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Satellite observations of the Antarctic surface since the 1990s, coupled with geophysical surveys of the flow and form of its giant ice sheet, have revealed accelerating loss of ice to the oceans. This, coupled with a reduction in floating sea ice surrounding the continent and the occurrence of unprecedented heatwaves, point to a continent being changed irreversibly by fossil-fuel burning and the global heating that results. A changing Antarctic continent will have global consequences, including sea level rise of possibly more than 1 meter in this century (and much more afterward) and by a reduced ability to naturally reflect incoming solar energy—which would lead to further heating by absorption on land and at sea as the ice pack retreats. [ABSTRACT FROM AUTHOR]

Marine heatwaves have caused massive mortality in coastal benthic ecosystems, altering community composition. Here, we aim to understand the effects of single and sequential sublethal heatwaves in a temperate benthic ecosystem, investigating their disturbance on various levels of ecological hierarchy, i.e. individual physiology, trophic groups' biomass and ecosystem carbon fluxes. To do so, we performed a near-natural experiment using outdoor benthic mesocosms along spring/summer, where communities were exposed to different thermal regimes: without heatwaves (0HW), with one heatwave (1HW) and with three heatwaves (3HWs). Gastropods were negatively impacted by one single heatwave treatment, but the exposure to three sequential heatwaves caused no response, indicating ecological stress memory. The magnitude of ecosystem carbon fluxes mostly decreased after 1HW, with a marked negative impact on mesograzers' feeding, while the overall intensity of carbon fluxes increased after 3HWs. Consumers' acclimation after the exposure to sequential heatwaves increased grazing activity, representing a threat for the macroalgae biomass. The evaluation of physiological responses and ecological interactions is crucial to interpret variations in community composition and to detect early signs of stress. Our results reveal the spread of heatwave effects along the ecological hierarchical levels, helping to predict the trajectories of ecosystem development. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'. [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]

Aim: This study investigates the biogeographic patterns of Pacific white‐sided dolphins (Lagenorhynchus obliquidens) in the Eastern North Pacific based on long‐term passive acoustic records. We aim to elucidate the ecological and behavioural significance of distinct echolocation click types and their implications for population delineation, geographic distribution, environmental adaptation and management. Location: Eastern North Pacific Ocean. Time Period: 2005–2021. Major Taxa Studied: Pacific white‐sided dolphin. Methods: Over 50 cumulative years of passive acoustic monitoring (PAM) data from 14 locations were analyzed using a deep neural network to classify two distinct Pacific white‐sided dolphin echolocation click types. The study assessed spatial, diel, seasonal and interannual patterns of the two click types, correlating them with major environmental drivers such as the El Niño Southern Oscillation and the North Pacific Gyre Oscillation, and modeling long‐term spatial‐seasonal patterns. Results: Distinct spatial, diel and seasonal patterns were observed for each click type. Significant biogeographical shifts in presence were observed following the 2014–2016 marine heatwave event. Main Conclusions: Distinct spatial distributions of the two click types support the hypothesis that Pacific white‐sided dolphins produce population‐specific echolocation clicks. Seasonal and diel patterns suggest spatiotemporal niche partitioning between the populations in Southern California. Interannual changes, notably initiated during the 2014–2016 marine heatwave, indicate climate‐driven range expansions and contractions related to gradual tropicalization of the Southern California Bight. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of heat waves on the productivity of the Italian food industry. Using daily weather and firm‐level data for the 2004–2019 period, we show that a heat wave causes, on average, a reduction in Total Factor Productivity (TFP) of about 3.2%. Smaller firms are more severely affected, with a reduction of approximately 7%, revealing unequal impacts within the same country and sector. The reduction in TFP can be partially attributed to lower workers' productivity, with labour input increased in order to compensate for productivity loss. The estimated effect is heterogeneous across subsectors, with some well‐known Italian products (e.g., wine production) more severely affected by heat waves. These findings have significant policy implications due to the expected increase in the frequency of heat waves caused by climate change, and are particularly important in the case of the Italian food industry, which is mainly composed of small firms. The paper highlights the need to investigate further the impacts of heat stress on the entire food system, as most of the literature has predominantly focused on the agricultural sector. [ABSTRACT FROM AUTHOR]

The likelihood of exposure to overheated indoor environments is increasing as climate change is exacerbating the frequency and severity of hot weather and extreme heat events (EHE). Consequently, vulnerable populations will face serious health risks from indoor overheating. While the relationship between EHE and human health has been assessed in relation to outdoor temperature, indoor temperature patterns can vary markedly from those measured outside. This is because the built environment and building characteristics can act as an important modifier of indoor temperatures. In this narrative review, we examine the physiological and behavioral determinants that influence a person's susceptibility to indoor overheating. Further, we explore how the built environment, neighborhood-level factors, and building characteristics can impact exposure to excess heat and we overview how strategies to mitigate building overheating can help reduce heat-related mortality in heat-vulnerable occupants. Finally, we discuss the effectiveness of commonly recommended personal cooling strategies that aim to mitigate dangerous increases in physiological strain during exposure to high indoor temperatures during hot weather or an EHE. As global temperatures continue to rise, the need for a research agenda specifically directed at reducing the likelihood and impact of indoor overheating on human health is paramount. This includes conducting EHE simulation studies to support the development of consensus-based heat mitigation solutions and public health messaging that provides equitable protection to heat-vulnerable people exposed to high indoor temperatures. [ABSTRACT FROM AUTHOR]

While a record-high in situ water temperature of 38.4 °C on July 24, 2023, has been measured from a local site in Florida's Manatee Bay, satellite images revealed more extensive record-high water temperature in South Florida estuaries and the Florida Keys Reef Tract in July 2023 as a response to the 2023 heatwave, with an average sea surface temperature (SST) anomaly of 1.59 °C above the 2003–2022 mean. Long-term annual SST anomalies and long-term SST trend components of the time series both show significant warming trends in these regions between 2003 and 2023 (0.70 °C/decade), which is 67% higher than in the Gulf of Mexico (0.42 °C/decade). Furthermore, the warming trend appears to have accelerated over the past decade. In the context of global warming in the twenty-first century, such a warming trend and response to heatwaves may lead to more heat stress on the precious coral reefs and seagrasses both in and downstream from these already fragile estuaries. [ABSTRACT FROM AUTHOR]

Drawing on five years of intermittent ethnographic fieldwork, this article examines the ritual ecology of the Nkolola girls’ initiation practice of the Tonga-speaking people of Mola, Zimbabwe. It focuses on the materiality framework to demonstrate the environmental contingencies of this ritual and how the breakdown of Nkolola indicates an environmental crisis. There are specific materials required for this ritual, but extreme weather patterns such as continuous droughts and heatwaves have made it challenging to gather essential items like red ochre, traditional herbs, firewood, and tree branches, as well as access to perennial rivers and streams needed to properly perform the ritual. The article discusses the importance of these materials in each stage of the ritual, as well as the significant consequences of their absence, including avoidance and delays in conducting the ceremony. It also explores an alternative ritual that is less material-intensive and demanding of natural resources. [ABSTRACT FROM AUTHOR]

Midlatitude Europe (ME) emerges as a prominent heatwave hotspot with rapid increases in summer surface air temperature and heatwave days since 1979, surpassing the global land averages by approximately 2.6 and 2.3 times, respectively. The circulation analogs‐based dynamic adjustment reveals that approximately 38% and 35% of these trends result from shifts in zonal dipolar circulation patterns over the North Atlantic (NA) and Europe, crucial for the enhanced warming compared to the global land average. The circulation changes are associated with warming sea surface temperatures in the NA. This warming pattern resembles the Atlantic Multidecadal Variability and is predominantly induced by greenhouse gases. Moreover, the stronger air temperature response in ME to decreased aerosols amplifies warming, contributing to the rapid increase in heatwave frequency. These findings highlight a prominent influence of anthropogenic forcings on the swift surge of European heatwaves compared to global land, with a potential implication for adaptation strategies and risk management. Plain Language Summary: Midlatitude Europe is experiencing a significant increase in heatwaves, with summer temperatures and heatwave occurrences rising much faster than the global land averages since 1979. One of the key contributors to this rapid warming is the changes in zonal dipolar circulation patterns over the NA and Europe, which are linked to the warm sea surface temperatures in the NA. This warming pattern, resembling the Atlantic Multidecadal Variability, is largely caused by greenhouse gases and additionally influenced by reduced aerosols and natural forcing. Furthermore, the stronger response of air temperatures in midlatitude Europe to decreased aerosol emissions intensifies summer warming, contributing to a rapid increase in heatwave days. These findings highlight the significant impact of anthropogenic forcings on the observed surge of heatwaves in Europe compared to global land, with an important implication for developing strategies to adapt to these changing climate conditions and managing the associated risks. Key Points: Midlatitude Europe exhibits more rapid increases in summer heatwave frequency than the global land averages in recent decadesAtmospheric circulation changes contributing about one third of the observed warming trend, further intensify the rapid increases in summer heatwave frequencyLocal air temperature response to reduced aerosol emissions contributes about half of the enhanced warming compared to the global land average [ABSTRACT FROM AUTHOR]

Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heatwave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We used experimental heatwaves to determine how high temperatures affect the bumblebees' ability to detect floral scents. Heatwaves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 h after heat events. Our results suggest that the projected increased frequency and severity of heatwaves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees' abilities to locate food sources and lead to declines in colonies and populations. [ABSTRACT FROM AUTHOR]

Concepts, approaches and frameworks for assessing the impacts of climate change are evolving quickly. Due to their particular geographic location, proximity to oceans, concentration of populated regions, and infrastructure, coastal communities are particularly sensitive to the effects of climate change. The present study aims to develop a thematic map based on the CID (climatic impact-drivers) framework proposed in the assessment report-6 of the Intergovernmental Panel on Climate Change (IPCC) to evaluate the climate change’s physical hazards in the coastal districts of India. The study points out that West Bengal and Odisha are the two states with the highest cyclone hazard index values making them most vulnerable to cyclones. At the same time, Kerala, Andhra Pradesh and West Bengal respectively fall in the extremely severe category of flood, heatwave and shoreline change hazards. The maritime state of Gujarat along with Diu and Daman experiences maximum severity for the sea level rise hazard. The multi-hazards index developed in the study by considering 14 threshold-based CID indices showed that the coastal state of Andhra Pradesh has the highest proneness to the physical hazards due to climate change [ABSTRACT FROM AUTHOR]

This study analyses the spatio‐temporal variability of heatwave characteristics and their association with large‐scale climate drivers across seven climatic sub‐regions in Vietnam, including the Northwest (R1), Northeast (R2), Red River Delta (R3), North Central (R4), South Central (R5), Central Highlands (R6) and the South (R7). The analysis is based on observed daily maximum temperatures from 102 meteorological stations, spanning the period 1980–2020. The obtained results reveal diverse heatwave patterns across the country. Amongst the seven climatic sub‐regions of Vietnam, the R3 and R4 sub‐regions experienced more frequent heatwaves and a higher number of heatwave days, but shorter durations. In contrast, other sub‐regions had fewer heatwave events and heatwave days but experienced longer‐lasting heatwaves. The intensity of heatwave events varies amongst sub‐regions, with the highest value in the R4 sub‐region, and the lowest in R7. Notably, the R1–R5 sub‐regions are affected by heatwaves over larger areas, compared to others. Additionally, the findings confirm that the lagged influence of El Niño–Southern Oscillation (ENSO) is the primary climatic driver of heatwave characteristics in Vietnam. Generally, heatwaves tend to occur more frequently in the years following El Niño events than after La Niña events. This observation provides opportunities for developing a system of seasonal predictions of heatwaves in Vietnam. The impact of ENSO on the number of heatwave events and heatwave days is evident in five out of seven sub‐regions, with less impact in the R2 and R7 sub‐regions. However, it does not significantly affect heatwave intensity. [ABSTRACT FROM AUTHOR]

Based on the observed maximum temperature (Tmax), relative humidity (RH) and NCEP/NCAR reanalysis data during 1981–2021, basic temporal features and dominant atmospheric circulation patterns of dry‐type and humid‐type heatwaves in North China are investigated and compared. Statistical results indicate the dry heatwaves occur mainly in early summer (from early June to early July), that is, before the rainy season of North China, while the humid heatwaves have a high frequency in mid‐July to mid‐August. During the research period, the increasing trend of dry heatwaves is 0.67 days·decade−1, while the humid heatwaves increase at a greatly higher rate of 1.85 days·decade−1. For the dry heatwave, a high ridge in the subtropical westerlies plays the main role, and the northerly wind in the east of the ridge reduces the air moisture convergence over the region. However, for the humid heatwave, the westward and northward propagations of the western Pacific subtropical high (WPSH) may make the major contribution, and the southerly wind anomalies in the west of the WPSH enlarge the water vapour to the region. The adiabatic heating in subsiding air at all levels and horizontal temperature advection at lower troposphere are stronger for dry heatwaves than for humid heatwaves, which cause a higher Tmax for the former type. These results highlight the diversity of the heatwaves in North China, which suggests that multiple local and large‐scale subseasonal circulations should be considered to improve the subseasonal to seasonal forecast skills for heat extremes. [ABSTRACT FROM AUTHOR]

Humid heat waves pose significant risks to human health and the ecosystem. Intuitively, rainfall often alleviates extreme humid heat. However, here we show that light rain often accompanies extreme humid heat, exacerbating its frequency and intensity, especially over arid and semi-arid regions compared to no rain and moderate-to-heavy rain cases. This is because light rain does not dramatically reduce solar radiation but increases near-surface humidity through enhanced surface evaporation. The water replenishment from light rain as well as a shallower planetary boundary layer is crucial for consecutive extremes where there are commonly sporadic drizzle days amidst several rain-free days. These extremes last longer than rain-free extremes. Current global climate models (GCMs) overestimate light rain. After reducing this bias in a GCM, underestimations of humid heat waves in energy-limited regions and overestimations in water-limited regions are largely alleviated. These findings underscore the underappreciated impact of light rain on extreme humid heat. The authors show that the frequency, intensity, and duration of extreme humid heat are exacerbated by light rain through the enhancement of the total enthalpy flux and the shallowing of the planetary boundary layer. [ABSTRACT FROM AUTHOR]

The observed increase in extreme weather has prompted recent methodological advances in extreme event attribution. We propose a machine learning-based approach that uses convolutional neural networks to create dynamically consistent counterfactual versions of historical extreme events under different levels of global mean temperature (GMT). We apply this technique to one recent extreme heat event (southcentral North America 2023) and several historical events that have been previously analyzed using established attribution methods. We estimate that temperatures during the southcentral North America event were 1.18° to 1.42°C warmer because of global warming and that similar events will occur 0.14 to 0.60 times per year at 2.0°C above preindustrial levels of GMT. Additionally, we find that the learned relationships between daily temperature and GMT are influenced by the seasonality of the forced temperature response and the daily meteorological conditions. Our results broadly agree with other attribution techniques, suggesting that machine learning can be used to perform rapid, low-cost attribution of extreme events. [ABSTRACT FROM AUTHOR]

This study explores aerosol direct, indirect, and feedback effects on meteorology and fine particulate matter during heat waves of August 2022 over eastern China by using an online coupled regional climate–chemistry–aerosol model. In this period, aerosols exerted mean direct (DRE) and indirect (IRE) radiative effects of −3.9 Wm−2 and −2.4 Wm−2 at TOA, which totally caused a decrease in average surface air temperature by 0.3 °C over east China, accompanied by decreases in PBLH (planetary boundary layer height) and precipitation and an increase in PM2.5 concentration. With the anthropogenic emission reduction from 2013 to 2022, DRE apparently decreased while IRE changed little, leading to a decrease in total aerosol radiative effect (TRE) by 27% at TOA. The weakened TRE resulted in increases in surface air temperature and precipitation by 0.14 °C and 2.7 mm, respectively, on average over east China, with the maximum warming exceeding 0.5 °C in BTH (Beijing–Tianjin–Hebei province). This study highlights a warming trend due to weakened TRE, which may exacerbate heat wave, and an increasing importance of aerosol IRE relative to DRE due to weak sensitivity of cloud properties to aerosol change during the emission reduction. [ABSTRACT FROM AUTHOR]

Introduction: Coastal marine ecosystems, are particularly susceptible to climate change. One such threat is atmospheric heatwaves, which are predicted to increase in frequency, duration, and intensity. Many intertidal organisms already live at the edge of their thermal tolerance limits and heatwaves can outstretch an organism's ability to compensate in the short term. In June 2021 the Pacific Northwest region of North America, including the Salish Sea, experienced a significant atmospheric heatwave during some of the lowest tides of the year. This was followed by numerous reports of dead and dying intertidal marine organisms region-wide. A semi-quantitative rapid assessment found a range of both species- and location-specific effects but generally recorded widespread negative impacts to intertidal shellfish species across the Salish Sea. Methods: Following these results, we opportunistically analyzed data collected by intertidal bivalve resource managers from the region. These datasets allowed us to examine regional density and size data for clam and oyster populations before and after the heatwave to increase our quantitative understanding of heatwave effects. Results: We found a range of responses including positive and negative effects of the heatwave on clam and oyster density. While we generally found small changes in bivalve size, some site-species combinations displayed large shifts in size frequency. Many of our analyses did not indicate even moderate statistical support, even with large changes in the mean, driven in part by high variability in the data. Time intervals between surveys, ranging from 2 to over 25 months, had little effect on observed variability indicating that any heatwave-induced effects may be masked by variability inherent to the population ecology and/or survey methodology. Discussion: This analysis has highlighted the need for intertidal resource managers, and the greater research community, to consider alternative survey approaches designed to constrain variability in order to detect the effects of acute or extreme events. With the effects of climate change predicted to become more intense, targeted survey approaches may be needed to detect the effects and implications of such events and to continue effective management of intertidal bivalves in the Salish Sea and worldwide. [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]

In July and August 2022, the Yangtze River basin (YRB) experienced its hottest summer since 1961. The SINTEX‐F2 seasonal prediction system initialized in early May predicted the hotter‐than‐normal summer due to its successful prediction of central Pacific La Niña, negative Indian Ocean Dipole and the resultant warming in the tropical West Pacific‐East Indian Ocean (TWP_EIO). The common SST forcing explains only about 26% to the heatwave strength, while the internal variations in the anomalous warming in the TWP_EIO and Europe, surplus precipitation in Pakistan, and local land‐air interaction account for approximately 65%, based on the analysis of 108 ensemble members. These factors have collectively increased the maximum temperature over the YRB through the enhancement and westward expansion of western North Pacific subtropical high. Our findings quantify the relative contributions of external forcing and internal variations to the unprecedented hot event, offering insights into its forming mechanism and potential predictability. Plain Language Summary: A record‐breaking heatwave event occurred in the YRB in July and August 2022, posing significant risks on human health, power supply, and social economic activities. Recognizing the importance of such an event, our study aims to identify key factors influencing its prediction using the SINTEX‐F2 system. The central Pacific La Niña, negative Indian Ocean Dipole and the resultant warming in the TWP_EIO provide the dominant predictability, but accounts only about 26% of the heatwave strength. However, internal variations in the anomalous warming in the TWP_EIO and Europe, surplus precipitation in Pakistan, and local land‐air interaction collectively explain about 65%. Our results suggest the necessity of large‐ensemble prediction in capturing this kind of unprecedented extreme event. Key Points: The SINTEX‐F2 initialized on 2022 early May captures the warmer‐than‐normal air temperatures in Yangtze River basinThe model successfully predicts co‐occurrences of CP La Niña and negative IOD in 2022However, the direct SST forcing contributes only 26% to the 2022 extreme event in Yangtze River basin [ABSTRACT FROM AUTHOR]

Large‐scale topographies affect global extreme weather and climate though dynamic and thermal forcing. However, the impacts of typical topographies on heat waves in different drylands globally remain unclear. In this study, we find that heat waves are mainly occurred in global drylands during 1940–2022. The frequencies and intensities of heat waves in global drylands have significantly increased after 1980s. Multiple numerical model simulations reveal that the impact range of Asian topography on heat waves in global drylands is widest, not only in East Asia, Central, and west Asia locally, but also can reach as far as North Africa and North America. While the impact ranges of topographies in Africa, Arabian Peninsula, North America, and South America on heat waves in drylands are relatively narrow, which are concentrated in localized and their surroundings. These conclusions could provide clues to understand the influence of topography on global weather and climate extremes. Plain Language Summary: Topographies have important impacts on heat waves in global drylands. Through numerical model simulations, this study reveals that Asian topography contributes significantly to heat waves in global drylands, with the widest impact ranges which can cover drylands of East Asia, Central and west Asia, North Africa, even North America. The impacts of the East African Plateau, the Arabian Plateau, the Sierra Madre in North America and the Andes in South America on heat waves are mainly in the local and surrounding regions. Key Points: Heat waves are mainly occurred in global drylands and experience significant increases after 1980sThe impact range of Asian topography on heat waves in global drylands is widest, which can reach as far as North Africa and North AmericaThe topographies in Africa, Arabian Peninsula, North America, and South America can only affect heat waves in localized and surroundings [ABSTRACT FROM AUTHOR]

Ectotherms are largely impacted by extreme climate events, essentially heatwaves. In Tunisia, the pine processionary moth (PPM), Thaumetopoea pityocampa, is a defoliator typically laying eggs in summer. Its geographical range is expanding northwards in Europe while retracting from southern Tunisia where summer temperatures can reach extreme heats. We explored the effects of climate change over the last 30 years on PPM at its southern range edge. We investigated variations of fecundity and causes of egg mortality over time using historical and contemporary collections of egg masses. Due to incomplete historical series, a clustering method was used to group climatically homologous sampling sites and perform allochronic analyses on clusters instead of individual localities. Our results suggest negative effects of summer heat on egg survival, down to 0% hatching rate in one site during a major heatwave. Such high hatching failures resulted partly from high egg sterility and aborted embryos, with little effects of parasitism rate, suggesting heat susceptibility during embryonic development, but our results do not allow distinguishing impeded mating success from failed egg maturation or early embryo death. Decreasing female fecundity was observed in regions where allochronic comparisons were possible, associated with a decrease in parasitism rate, while climatic variability increased. Previous studies have confirmed experimentally the thermal sensitivity of PPM early instars to temperatures observed in the present work, including one population from southern Tunisia. However, further work is required to evaluate the relative importance of warming summers among populations, since the risk of heat stress depends on the phenology of sensitive instars, and populations from the warmest areas may not necessarily be the most vulnerable to climate change if they already evolved phenological heat avoidance. In addition to heat‐induced mortality, the ultimate fitness of heat survivors should also be explored to determine potential carry‐over effects on subsequent life stages. [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]

The increasing frequency and severity of heatwaves will intensify stress on plants. Given regional variation in heatwave exposure and expected differences in thermal tolerance between species it is unlikely that all plant species will be affected equally by climate change. However, little is currently known about variation in the responses of plants to heat stress, or how those responses differ among closely related species adapted to different environments. Here we quantify the response of 17 Acacia species (175 RNA‐seq libraries), from across Australia's diverse biomes, to a multi‐day experimental heatwave treatment to identify variation in transcriptomic and physiological responses to heat stress. Genes with known heat response functions showed consistent responses across Acacia species. Up to 10% of all genes and over 100 gene families showed significant clinal variation in the magnitude of their expression plasticity across species. Specifically, gene families linked to the temperature stress response were overrepresented among significant relationships with home range temperature conditions. Gene expression responses seen on the first day of the heatwave were more frequently associated with home range climates, while expression responses by day four were more commonly related to photosystem II acclimation. Comparative transcriptomics on non‐model species has the potential to provide key information on stress response plasticity, especially when linked with our understanding of model species. Our study indicates that the pressing challenge to identifying potentially vulnerable species to climate change could be benefited by the further exploration of clinal variation in transcriptome plasticity. [ABSTRACT FROM AUTHOR]

Climate change has increased the frequency and severity of weather extremes, including droughts, heat waves and compound drought and heatwave (CDHW) events. CDHW events profoundly impact water availability, agriculture, public health and energy production, particularly in the Horn of Africa (HOA). This study examined the historical spatiotemporal patterns of CDHW periods in the HOA during three periods (1951–1980, 1971–2000 and 1991–2020) using the ERA5 reanalysis dataset. This study utilized monthly Standardized Precipitation Evapotranspiration Index (SPEI) data to detect droughts and daily maximum temperature data to identify heatwaves for characterizing the duration, severity and magnitude of CDHW events. The results show a substantial increase in the duration of CDHW events in recent years, with durations reaching up to 25 days. The average duration of heat waves also increased from 7 days before 1993 to 18 days by 2011, culminating in a record‐breaking 43‐day heat wave in 2019. Most areas experienced a significant increase in heatwave duration by more than 12 days from the early period of 1951–1980 to the late period of 1991–2020. Although around 76% and 69% of the HOA exhibited insignificant heatwave trends in the first two periods, Ethiopia and Kenya experienced substantial increases of more than 18 days during the most recent period, with some durations exceeding 25 days in recent decades. The magnitude of CDHW events generally decreased as drought duration intensified, but specific areas, particularly southwest Kenya and Eritrea, exhibited higher CDHW values in the last period. These findings underscore the urgent need to understand and address CDHW events in the HOA. Targeted interventions for disaster risk reduction and resilience‐building are needed to mitigate the adverse effects of these events in this vulnerable region. This study provides a basis for future research and policy formulation in the HOA. [ABSTRACT FROM AUTHOR]

The exponential growth in population and physical infrastructure since 1980 has imposed immense pressure on Dhaka Metropolitan City (DMC), triggering extensive urbanization and a surge in built-up areas. This urban expansion has intensified the urban heat island (UHI) effect (the phenomenon where urban areas experience significantly higher temperatures compared to surrounding areas), resulting in adverse global urban climate changes such as temperature spikes, erratic rainfall, and compromised air quality. This study aims to discern the heat wave trends in DMC from 1972 to 2020 and elucidate their impact on public health and livelihoods. Employing a blend of quantitative and qualitative methodologies, the research analysis of land surface temperatures (LST) and land cover indices reveals a significant increase in built-up areas, particularly in western and central parts of the city, correlating with higher LST. Satellite imagery (Landsat 5 and 8) with 30-m resolution and meteorological data indicate a rise in surface temperatures. Analysis reveals April, May, and June as the peak months for heat wave occurrences, with DMC enduring a total of 328 heat wave days according to heat index (a measurement of perceived temperature in human body indicating how hot it feels when relative temperature is added to the actual air temperature) classifications. Notably, the density of built-up areas, particularly in central and western regions, exacerbates the UHI effect, evident in rising surface temperatures reaching 40.1 °C in 2014. The study underscores the dire health hazards posed by heat waves, with vulnerable populations, such as slum dwellers and outdoor laborers, facing heightened risks. Despite widespread impacts, public awareness about heat waves remains deficient, as evidenced by respondents' limited understanding of the term. These outcomes and prepared maps of the current research will be supportive for the local inhabitant, urban planner, and environmental resources management manager, national and international policy advisor, government and non-movement stakeholder, and researcher to observe the urban climate, trend of heat wave, and its impact on exposed people. [ABSTRACT FROM AUTHOR]

Mortality of tree species around the globe is increasingly driven by hotter drought and heat waves. Tree juveniles are at risk, as well as adults, and this will have a negative effect on forest dynamics and structure under climate change. Novel management options are urgently needed to reduce this mortality and positively affect forest dynamics and structure. Potential drought-ameliorating soil amendments such as nanochitosan - a biopolymer upcycled from byproducts of the seafood industry - may provide an additional set of useful tools for reducing juvenile mortality during hotter droughts. Nanochitosan promotes water and nutrient absorption in plants but has not been tested in the context of drought and heat stress. We evaluated factors affecting mortality risk and rate for dryland Pinus edulis juveniles (2-3 years old) in a growth chamber using a factorial experiment that included ambient and +4°C warmer base temperatures, with and without a 10 day +8°C heat wave, and with and without a nanochitosan soil amendment. The nanochitosan treatment reduced the relative risk of mortality, emphasizing a protective function of this soil amendment, reducing the relative risk of mortality by 37%. Importantly, the protective effects of nanochitosan soil amendment in delaying tree mortality under hotter drought and heat waves provides a new, potentially positive management treatment for tree juveniles trying to survive in the climate of the Anthropocene. [ABSTRACT FROM AUTHOR]

The world's oceans are under threat from the prevalence of heatwaves caused by climate change. Despite this, there is a lack of understanding regarding their impact on seawater oxygen levels - a crucial element in sustaining biological survival. Here, we find that heatwaves can trigger low-oxygen extreme events, thereby amplifying the signal of deoxygenation. By utilizing in situ observations and state-of-the-art climate model simulations, we provide a global assessment of the relationship between the two types of extreme events in the surface ocean (0–10 m). Our results show compelling evidence of a remarkable surge in the co-occurrence of marine heatwaves and low-oxygen extreme events. Hotspots of these concurrent stressors are identified in the study, indicating that this intensification is more pronounced in high-biomass regions than in those with relatively low biomass. The rise in the compound events is primarily attributable to long-term warming primarily induced by anthropogenic forcing, in tandem with natural internal variability modulating their spatial distribution. Our findings suggest the ocean is losing its breath under the influence of heatwaves, potentially experiencing more severe damage than previously anticipated. The authors show that the global ocean is experiencing a significant rise in simultaneous heatwaves and low-oxygen extreme events that pose threats to marine life worldwide. [ABSTRACT FROM AUTHOR]

Unprecedentedly extreme precipitation occurred in Pakistan (PAK), and mega heat waves persisted along the Yangtze River Valley (YRV) from July to August 2022. Using the advanced multiscale window transform-based canonical transfer attribution framework, we quantitatively delineated intra-scale and inter-scale interactions leading to record-breaking spatially concurrent extremes in 2022 and comprehensively revealed differences in dynamic processes affecting extreme events in July and August. The basic flow scale window lost the available potential energy (APE), and through APE canonical transfers to the intraseasonal-scale and synoptic-scale windows, the inter-scale dynamic processes and barotropic instability of the basic flow scale preserved the concurrent extreme in July. In August, the eruptive synoptic-scale kinetic energy convergence provided dynamic conditions for the sinking motion of the YRV and its advection to PAK from the Indian Ocean. Consequently, the interaction between high- and low-frequency processes drove atmospheric circulation in summer, but the high-frequency process in August played a vital role in extreme events. Additionally, the heat source in the tropical western-central Pacific is considered one of the key drivers for localized repetitive bursts of energy. This study emphasizes both the interactions between multiple scales of atmospheric dynamics and reveals the driving mechanisms behind the impacts of warming on extreme events, linking the external forcing issue with the free problem of atmospheric internal instability. [ABSTRACT FROM AUTHOR]

Increasing heatwave intensity and mortality demand timely and accurate heatwave prediction. The present study focused on teleconnection, the influence of distant land and ocean variability on local weather events, to drive long-term heatwave predictions. The complexity of teleconnection poses challenges for physical-based prediction models. In this study, we employed a machine learning model and explainable artificial intelligence to identify the teleconnection drivers for heatwaves in South Korea. Drivers were selected based on their statistical significance with annual heatwave frequency (| R | > 0.3, p < 0.05). Our analysis revealed that two snow depth (SD) variabilities—a decrease in the Gobi Desert and increase in the Tianshan Mountains—are the most important and predictive teleconnection drivers. These drivers exhibit a high correlation with summer climate conditions conducive to heatwaves. Our study lays the groundwork for further research into understanding land–atmosphere interactions over these two SD regions and their significant impact on heatwave patterns in South Korea. [ABSTRACT FROM AUTHOR]

Central America and the Caribbean are regularly battered by megadroughts, heavy rainfall, heat waves, and tropical cyclones. Although 21st‐century climate change is expected to increase the frequency, intensity, and duration of these extreme weather events (EWEs), their incidence in regional protected areas (PAs) remains poorly explored. We examined historical and projected EWEs across the region based on 32 metrics that describe distinct dimensions (i.e., intensity, duration, and frequency) of heat waves, cyclones, droughts, and rainfall and compared trends in PAs with trends in unprotected lands. From the early 21st century onward, exposure to EWEs increased across the region, and PAs were predicted to be more exposed to climate extremes than unprotected areas (as shown by autoregressive model coefficients at p < 0.05 significance level). This was particularly true for heat waves, which were projected to have a significantly higher average (tested by Wilcoxon tests at p < 0.01) intensity and duration, and tropical cyclones, which affected PAs more severely in carbon‐intensive scenarios. PAs were also predicted to be significantly less exposed to droughts and heavy rainfall than unprotected areas (tested by Wilcoxon tests at p < 0.01). However, droughts that could threaten connectivity between PAs are increasingly common in this region. We estimated that approximately 65% of the study area will experience at least one drought episode that is more intense and longer lasting than previous droughts. Collectively, our results highlight that new conservation strategies adapted to threats associated with EWEs need to be tailored and implemented promptly. Unless urgent action is taken, significant damage may be inflicted on the unique biodiversity of the region. [ABSTRACT FROM AUTHOR]

Heat waves are natural disasters that can result in large numbers of casualties. The frequency and damage caused by heat waves have been increasing in Korea due to climate change. The regional impacts of heat waves can vary according to environmental and socioeconomic factors regardless of duration and intensity. This study assessed the risks posed by heat waves for administrative districts in Korea according to climate change scenarios and the risk assessment framework of Fifth Assessment Report presented by the Intergovernmental Panel on Climate Change. The risk of heat waves is usually based on a combination of hazard, exposure, and vulnerability. Unlike previous studies using subjective weights, this study employed partial least squares—structural equation modeling (PLS-SEM) and entropy weighting, which are more objective methods of determining the indicators and weights, to estimate the exposure and vulnerability of heat waves. The results showed that at least 40% and 46% of administrative districts are expected to experience a high level of risk according to the representative concentration pathway scenarios, i.e., RCP 4.5 and 8.5, respectively. In addition, significant differences were observed in the heat wave risks calculated in this study for the upper and lower regions, with respect to cumulative heat-related morbidity rates, whereas the heat wave risk reported by the Korean Ministry of Environment was found to be insignificant. The results of this study can be used to prepare for heat waves and minimize damage caused by them. [ABSTRACT FROM AUTHOR]

Purpose: The rising frequency of extreme heat events poses an escalating threat of heat-related illnesses and fatalities, placing an additional strain on global healthcare systems. Whether the risk of heat-related issues is sex specific, particularly among the elderly, remains uncertain. Methods: 16 men and 15 women of similar age (69 ± 5 years) were exposed to an air temperature of 39.1 ± 0.3 °C and a relative humidity (RH) of 25.1 ± 1.9%, during 20 min of seated rest and at least 40 min of low-intensity (10 W) cycling exercise. RH was gradually increased by 2% every 5 min starting at minute 30. We measured sweat rate, heart rate, thermal sensation, and the rise in gastrointestinal temperature (Tgi) and skin temperature (Tsk). Results: Tgi consistently increased from minute 30 to 60, with no significant difference between females and males (0.012 ± 0.004 °C/min vs. 0.011 ± 0.005 °C/min; p = 0.64). Similarly, Tsk increase did not differ between females and males (0.044 ± 0.007 °C/min vs. 0.038 ± 0.011 °C/min; p = 0.07). Females exhibited lower sweat rates than males (0.29 ± 0.06 vs. 0.45 ± 0.14 mg/m2/min; p < 0.001) in particular at relative humidities exceeding 30%. No sex differences in heart rate and thermal sensation were observed. Conclusion: Elderly females exhibit significantly lower sweat rates than their male counterparts during low-intensity exercise at ambient temperatures of 39 °C when humidity exceeds 30%. However, both elderly males and females demonstrate a comparable rise in core temperature, skin temperature, and mean body temperature, indicating similar health-related risks associated with heat exposure. [ABSTRACT FROM AUTHOR]

Background and aims: A better understanding of plant carbon assimilation, water status and photosystem performance responses to combined heat and drought stress would help to optimize grapevine management under such limiting conditions. Methods: Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (Tmax = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines. Results: Photosynthesis and stomatal conductance in HW vines increased during the morning and dropped in the afternoon with respect to CW vines. Daily plant transpiration in HW almost doubled that of CW vines. When grapevines were already exposed to drought, the effects of the heat wave were negligible, with HD plants showing similar leaf photosynthesis and transpiration to their CD counterparts. Heat, but not drought stress, decreased the maximum (Fv/Fm) and effective photochemical quantum yield of PSII (φPSII), and also affected the use of absorbed energy. HW plants dissipated more radiative energy as heat, a protective mechanism of the photosystem, while HD vines increased the energy dissipated by non-regulated non-photochemical pathways, which might lead to photoinhibition damages. The different behavior could be due to the enhanced transpiration rate and consequent decrease in leaf temperature in HW as compared to HD vines. After the heat wave, only HW vines recovered the afternoon values of photosynthesis, stomatal conductance and φPSII to similar levels as those in CW vines. Conclusion: Drought had a more significant effect than heat stress on photosynthesis, stomatal conductance and transpiration. The combined heat and drought stress, however, increased the proportion of energy lost by the leaves through harmful non-regulated dissipative pathways. With adequate soil water availability, grapevines withstood the heat wave period through an increase in leaf transpiration, which decreased leaf temperature and protected the PSII from heat damage. Highlights: Drought had a stronger impact on gas exchange parameters than elevated temperature during a simulated heatwave, while heat stress was the main driver of PSII functionality and absorbed energy partitioning. Well-watered grapevines were able to recover their physiological function after a six-day heatwave (Tmax 40 °C), while plants under heat and drought stress were unable to resume PSII performance after one day of recovery. [ABSTRACT FROM AUTHOR]

Future projections indicate a global increase in heat waves, especially in urban areas due to climate change and the heat island effect, leading to adverse human, economic, and environmental outcomes. Cities worldwide respond by integrating climate mitigation and adaptation measures. While long-term strategies dominate research, this paper explores the increasing interest in short-term solutions, examining the Barcelona Climate Shelter Network. Investigating climate shelter initiatives, it highlights the use of public or private spaces for respite during extreme heat. This model offers insights for other European cities facing escalating heat waves, encouraging reflections on reshaping public services amidst climate crises. [ABSTRACT FROM AUTHOR]

Extreme heat alerts are the most common form of weather forecasting services used in Australia, yet very limited studies have documented their effectiveness in improving health outcomes. This study aimed to examine the temporal changes in temperature-related mortality in relation to the activation of the heat-health alert and response system (HARS) in the State of Victoria, Australia. We examined the relationship between temperatures and mortality using quasi-Poisson regression and the distributed lag non-linear model (dlnm) and compared the temperature-mortality association between the two periods: period 1– prior-HARS (1992–2009) and period 2– post-HARS (2010–2019). Since the HARS heavily weights heatwave effects, we also compared the main effects of heatwave events between the two periods. The heatwaves were defined for three levels, including 3 consecutive days at 97th, 98th, and 99th percentiles. We also controlled the potential confounding effect of seasonality by including a natural cubic B-spline of the day of the year with equally spaced knots and 8 degrees of freedom per year. The exposure-response curve reveals the temperature mortality was reduced in period 2 in comparison with period 1. The relative risk ratios (RRR) of Period 2 over Period 1 were all less than one and gradually decreased from 0.86 (95% CI, 0.72–1.03) to 0.64 (95% CI, 0.33–1.22), and the differences in attributable risk percent increased from 13.2 to 25.3%. The reduction in the risk of heatwave-related deaths decreased by 3.4% (RRp1 1.068, 95% CI, 1.024–1.112 versus RRp2 1.034, 95% CI, 0.986–1.082) and 10% (RRp1 1.16, 95% CI, 1.10–1.22 versus RRp2 1.06, 95% CI, 1.002–1.119) for all groups of people. The study indicated a decrease in heat-related mortality following the operation of HARS in Victoria under extreme heat and high-intensity heatwaves conditions. Further studies could investigate the extent of changes in mortality among populations of differing socio-economic groups during the operation of the heat-health alert system. [ABSTRACT FROM AUTHOR]

SLNE is the coupled model, that was developed in 2023. SL and NE here are the first two letters from SLAV (Semi-Lagrangian, based on Absolute Vorticity equation) model of the atmosphere and NEMO (Nucleus for European Modelling of the Ocean) ocean model that have been coupled using OASIS3-MCT software. The initial conditions for SLAV and NEMO are specified from an atmospheric and ocean analyses produced in Hydrometcentre of Russia. The 2010–2021 hindcast accuracy study shows, that SLNE has comparable errors to the operational SLAV model on a sub-seasonal time scale. The SLNE model has improved prediction skill of the 2010 heatwave features in comparison to SLAV, that is a motivation for further work to improve the coupled model. [ABSTRACT FROM AUTHOR]

Allergic diseases such as asthma, atopic dermatitis, and food allergies are a burgeoning health challenge in the Asia‐Pacific region. Compounding this, the region has become increasingly susceptible to the impacts of climate change. The region has weathered extreme precipitation, intense heat waves, and dust storms over the recent decades. While the effects of environmental and genetic factors on allergic diseases are well understood, prevailing gaps in understanding the complex interactions between climate change and these factors remain. We aim to provide insights into the various pathways by which climate change influences allergic diseases in the Asia‐Pacific population. We outline practical steps that allergists can take to reduce the carbon footprint of their practice on both a systemic and patient‐specific level. We recommend that allergists optimize disease control to reduce the resources required for each patient's care, which contributes to reducing greenhouse gas emissions. We encourage the responsible prescription of metered dose inhalers by promoting the switch to dry powder inhalers for certain patients, at each clinician's discretion. We also recommend the utilization of virtual consultations to reduce patient travel while ensuring that evidence‐based guidelines for rational allergy management are closely adhered to. Finally, eliminating unnecessary testing and medications will also reduce greenhouse gas emissions in many areas of medical care. [ABSTRACT FROM AUTHOR]

Temperature variation is one of the best‐known and studied factor constraining life history along the altitudinal gradients.Ectotherms such as insects are sensitive to temperature across all life stages, resulting in a wide range of adaptations in populations and species living at different elevations. In butterflies, the egg stage is particularly sensitive to temperature variation as eggs cannot move and deploy behavioural responses to overheating.Using a gradient polymerase chain reaction thermocycler to finely control temperature treatments, we tested for differences in egg heat tolerance between five closely related Coenonympha (Nymphalidae: Satyrinae) species living at different elevations.We found strong differences in egg heat tolerance ranges between lowland species (C. arcania (Linnaeus) and C. pamphilus (Linnaeus)) and two high elevation alpine species (C. gardetta (Prunner) and C. cephalidarwiniana Verity). Surprisingly, the third alpine species (C. darwiniana Staudinger) showed a heat tolerance range closer to that of the lowland species than that of alpine species.The sensitivity of eggs to overheating matched the temperature regimes recorded in the microhabitats utilised for oviposition and may explain the oviposition site selection of females observed in the wild.The narrower egg heat tolerance of some of alpine species may partly explain the position of their lower elevational limit but also raises concern about the fate of these species in the face of current climate change.Our results highlight the need to study all life stages, as well as microclimate choice for oviposition, to understand species distribution and the threats to their persistence. [ABSTRACT FROM AUTHOR]

Summer high temperature is an important climate issue. Severe heat waves occurred over China during summer 2022. Using daily temperature, we examine the severity of the 2022 high‐temperature event, and explore the dominance of summer cumulative temperature from the frequency and intensity of high temperature, for both the interannual variation of the 63 years (1960–2022) and the year of 2022. Corresponding to different “high” temperature thresholds, the frequency (number of the days) of high temperature, the summer cumulative temperature, and the intensity of high temperature are obtained for each summer with the daily data. Statistical tests show that cumulative temperature can be linearly regressed to frequency and intensity, which can help find the dominance from the two factors. For interannual variation, the comparison of the normalized regression coefficients suggests that, in the variation of cumulative temperature, the relative importance can vary from “dominated by intensity”, which corresponds to low temperature threshold (28°C), to “dominated by frequency”, which corresponds to high threshold (36°C). For the year 2022, we compare the two terms in the regression, which uses the coefficients from multi‐year regression along with the normalized frequency and intensity of this year, to determine the relative importance. Results show that overall it also varies from “dominated by intensity” to “dominated by frequency”, with the increase in threshold. Note that, for the two cases, these are the overall situation for the whole country; however, for each specific station, whether frequency or intensity dominates needs to be determined with the measures. A moderate threshold of 32°C, which considers both frequency and intensity, is suggested for practical applications. [ABSTRACT FROM AUTHOR]

Aim: Global change factors, such as warming, heatwaves, droughts and land‐use changes, are intensifying fire regimes (defined here as increasing frequency or severity of fires) in many ecosystems worldwide. A large body of local‐scale research has shown that such intensified fire regimes can greatly impact on ecosystem structure and function through altering plant communities. Here, we aim to find general patterns of plant responses to intensified fire regimes across climates, habitats and fire regimes at the global scale. Location: Worldwide. Time period: Studies published 1962–2023. Major taxa studied: Woody plants, herbs and bryophytes. Methods: We carried out a global systematic review and meta‐analysis of the response of plant abundance, diversity and fitness to increased fire frequency or severity. To assess the context dependency of those responses, we tested the effect of the following variables: fire regime component (fire frequency or severity), time since the last fire, fire type (wildfire or prescribed fire), historical fire regime type (surface or crown fire), plant life form (woody plant, herb or bryophyte), habitat type and climate. Results: Intensified fire regimes reduced overall plant abundance (Hedges' d = −0.24), diversity (d = −0.27), and fitness (d = −0.69). Generally, adverse effects of intensified fire regimes on plants were stronger due to increased severity than frequency, in wildfires compared to prescribed fires, and at shorter times since fire. Adverse effects were also stronger for woody plants than for herbs, and in conifer and mixed forests than in open ecosystems (e.g. grasslands and shrublands). Main conclusions: Intensified fire regimes can substantially alter plant communities in many ecosystems worldwide. Plant responses are influenced by the specific fire regime component that is changing and by the biotic and abiotic conditions. [ABSTRACT FROM AUTHOR]

Effects of climate change and especially the associated climate variability require farmers to adjust to increasing frequencies of extreme events. In the agriculturally highly productive Romanian Plain, the frequency, intensity, and duration of heatwaves and drought have increased over the past 20 years. Although recent surveys revealed farmers' awareness of climate change and enumerated a number of farm adaptation measures in the Romanian context, a systems approach to adaptation that allows conclusions on farm vulnerability and adaptive capacity is missing. Here, we use archetypal analysis to elucidate and characterize for the first time the types of adaptation responses of arable farmers in southern Romania. We conducted semi-structured interviews with 30 farmers managing 51,500 ha located across the southern lowlands of Romania, selected for their diversity of management approaches. Farmers were asked about experienced climatic disturbances, crop production losses during the most extreme events over the past 5–10 years, and the adaptation measures they implemented over that period of time. In addition, structural characteristics of the farm were recorded. The adaptation measures were classified and mapped on the efficiency, substitution, and redesign gradient used to classify sustainability stages. Results revealed three archetypes of adaptation, consisting of measures at field and farm level ranging from predominantly efficiency-enhancing ones (e.g., crop choice and management and risk insurance) to complete farm redesign involving agrotechnical and financial management changes. Structural farm characteristics did not explain differences between farms in their association with one of the archetypes. Our approach and results show for the first time both the need for strengthening farmer-level support in one of Europe's key food production areas and the lessons that can be drawn from the outlier adaptation examples. Current European and national policies offer opportunities for farmer organizations in Romania to make these conclusions actionable. [ABSTRACT FROM AUTHOR]

Heatwaves, which are escalating in frequency, duration and intensity, have prompted governments worldwide to issue vital health warnings to protect populations. These include urging individuals to stay cool, hydrated, avoid direct sun exposure and minimise strenuous activities. Regrettably, a significant segment of the population faces substantial challenges in accessing these crucial recommendations due to a range of issues termed "systemic cooling poverty". Systemic cooling poverty encompasses intricate layers of physical, social and intangible infrastructural deficiencies, impeding the provision of essential services necessary to ensure thermal safety during extreme heat episodes. Through an intersectional mixed-method examination, this study brings empirical evidence of the structural factors that exacerbate inequalities in attaining thermal safety among the African–Brazilian community, LGBTQI+ and disabled, living in two favelas in Rio de Janeiro. By shedding light on these lived experiences of cooling poverty, we contribute to the understanding of targeted interventions and policy measures that can alleviate the impacts of extreme heat and safeguard public health and well-being as temperatures rise. [ABSTRACT FROM AUTHOR]

The 2021 heatwave over Western North America (WNA) led to record‐breaking air temperatures and human‐perceived heat stress (humidex) values. The event was accompanied by drier conditions driven by prolonged atmospheric blocking. During the heatwave, the maximum 6‐day means of humidex and temperature (HX‐6 and TX‐6) exhibited larger anomalies (6.70 and 5.57°C) compared to the 95th percentiles (HX95 and TX95) (4.12 and 3.73°C), relative to 1981–2021 extended summer (June‐September) averages. Extreme indices of humidex show faster and larger increases than those of temperature, reflecting the nonlinear positive relationship between humidex and temperature. Future projections from a multi‐model ensemble of 19 Coupled Model Intercomparison Project Phase six (CMIP6) Global Climate Models (GCMs) clearly show an increase in humidex and temperature extremes, especially under intermediate and high emissions scenarios. Humidex indices (HX‐6 and HX95) show faster and larger increases than temperature indices (TX‐6 and TX95) for the same future years and global warming levels. Controlling for differences in GCM climate sensitivity to greenhouse gas forcing yields robust projections at various global warming levels, reducing the ranges of projected changes from the multi‐model ensemble. At 3.0°C global warming from pre‐industrial, the multi‐model ensemble projects occurrences of HX‐6, TX‐6, HX95, and TX95 over WNA that exceed 2021 levels to occur every 3.9, 1.7, 1.4, and 2.2 years, respectively, increasing to almost annually at 4.0°C. Plain Language Summary: In 2021 summer, Western North America (WNA) experienced an unprecedented heatwave, breaking air temperature and human‐perceived heat stress (humidex) records despite lower humidity due to prolonged atmospheric blocking. During the heatwave, consecutive 6‐day means of heat stress (HX‐6) and temperature (TX‐6) showed larger anomalies (6.70 and 5.57°C) compared to the 95th percentiles (HX95 and TX95) (4.12 and 3.73°C) over the region, relative to their averages over the 1981–2010 summer period (June‐September). Heat stress increased faster and more significantly than air temperature due to their nonlinear relationship. Future projections from 19 climate models reveal clear increases in heat stress and temperature, especially under intermediate and high emission scenarios. Heat stress indices show larger and faster increases than temperature indices at the same future years and global warming levels. Accounting for uncertainty related to climate model sensitivity enhances projection reliability. At 3.0°C global warming from pre‐industrial levels, 2021‐level events over WNA are projected to occur every few years, becoming an almost annual occurrence at 4.0°C. The study underscores the critical need for robust projections using multi‐model ensembles. Key Points: Unprecedented 2021 summer heatwave over Western North America resulted in record‐breaking humidex and air temperature extremesLarger increases in humidex than temperature, exceeding their 2021 levels, under intermediate and high emissions scenariosRobust projections of multi‐model ensemble, mitigating climate sensitivity uncertainty of GCMs response to greenhouse gas emissions [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]

Extreme heat events commonly occur under climate warming. All life stages of insects may experience the occurrence of extremely high temperatures. However, the effects of short-term extreme heat events on life-history traits remain unclear in most migratory pests. Here, we investigated the biological effects of short-term heat exposure (35 °C for 4 h) at different life stages on Mythimna separata Walker (Lepidoptera: Noctuidae), a typical migratory pest. We found that the reproductive sensitivity of pupae and adults was higher than that of 3rd-instar larvae. Increasing the frequency of heat exposure decreased the reproductive performance of M. separata at all life stages. Parental short-term heat exposures could cause transgenerational damage to offspring survival and reproductive fitness when the exposure frequency reached 3 times. Our results suggest that short-term exposure to extreme temperatures could impact reproductive fitness across different life stages in M. separata. This should be taken into consideration in the population prediction of migratory pests under climate change. [ABSTRACT FROM AUTHOR]

Amongst various form of urbanization induced climate change, changing thermal environment is the most widely studied and understood phenomenon. The impervious surfaces in urban areas absorb and re-emit the heat from solar radiation more than those of natural landscape which causes an elevated temperature in global cities. Due to increasing impervious surfaces and emissions from anthropogenic sources, the diurnal temperature range (DTR) is declining in cities while the frequency of extreme temperature events (TXX) is increasing. Hence, in this study, the trend of DTR and TXX has been examined in Delhi and Mumbai mega cities of India. For this study, India Meteorological Department (IMD) provided daily temperature data for 13 meteorological stations in Mumbai and 21 meteorological stations in Delhi. The DTR and TXX have been analysed using the RClimDex-Extraqc package while the trend of DTR and TXX has been analysed using the innovative trend analysis (ITA). The result showed that during 1991–2018, DTR has declined by about 1.5 °C in Delhi and about 0.2–0.4 °C in Mumbai, while TXX has increased by about 0.1–1.4 °C in Delhi and about 4 °C in Mumbai. The trend analysis of DTR and TXX using ITA showed that the DTR has a declining trend in both the cities while TXX has an increasing trend. The declining DTR and increasing TXX may increase the vulnerability to heat waves for the city dwellers and deteriorate the urban thermal comfort in both the cities. [ABSTRACT FROM AUTHOR]

Extreme heat poses severe health threats, as the increased numbers of hospitalizations and fatalities during heat waves show, though little is known about adaptive behavior toward heat. We conducted a household survey on individual perceptions of heat stress and individual heat protection in the summer and autumn of 2019. In total, 1417 people from three medium‐sized German cities participated via telephone or online. Based on the Protective Action Decision Model (PADM), which we adapted to heat stress, we analyzed links between risk perception, environmental and demographic factors, perceptions of stakeholders, different heat warning messages, as well as actual and intended adaptive behavior. Overall, the PADM constructs explained around 16% of the variance in protection motivation, 19% in protective response, and 23% in emotion‐focused coping. Context factors (i.e., temperature, risk communication, gender, age, and homeownership) were significant predictors of the addressed outcome variables as were psychological factors (i.e., perceived personal vulnerability, response efficacy, response costs, preparedness, and perceived external responsibility). We further explored the effect of different warning messages on situational knowledge and intended behavioral adaptation in an experimental setting. Results showed that respondents felt significantly better informed after receiving a warning with action recommendations and reported more intended specific behaviors. Our research gives insights into individual protective action decision‐making processes. Based on our findings, we recommend tailoring risk communication strategies and combining heat warnings with action recommendations whenever possible to increase understanding and individual adaptation. [ABSTRACT FROM AUTHOR]

The escalating frequencies and intensities of heat waves have become a global concern in the face of climate change. Cities are increasingly vulnerable to overheating due to the amplification of urban heat island (UHI) during heat waves. Factors influencing the synergetic impact of UHI and heat waves on the built environment are complex, mainly including the degree of urbanization, land use patterns, building morphology, thermal properties of construction materials, and variations in moisture fluxes and heat sinks. Researchers worldwide are extensively exploring the characteristics of heat waves, the factors influencing heat waves in urban areas, and the impact of heat waves on built environments, as well as possible mitigation measures. However, the existing literature lacks a holistic and comprehensive understanding of the complexities between heat waves and the built environment that is needed for planning and implementing effective mitigation measures in the future. This study systematically presents a comprehensive overview of the global literature of the past three decades related to heat waves and urban built environments, spanning variations in heat wave definitions, factors influencing heat waves in urban areas, heat wave impacts on buildings, energy, occupant health, and infrastructure, mitigation measures, case studies, best practices, future considerations, and challenges. The objective is to synthesize current knowledge and highlight gaps in understanding, providing a foundation for future research. The review suggests that implementing a combination of strategies across various scales, from individual buildings to entire neighborhoods and cities, can contribute to effectively mitigating heat. This includes prioritizing compact and mid-rise buildings with light-colored exteriors, integrating large parks and green spaces, utilizing cool and super cool materials, ensuring effective insulation, employing passive and mixed-mode cooling and ventilation systems in buildings, and incorporating sustainable technology and innovation. Additionally, community participation and social equity are crucial for addressing vulnerabilities at a local level. It highlights the complexity of the relationship between heat waves and the built environment, emphasizing the need for interdisciplinary approaches for sustainable urban development in the face of heat waves. The outcomes can contribute to the formulation of informed policies to mitigate the adverse impacts of heat waves on built surroundings. [ABSTRACT FROM AUTHOR]

The ecological success of shallow water corals hinges on their association with photosynthetic Symbiodiniaceae algae. This is affected by environmental drivers among which sea temperature is pivotal. In 2016, a prolonged heat wave challenged New Caledonia reefs triggering a severe bleaching event. Here, we tracked 72 coral colonies comprising two species of Pocillopora and Porites from a cross-shelf gradient during the event and subsequent recovery period. Symbiodiniaceae association over time was assessed using the ITS2 marker. Bleaching prevalence and photosynthetic efficiency showed that 83% of Pocillopora and 29% of Porites colonies were affected, with corals from a mid-shelf site having been most impacted. The majority of tracked colonies recovered by December 2016, with a recorded 33% mortality of Pocillopora, while Porites showed higher resilience. Consistent with previous studies, genotyping data suggest stable, species- and site-specific associations between corals and Symbiodiniaceae. [ABSTRACT FROM AUTHOR]