which would increase the likelihood of a marine heatwave occurring. However, ocean state must also be conducive to reach MHW conditions. Our findings suggest that co-occurring terrestrial and marine heatwaves co-occur more frequently than chance would dictate, and that large scale synoptics may be conducive to both coastal terrestrial and marine heatwaves.
... In similar works, observations and/or simulations indicate that the increase in air temperature is accompanied by an increase in the humidity ratio but also in changes in the maximum wet-bulb temperatures [51]. There is the danger that simultaneous occurrence of higher air temperature and humidity could make climate conditions in some areas intolerable to humans in the future [52]. ...
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Article
As climatic conditions affect the energy performance of buildings, the changes in outdoor air temperature and humidity will inevitably lead to significant alterations in energy consumption and costs for the heating, ventilating and air conditioning (HVAC) of buildings. The availability and quality of climatic data play an important role in the accuracy of energy analysis results. In this study, the hourly temperature and relative humidity of outdoor air measurements, for a period of three decades (1983–2012), recorded at the climatic station of the National Observatory of Athens were processed, and an up-to-date set of specific data for the application of bin methods was produced and presented. The data were then used to calculate changes in the energy demands in a typical office building throughout the specified period. Results showed a progressive reduction in the low and increase in the high temperature intervals, leading to an increase in the building’s annual energy requirements for air conditioning of up to 14.5% from the first to the third decade, with decrease in the energy demands for heating and increase in the energy demands for cooling.
... Current models of global climate change have indicated that Southwest Asia (or Middle East) has a high risk of exposure to extreme climatic events (Evans, 2009;Lelieveld et al., 2012). Warming in this region is projected to exceed the thresholds of human tolerance and adaptability (Pal & Eltahir, 2015;Schär, 2016), and aridity is expected to increase across the entire region during the coming decades (Chenoweth et al., 2011). The region has high species diversity, resulting from its crossroad location at the intersection of three biogeographical realms (Palaearctic, Saharo-Arabian and Oriental), but the potential impacts of climate change on its biodiversity remain largely unknown. ...
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Article
Aim The negative impacts of climate change on mammals have been largely based on assessments of total species’ assemblages or individual species at broad scales. Here, we evaluate how the predicted magnitude and velocity of climate change in the arid region of southwest Asia might affect regional functional groups of terrestrial mammals. Location Iran. Methods We gathered data from 186 species to map diversity hotspots of 12 functional groups, threatened species richness and total species richness. We mapped areas with high risk of exposure to extreme drying and warming events and calculated the velocity of climate change by using precipitation and temperature data from current and future periods. We then quantified the exposure of these hotspots to extreme changes in magnitude and velocity. Results Hotspots of functional groups, threatened species and species richness were most exposed to precipitation decline in current and future scenarios (average of 17.9% and 29.9% respectively), compared to temperature rise. While most hotspots are found in mountains, hotspots located in lowlands were more exposed to extreme drying, particularly for carnivore, desert and large-bodied functional groups, as well as threatened species. These patterns remained intact when we considered only hotspots covered by existing protected areas. The impacts of velocity also varied significantly among functional groups, with highest levels for carnivore, large-bodied and specialist groups and threatened species. Main conclusions We show that climate change does not equally impact all species within a community and that vulnerability to these changes differed between functional groups. We found that the areas with the highest risk of exposure to extreme climates are located in lowlands and not in mountains. We found that extreme drying, rather than warming, is the major threat to regional mammal diversity in this arid region, particularly for large-bodied and threatened species.
... Current models of global climate change have indicated that Southwest Asia (or Middle East) has a high risk of exposure to extreme climatic events (Evans, 2009;Lelieveld et al., 2012). Warming in this region is projected to exceed the thresholds of human tolerance and adaptability (Pal & Eltahir, 2015;Schär, 2016), and aridity is expected to increase across the entire region during the coming decades (Chenoweth et al., 2011). The region has high species diversity, resulting from its crossroad location at the intersection of three biogeographical realms (Palaearctic, Saharo-Arabian and Oriental), but the potential impacts of climate change on its biodiversity remain largely unknown. ...
... Anthropogenic emissions have most likely increased (Schär et al. 2004;Meehl and Tebaldi 2004;Wehner et al. 2016). The likelihood of existing heat waves and the predicted potential warming of the atmosphere is proving to increase the incidence of extreme heatwaves (Hayhoe et al. 2010;Jones et al. 2015;Schär 2016). It has made the intense heat waves and is projected to make heat waves even hotter and more frequent in the future (Vose et al. 2017;Diffenbaugh and Scherer 2013). ...
Full-text available
Article
Even though climate change involves much more than warming, it is the name given to a set of physical phenomena. It is a long-term change in weather patterns that characterises different regions of the world. The warming effect in the earth’s atmosphere has dramatically increased through the influence of some heat-taping gases emitted by various human activities, especially fossil fuel burning. The more the input of such gases, the more will be the warming effect in the coming times. Global climate change is already visible in various parts of the larger ecosystems like forests, fisheries, biodiversity, and agriculture; however, it is now also influencing the supply of freshwater, human health, and well-being. This paper reviews climate change drivers, its global scenario, major global events, and assessing climate change impacts. The most daunting problem of economic and ecological risks, along with the threats to humanity, is also discussed. The paper further reviews the species’ vulnerability to climate change and the heat waves and human migration vis-à-vis climate change. Climate change politics and coverage of climate change episodes in mass media is the special focus of this review that concludes with a few mitigation measures.
... These may reduce uterine blood flow, which could affect fetal metabolic responses and trigger contractions, and result in PTB (Dreiling andCarman 1991, Stan et al 2013). It is expected that the frequency, intensity, and duration of heatwaves will increase due to climate change (Schär 2015, Hoegh-Guldberg et al 2018, which will add to the existing PTB burden. Understanding the effect of heatwaves on PTB and identifying optimal thresholds to activate interventions targeting pregnant women is particularly important in the context of climate change. ...
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Article
Background: Exposure to high air temperature in late pregnancy is increasingly recognized as a risk factor for preterm birth (PTB). However, the combined effects of heatwaves with air pollution and green space are still unexplored. In the context of climate change, investigating the interaction between environmental factors and identifying communities at higher risk is important to better understand the etiological mechanisms and design targeted interventions towards certain women during pregnancy. Objectives: To examine the combined effects of heatwaves, air pollution and green space exposure on the risk of PTB. Methods: California birth certificate records for singleton births (2005-2013) were obtained. Residential zip code-specific daily temperature during the last week of gestation was used to create 12 definitions of heatwave with varying temperature thresholds and durations. We fit multi-level Cox proportional hazard models with time to PTB as the outcome and gestational week as the temporal unit. Relative risk due to interaction (RERI) was applied to estimate the additive interactive effect of air pollution and green space on the effect of heatwaves on PTB. Results: In total, 1,967,300 births were included in this study. For PM2.5, PM10 and O3, we found positive additive interactions (RERIs >0) between heatwaves and higher air pollution levels. Combined effects of heatwaves and green space indicated negative interactions (RERIs <0) for less intense heatwaves (i.e., shorter duration or relatively low temperature), whereas there were potential positive interactions (RERIs >0) for more intense heatwaves. Conclusion: This study found synergistic harmful effects for heatwaves with air pollution, and potential positive interactions with lack of green space on PTB. Implementing interventions, such as heat warning systems and behavioral changes, targeted toward pregnant women at risk for high air pollution and low green space exposures may optimize the benefits of reducing acute exposure to extreme heat before delivery.
... Climate change will lead to a further increase in the number and intensity of catastrophic weather events such as heat waves, floods, and droughts [1][2][3][4][5]. Of these, flooding is already the most common and destructive of climate-related disaster in many countries, including Canada. ...
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Article
Climate change is predicted to increase the frequency and intensity of floods in the province of Quebec, Canada. Therefore, in 2015, to better monitor the level of adaptation to flooding of Quebec residents living in or near a flood-prone area, the Quebec Observatory of Adaptation to Climate Change developed five indices of adaptation to flooding, according to the chronology of events. The present study was conducted 4 years later and is a follow-up to the 2015 one. Two independent samples of 1951 (2015) and 974 (2019) individuals completed a questionnaire on their adoption (or non-adoption) of flood adaptation behaviors, their perception of the mental and physical impacts of flooding, and their knowledge of the fact that they lived in a flood-prone area. The results of the study demonstrated the measurement invariance of the five indices across two different samples of people over time, ensuring that the differences (or absence of differences) observed in flood-related adaptive behaviors between 2015 and 2019 were real and not due to measurement errors. They also showed that, overall, Quebeckers’ flood-related adaptive behaviors have not changed considerably since 2015, with adaptation scores being similar in 2019 for four of the five flood indices. Moreover, the results indicated an increase in self-reported physical and mental health issues related to past flooding events, as well as a larger proportion of people having consulted a health professional because of these problems. Thus, this study provides a better understanding of flood adaptation in Quebec over the past 4 years and confirms that the five adaptive behavior indices developed in 2015 are appropriate tools for monitoring changes in flood adaptation in the province. Finally, our results showed that little has changed in Quebeckers’ adoption of adaptive behaviors, highlighting the need for awareness raising in order to limit the impacts that climate change will have on the population.
... The current climate in southern Iraq already contains days with temperatures higher than 50 • C [4]. Exposure of humans and other mammals to high temperatures for extended periods would be at risk for life-threatening hyperthermia and dehydration [5]. ...
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Article
Fortunately, extreme temperatures reaching 50 °C are not common on our planet. The capability of the consortium for small-scale modelling regional climate model (COSMO-CLM), with 0.44° resolution, to project future trends of an extremely hot environment with direct model output (DMO) is questioned. The temperature distribution of COSMO-CLM output driven by reanalysis and RCP4.5 scenario in southern Iraq was remarkably good, with a slight temperature overestimation, compared to the overlapping observations from Basra airport. An attempt to enhance the DMO with a statistical downscaling method did not improve the results. The COSMO-CLM projection indicates that a very sharp increase in the number of consecutive hours and days with the temperature reaching 50 °C or higher will occur. During 1951–1980, consecutive hours and days reaching 50 °C were rare events. By the end of the century, the projected climate in southern Iraq contains up to 13 consecutive hours and 21 consecutive days reaching 50 °C or higher. As the average projected temperature will increase by ~2 °C compared to the recent climate, new records may be expected. However, the major climate change feature is the increase in consecutive hours and days of very high temperatures. These findings require adaptation measures to support future habitation of the region.
... Changes in the intensity and frequency of extremes have drawn much attention during recent decades (Coumou et al., 2014;Horton et al., 2016;IPCC, 2012), mainly due to their large impacts on natural environment, economy and human health (Ciais et al., 2005;Kovats & Kristie, 2006). Due to the inherent nature of extreme events, the variability of high-temperature extremes differs from that of mean temperature (Raible et al., 2007;Schär, 2015). Therefore, we need to understand the causes of climate extremes in the twentieth century and in a more distant past. ...
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Article
The past provides evidence of abrupt climate shifts and changes in the frequency of climate and weather extremes. We explore the nonlinear response to orbital forcing and then consider climate millennial variability down to daily weather events. Orbital changes are translated into regional responses in temperature, where the precessional response is related to nonlinearities and seasonal biases in the system. We question regularities found in climate events by analyzing the distribution of interevent waiting times. Periodicities of about 900 and 1,150 yr are found in ice cores besides the prominent 1,500 yr cycle. However, the variability remains indistinguishable from a random process, suggesting that centennial-to-millennial variability is stochastic in nature. New numerical techniques are developed allowing for a high resolution in the dynamically relevant regions like coasts, major upwelling regions, and high latitudes. Using this model, we find a strong sensitivity of the Atlantic meridional overturning circulation depending on where the deglacial meltwater is injected into. Meltwater into the Mississippi and near Labrador hardly affect the large-scale ocean circulation, whereas subpolar hosing mimicking icebergs yields a quasi shutdown. The same multiscale approach is applied to radiocarbon simulations enabling a dynamical interpretation of marine sediment cores. Finally, abrupt climate events also have counterparts in the recent climate records, revealing a close link between climate variability, the statistics of North Atlantic weather patterns, and extreme events.
... Extreme thermal stress events have considerably increased in recent years, both in frequency and in magnitude, and this trend is expected to continue with future global warming, especially in some world regions as southwest Asia [1,2]. This will most probably exacerbate other challenges, such as the buildings energy use for cooling with consequent greenhouse gas (GHG) emissions; the ability to work resulting in lower productivity; the durability of building materials and infrastructures, the possibility to use public spaces thus constraining social life and, above all, public health directly as well as by increasing the burden of air pollution. ...
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According to the challenge of global warming, trees play an effective role in reducing heat islands and improving thermal comfort. In this study, the impact of urban greening on microclimate and pedestrian comfort is studied using ENVI met v4 for a residential district in Tabriz, Iran. In-situ measurements of air temperature and relative humidity have been preliminary performed on ten points in the studied site and collected data used to successfully validate the model. Four scenarios with different trees species and patterns were simulated during typical summer and winter days, to assess benefits and disadvantages during different seasons, in terms of air temperature (Ta) and relative humidity (RH), mean radiant temperature (Tmrt) and physiologically equivalent temperature (PET). Result showed that the best scenario provides great summer cooling without compromising winter comfort. In summer Ta and Tmrt are decreased by respectively 0.29 °C and 20.04 °C; while in winter, they reach respectively 6.92 °C and 13.22 °C, compared the reference scenario characterised by 6.28 °C (Ta) and 23.47 °C (Tmrt). These results in a summer PET improvement from 34.92 °C to 26.16 °C, thus moving from an original hot thermal sensation to a slightly warm one. Based on the outcomes of the study, it is possible to provide useful design recommendation for urban adaptation plans.
... Sustainable Development Goals 3 and 11, (United Nations, 2015). There is extensive evidence that anthropogenic climate change, both observed and modelled, continues to raise the frequency and intensity of extreme heat events, especially in urban regions and their public areas (Bastin et al., 2019;Christidis, Jones, & Stott, 2014;Russo, Sillmann, & Fischer, 2015;Schär, 2015;Tomczyk & Bednorz, 2016;Wang, Jiang, & Lang, 2017;Wouters et al., 2017;Zhao et al., 2018). Heat extremes can be detrimental to human health, including dehydration, discomfort or exhaustion (de' Donato et al., 2015;Keeler et al., 2019;Lafortezza, Carrus, Sanesi, & Davies, 2009;Nikolopoulou & Lykoudis, 2006;Ragettli, Vicedo-Cabrera, Schindler, & Roosli, 2017;Schuster, Honold, Lauf, & Lakes, 2017;Vogel, Zscheischler, Wartenburger, Dee, & Seneviratne, 2019;Zhao et al., 2018) and can increase heat-related mortality (de' Donato et al., 2015;Lafortezza et al., 2009;Muthers, Laschewski, & Matzaraki, 2017;Ragettli et al., 2017;Rüegg, 2019;Schuster et al., 2017). ...
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... Furthermore, some other studies have showed prolonged periods of hightemperature exposure, which was usually defined as a heatwave event, can significantly heighten the risk (Kent et al. 2014;Sun et al. 2019;Wang et al. 2013). In the context of climate change, the frequency and intensity of heatwaves are expected to increase (Hoegh-Guldberg et al. 2018;Schär 2016), which will accordingly add to the existing global PTB burden. ...
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... Heat wave literature, particularly studies, focused on the physical mechanisms driving onset and intensity traditionally focus on the sensible heat contribution to atmospheric heat content through analysis of maximum temperature (Diffenbaugh & Ashfaq, 2010;Mueller & Seneviratne, 2012;Oswald & Rood, 2014;Russo et al., 2014). However, recent studies highlight the increasingly important role of atmospheric humidity during heat waves and societal vulnerability to these events (Mitchell et al., 2016;Pal & Eltahir, 2016;Schär, 2016); the nature of heat events is dependent on local soil moisture availability and antecedent precipitation conditions . Specifically, near-surface humidity conditions during periods of elevated temperatures can result in dramatically different human health outcomes (Anderson & Bell, 2009;Davis et al., 2016;Kunkel et al., 1996). ...
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Climate models' outputs are affected by biases that need to be detected and adjusted to model climate impacts. Many climate hazards and climate-related impacts are associated with the interaction between multiple drivers, i.e. by compound events. So far climate model biases are typically assessed based on the hazard of interest, and it is unclear how much a potential bias in the dependence of the hazard drivers contributes to the overall bias and how the biases in the drivers interact. Here, based on copula theory, we develop a multivariate bias-assessment framework, which allows for disentangling the biases in hazard indicators in terms of the underlying univariate drivers and their statistical dependence. Based on this framework, we dissect biases in fire and heat stress hazards in a suite of global climate models by considering two simplified hazard indicators: the wet-bulb globe temperature (WBGT) and the Chandler burning index (CBI). Both indices solely rely on temperature and relative humidity. The spatial pattern of the hazard indicators is well represented by climate models. However, substantial biases exist in the representation of extreme conditions, especially in the CBI (spatial average of absolute bias: 21 ∘C) due to the biases driven by relative humidity (20 ∘C). Biases in WBGT (1.1 ∘C) are small compared to the biases driven by temperature (1.9 ∘C) and relative humidity (1.4 ∘C), as the two biases compensate for each other. In many regions, also biases related to the statistical dependence (0.85 ∘C) are important for WBGT, which indicates that well-designed physically based multivariate bias adjustment procedures should be considered for hazards and impacts that depend on multiple drivers. The proposed compound-event-oriented evaluation of climate model biases is easily applicable to other hazard types. Furthermore, it can contribute to improved present and future risk assessments through increasing our understanding of the biases' sources in the simulation of climate impacts.
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Data on the weather conditions and monitoring of vegetation ecosystems in the Northern Caspian semi-desert for the 70-year period were analyzed. A gradual increase in the average air temperature per hydrological year by 2.73ºC (0.039ºC/year) has been revealed. Before and after the 2000s its increase was caused by warming of the cold and warm period of the year, respectively. An increase of the annual atmospheric precipitation in the spring-summer period was detected, mainly in 1978–1995 due to April-June precipitation. The humidification coefficient dynamics allows distinguishing three periods. The first period (1951–1977) is characterized by insignificant fluctuations around the average value (0.30); the second period (1978–1994) is characterized by good moisture, and the third period (1995–2020), on the contrary, – by severe aridity. These climate changes have led to significant transformation of the snow cover formation mechanisms, the surface runoff of spring melt water, and the ground water level. Despite such fluctuations of natural conditions, the annual productivity of virgin vegetation remains in dynamic equilibrium, changing over time in a wave-like manner, with no introduction of heterogeneous species. The protective afforestation has no chance for sustainable development due to warming of the winter months by 2000, which led to the absence of additional moistening of forest crops for a long period due to the deficiency of snow accumulation and surface inflow of spring melt water. The shrinkage of forest stands was intensified by recurrent annual summer atmospheric droughts. The production of agricultural crops was discontinued since the mid-1990s due to their annual failure, as well as the aridity of the growing seasons. The climate warming of the last two decades has brought the landscape of the flat semi-desert territory of the Northern Caspian region ever closer to its original state without agricultural fields and forest plantations. The population of the region is forced to return to extensive cattle breeding, which has existed here since ancient times.
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Introduction Climate change is one of the major threats of the 21st century. One of the major data sources for studying climate change is the general circulation model (GCM), which is widely used to assess and project past and future climate change and to manage regional risk hazards. GCMs can make significant assessments of temperature and precipitation. The application of individual models has high uncertainty. Therefore, in this study, applying an ensemble approach has been considered to project future temperature changes in Iran. The purpose of this study is to create a multi-model ensemble (MME) with bias-corrected CMIP6 models to project the temperature of Iran and the warm spell duration index (WSDI) in the near future (2021-2040). Materials and methods To evaluate the CMIP6 models in simulating the average annual temperature for the period of 1995 to 2014 (these 20 years were considered as the historical period), we used 120 synoptic stations in Iran. In this study, five CMIP6 models (GFDL-ESM4, MPI-ESM1-2-HR, IPSL-CM6A-LR, MRI-ESM2-0, UKESM1-0-LL) with a horizontal resolution of 0.5 degrees were used. Using intermediate (SSP3-7.0) and worst-case (SSP5-8.5) scenarios, annual temperature and heat stress were projected under climate change conditions for the near future (2040-2021). In this study, normalized root mean square error (NRMSE) and mean bias error (MBE) were used to validate the performance of the models. To correct the bias of CMIP6 models, Delta change Factor (DCF) method with 120 synoptic station was used. Then, independence weighted mean (IWM), were used to ensemble five models. In this study, in addition to temperature anomalies, warm spell duration index (WSDI) was also projected by 2040. The warm spell duration index is the number of days per year with at least 6 consecutive days when TX > TX90th, where TX is the daily maximum temperature and TX90th is the calendar day 90th percentile. Results and discussion Based on the Direct Model Output (DMO) in the climates of Sea of Oman and Caspian Sea coasts, all five CMIP6 models underestimated the average annual temperature (Chabahar and Rasht stations). However, CMIP6 models in other climates of Iran overestimated the average annual temperature. The mean bias of 1.00, 0.962, 0.983, 1.001, 0.936 degrees Celsius is compute for GFDL-ESM4, IPSL-CM6A-LR, MPI-ESM1-2-HR, MRI-ESM2-0 and UKESM1-0-LL, respectively. Therefore, UKESM1-0-LL and IPSL-CM6A-LR models are efficient models among the studied models for estimating Iran temperature, respectively. The temperature bias values fluctuate from -2.27 to 2.70 degrees Celsius in Iran. The average annual temperature based on MME-CMIP6 output fluctuates between 6.27 and 27.7 degrees Celsius. The coasts of the Persian Gulf and the Sea of Oman showed the maximum temperature and the northwestern regions of Iran showed the minimum temperature. The warm spell duration index varies between 3.48 to 12.5 days during the historical period. The temperature projected for both SSP3-7.0 and SSP5-8.5 scenarios show a further increase in the interior, northwest, north, and northeast of Iran. The average annual anomaly in Iran is estimated to be 1.13 and 1.26 degrees Celsius, based on SSP3-7.0 and SSP5-8.5 scenarios, respectively for the near future during the years 2021-2040. According to the SSP3-7.0 scenario, the minimum temperature anomaly of the country is 0.765 and the maximum is 1.227 degrees Celsius. Also, for the SSP5-8.5 scenario, temperature anomalies for minimum and maximum annual temperature are estimated to be 0.785 and 1.380 degrees Celsius, respectively. Projecting the time-series changes of the temperature in eight representative stations of Iran under the scenarios of SSP3-7.0 and SSP5-8.5 showed that the amount of warm spell duration varies in different regions of Iran. The anomaly of the warm spell duration index (WSDI) in Iran according to the SSP3-7.0 scenario will increase by at least 13.1 and at most 58.6 days. Also, the results related to the worst-case scenario (SSP5-8.5) have shown a minimum increase of 17.4 days and a maximum of 74.5 days in Iran. Conclusion Evaluation of direct output of five models from the series of Coupled Model Intercomparison project (GFDL-ESM4, MPI-ESM1-2-HR, IPSL-CM6A-LR, MRI-ESM2-0, UKESM1-0-LL) In the historical period (1995-2014) showed that although some models performed better in some climate regions of the country, the use of the direct output of individual models will increase the uncertainty in the results. For this purpose, using the independent weighted average (IWM) method, the output of the models was improved. The evaluation of the output of the ensemble model emphasizes this result. In general, the results of model validation showed that the output of CMIP6 models has higher performance for arid and semi-arid regions of Iran, whether before or after bias-correction. However, using either individual or bias-corrected and ensemble models in very humid climates (The northern parts of Iran) should be used with more caution because even with the correction of bias and doing ensemble, the positive bias is more than 2 degrees Celsius for the mentioned areas. The projection by using MME-CMIP6 show the annual temperature increase in near future (2021-2040). The average annual temperature anomaly will increase by 1.13 and 1.26 degrees Celsius, under the scenarios of SSP3-7.0 and SSP5-8.5 respectively, during the near future (2021-2040). The results indicate the very important role of unevenness in the heterogeneous distribution of temperature in increasing the average annual temperature of the country in the next two decades. The minimum temperature anomaly is projected in the southeast of Iran and the maximum in the northwestern and central regions. Projecting the warm spell duration index (WSDI) indicates an increasing anomaly of that in the country. The main hotspot of WSDI is on the southern coast of Iran, especially in the Persian Gulf area, which according to the results of the worst-case scenario will increase by 74.5 days by 2040. Analysis of changes in the average annual temperature of MME-CMIP6 shows that Iran will warm up more rapidly in the near future (2021-2040) than in the historical period (1995-2014). More warming, especially in high and snowy areas, will affect natural ecosystems and limit future access to water resources. Most of the interior, east and south of Iran has arid and semi-arid climate and a sharp rise in temperature under the worst-case scenario (SSP5-8.5) leads to environmental degradation and intensification of drought on the one hand and increased desertification on the other.
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The summer of 2010 was exceptionally warm in eastern Europe and large parts of Russia. We provide evidence that the anomalous 2010 warmth that caused adverse impacts exceeded the amplitude and spatial extent of the previous hottest summer of 2003. “Mega-heatwaves” such as the 2003 and 2010 events likely broke the 500-year-long seasonal temperature records over approximately 50% of Europe. According to regional multi-model experiments, the probability of a summer experiencing mega-heatwaves will increase by a factor of 5 to 10 within the next 40 years. However, the magnitude of the 2010 event was so extreme that despite this increase, the likelihood of an analog over the same region remains fairly low until the second half of the 21st century.
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Daily numbers of deaths at a regional level were collected in 16 European countries. Summer mortality was analyzed for the reference period 1998-2002 and for 2003. More than 70,000 additional deaths occurred in Europe during the summer 2003. Major distortions occurred in the age distribution of the deaths, but no harvesting effect was observed in the months following August 2003. Global warming constitutes a new health threat in an aged Europe that may be difficult to detect at the country level, depending on its size. Centralizing the count of daily deaths on an operational geographical scale constitutes a priority for Public Health in Europe.
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A human body may be able to adapt to extremes of dry-bulb temperature (commonly referred to as simply temperature) through perspiration and associated evaporative cooling provided that the wet-bulb temperature (a combined measure of temperature and humidity or degree of "mugginess") remains below a threshold of 35 °C. (ref.). This threshold defines a limit of survivability for a fit human under well-ventilated outdoor conditions and is lower for most people. We project using an ensemble of high-resolution regional climate model simulations that extremes of wet-bulb temperature in the region around the Arabian Gulf are likely to approach and exceed this critical threshold under the business-as-usual scenario of future greenhouse gas concentrations. Our results expose a specific regional hotspot where climate change, in the absence of significant mitigation, is likely to severely impact human habitability in the future.
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The short but intense heat wave in mid-July 1995 caused 830 deaths nationally, with 525 of these deaths in Chicago. Many of the dead were elderly. and the event raised great concern over why it happened. Assessment of causes for the heat wave-related deaths in Chicago revealed many factors were at fault, including an inadequate local heat wave warning system, power failures, questionable death assessments, inadequate ambulance service and hospital facilities, the heat island, an aging population, and the inability of many persons to properly ventilate their residences due to fear of crime or a lack of resources for fans or air conditioning. Heat-related deaths appear to be on the increase in the United States. Heat-related deaths greatly exceed those caused by other life-threatening weather conditions. Analysis of the impacts and responses to this heat wave reveals a need to 1) define the heat island conditions during heat waves for all major cities is a means to improve forecasts of threatening conditions, 2) develop a nationally uniform means for classifying heat-related deaths, 3) improve warning systems that are designed around local conditions of large cities, and 4) increase research on the meteorological and climatological aspects of heat stress and heat waves.
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Despite the uncertainty in future climate-change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation. Peak heat stress, quantified by the wet-bulb temperature T(W), is surprisingly similar across diverse climates today. T(W) never exceeds 31 degrees C. Any exceedence of 35 degrees C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible. While this never happens now, it would begin to occur with global-mean warming of about 7 degrees C, calling the habitability of some regions into question. With 11-12 degrees C warming, such regions would spread to encompass the majority of the human population as currently distributed. Eventual warmings of 12 degrees C are possible from fossil fuel burning. One implication is that recent estimates of the costs of unmitigated climate change are too low unless the range of possible warming can somehow be narrowed. Heat stress also may help explain trends in the mammalian fossil record.
Climate Change 2013: The Physical Science Basis
  • G. J. Van Oldenborgh