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The detrimental impact of extreme heat exposure on the health and well-being of children is widely acknowledged. The direct and indirect effects of climate change have led to an increased risk of certain cardiovascular events which may be particularly harmful to children who are born with, or develop, heart disease. Purpose: To highlight the worrying paucity of investigative research aimed at differentiating how higher ambient temperatures further tax an already compromised cardiovascular system in children. Methods: This commentary describes basic thermoregulatory concepts relevant to the healthy pediatric population and summarizes common heart diseases observed in this population. Results: We describe how heat stress and exercise are important factors clinicians should more readily consider when treating children with heart disease. Countermeasures to physical inactivity are suggested for children, parents, clinicians, and policymakers to consider. Conclusions: As sudden, excessive heat exposures continue to impact our rapidly warming world, vulnerable populations like children with underlying heart conditions are at greater heat health risk, especially when coupled with the negative physical activity and fitness trends observed worldwide. [ABSTRACT FROM AUTHOR]

[Display omitted] Climate change is increasing the frequency and intensity of heatwaves, raising concerns about their detrimental effects on air quality. However, a role for heatwave-human-environment interactions in air pollution exacerbation has not been established. In the summer of 2022, record-breaking heatwaves struck China and Europe. In this study, we use integrated observational data and machine learning to elucidate the formation mechanism underlying one of the most severe ozone pollution seasons on record in central eastern China, an area that encompasses approximately half of China's total population and sown land. Our findings reveal that the worsened ozone and nitrogen dioxide pollution resulted from a mismatch between energy demand and supply, which was driven by both heatwaves and energy policy-related factors. The observed adverse heatwave-energy-environment feedback loop highlights the need for the diversification of clean energy sources, more resilient energy structures and power policies, and further emission control to confront the escalating climate challenge in the future. [ABSTRACT FROM AUTHOR]

Nighttime oxidation of monoterpenes (MT) via the nitrate radical (NO3) and ozone (O3) contributes to the formation of secondary organic aerosol (SOA). This study uses observations in Atlanta, Georgia from 2011 to 2022 to quantify trends in nighttime production of NO3 (PNO3) and O3 concentrations and compare to model outputs from the EPA's Air QUAlity TimE Series Project (EQUATES). We present urban‐suburban gradients in nighttime NO3 and O3 concentrations and quantify their fractional importance (F) for MT oxidation. Both observations and EQUATES show a decline in PNO3, with modeled PNO3 declining faster than observations. Despite decreasing PNO3, we find that NO3 continues to dominate nocturnal boundary layer (NBL) MT oxidation (FNO3 = 60%) in 2017, 2021, and 2022, which is consistent with EQUATES (FNO3 = 80%) from 2013 to 2019. This contrasts an anticipated decline in FNO3 based on prior observations in the nighttime residual layer, where O3 is the dominant oxidant. Using two case studies of heatwaves in summer 2022, we show that extreme heat events can increase NO3 concentrations and FNO3, leading to short MT lifetimes (<1 hr) and high gas‐phase organic nitrate production. Regardless of the presence of heatwaves, our findings suggest sustained organic nitrate aerosol formation in the urban SE US under declining NOx emissions, and highlight the need for improved representation of extreme heat events in chemistry‐transport models and additional observations along urban to rural gradients. Plain Language Summary: Monoterpenes are important precursors of secondary organic aerosol (SOA), which influence air quality and climate. At night, they react with the nitrate radical (NO3) and ozone (O3). Trends in these two oxidants and their role on air quality in the southeastern United Sates (SE US) is partially dictated by changes in nitrogen oxide (NOx = NO + NO2) emissions which have declined in recent years. We find that NO3 dominates present‐day monoterpene loss in the summer, and may continue to do so even as NOx concentrations decrease in the future. We show that heatwaves in the SE US further elevate both O3 and NO3 concentrations at night, with a larger relative importance for NO3. We compare observations to a regional air quality model, and find the model overpredicts both oxidant concentrations. This overprediction may impact model‐based studies of future nighttime chemistry. Key Points: Nitrate radical (NO3) continues to control nocturnal boundary layer monoterpene oxidation in the urban SE USRegional model overpredicts oxidant concentrations and fractional NO3 contribution to monoterpene lossExtreme heat events increase nighttime NO3 concentrations, monoterpene oxidation rates, and gas‐phase organic nitrate production [ABSTRACT FROM AUTHOR]

The prediction of European heatwaves at the subseasonal range is of key importance to mitigate their impact. This study builds on previous work which identifies five main European heatwave types based on their atmospheric circulation patterns (CPs). These CPs are potential predictors of heatwaves, as these patterns are connected with a high probability of 2-meter temperature exceeding the 90th percentile. Therefore, the aim of this study is to use these patterns to construct a pattern-based forecast method. The skill of this method to forecast extreme warm temperatures is then assessed and compared with the direct grid-point based forecast (using the direct 2-meter temperature forecast of the model). The extended (or subseasonal) range reforecast data from the European Centre for Medium-Range Weather Forecasts (ECMWF) is used for the skill evaluation. Firstly, the skill of the extended range model is assessed in predicting CPs. The pattern-based methodology is then compared with the direct prediction of extreme warm temperatures. The results show that the pattern-based methodology has a low skill at the short to medium range compared to the direct method, however it maintains skill for longer lead times, extending the forecast skill horizon significantly by up to six days over key heatwave regions. This improvement is localized over regions with the highest conditional probability of extreme warm temperatures. Furthermore, the prediction skill of 4-day periods of high temperatures using CPs lasting at least five days is also assessed. A similar improvement in forecast skill horizon is observed but the improvement is more modest and even more localized. This methodology provides skilful forecast at longer lead times to the end of the medium range and into the subseasonal range, which would be beneficial for early warnings of European heatwaves and therefore support the timely implementation of mitigation plans. [ABSTRACT FROM AUTHOR]

Older adults are at elevated risk of heat-related mortality due to age-associated declines in thermoregulatory and cardiovascular function. However, the inter-individual factors that exacerbate physiological heat strain during heat exposure remain unclear, making it challenging to identify more heat-vulnerable subgroups. We therefore explored factors contributing to inter-individual variability in physiological responses of older adults exposed to simulated hot weather. Thirty-seven older adults (61–80 years, 16 females) rested for 8 h in 31 and 36 °C (45% relative humidity). Core (rectal) temperature, heart rate (HR), HR variability, mean arterial pressure (MAP), and cardiac autonomic responses to standing were measured at baseline and end-exposure. Bootstrapped least absolute shrinkage and selection operator regression was used to evaluate whether variation in these responses was related to type 2 diabetes (T2D, n = 10), hypertension (n = 18), age, sex, body morphology, habitual physical activity levels, and/or heat-acclimatization. T2D was identified as a predictor of end-exposure HR (with vs. without: 13 beats/min (bootstrap 95% confidence interval: 6, 23)), seated MAP (−7 mmHg (−18, 1)), and the systolic pressure response to standing (20 mmHg (4, 36)). HR was also influenced by sex (female vs. male: 8 beats/min (1, 16)). No other predictors were identified. The inter-individual factors explored did not meaningfully contribute to the variation in body temperature responses in older adults exposed to simulated indoor overheating. By contrast, cardiovascular responses were exacerbated in females and individuals with T2D. These findings improve understanding of how inter-individual differences contribute to heat-induced physiological strain in older persons. [ABSTRACT FROM AUTHOR]

Previous research has shown a link between extreme weather events and people's beliefs about climate change and their pro-environmental behaviour. This indicates that people may become more environmentally friendly amid increasing extreme weather events. Still, the influence of experiencing extreme weather events on actual behaviour has rarely been tested with large-scale individual-level data and longitudinal methods. This study links panel data from 35,678 individuals to floods across England and heatwaves across the UK and applies within-person estimators to account for pre-existing differences between affected and unaffected individuals. Results reveal that individuals are more likely to believe in climate change after being affected by a geographically proximate flood or a temporally proximate heatwave. This association is stronger among initially right-leaning partisans and those initially more sceptic about the existence of climate change, thereby indicating attitudinal updating due to experiential learning. However, those exposed to extreme weather events do not change their environmental behaviour such as energy saving, sustainable shopping or mode of transportation. Even among those who are more likely to believe in climate change, people's behaviour does not react to extreme weather events. [ABSTRACT FROM AUTHOR]

Global warming will lead to more frequent and intense heatwaves across all regions of the world in the coming decades. Adaptation at the individual level plays a key role in helping populations cope with these extreme events. This study undertakes a systematic review of the academic literature on the determinants of heat-adaptive behaviours (HABs) following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. A Boolean algorithm was used on two online databases (PubMed and Web of Science Core Collection) to retrieve 73 relevant, quantitative, peer-reviewed papers. All included studies focus on high-income economies (N = 48) or middle-income economies (MIEs, N = 25). A meta-analysis was performed on 34 studies using a random-effects model, with an emphasis on heat-related perceptions (perceived efficacy, risk and threat) and heat-related knowledge (HRK), as these variables are the most likely levers of behavioural change. Perceived efficacy, HRK, perceived threat and gender (i.e. being female) are positively associated with the adoption of HABs. A moderation analysis reveals heterogeneity in the effect of these variables by country income group, with low HRK and perceived threat constituting stronger barriers to HABs in MIEs. This study also highlights various gaps in the current literature, regarding the populations studied, the statistical methods used, and the lack of standardization of HABs and perception concepts. Key policy insights: Heat-adaptive behaviours (HABs) are influenced by both psychological and non-psychological factors. Information and communication campaigns may be designed to influence the determinants of psychological factors and use them as adaptation levers. Policymakers should implement information campaigns to underline the characteristics and adverse health effects of heatwaves, as well as reminding people of ways to cope with heatwaves, especially in middle-income economies (MIEs). Information and prevention campaigns in MIEs should clearly highlight the frequency and severity of the health hazards associated with heatwaves in order to improve public awareness of these risks. Information campaigns based on simple infographics showing the most effective HABs and reminding people of the efficacy of HABs to reduce heatwave health risks may be especially impactful in high-income economies. [ABSTRACT FROM AUTHOR]

The increasing use of time-series analyses in exploring the relationship between daily ambient temperature and mortality has expanded our understanding of the potential health impacts of climate change. However, it raises significant concerns about the risk of overinterpretation and misattribution of statistical findings. This review examines the methodological assumptions and interpretation pitfalls prevalent in current research on ambient temperature-mortality associations. Extremely elevated ambient temperatures are well-known to elicit physiological stress and increase mortality risk; however, there is no physiological evidence for lethality risk within normal ambient temperature ranges. Despite this, many studies attribute mortality risks across the entire ambient temperature-mortality curve, including normal range ambient temperatures, thus oversimplifying complex underlying physiological processes. Overinterpretation may lead to inaccurate assessments and misguided public health policies. We caution against the tendency to extrapolate results from extreme heat conditions to milder, more typical summer ambient temperature ranges. We advocate for an interdisciplinary approach that combines physiological, clinical, and epidemiological perspectives, with a strong emphasis on the role of behavioral thermoregulation and socio-economic factors to link normal range ambient temperatures with mortality. We recommend analyses centered on excess mortality during defined heatwave periods, and to incorporate heat stress biomarkers to substantiate causal claims for temperatures below heatwaves threshold. A careful approach to interpreting ambient temperature-mortality associations is crucial for formulating evidence-based public health policies. [ABSTRACT FROM AUTHOR]

In this study, we analyze the spatiotemporal patterns of propagation of pre‐monsoon heatwaves and their drivers in India. Using complex networks, we find that heatwaves originate most frequently in northwest India and propagate in the northeast or southeast direction. Heatwaves propagating in the northeast direction have a higher intensity, lower moving distance, smaller areal coverage, and shorter duration than heatwaves moving in the southeast. We find that the larger area and duration of heatwaves propagating southeast are a result of development of larger and more persistent high‐pressure systems extending over entire northern and eastern India, which are influenced by El Niño Southern Oscillation. On the other hand, higher radiative fluxes and larger heat entrainment in the boundary layer in the heatwaves propagating northeast contribute to their higher intensities. Plain Language Summary: We analyze the spatial patterns of where heatwaves originate and how they spread in the pre‐monsoon period in India. We find that most heatwaves originate in northwest India. Some of these heatwaves spread to north and central India while some propagate to south India. Heatwaves in northern and central India have higher intensity and last for a shorter period of time as compared to those which spread to south India. The area and duration of heatwaves moving toward south India are influenced by El Nino events. On the other hand, the intensity of heatwaves of central and north India is higher due to greater shortwave radiation and heat entrainment in the boundary layer. Key Points: Regions of origin and termination of pre‐monsoon heatwaves in India are identified using complex networks and event synchronizationMajority of heatwaves originate from northwest India and propagate in the northeast or southeast directionHeatwaves propagating southwards have larger duration and areal extent and are influenced by El Niño Southern Oscillation [ABSTRACT FROM AUTHOR]

Under global warming, heatwaves (HWs) are exerting increasing impacts on human life. In order to explore the thermal sensation of HWs under the combined influence of air temperature, humidity, radiation and wind speed, this study utilized the hourly Universal Thermal Climate Index (UTCI) data from the ECMWF Reanalysis v5 (ERA5) to define daytime, night‐time and compound HWs, and then comparatively analysed their occurrences in China during 1981–2020. Results revealed that daytime HWs affect the majority of regions in China with the exception of the Tibetan Plateau, while both night‐time and compound HWs mainly strike the Yangtze River Basin and the Guangdong–Guangxi region in southeastern China. Additionally, it is noteworthy that a substantial portion of regions experiencing night‐time HWs also encounter compound HWs. The frequency and intensity of all three types of HWs show increasing trends generally in regions where HWs occur. The spatial coverage of HWs grows at rates of 8.05%/10a, 2.11%/10a and 1.62%/10a for the daytime, night‐time and compound types, respectively. For each summer month, the spatial coverage of daytime HWs notably surpasses that of night‐time and compound HWs. Further classifying HWs with intensity, it is found that the spatial coverage of both moderate and severe HW events exhibits discernible rising trends across all three types of HWs. Furthermore, regions with higher HW frequencies are more likely to experience severe HWs as well as record‐breaking ones. Additionally, the spatial coverage of daytime, night‐time and compound record‐breaking HWs is expanding. [ABSTRACT FROM AUTHOR]

As temperatures increase across the globe due to climate change, human exposure to extreme heat is a public health challenge. During sporting events, athletes, officials, spectators, and staff are at risk of heat stress and resulting illness. The objective of this review was to explore the impact of heat on the health outcomes of these groups and the wider health system and discuss implications for outdoor mass-gathering sporting events in Australia. A systematic review was undertaken to identify literature published from 2010 to 2023. Seven databases were searched: Web of Science, SportDiscus, Scopus, Medline, CINAHL, Emcare, and PsychInfo, for relevant key search terms such as heatwave, heat stress, extreme heat, stadium, arena, sports facilit*, sport, athletic, and Olympic. An inductive thematic analysis was undertaken. Articles were quality checked using Joanna Briggs Institute critical appraisal tools and data were extracted, tabulated, and synthesized. Forty papers were included in the final analysis: 17 quantitative, and 23 descriptive and qualitative (including reviews). Health outcomes explored across the literature included exertional heat illness, exertional heat stroke, hyperthermia, and general heat related illness. Six recommendation themes emerged: planning, mitigation strategies, medical, policy, research, and education. The impact of heat on health outcomes during sporting events is significant, and should be considered by individuals, coaches, officials, and organizers before, during, and after mass-gathering sporting events. These findings can inform evidence-based preparedness strategies to protect the health of those attending and competing in mass-gathering sporting events now and into the future. [ABSTRACT FROM AUTHOR]

The impact of heatwaves (HWs) on human health is a topic of growing interest due to the global magnification of these phenomena and their substantial socio‐economic impacts. As for other countries of Southern Europe, Spain is a region highly affected by heat and its increase under climate change. This is observed in the mean values and the increasing incidence of extreme weather events and associated mortality. Despite the vast knowledge on this topic, it remains unclear whether specific types and characteristics of HW are particularly harmful to the population and whether this shows a regional interdependency. The present study provides a comprehensive analysis of the relationship between HW characteristics and mortality in 12 Spanish cities. We used separated time series analysis in each city applying a quasi‐Poisson regression model and distributed lag linear and non‐linear models. Results show an increase in the mortality risk under HW conditions in the cities with a lower HW frequency. However, this increase exhibits remarkable differences across the cities under study not showing any general pattern in the HW characteristics‐mortality association. This relationship is shown to be complex and strongly dependent on the local properties of each city pointing out the crucial need to examine and understand on a local scale the HW characteristics and the HW‐mortality relationship for an efficient design and implementation of prevention measures. Plain Language Summary: Heatwaves (HWs) are episodes of extreme heat sustained in time with devastating socio‐economic impacts. Due to their global magnification, the interest in their impacts on human health has increased. Spain, in Southern Europe, is a climate change hot spot, particularly in relation to increasing temperature extremes. Despite the relevance of the topic, it is still unclear if there are particular characteristics of heatwaves with a larger impact on mortality. In the present study, we analyze the relationship between heatwaves' characteristics and mortality risk in 12 Spanish cities. Results show no general pattern for the relationship between mortality and heatwave characteristics over the 12 cities under study, but local relations point out the need for local studies to accurately assess the relationship between heatwave characteristics and mortality for an efficient implementation of prevention measures. Key Points: No general patterns found describing the heatwave characteristics‐mortality associationThe heatwave characteristics‐mortality coupling needs a local scale analysis due to its complex and strong dependence on local propertiesThe health indices recovery factor and excess heat factor do not always represent the heatwave‐mortality association [ABSTRACT FROM AUTHOR]

Surface anticyclones connected to the ridge of an upper‐tropospheric Rossby wave are the main dynamical drivers of mid‐latitude summer heatwaves. It is, however, unclear to what extent an anomalously low zonal phase speed of the wave in the upper troposphere is necessary for persistent temperature extremes at the surface. Here, we use spectral decomposition to separate fast and slow synoptic‐scale waves. A composite analysis of ERA5 reanalysis data reveals that, while in some regions heatwaves become more frequent during episodes of weak or no phase propagation, temperature extremes in other regions are commonly associated with more rapidly eastward propagating Rossby waves. Reflected in the mean heatwave duration as well, this relationship is possibly linked to a longitudinal phase preference of slow and fast waves or a meridional storm track shift. These findings open up new questions about the influence of mid‐latitude dynamics on temperature extremes. Plain Language Summary: High pressure systems tend to be associated with mid‐latitude summer heatwaves, defined as multiple consecutive hot days. The persistence of heatwaves raises the question whether the associated high pressure system has to be anomalously persistent as well to cause a heatwave. Using a combination of observational data and atmospheric model output that is commonly regarded as ground truth for prediction purposes we find that this is not the case. By re‐distributing the location of on‐average high air pressure, some regions experience an increased heatwave frequency even if the atmospheric circulation is less persistent than usual. Understanding the link between persistent surface temperature extremes and the atmospheric circulation is important for the prediction and projection of extreme events in a warming climate. Key Points: Phase speed of synoptic‐scale waves is crucial for where, but less important for whether heatwaves occurA longitudinal phase preference of slow and fast waves is reflected in the mean heatwave durationChanges in phase speed are linked to a meridional storm track shift [ABSTRACT FROM AUTHOR]

Urbanization alters local climates and exacerbates urban heat islands. Understanding and addressing the impacts of urbanization on regional high impact weather systems is critical. This study examines the feedback loop between urbanization and heatwaves (HWs) in inland and coastal Indian cities of Hyderabad and Bhubaneswar which have been profoundly affected by urbanization and temperature extremes. Observational analysis reveals that during the pre‐monsoon season, daytime and nighttime air temperature anomalies, and the frequency of 90th percentile days, have increased by ~0.35°C and ~3 days for Hyderabad, and by ~0.2°C, and ~6 days for Bhubaneswar in the last two decades (2001–2020) relative to the previous decades (1981–2000). Analysis of  land‐use land‐cover (LULC) datasets shows a dramatic urban expansion by ~13 and ~11 times in Hyderabad and Bhubaneswar, respectively, between 1993 and 2019. Numerical experiments with the Weather Research and Forecasting model were undertaken considering hectometer spatial resolution (~500 m) and a lower boundary conditions representing the 1993 and 2019 LULC. The impact of urbanization on temperature changes and HWs in particular were analyzed. The HW simulations indicate that urbanization significantly enhances air and surface temperatures by ~4–6°C, particularly during nighttime rather than daytime. Urbanization effects are discerned in surface temperatures at night by 1–2°C relative to  air temperatures. Unlike nighttime, urbanization showed a negative or little influence on air and surface temperatures during the daytime. In contrast to surface and air temperatures, increased urbanization runs indicated enhanced regional soil temperature by ~5°C more during the daytime than at nighttime. The rise in nighttime air and surface temperatures is due to an increase in surface sensible heat fluxes by ~40–50 W/m2 in urban areas. The influence of urbanization on nighttime temperatures emphasizes the necessity for cool housing and engineering recommendations in urbanized regions of India. [ABSTRACT FROM AUTHOR]

Climate change leading to Climate extremes in the twenty-first century is more evident in megacities across the world, especially in West Africa. The Greater Accra region is one of the most populated regions in West Africa. As a result, the region has become more susceptible to climate extremes such as floods, heatwaves, and droughts. The study employed the Coupled Model Intercomparison Project 6 models in simulating climate extreme indices under the Shared Socioeconomic Pathway scenarios (SSPs) over West Africa between 1979 and 2059 as exemplified by the Greater Accra region. The study observed a generally weak drought in the historical period and expected to intensify especially under SSP585 in Greater Accra. For instance, continuous dry days (CDD) reveal an increasing trend under the SSPs. Similarly, the overall projected trend of CDD over West Africa reveals an increase signifying a more frequent and longer drought in the future. The flood indices revealed a surge in the intensity and duration of extreme precipitation events under the SSPs in the region. For instance, R99pTOT and Rx5days are expected to significantly increase under the SSPs with intensification under the SSP245, SSP370, and SSP585. A similar trend has been projected across West Africa, especially along the Guinean coast. The study foresees a gradual and intensifying rise in heatwave indices over the Greater Accra region. The warming and cooling indices reveal an increasing and decreasing trend respectively in the historical period as well as under the SSPs particularly within urban centers like Accra and Tema. Most West African countries are projected to observe more frequent warm days and nights with cold nights and days becoming less frequent. Expected effects of future climate extreme indices pose potential threats to the water, food, and energy systems as well as trigger recurrent floods and droughts over Greater Accra. The findings of the study are expected to inform climate policies and the nationally determined contribution of the Paris Agreement as well as address the sustainable development goal 11 (Sustainable cities) and 13 (Climate action) in West Africa. [ABSTRACT FROM AUTHOR]

To assess the association between ambient heat and all-cause and cause-specific emergency department (ED) visits and acute hospitalizations among Medicare beneficiaries in the conterminous United States. Retrospective cohort study. Conterminous US from 2008 and 2019. 2% random sample of all Medicare fee-for-service beneficiaries eligible for Parts A, B, and D. All-cause and cause-specific (cardiovascular, renal, and heat-related) ED visits and unplanned hospitalizations were identified using primary ICD-9 or ICD-10 diagnosis codes. We measured the association between ambient temperature – defined as daily mean temperature percentile of summer (June through September) – and the outcomes. Hazard ratios and their associated 95% confidence intervals were estimated using multivariable Cox proportional hazards regression, adjusting for individual level demographics, comorbidities, healthcare utilization factors and zip-code level social factors. Among 809,636 Medicare beneficiaries (58% female, 81% non-Hispanic White, 24% <65), older beneficiaries (aged ≥65) exposed to >95th percentile temperature had a 64% elevated adjusted risk of heat-related ED visits (HR [95% CI], 1.64 [1.46,1.85]) and a 4% higher risk of all-cause acute hospitalization (1.04 [1.01,1.06]) relative to <25th temperature percentile. Younger beneficiaries (aged <65) showed increased risk of heat-related ED visits (2.69 [2.23,3.23]) and all-cause ED visits (1.03 [1.01,1.05]). The associations with heat related events were stronger in males and individuals dually eligible for Medicare and Medicaid. No significant differences were observed by climatic region. We observed no significant relationship between temperature percentile and risk of CV-related ED visits or renal-related ED visits. Among Medicare beneficiaries from 2008 to 2019, exposure to daily mean temperature ≥ 95th percentile was associated with increased risk of heat-related ED visits, with stronger associations seen among beneficiaries <65, males, and patients with low socioeconomic position. Further longitudinal studies are needed to understand the impact of heat duration, intensity, and frequency on cause-specific hospitalization outcomes. [ABSTRACT FROM AUTHOR]

Heatwaves have significant effects on ecosystems and human health. Human habitability is impacted severely as human exposure to heatwaves is projected to increase, however, the contribution of soil moisture effects to the increased exposure is unknown. We use data from four climate models, in which two experiments are used to isolate soil moisture effects and in this way to examine projected changes of soil moisture contributions to projected increases in heatwave events. Contributions from soil moisture to future population exposure to heatwaves are also investigated. With soil moisture effects combined with global warming, the longest yearly heatwaves are found to increase by up to 20 days, intensify by up to 2°C in mean temperature, with an increasing of frequency by 15% (the percentage relative to the total number of days for a year) over most mid‐latitude land regions by 2040–2070 under the SSP585 high emissions scenario. Furthermore, soil moisture changes are found to have a significant role in projected increases of multiple heatwave characteristics regionally compared with the global land area and contribute to more global population exposed to heatwaves. Plain Language Summary: Heatwaves have great impacts on human health, agriculture, economy, and many other related societal factors. Existing research has not formed a comprehensive understanding of the influences from soil moisture and drought on population exposure to global heatwaves. This study aims to provide a better perception and quantification of soil moisture effects on changes of both heatwaves per se and population exposure to heatwaves, which will help to enhance further insights of climate change impacts on human society. Using outputs from dedicated climate model experiments, it is found detectable contributions from soil moisture changes on exacerbating heatwaves and increasing population exposure to them. This study can inform evidence‐based policies and potential land management techniques such as irrigation, land radiative management, and forestation, for mitigating the impacts of climate extremes. Key Points: We conducted the first global analysis of soil moisture effects on population exposure to heatwavesEffects of projected soil moisture changes constitute a strong component in the exacerbation of heatwaves over most land regionsPopulation exposure to heatwaves rises sharply in Asia, Australia, US, Europe, and central and southern Africa [ABSTRACT FROM AUTHOR]

This study examines the effects of extreme temperature events, defined explicitly as the 98th percentile temperature for heat, in Tanzania from 1981 to 2023. The study utilises percentile analysis, z-score calculations, and trend mapping to highlight the prevalence of extreme temperatures. The z-score analysis examines the occurrence of extreme temperatures and their distribution in terms of frequency and space. It identified Tanzania’s mid-eastern and north-western regions as areas with a high concentration of extreme temperatures over the previous 43 years. The study analyses the length of extreme occurrences and reveals changing patterns. In 2020, the events were shorter, while in 2021 and 2022, they became longer-lasting, and there was a notable concentration of extended anomalies near the northern coastline. In 2023, the highest temperatures ever recorded were observed, with more than half of the regions seeing prolonged periods of extreme temperatures lasting for a week and significant deviations from the norm staying for four weeks or more. This was particularly notable in the southern regions of Lindi and Mtwara. The harmonic trend analysis of temperature shows an upward temperature trend noticeably in regions such as Arusha, Kilimanjaro, Kagera, Morogoro, Simiyu, and Shinyanga and is somewhat inconspicuous in most areas.

Abstract Climate change leading to Climate extremes in the twenty-first century is more evident in megacities across the world, especially in West Africa. The Greater Accra region is one of the most populated regions in West Africa. As a result, the region has become more susceptible to climate extremes such as floods, heatwaves, and droughts. The study employed the Coupled Model Intercomparison Project 6 models in simulating climate extreme indices under the Shared Socioeconomic Pathway scenarios (SSPs) over West Africa between 1979 and 2059 as exemplified by the Greater Accra region. The study observed a generally weak drought in the historical period and expected to intensify especially under SSP585 in Greater Accra. For instance, continuous dry days (CDD) reveal an increasing trend under the SSPs. Similarly, the overall projected trend of CDD over West Africa reveals an increase signifying a more frequent and longer drought in the future. The flood indices revealed a surge in the intensity and duration of extreme precipitation events under the SSPs in the region. For instance, R99pTOT and Rx5days are expected to significantly increase under the SSPs with intensification under the SSP245, SSP370, and SSP585. A similar trend has been projected across West Africa, especially along the Guinean coast. The study foresees a gradual and intensifying rise in heatwave indices over the Greater Accra region. The warming and cooling indices reveal an increasing and decreasing trend respectively in the historical period as well as under the SSPs particularly within urban centers like Accra and Tema. Most West African countries are projected to observe more frequent warm days and nights with cold nights and days becoming less frequent. Expected effects of future climate extreme indices pose potential threats to the water, food, and energy systems as well as trigger recurrent floods and droughts over Greater Accra. The findings of the study are expected to inform climate policies and the nationally determined contribution of the Paris Agreement as well as address the sustainable development goal 11 (Sustainable cities) and 13 (Climate action) in West Africa.

Compound drought and heatwave (CDHW) events have garnered increased attention due to their significant impacts on agriculture, energy, water resources, and ecosystems. We quantify the projected future shifts in CDHW characteristics (such as frequency, duration, and severity) due to continued anthropogenic warming relative to the baseline recent observed period (1982 to 2019). We combine weekly drought and heatwave information for 26 climate divisions across the globe, employing historical and projected model output from eight Coupled Model Intercomparison Project 6 GCMs and three Shared Socioeconomic Pathways. Statistically significant trends are revealed in the CDHW characteristics for both recent observed and model simulated future period (2020 to 2099). East Africa, North Australia, East North America, Central Asia, Central Europe, and Southeastern South America show the greatest increase in frequency through the late 21st century. The Southern Hemisphere displays a greater projected increase in CDHW occurrence, while the Northern Hemisphere displays a greater increase in CDHW severity. Regional warmings play a significant role in CDHW changes in most regions. These findings have implications for minimizing the impacts of extreme events and developing adaptation and mitigation policies to cope with increased risk on water, energy, and food sectors in critical geographical regions.

This pitching research letter (PRL) applies the systematic 2-page pitch template developed by Faff (2021, 2015) to organise a future PhD research topic regarding the effects of heatwaves on antimicrobial resistance and public health. By adhering to the template, it helps researchers to extract the succinct information required by a research proposal. The thoughtful design of the template renders it an invaluable tool for novice researchers in developing a new research plan and communicating it in an organised and structured manner.

The Urban Trees Ecophysiology Network (UTEN) held its inaugural workshop in Athens, GA, USA, bringing together 40 specialists from various disciplines to study the physiological functioning of urban trees. The workshop aimed to understand how the urban environment affects tree health and functioning, as well as how trees impact the microclimate of cities. Urban trees provide numerous benefits, such as reducing air pollution, improving mental health, lowering temperatures, and mitigating climate change. However, there are disparities in tree distribution, with low-income areas having less tree cover and experiencing higher temperatures. The workshop discussed methods for data management, research design, and communication with stakeholders, and proposed the installation of informative panels and QR codes on monitored trees for public engagement. The network plans to establish a global urban tree monitoring network and expand its nodes to currently underrepresented regions. [Extracted from the article]

Daily maximum, TX, and minimum, TN, temperatures recorded at Fabra Observatory, for the period 1914–2020 (from June to September), have permitted to identify the daytime and night time heatwaves, HWs, at the Barcelona Metropolitan Region, BMR, along 107 years. Four heatwaves indices have been computed both for maximum and minimum temperatures: the number of events per season, HWN; their maximum duration, HWD; their frequency of occurrence, HWF; and the amplitude of the hottest day event, HWA. Trends in these indices have been obtained and their statistical significance quantified by means of the Mann-Kendall test. For the whole period (1914–2020), positive significant trends have been detected for the four indices, with a marked positive trend since year 2000 for TX, and since 1985 for TN. Nevertheless, when 31-year moving windows have been analysed, both positive and negative significant trends are obtained, being remarkable the change in trend signs around 1960s. The convenience of using the four HW indices is evaluated applying a Principal Component Analysis, PCA, obtaining two principal components. Additionally, the spatial distributions of the MODIS land surface temperatures, LST, corresponding to some extreme heatwaves, permits the detection of two hotspots in the BMR, one for TX and the other for TN. It is also worth mentioning that correlations between the Western Mediterranean Oscillation index, WeMOi, and HW episodes are detected, being notable that, at the beginning of these episodes, WEMOi values are usually lower. These correlations could improve the HWs forecasting. [ABSTRACT FROM AUTHOR]

Heatwaves (HWs) are high-impact phenomena stressing both societies and ecosystems. Their intensity and frequency are expected to increase in a warmer climate over many regions of the world. While these impacts can be wide-ranging, they are potentially influenced by local to regional features such as topography, land cover, and urbanization. Here, we leverage recent advances in the very high-resolution modelling required to elucidate the impacts of heatwaves at these fine scales. Further, we aim to understand how the new generation of km-scale regional climate models (RCMs) modulates the representation of heatwaves over a well-known climate change hot spot. We analyze an ensemble of 15 convection-permitting regional climate model (CPRCM, ~ 2–4 km grid spacing) simulations and their driving, convection-parameterized regional climate model (RCM, ~ 12–15 km grid spacing) simulations from the CORDEX Flagship Pilot Study on Convection. The focus is on the evaluation experiments (2000–2009) and three subdomains with a range of climatic characteristics. During HWs, and generally in the summer season, CPRCMs exhibit warmer and drier conditions than their driving RCMs. Higher maximum temperatures arise due to an altered heat flux partitioning, with daily peaks up to ~ 150 W/m2 larger latent heat in RCMs compared to the CPRCMs. This is driven by a 5–25% lower soil moisture content in the CPRCMs, which is in turn related to longer dry spell length (up to double). It is challenging to ascertain whether these differences represent an improvement. However, a point-scale distribution-based maximum temperature evaluation, suggests that this CPRCMs warmer/drier tendency is likely more realistic compared to the RCMs, with ~ 70% of reference sites indicating an added value compared to the driving RCMs, increasing to 95% when only the distribution right tail is considered. Conversely, a CPRCMs slight detrimental effect is found according to the upscaled grid-to-grid approach over flat areas. Certainly, CPRCMs enhance dry conditions, with knock-on implications for summer season temperature overestimation. Whether this improved physical representation of HWs also has implications for future changes is under investigation. [ABSTRACT FROM AUTHOR]

Heatwaves have long been recognized as a serious public health threat. Effective adaptation measures can reduce the risks to people and ecosystems. The purpose of this study was to explore the determinants of heatwave adaptive behaviors using the Health Belief Model (HBM) as a framework. A cross-sectional study was conducted among a sample of 686 participants who were registered volunteers at the Alkhidmat Foundation in Pakistan, using an online questionnaire. For individual adaptive behaviors, only perceived benefits and self-efficacy were observed as significant predictors. For household adaptive behaviors, only cues to action and self-efficacy were found as significant predictors. In terms of overall adaptive behaviors, perceived benefits, perceived barriers, cues to action, and self-efficacy were significant predictors. Our study explores the influence of the HBM constructs on adaptive behaviors across various subgroups, highlighting their differential significance in rural and urban settings, formal and informal occupations, and experiences within heatwaves. These findings highlight the potential of the HBM in guiding the creation of impactful interventions that facilitate behavioral changes during heatwaves, thereby enhancing people’s adaptive behaviors. By emphasizing the association of the HBM with adaptive behaviors, our findings offer valuable insights for authorities seeking to make informed decisions and policies. [ABSTRACT FROM AUTHOR]

Urban parks serve as vital spaces for leisure, social interaction, and nature engagement. At the same time, climate change disproportionately impacts densely populated megacities. While extensive research exists on climate change's effects on mortality, agriculture, and economic activities, less is known about its impact on urban park usage. Understanding their temporal usage and how temperature changes affect park visitation is crucial for maximizing park benefits and building resiliency. This study analyzes long-term, hourly park visitation data on Dallas, Texas, using digital trace data from SafeGraph (San Francisco, CA, USA), which covers mobile records from approximately 10% of U.S. devices. We focus on five established parks in Dallas and examine their historical temperature data from 2018 to 2022. Descriptive statistics and scatter graphs are utilized to analyze temperature- and demographic-specific visitation patterns. The results of the study highlight the impact of climate change on park visitation and reveal how extreme temperatures influence visitation patterns across parks in Dallas. Additionally, this study explores the differences in visitation based on weekdays versus weekends and highlights demographic disparities. Notably, we examine the implications of nighttime park usage during extreme heat conditions. Our work is informative for urban planners seeking to improve park facilities and comfort amid climate change, ultimately enhancing the resilience and well-being of urban communities. [ABSTRACT FROM AUTHOR]

Human-induced climate change has profound effects on extreme events, particularly those linked to global warming, such as heatwaves, droughts, and wildfires. These events disrupt ecosystems, emphasizing the imperative to understand the interactions among them to gauge the risks faced by vulnerable communities. Vulnerability levels vary primarily based on a community's resources. Rural areas, especially in the Mediterranean region of Europe, are experiencing acute depopulation, creating a complex situation affecting various aspects of society, from economic declines to cultural heritage loss. Population decline in rural regions weakens resources, leading to the abandonment of built environments, fostering desertification, and elevating the risk of wildfires. Communities undergoing this deterioration process become exceptionally vulnerable, especially when dealing with and recovering from extreme natural phenomena. This review offers insights into the dynamics of these hazards and the predominant challenges in rural areas. By focusing on a topic that has received limited attention, the aim is to inform future research initiatives, ultimately improving risk assessment and mitigation strategies for these vulnerable communities. [ABSTRACT FROM AUTHOR]

The urban heat island (UHI) is a crucial factor in developing sustainable cities and societies. Appropriate data collection, analysis, and prediction are essential first steps in studying the effects of the UHI. This research systematically reviewed the papers related to the UHI that have used on-site data collection in the United States and Canada and the papers related to predicting and analyzing this effect in these regions. To achieve this goal, this study extracted 330 articles from Scopus and Web of Science and, after selecting the papers, reviewed 30 papers in detail from 1998 to 2023. The findings of this paper indicated a methodological shift from traditional sensors and data loggers towards more innovative and customized technologies. Concurrently, this research reveals a growing trend in using machine learning, moving from supportive to direct predictive roles and using techniques like neural networks and Bayesian networks. Despite the maturation of UHI research due to these developments, they also present challenges in technology complexity and data integration. The review emphasizes the need for future research to focus on accessible, accurate technologies. Moreover, interdisciplinary approaches are crucial for addressing UHI challenges in an era of climate change. [ABSTRACT FROM AUTHOR]

Heat stress-induced bleaching has been shown to lower the photosynthetic and physiological performances and even causes mortality in giant clams. However, there is a lack of information on the responses of sub-tropical giant clams to bleaching stress as well as their recovery from bleaching. Here we exposed the giant clams Tridacna crocea from sub-tropical Okinawa to different temperature conditions for 21 days and then examined their recovery at control temperatures (28–29 °C) within 42 days. T. crocea in control and in 30–31 °C retained their colors, whereas bleaching was observed in 32–33 °C and in the increasing temperatures (29–33 °C, 1 °C change every 5 days). The Fv/Fm decreased at 32–33 °C and in the increasing temperatures (29–33 °C), even before the onset of bleaching, but the Fv/Fm returned to baseline values at day 9 of recovery period. Zooxanthellae density and chlorophyll a + c concentrations were decreased, whereas the zooxanthellae cell size was increased in all elevated temperatures at day 21 of exposure period. Respiration (R) in all temperature conditions was not affected during exposure period, whereas gross photosynthesis (Pg) and Pg/R were reduced at 32–33 °C. At day 42 of recovery period, most bleached individuals regained their colors, phototrophic potential, and zooxanthellae population. No giant clams died within 21 days of exposure period, but mortalities were observed at 32–33 °C and at increasing temperatures (29–33 °C) during recovery period. This study shows that the sub-tropical giant clams are vulnerable to heat stress, but their ability to recover may suggest their persistence in a warming ocean. [ABSTRACT FROM AUTHOR]

In response to the urgent global threat posed by human-induced extreme climate hazards, heatwaves are still systematically under-reported and under-researched in Thailand. This region is confronting a significant rise in heat-related mortality, which has resulted in hundreds of deaths, underscoring a pressing issue that needs to be addressed. This research article is one of the first to present a solution for assessing heatwave dynamics, using machine learning (ML) algorithms and geospatial technologies in this country. It analyzes heatwave metrics like heatwave number (HWN), heatwave frequency (HWF), heatwave duration (HWD), heatwave magnitude (HWM), and heatwave amplitude (HWA), combining satellite-derived land surface temperature (LST) data with ground-based air temperature ( T air ) observations from 1981 to 2019. The result reveals significant marked increases in both the frequency and intensity of daytime heatwaves in peri-urban areas, with the most pronounced changes being a 0.45-day/year in HWN, a 2.00-day/year in HWF, and a 0.27-day/year in HWD. This trend is notably less pronounced in urban areas. Conversely, rural regions are experiencing a significant escalation in nighttime heatwaves, with increases of 0.39 days/year in HWN, 1.44 days/year in HWF, and 0.14 days/year in HWD. Correlation analysis ( p < 0.05 ) reveals spatial heterogeneity in heatwave dynamics, with robust daytime correlations between T air and LST in rural (HWN, HWF, HWD, r > 0.90 ) and peri-urban (HWM, HWA, r > 0.65 ) regions. This study emphasizes the importance of considering microclimatic variations in heatwave analysis, offering insights for targeted intervention strategies. It demonstrates how enhancing remote sensing with ML can facilitate the spatial–temporal analysis of heatwaves across diverse environments. This approach identifies critical risk areas in Thailand, guiding resilience efforts and serving as a model for managing similar microclimates, extending the applicability of this study. Overall, the study provides policymakers and stakeholders with potent tools for climate action and effective heatwave management. Furthermore, this research contributes to mitigating the impacts of extreme climate events, promoting resilience, and fostering environmental sustainability. [ABSTRACT FROM AUTHOR]

Increasingly frequent and intense heatwaves threaten ecosystem health in a warming climate. However, plant responses to heatwaves are poorly understood. A key uncertainty concerns the intensification of transpiration when heatwaves suppress photosynthesis, known as transpiration–photosynthesis decoupling. Field observations of such decoupling are scarce, and the underlying physiological mechanisms remain elusive. Here, we use carbonyl sulphide (COS) as a leaf gas exchange tracer to examine potential mechanisms leading to transpiration–photosynthesis decoupling on a coast live oak in a southern California woodland in spring 2013. We found that heatwaves suppressed both photosynthesis and leaf COS uptake but increased transpiration or sustained it at non‐heatwave levels throughout the day. Despite statistically significant decoupling between transpiration and photosynthesis, stomatal sensitivity to environmental factors did not change during heatwaves. Instead, midday photosynthesis during heatwaves was restricted by internal diffusion, as indicated by the lower internal conductance to COS. Thus, increased evaporative demand and nonstomatal limitation to photosynthesis act jointly to decouple transpiration from photosynthesis without altering stomatal sensitivity. Decoupling offered limited potential cooling benefits, questioning its effectiveness for leaf thermoregulation in xeric ecosystems. We suggest that adding COS to leaf and ecosystem flux measurements helps elucidate diverse physiological mechanisms underlying transpiration–photosynthesis decoupling. Summary statement: During heatwaves, plants can lose more water to sustain the same level of photosynthesis, but it is unclear what makes them do so. Here, we leverage leaf carbonyl sulphide flux measurements to show that restricted gas diffusion within leaves led to this heatwave response in a southern California oak. [ABSTRACT FROM AUTHOR]

This article examines diverse perspectives on heatwave resilience in public health planning, interviewing stakeholders from various sectors. It identifies challenges, including operational, political, economic, and cultural aspects, hindering effective strategies. The study advocates for a holistic approach to heatwave resilience, emphasising interdisciplinary research and collaboration for targeted interventions. Enhancing resilience is crucial to mitigating adverse health impacts and safeguarding vulnerable populations during heatwaves. Conceptualisations of resilience related to heatwave public health planning and heatwave resilience vary significantly. There is a need to unveil the multifaceted nature of resilience in the context of heatwaves and identify key challenges that hinder effective public health planning efforts. Qualitative study to explore key stakeholders' conceptualisations of resilience and highlight challenges and opportunities needed for greater heatwave resilience and public health planning. Interviews were conducted with a diverse group of key stakeholders involved in local, regional, and national heatwave planning, academics, civil sector and private sector representatives. The findings of this study highlight diverse conceptualisations of resilience. Conceptualisations of resilience mainly differ on the following: ' whom '; ' what '; ' how '; ' when '; and ' why '. This analysis shows that the concept of resilience is well understood but has different functions. The analysis of challenges revealed several key problems, such as operational and technical; political and governance; organisational and institutional; economic; linguistic; cultural, social, and behavioural; and communication, information, and awareness. These significantly hinder effective heatwave public health planning strategies. The study emphasises the need for a holistic and integrated approach to heatwave resilience. Addressing these challenges is crucial for enhancing heatwave public health planning. This study provides valuable insights into the complexities of heatwave resilience, offering guidance for different sectors of society to develop targeted interventions and strategies. The development of new resilience interdisciplinary and intersectoral research, practice, and governance will prove crucial to ongoing efforts to strengthen national heatwave resilience public health planning. By fostering resilience, societies can mitigate the adverse impacts of heatwaves and safeguard the health and well-being of vulnerable populations. [ABSTRACT FROM AUTHOR]

In Canada, extreme heat occurrences present significant risks to public health, particularly for vulnerable groups like older individuals and those with preexisting health conditions. Accurately predicting indoor temperatures during these events is crucial for informing public health strategies and mitigating the adverse impacts of extreme heat. While current systems rely on outdoor temperature data, incorporating real-time indoor temperature estimations can significantly enhance decision-making and strengthen overall health system responses. Sensor-based technologies, such as ecobee smart thermostats installed in homes, enable effortless collection of indoor temperature and humidity data. This study evaluates the efficacy of deep learning models in predicting indoor temperatures during heat waves using smart thermostat data, to enhance public health responses. Utilizing ecobee smart thermostats, we analyzed indoor temperature trends and developed forecasting models. Our findings indicate the potential of integrating IoT and deep learning into health warning systems, enabling proactive interventions, and improving sustainable health care practices in extreme heat scenarios. This approach highlights the role of digital health innovations in creating the resilient and sustainable healthcare systems against climate-related health adversities. [ABSTRACT FROM AUTHOR]

Droughts and heat waves exhibit synergistic effects and are among the world's most costly disasters. To explore the spatiotemporal differences and formation mechanisms of the combined vulnerability to droughts and heat waves in Shandong Province over the past 20 years, a vulnerability scoping diagram (VSD) model with three dimensions—exposure, sensitivity, and adaptability—was constructed to assess and compare the combined vulnerability to high-temperature and drought events, considering economic and social conditions. The results showed that (1) over the past 20 years, heat waves and droughts have increased in Shandong Province. The number of high-temperature events significantly increased in the west and decreased along the eastern coast, and drought change was characterized by an increase in the south and a decrease in the north. (2) The combined exposure to summer droughts and heat waves in Shandong Province showed a significant increasing trend (P < 0.05) at a rate of approximately 0.072/10a; the combined sensitivity significantly decreased (P < 0.05) at a rate of approximately 0.137/10a, and the combined adaptability continued to increase at a rate of approximately 0.481/10a. (3) The combined vulnerability to summer droughts and heat waves in the western inland area of Shandong Province was high and gradually decreased toward the southeastern coast. The overall decrease trend was nonsignificant with a decrease of approximately 0.126/10a, and the decline rate decreased from northwest to southeast, in which Laiwu, Yantai, Jinan, and Zibo cities exhibited a significant decreasing trend (P < 0.05). Although the compound vulnerability of Shandong Province has decreased insignificantly, the frequency of combined drought and heat wave events has increased, and the combined vulnerability will increase in the future. [ABSTRACT FROM AUTHOR]

We study the impact of recent global warming on extreme climatic events in Central Asia (CA) for 1901-2019 by comparing the composite representation of the observational climate with a hypothetical counterfactual one that does not include the long-term global warming trend. The counterfactual climate data are produced based on a simple detrending approach, using the global mean temperature (GMT) as the independent variable and removing the long-term trends from the climate variables of the observational data. This trend elimination is independent of causality, and the day-to-day variability in the counterfactual climate remains preserved. The analysis done in the paper shows that the increase in frequency and magnitude of extreme temperature and precipitation events can be attributed to global warming. Specifically, the probability of experiencing a +7 K temperature anomaly event in CA increases by up to a factor of seven in some areas due to global warming. The analysis reveals a significant increase in heatwave occurrences in Central Asia, with the observational climate dataset GSWP3-W5E5 (later called also factual) showing more frequent and prolonged extreme heat events than hypothetical scenarios without global warming. This trend, evident in the disparity between factual and counterfactual data, underscores the critical impact of recent climatic changes on weather patterns, highlighting the urgent need for robust adaptation and mitigation strategies. Additionally, using the self-calibrated Palmer drought severity index (scPDSI), the sensitivity of dry and wet events to the coupled precipitation and temperature changes is analyzed. The areas under dry and wet conditions are enhanced under the observational climate compared to a counterfactual scenario, especially over the largest deserts in CA. The expansion of the dry regions aligns well with the pattern of desert development observed in CA in recent decades. [ABSTRACT FROM AUTHOR]

During the 2022 summer, Europe experienced heatwaves with record temperatures, and a study has argued that they caused about 62,000 deaths between 30 May and 4 September. The total number of excess deaths during the same period was about 137,000, indicating that the heatwaves were a substantial contributor. Not ruling out that explanation entirely, this paper argues that it was unlikely a strong cause. First, if the heatwaves were a strong cause of numerous deaths, one would assume that the older and deprived were relatively likely to die. However, during the 2022 summer heatwaves in England, which were claimed to have caused about 2900 deaths, the oldest age cohort did not have a higher excess death rate than the middle age cohort, and the excess death rate actually decreased with deprivation status. Moreover, Iceland had among Europe's highest excess death rates during the summer, which cannot be attributed to heatwaves. During June, July, and August 2022, comparable southern hemisphere countries furthermore had high excess death rates, which cannot be attributed to heatwaves either, as it was during their winter. Also, Europe's excess death rate was higher during the 2022–2023 winter than during the 2022 summer, and intuitively not attributed to heatwaves, but neither to cold weather, as that winter was abnormally mild. Finally, the paper discusses the puzzling issue that about 56% more women than men, relative to the population, presumably died from the heatwaves. [ABSTRACT FROM AUTHOR]

The rise in outdoor temperatures and heatwaves highlights the limitations of buildings in adapting to warming conditions, even in temperate climates. This paper analyses the indoor overheating of residential dwellings in Pamplona (a city in northern Spain, with a Cfb climate) using an urban-scale diagnostic methodology and presents different envelopes' retrofitting scenarios as a strategy to reduce it. The results come from energy simulations conducted during an extremely warm summer in 2022, considering the microclimate effects. The residential typologies most vulnerable to overheating are those with only one orientation, built before the EPBD 2002, and located on top floors. These dwellings show a 23.7% mean of indoor overheating hours (IOH), representing approximately 870 h above the EN 16798-1:2019 adaptive threshold from May to September. Renovating building envelopes to meet current energy standards reduces the IOH by an average of 8.6% and up to 15.35% in the most vulnerable typologies. In the retrofitting scenario with green roof systems, indoor temperatures are up to 0.5 °C lower than when roofs are renovated with traditional systems. This study assists policy-makers in preventing the risk of overheating within cities and encourages them to promote nature-based solutions in order to adapt urban residential buildings and cities to warming conditions. [ABSTRACT FROM AUTHOR]

Climate change models predict that the frequency and intensity of heatwaves are likely to increase, therefore understanding population responses to these extreme climatic events will be key in mitigating biodiversity loss. Here, using the male dimorphic bulb mite, Rhizoglyphus robini, we investigate and compare the impact of experimental heat stress on survival and fertility between females and male morphs that differ in the expression of a sexually selected weapon. We show that lethal limits are similar among all individuals, but find clear sex differences, although no difference between morphs, in sub‐lethal temperatures causing sterility: female fertility remains high close to lethal limits, whereas both male morphs suffer fertility loss at more than 2.5°C below their lethal limits. Contrastingly, when thermal stress was lower the sexes and morphs do not differ in their thermal sensitivity and declines in reproductive output are comparable. These declines appear to be additive as we observe the greatest declines when both sexes were exposed to thermal stress. In addition, during assays we included an extra treatment that allowed individuals two extra days to recover and found that fertility loss was almost fully recovered when thermal stress was low, but only partially recovered under the most extreme temperatures. The impact of heat stress on fertility therefore appears to be temporary with individuals rapidly recovering: whether recovery can negate negative population level effects remains to be investigated. Our experiments reveal the impact of heat stress on survival and fertility, finding sex‐specific fertility loss under the most extreme thermal conditions. [ABSTRACT FROM AUTHOR]

Heatwaves are known to arise from the interplay between large‐scale climate variability, synoptic weather patterns, and regional to local‐scale surface processes. Though recent research has made important progress for each individual contributing factor, ways to properly incorporate multiple or all of them in a unified analysis are still lacking. In this study, we consider a wide range of possible predictor variables from the ERA5 Reanalysis version 5 and ask how much information on heatwave occurrence in Europe can be learned from each of them. To simplify the problem, we first adapt the recently developed logistic principal component analysis to the task of compressing large binary heatwave fields to a small number of interpretable principal components. The relationships between heatwaves and various climate variables can then be learned by a neural network. Starting from the simple notion that the importance of a variable is given by its impact on the performance of our statistical model, we arrive naturally at the definition of Shapley values. Classic results of game theory show that this is the only fair way of distributing the overall success of a model among its inputs. We find a nonlinear model that explains 70% of reduced heatwave variability. The biggest individual contribution (27% of the 70%) comes from upper level geopotential; top‐level soil moisture is in second place (15%). Beyond this decomposition, Shapley interaction values enable us to quantify overlapping information and positive synergies between all pairs of predictors. [ABSTRACT FROM AUTHOR]

This work aims to define a set of representative weather patterns for South Africa that can be utilized to support impact‐based forecasting of heatwave events. Sets of weather patterns have been generated using k‐means clustering on daily ERA5 reanalysis data between 1979 and 2020. Different pattern sets were generated by varying the clustering atmospheric variable, the spatial domain and the number of weather patterns. These weather patterns are evaluated using the explained variation score to assess their ability to represent the variability of the maximum daily 2m temperature (Tmax,2m). The results indicate that a set of 30 weather patterns generated using mean sea‐level pressure, with a clustering domain in the range 15°–34°E and 21°–36°S, provides a reasonable representation of Tmax,2m variability across South Africa. The implementation of an appropriate weather pattern set into a medium‐range forecasting tool has the potential to extend the prediction of high‐impact weather events in South Africa, such as heatwaves, and also highlight specific impacts on the population, for example, food and water insecurity, heat exhaustion or energy and transport impacts. [ABSTRACT FROM AUTHOR]

Due to climate change, rapid warming and its further intensification over different parts of the globe have been recently reported. This has a direct impact on human health, agriculture, water availability, power generation, various ecosystems, and socioeconomic conditions of the exposed population. The current study thus investigates the frequency and duration of heatwaves, human discomfort, and exposure of the human population to these extremes using the high-resolution regional climate model experiments under two Representative Concentration Pathways (RCP2.6, RCP8.5) over India. We find that more than 90% of India will be exposed to uncomfortable warm nights by the end of the 21st century with the highest rise over western India, Madhya Pradesh (MP), Uttar Pradesh (UP), Punjab, and the Haryana region. States like Odisha, Chhattisgarh, eastern parts of MP and UP, and some parts of J&K will be the worst hit by the intense and frequent heatwaves and human discomfort followed by the densely populated Indo-Gangetic plains under RCP8.5. Strict enforcement of the stringent policies on stabilization of population growth, improvement of local adaptive capacities, and economic status of the vulnerable population along with enforcing effective measures to curb greenhouse gas emissions are important to reduce human exposure to future heat stress. We demonstrate that a proper mitigation-based development (RCP2.6) instead of a business-as-usual scenario (RCP8.5) may help to reduce 50–200 heatwave days, 3–10 heatwave spells, and 10–35% warm nights over the Indian region. Consequently, this can avoid the exposure of 135–143 million population to severe discomfort due to extreme heat conditions by the end of the 21st century. [ABSTRACT FROM AUTHOR]

Streamflow, dissolved oxygen, and water temperature underpin stream fish habitat suitability, so climate change could cause widespread habitat deterioration. Identifying stream characteristics that mediate habitat resilience to heatwaves will allow conservation effort prioritisation. Here, a set of readily applied metrics were used to assess hydrological and oxythermal responses of neighbouring salmonid streams, with distinctive geologies, soil‐types, and localised riparian shading, to periods of anomalously warm conditions. During heatwaves, low flows, warm‐water temperatures, and diel oxygen variability, associated with biogenic production and respiration, predominated. In a low‐shade stream lacking significant catchment water storage, high daytime (>22°C) and night‐time (>19°C) water temperatures and low early morning O2 concentrations (<5 mg L−1) accumulated oxythermal stress for salmonids throughout summer. A stream with localised shading and a higher proportion of underlying aquifers and permeable soils throughout its watershed experienced considerably less cumulative oxythermal stress (O2 > 6 mg L−1; temperatures <19°C), whilst slower release of subsurface water bolstered base flows during dry spells. Our findings support conservation of shaded streams with permeable watersheds characterised by higher soil infiltration rates and aquifer storage capacity as salmonid sanctuaries under a warmer, drier summer climate. Preventing water quality and hydromorphological deterioration are paramount for safeguarding their role as climate refugia. [ABSTRACT FROM AUTHOR]

Most studies assessing the combined effects of chemical and non-chemical stressors on aquatic ecosystems have been based on synchronous stressor applications. However, asynchronous exposure scenarios may be more common in nature, particularly for pulsed stressors such as heatwaves and pesticide concentration peaks. In this study, we investigated the single and combined effects of the insecticide chlorpyrifos (CPF) and a heatwave (HW) on a zooplankton community representative of a Mediterranean coastal wetland using synchronous (CPF+HW) and asynchronous (HW→CPF and CPF→HW) exposure scenarios. CPF was applied at a concentration of 0.8 µg/L (single pulse), and the HW was simulated by a temperature increase of 8°C above the control temperature (20°C) for 7 days in freshwater microcosms. The interaction between stressors in synchrony resulted in synergistic effects at the population level (Daphnia magna) and additive at the community level. The partial reduction of sensitive species resulted in an abundance increase of competing species that were more tolerant to the evaluated stressors (e.g. Moina sp.). The asynchronous exposure scenarios resulted in a similar abundance decline of sensitive populations as compared to the synchronous one; however, the timing of stressor resulted in different responses in the long term. In the HW→CPF treatment, the D. magna population recovered at least one month faster than in the CPF+HW treatment, probably due to survival selection and cross-tolerance mechanisms. In the CPF→HW treatment, the effects lasted longer than in the CPF+HW, and the population did not recover within the experimental period, most likely due to the energetic costs of detoxification and effects on internal damage recovery. The different timing and magnitude of indirect effects among the tested asynchronous scenarios resulted in more severe effects on the structure of the zooplankton community in the CPF→HW treatment. Our study highlights the relevance of considering the order of stressors to predict the long-term effects of chemicals and heatwaves both at the population and community levels.

Angola is exceptionally vulnerable to climate change, and sectors such as health, agricultural, water resources and ecosystems may endure severe impacts. Here, an extensive analysis of the signal of climate change on temperature, precipitation, extremes and compound events, for the end of the 21st century, is presented. The analysis is based on a CORDEX-Africa multi-model ensemble at 0.44° resolution built with 19 individual simulations, which allows a robust study of climate change future projections and depict model's uncertainty. For the RCP8.5, the end of the century future warming can reach maxima values ∼ 7 °C for maximum temperature in south-eastern Angola, and 6 °C for minimum temperature. The extreme temperatures (90th percentile) is projected to rise more than 7 °C in southern areas. In general, projections display a rainfall reduction in the drier seasons and a rise in the wet seasons, leading to sharper annual cycles; it is also projected a growth on extreme precipitation (95th percentile), as much as plus ∼ 50 % in some coastal regions. Angola is projected to endure in the future more frequent and longer heatwaves and droughts. In agreement with the RCP8.5, up to 10 heatwaves and more 4 moderate droughts will occur, respectively in coastal and interior areas. Finally, the number of days when a compound of heatwave and moderate drought occurs is projected to growth immensely, around +30 % for many regions, which corresponds to multiply by 10 these events in the future. For the RCP4.5, changes are projected to be smaller but significant in what regards especially extremes and compound events. The magnitude of the projected changes for vulnerable countries as Angola constitute an urgent call for global mitigation and national to regional adaptation strategies, and ultimately to a constant effort of updating and deepen the quality of climate information produced.