Orals: Tue, 29 Apr | Room 1.31/32
We calculate the hourly wet bulb globe temperature (WBGT) values for the last 50 years over Western Africa to assess the emergence of new heatwave hotspots and the interplay between moist and dry heatwaves. In the formulation used, WBGT is derived using the grided data from ERA5 and ERA5-HEAT: 2-m air temperature, relative humidity, 10-m wind speed and mean radiant temperature (a measure of incidence of radiation on a body), and is thus representative of outdoor conditions.
We find that the heat stress estimated through WBGT does not peak over the same geographical regions as the air temperature, suggesting an important role of humidity in intensifying heatwaves over certain regions. While the highest temperatures are reached in the northern Sahel and Saharan regions, the highest heat stress values are found further to the south, in the region bordering Senegal, Mauritania and Mali and in southwest Niger. These are the same regions where the WBGT threshold of 33 °C (conditions dangerous even at resting metabolic rates (MR) < 115 W) have recently been crossed for up to 40 hours per year.
The duration of exposure to WBGT > 30 °C (conditions dangerous at light physical activity, MR < 180 W) has been increasing over almost the entire West Africa, at rates from 30 to 100 hours/decade. Over the Senegal - Mauritania - Mali border and southern Niger, exposure to WBGT > 33 °C has been increasing by 1-4 hours/decade.
Dangerous WBGT thresholds can be crossed at a wide range of temperatures and are often not associated with the highest temperature percentiles. For example, in Niamey, a WBGT of 30 °C has been crossed in the temperature range from ~ 29 to 44 °C, in Thies (Dakar) and Ouagadougou from ~ 28 to 43 °C, and in Abidjan from ~ 28 - 36 °C. In September 2019 and July 2020, in Niamey we find the first occurrences of air temperatures below 36 °C being associated with very dangerous heat stress values (WBGT > 33 ° C).
We conclude that for much of continental West Africa, and particularly for the Senegal - Mauritania - Mali border region and southern Niger, extreme heat alerts should at a minimum include indicators accounting for temperature and humidity, in order to capture the dangerous moist heatwave conditions occurring at temperatures well below the highest temperature percentiles. More complex indicators that additionally account for wind and radiation are very desirable for estimates of outdoor safety.
How to cite: Cvijanovic, I., Sultan, B., Mbengue, A., and Lavaysse, C.: Emergence of new heat stress hotspots over the West Africa, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3128, https://doi.org/10.5194/egusphere-egu25-3128, 2025.
Temperature rise, amplified by climate change, has a direct impact on human health, exacerbating the risk of heat-related illnesses, such as heat stroke and dehydration. The ((HI) is a parameter that combines air temperature and relative humidity to assess the degree to which the human body perceives heat. In this study, we used the Steadman Man-Kendall HI equation, Sen's slope estimator to evaluate monthly and annual heat index trends for Kano and Bamako between 1992 and 2022. The results indicated that the heat index exhibited a positive trend of 0.01°C yr-1, although this trend was less statistically significant with a p-value greater than 0.05. In contrast, a significant negative trend was observed in Bamako, with an annual change of approximately -0.06°C yr-1. It was also observed that the highest heat index values, demonstrating the risk of heat exhaustion, were recorded between April and May, ranging from 30 and 41°C in Kano and 31 to 42°C in Bamako. In contrast, December, January, and February were the coolest months for both cities, with HI values ranging from 23 °C to 28°C in Kano and 25 °C to 28°C in Bamako. These findings underscore the need for policymakers to adopt adaptive strategies to address the health challenges posed by the extreme Heat Index in vulnerable regions.
How to cite: Dicko, K., Umaru, E. T., Sanogo, S., Loewner, R., and Okhimamhe, A. A.: Assessing changes in heat index associated with climate variability in Sahelian Cities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12625, https://doi.org/10.5194/egusphere-egu25-12625, 2025.
The increase of heatwaves has been observed due to the influence of a changing climate on the planet. Among populations, this phenomenon is associated with a rise in various types of cardiovascular diseases, particularly among vulnerable groups such as the elderly and individuals with pre-existing conditions. This presents a growing concern for healthcare systems and urban management. Although the literature predominantly highlights these events on the European continent, it is known that heatwaves are not confined to this region. Thus, the objective of this study is to evaluate the temporal evolution of the phenomenon through an index developed by LAMMOC/UFF to detect extreme heatwaves in the 26 Brazilian capitals and the Federal District. For this purpose, ERA5 reanalysis data from January 1950 to September 2024 were utilized. The index was calculated hourly and aggregated on a daily and monthly basis. Initially, the Mann-Kendall test was employed to assess the trends in the time series. It was observed that 19 of the analyzed cities exhibited a positive trend, two showed no trend (Florianópolis and Fortaleza), and six coastal cities (primarily in northeastern region, except for Teresina and Recife) located in a region with barotropic conditions did not show occurrences of extreme heat waves during the study period. Subsequently, a correlation matrix between the time series was analyzed, along with clustering, identifying three distinct groups: one less affected by extreme heat waves, a second intermediate group with a positive trend, and a third group that exhibited the most significant positive trends. The time series were then divided, applying a clustering technique, into three distinct periods: 1950–1974 (P1), 1975–1999 (P2), and 2000–2024 (P3). This allowed the calculation of the average accumulated values for these three periods across all evaluated cities to observe the percentage differences. For instance, from P1 to P3, in the southeastern region, the cities of Rio de Janeiro and São Paulo presented an approximate 613% and 643% increase in extreme heatwave occurrences, while in the south region, Porto Alegre had an increase of 557%. In the midwest, Campo Grande and Cuiabá presented an increase of 983% and 671% and in the northeast Recife and Teresina presented an increase of 217% and 257%. Furthermore, the third cluster displayed the highest trends and averages, encompassing most cities of the Northern region. Therefore, cities such as Macapá, Rio Branco, Manaus and Belém experienced an increase of 3154%, 1339%, 1100% and 1028%, respectively. Notably, it was observed that this third cluster predominantly comprised cities in the northern region of the country, situated within the Amazon biome. These findings call for further investigation into the relationship between this trend and factors such as increasing deforestation and forest fires in the region. These alarming results highlight the urgent challenges in environmental, healthcare, and urban management driven by climate change and extreme events, emphasizing the need for investments in municipal health, resilience, and climate mitigation and adaptation strategies.
How to cite: Galves, V. L., Cataldi, M., Alcoforado Sphaier, L., and da Fonseca Aguiar, L.: Temporal Evolution and Intensification of Extreme Heatwaves in Brazil’s capitals: Insights from the XHW Index (1950–2024), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12454, https://doi.org/10.5194/egusphere-egu25-12454, 2025.
Since the early 2000s, Spain has experienced a consistent increase in the frequency and severity of heatwaves. Studies indicate that the number of days with extreme heat summer temperatures has increased, particularly in regions such as Andalusia, Valencia, and Madrid. The 2003 heatwave, regarded as a pivotal event in Europe, resulted in over 70,000 additional deaths across European countries, with Spain contributing almost 20% to this statistic (approximately 13,000 deaths). Further studies emphasise that extreme heatwave events, like the 2003 episode, are no longer exceptional phenomena but are becoming recurrent, even in areas where such events were rare before 1980. These extreme heatwave episodes can pose a serious risk to human health, even leading to severe heat illnesses such as heatstroke, hyperthermia, and critical dehydration. Furthermore, they can also exacerbate pre-existing pathologies like cardiovascular and respiratory diseases. This results in a substantial increase in hospitalisations and even fatalities. This study aims to employ a novel Extreme Heatwave (XHW) characterization index, based on the human body's response to water loss during such events, to evaluate the temporal evolution of these occurrences across Spain, with a special focus on the 13 most populated cities (> 300,000 inhabitants). The analysis utilised ERA5 reanalysis (~25 km resolution) for the period 1950–2024. The results showed that, through the application of a k-means clustering technique, XHW occurrences in Spain could be categorised into three distinct periods: 1950–1977 (P1), 1978–2002 (P2), and 2003–2024 (P3). For this assessment, the daily XHW index values were accumulated monthly and then annually at each grid point of the reanalysis data subsequently interpolated using Bilinear Interpolation for the 13 Spanish cities. The highest percentage increases in cumulative XHW index values were observed in Andalusia, exceeding 1000% in certain grid points when comparing the sums of P3 and P1. Some regions and cities, such as Madrid and Barcelona, experienced virtually no XHW episodes during P1, but these became relatively frequent (in over 80% of the years) during P3. In certain cities and regions, particularly in the Southwest of the country, it was found that during P3, one in every four summer days, on average, presented an XHW index value greater than zero. The results revealed and quantified an alarming scenario regarding the increased intensity and frequency of XHW episodes in Spain. This trend is compounded by the broader context of climate change, which coincides with the warming of the North Atlantic Ocean near the western coast of the Iberian Peninsula and the Mediterranean Sea along the remaining coastal regions of the country. Such developments are likely to exacerbate this situation further in the coming years, potentially precipitating a severe crisis in the Spanish public healthcare system.
How to cite: Cataldi, M., Victalino Galves, V. L., Alcoforado Sphaier, L., and Garnés-Morales, G.: Quantifying the Escalation of Heatwave Events in Spain: A Study Based on the new XHW Index, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12585, https://doi.org/10.5194/egusphere-egu25-12585, 2025.
The West African Sahel has suffered an unprecedented hot season in the first half of 2024. This preliminary observational study characterises this extreme heat in the urban context of Ouagadougou, one of the major cities in the region where significant death casualty was reported. Using data from the national meteorological agency and the European reanalysis (ERA5), the study investigated both the daytime (Tmax) and nighttime temperatures (Tmin) with the 1991-2020 as reference period. The results show that the average monthly Tmax anomaly ranged from 1.42 °C in January 2024 to 2.41 °C in June 2024, versus -0.4 °C in January 2024 and 2.05 °C in June 2024 for Tmin, showing that the heat was more important in 2024 than in the historical period. Using the heat wave definition of the Burkina Faso Red Cross heat wave early action protocol, a total of four (one) daytime (nighttime) heat waves were recorded in the city between March and May. This is to be compared with a historical frequency of one event every four years. The longest daytime heat lasted six days with Tmax reaching a maximum of 44.5°C. The unique nighttime heat wave was twice as long as the longest daytime heat wave, persisting for 13 days between late April and early May, a record in the city. From a spatial perspective, the heat was not evenly distributed as some neighbourhoods were significantly hotter than the rest of the city. Furthermore, the initial findings of a household survey conducted in the city corroborated the unprecedentedness of the situation as most respondents reported having never experienced such heat levels in the past with considerable impacts on their health and livelihoods. These results underscore the need for more efforts towards heat wave risk management in African cities.
How to cite: Wendkuni Ghislain, N., Kiswendsida H., G., Dazangwende E., P., and Thomas R., B.: Identification and characterization of 2024 Heat waves in Burkina Faso., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-817, https://doi.org/10.5194/egusphere-egu25-817, 2025.
The unprecedented heatwave over India in May- June 2024 has raised significant concerns regarding its underlying dynamics and potential impacts. This study investigates the prolonged heatwave event by combining dynamical diagnostics and numerical simulations using the Global Forecast System (GFS) model used by the India Meteorological Department (IMD). We first analyze the synoptic conditions and large-scale atmospheric patterns contributing to the persistence and intensity of the heatwave. The dynamical diagnostics reveal the role of Hadley Cell expansion, blocking high-pressure systems and regional thermodynamic conditions in sustaining extreme temperatures. Further, IMD’s GFS model products evaluate and validate the heatwave event, focusing on capturing temperature anomalies' spatial and temporal evolution. The model outputs are validated against observational data, demonstrating high accuracy in reproducing the critical characteristics of the heatwave. The results indicate that the combined effect of rapid solar insolation and anomalous atmospheric circulation patterns played a crucial role in the development and persistence of the heatwave. The study also highlights the importance of high-resolution numerical simulations in understanding complex meteorological phenomena and provides insights into improving heatwave prediction and preparedness strategies. This comprehensive analysis of the May-June 2024 heatwave over India would contribute to the broader understanding of extreme weather events in the context of climate variability and change.
How to cite: Amat, H. B., Lohan, N., and Pattanaik, D. R.: Dynamical Diagnostics of the Prolonged May-June 2024 Heatwave Over India: Evaluation and Validation using IMD’s GFS Model. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-772, https://doi.org/10.5194/egusphere-egu25-772, 2025.
Heat stress and extreme humid heat pose an escalating threat to many regions worldwide, particularly along coastal regions in the Middle East, where conditions can occasionally reach life-threatening levels. Projections indicate that humid heat extremes will become more frequent and intense as global temperatures rise. We analyze humid heat extremes in the two first-ever fully-coupled, multi-decadal, high-resolution (~10 km) Earth System Models (ICON and ECMWF-IFS) projections performed within the H2020 Next Generation Earth Modelling Systems (nextGEMS) project.
We here demonstrate that extreme humid heat events tend to be substantially underestimated at the resolution of CMIP6 models, especially in coastal hotspot regions where localized dynamics play a significant role. We focus on the Red Sea, Persian Gulf and Mediterranean coasts, which are hotspots for humid heat and areas characterized by dense populations and critical relevance for economic activity and assess the added value 10-km global coupled models in simulating extreme Wet Bulb Temperature (TW), a critical metric that combines air temperature and humidity.
We demonstrate that at the higher resolution of the nextGEMS Storm-Resolving Models TW maxima are more than 2–3°C higher than at the coarser resolution commonly used within the CMIP6 models. Furthermore, the coarser resolutions often fail at capturing localized extremes and the effects of topography, particularly in coastal areas. Additionally, the findings reveal that onshore wind convergence plays a pivotal role in amplifying TW maxima by enhancing moisture accumulation and limiting atmospheric mixing. These results underscore the indispensable role of Storm-Resolving models in accurately assessing extremes and providing actionable insights for adaptation strategies in regions with significant human and economic vulnerabilities.
How to cite: Carniel, C. E., Wille, J. D., and Fischer, E.: Higher coastal heat stress maxima in storm-resolving GCMs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8553, https://doi.org/10.5194/egusphere-egu25-8553, 2025.
As climate change intensifies, heat extremes pose an increasing threat to human health, leading to heightened morbidity and mortality particularly among vulnerable populations.
Physiological evidence demonstrates that high humidity exacerbates heat strain by impairing the body’s ability to thermoregulate through sweat evaporation. Therefore, metrics such as the wet bulb temperature, which combine both temperature and humidity effects, are commonly used to assess heat-related health risks, highlighting tropical and other humid regions as particularly at risk, while regions dominated by dry heat in the mid-to high latitudes appear comparatively less affected.
However, the tens of thousands of excess deaths caused by prolonged exposure to high ambient temperatures during e.g. recent record-breaking European heatwaves in 2003 and 2022 suggest that heatwave characteristics beyond temperature and humidity might need to be accounted for to accurately capture severe health impacts under dry heat conditions.
Here, we propose to enhance global heat stress assessments by addressing emerging spatio-temporally compounding features of heat extremes, which could greatly aggravate health impacts but due to their complexity are often not considered. Preliminary results will be presented from our efforts to develop a standardized, impact-focused heat stress metric that provides more robust and consistent assessments across diverse regional and climatic settings by integrating the cumulative effects of prolonged and sequential heat exposure.
How to cite: Langer, R. and Kornhuber, K.: Towards Improved Global Heat Stress Projections by Accounting for Spatio-Temporally Compounding Risks, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19232, https://doi.org/10.5194/egusphere-egu25-19232, 2025.
Humid heat is a serious risk to human health, reducing the body’s ability to cool through sweating. The intensity, frequency and impact of humid heat extremes will increase under climate change, particularly in tropical and sub-tropical ‘hot spots’, such as equatorial Africa and the Indian subcontinent, which are highly populated, and already very hot and humid. Research on the meteorological drivers of humid heat extremes is immature compared to that for dry heatwaves. Here an overview of the latest results from the Humid heat extremes in the Global (Sub)Tropics (H2X) project will be presented. We have shown that rainfall is a key ingredient for humid heat, and its role varies depending on the type of land-atmosphere coupling regime. In moisture-limited environments, mostly in the semi-arid sub-tropics, humid heat extremes occur during or immediately after rainfall through increased evaporation into a shallower boundary layer. In energy-limited environments, mostly in the moist tropics, humid heat extremes occur during the easing of rainfall through increased solar heating. Our most recent work focuses on atmospheric waves as a source of predictability. Equatorial Kelvin waves modulate humid heat, where the convergent phase of the wave (in the 850hPa winds) brings rainfall, followed by increased solar heating in the divergent phase. A similar process occurs over the Sahel region of west Africa within African Easterly Waves. We have also performed a set of idealised experiments with the Met Office Unified Model to quantify the role of surface moisture sources such as lakes, wetlands, and patches of wet soil from rainfall on evaporation, mesoscale circulations, and humid heat. Our results are valuable for identifying processes that must be well represented in weather and climate models for accurate weather forecasts and climate projections, and for informing early warning system development.
How to cite: Birch, C., Jackson, L., Chagnaud, G., Hidayat, A., Taylor, C., Law, J., and Marsham, J.: Meteorological drivers of humid heat extremes across the global (sub)tropics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5617, https://doi.org/10.5194/egusphere-egu25-5617, 2025.
Compound hazards, such as the sequential occurrence of Tropical Cyclones (TC) and humid heatwaves in close succession, are more destructive than individual and isolated occurrences of each hazard. While landfalling TCs cause catastrophic consequences from storm surges, strong winds, heavy rain, and pluvial flooding, they are often compounded by anomalous heat. The TC-heat joint occurrence raises significant concerns for public health and critical infrastructure, particularly since powerful TCs may lead to major power outages. For example, TC Remal in May 2024 damaged the coastlines of India and Bangladesh, bordering the Bay of Bengal (BoB), impacting > 10 million people without access to electricity and shelter, with an estimated damage totaling $600 million. For the eastern coast of India, with many small to large port cities, including two major urban agglomerates, Kolkata and Chennai, with populations > 10 million, the likelihood of TC-heat joint occurrence has not been assessed so far. We analyze 251 landfalling TCs on the eastern coast of India between 1982 and 2023. We show that ~16% of terrestrial humid heatwave peaks are compounded by the landfalling TCs, and ~8% of moist heat follows TCs. Further, we show the relative increase in peak wet-bulb temperature in TC-compounded heatwaves is as high as around 7−10% in pre-monsoon (April−May) and post-monsoon (October−December) seasons compared to heatwaves not compounded by the TCs. An anomalous rise in TC-compounded heatwave peaks is more pronounced and often exceeds terrestrial heatwave peaks during the post-monsoon season. Although the annual counts of landfalling TCs over BoB show a decreasing trend, our observational analysis of precursor coincidence rate confirms the increased likelihood of TC-compounded humid heat stress, preconditioned by strong to severe marine heat waves. The derived insights highlight a need to prepare adaptation planning for unprecedented compound tropical cyclones and extreme heat hazards when such sequential hazards are expected to occur more frequently in a warming climate.
How to cite: Ganguli, P. and Lin, N.: Mapping Compound Hazard Potential of Tropical Cyclone and Anomalous Heat in Eastern Coast of India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-215, https://doi.org/10.5194/egusphere-egu25-215, 2025.
According to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment (AR6) report, continued global warming and changes in the climate system will increase the likelihood of severe impacts on both people and ecosystems. Accurately assessing the impacts of extreme heat has become a pressing research challenge, particularly as heatwave and heat-health warning systems evolve. Identifying key indicators of heat-related mortality and morbidity is critical to mitigating these impacts. Despite its importance, a comprehensive national-level assessment of heat vulnerability in India remains underdeveloped, leaving a significant research gap in heatwave disaster management. Moreover, the notion of vulnerability has evolved continuously, especially with updates in IPCC assessments, and it varies across communities, societies, regions, and countries and changes over time. This study analyses district-level (640 districts) vulnerability in India based on multiple methodologies, including the Simple Average Method, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), the Principal Component 1 (PC1) method, and the Cutter and Finch (2008) approach, supported by a refined set of vulnerability indicators. Key data sources include the Census of India (CoI), alongside other datasets. The spatial distribution of vulnerability indicates that North and Eastern India are the most susceptible to heat related vulnerability. In the context of India’s agrarian economy, this mapping is crucial for supporting the livelihoods of farmers and outdoor workers, who are among the most susceptible to extreme heat events. This study underscores the urgent need for a robust, methodologically comprehensive national heat vulnerability assessment to guide targeted policy interventions and enhance resilience against the escalating threat of extreme heat in India. The vulnerability map developed will serve as a foundational tool for creating a comprehensive risk map by integrating hazard and exposure, enabling targeted interventions to mitigate heat-related risks.
Keywords: Heatwave, Heat Stress, India, IPCC, Vulnerability.
How to cite: Shilin, A. and Karmakar, S.: Unveiling Heat Vulnerability Across India: A Multi-Method Analysis of District-Level Indicators in the Context of Climate Change., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10921, https://doi.org/10.5194/egusphere-egu25-10921, 2025.
Heatwaves have become more frequent and more intense under the influence of climate change, resulting in increased impacts on human health, infrastructure and economic activities. However, heatwaves climatic characteristics do not always inform properly on the actual human and material impacts resulting from heatwaves. In other terms, heatwaves with a high intensity in the climatological sense may not be equivalently as intense in terms of impacts. In this study, we empirically investigate, in Europe, the link between the climatic characteristics of heatwaves and their impacts, as listed in the EM-DAT disaster database. We apply indices available in the literature to characterize heatwaves for the 1950-2021 period found in the ERA5 and E-OBS datasets. We also propose new indices, combining meteorological and demographic data, that we compare to the existing ones, and to the heatwave’s impacts. We show that including demographic data in the heatwaves indices is key to ensure that heatwave climatic indices reflect more accurately the impacts of heatwaves. We also investigate the top 10 heatwaves that are considered extreme based on our best performing index but are not in the impact data-base and find references of their impacts for 8 of them, meaning that this type of methodology could be used to enrich existing impact databases by flagging events of interest.
How to cite: Mandonnet, L., Jézéquel, A., D'Andrea, F., and Vallet, A.: Extreme heatwaves in Europe 1950-2021: analysis of the links between meteorology, population, and impacts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3676, https://doi.org/10.5194/egusphere-egu25-3676, 2025.
Countless heat records were broken in recent years, leading to thousands of heat-related deaths. This raises the question of how much worse heat-related mortality could become in coming years if a potential worst-case heatwave lasts for several weeks or reaches unprecedented intensity. Here, we develop impact storylines for worst-case heatwaves and associated heat-related mortality in France, Germany, and Switzerland.
We compare several physical climate storyline approaches to quantify plausible extreme heatwaves and combine these with empirical heat-mortality relationships. The storylines are based on (a) using a Single-Model Initial Condition Large Ensemble (SMILE), (b) ensemble boosting, and by looking for the most extreme events (UNSEEN approach) in the initialized (c) 45-day sub-seasonal re-forecast and (d) 7-months seasonal forecasting system using the ECMWF Integrated Forecast System (IFS).
In all four approaches we find physically consistent week-long heatwaves possible in the climate of 2020 that exceed the observed 7-day record temperatures by more than 5°C and associated mortality impacts exceeding the observed maximum by 30-90%. Even more severe consequences would arise from possible five-week heat periods of unprecedented intensity, which would lead to more than a doubling of impacts. Developing these impact storylines can inform the stress-testing of socio-economic systems for preparing appropriate emergency response capacities.
How to cite: Vicedo Cabrera, A. M., Luthi, S., Huber, V., Pascal, M., Beyerle, U., Pyrina, M., Domeisen, D., and Fischer, E.: Storylines for month-long heatwaves and associated heat-related mortality impacts over Western Europe, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20537, https://doi.org/10.5194/egusphere-egu25-20537, 2025.
The impacts of extreme heat and other climate extremes have intensified with climate change, compounded by international pressures from geopolitical tensions that exacerbate socioeconomic inequalities and harm human wellbeing. This study examines factors affecting life expectancy in the United Kingdom, focusing on the relative influence of socioeconomic characteristics and climate change variables, such as heat and flood exposure. The primary research question explored whether wealth could offset the adverse effects of climate change on life expectancy. The analysis covered various age groups, from 0–9 years to 80–89 years, across UK local authority regions. For instance, among 40–49-year-olds, the life expectancy gap between low- and high-life expectancy regions in England was 2 years, 9 months, and 24 days (84.0 vs. 85.97 years). Socioeconomic factors and climate change indicators, including heatwave occurrence, accounted for 77% of this disparity, while extreme rainfall showed no significant effect. The findings highlight that climate change, particularly through the rising frequency of heatwaves, has significantly influenced life expectancy in certain UK regions. This highlights the critical need to address the interplay between climate risks and socioeconomic inequalities to safeguard public health and wellbeing.
How to cite: Brimicombe, C. and Otto, I.: Heat exposure can reduce life expectancy even across wealthy regions: a UK case study, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16500, https://doi.org/10.5194/egusphere-egu25-16500, 2025.
Heat stress events in China are becoming increasingly frequent and severe, exacerbated by the nation’s rapidly aging population. Elderly individuals, as a particularly vulnerable group, face heightened risks and have a reduced ability to withstand such hazards. However, research on the long-term dynamics of heat stress risks among the elderly remains limited. This study addresses this gap by employing the Intergovernmental Panel on Climate Change (IPCC) risk framework to evaluate the evolving heat health risks for the elderly in China since the start of the 21st century. By integrating satellite remote sensing, meteorological observations, and socio-ecological statistics, the study captures the dynamic interplay between hazards, vulnerabilities, and exposure. The findings reveal that the combination of rising heat hazard days and a worsening aging population has led to a steady increase in the elderly population exposed to heat stress, amplifying both vulnerability and exposure risks over time. Regional disparities in comprehensive risk are striking, driven by differing levels of aging and socio-economic development across China. The central region consistently exhibits the highest and fastest-growing comprehensive heat risk, while the northwest and northeast maintain the lowest risk levels. Conversely, socio-economically advanced provinces in the east, such as Shanghai and Beijing, show declining risk levels due to significant reductions in vulnerability facilitated by rapid social progress. This study provides a dynamic and regionally nuanced perspective on the intersection of aging and heat stress risks, offering critical insights to inform targeted policies and resource allocation. Its findings hold particular relevance for developing countries navigating the dual challenges of climate change and aging populations.
How to cite: Liu, C., Chen, S., Huang, J., Zhang, C., Lian, L., Jiang, Y., and Tu, X.: Dynamic assessment of heat stress risks among the aging population in China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4780, https://doi.org/10.5194/egusphere-egu25-4780, 2025.
Increased frequency of extreme urban heat and its exposure to urban populations is one of the challenges presented by climate change, especially in urban clusters. Due to the rapid but unequal development, heat exposure disproportionately increased in the underdeveloped regions compared to the developed regions in urban agglomeration. To address this issue, it is crucial to clarify the spatial pattern of heat health risk (HHR) inequality for urban heat resilience. However, analyses for the disparity of HHR inequality often used a single scale, neglecting important spatial context effects at other scales. Moreover, the rationale of HHR inequality remains unclear. Here, we took the well-developed and highly urbanized Yangtze River Delta (YRD) region as a case study and employed multiscale approaches to examine how and why the HHR inequality varied at and within the regional scale. We first assessed HHR using a comprehensive assessment framework at a 1km grid level. Then, we quantified the inequality between regions using local Moran's I and KS distance. Therefore, we utilized the Gini coefficient and Bayes quantile regression to quantify inequality and identify its drivers within the regional scale. Finally, we proposed a conceptual framework to inform policymaking in regions with different patterns of multiscale equality. Our results found that the HHR in YRD exhibited significant spatial inequality at the regional scale (Moran’s I=0.562, P<0.001) and within the regional scale (Gini coefficient: 0.27-0.54). Higher population concentrations and building densities often led to higher HHR. In high HHR areas, intra-regional inequality was often lower due to high and coordinated socioeconomic levels (Gini coefficient: 0.27-0.34). Additionally, in areas with low and medium levels of risk, healthcare resource availability and local temperatures had a greater impact on intra-regional inequities, which varied at different levels of inequality. This study contributes to a better understanding of multiscale HHR inequality, which helps optimize heat risk management strategies and regional sustainable development.
How to cite: Wu, H., Zhao, C., Zhu, Y., and Pan, Y.: A multiscale examination of heat health risk inequality and its drivers in mega-urban agglomeration: A case study in the Yangtze River Delta, China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4661, https://doi.org/10.5194/egusphere-egu25-4661, 2025.
In recent decades, ecosystems have faced extreme climatic events, such as high temperatures, which have significantly impacted human health, wildfires, and agricultural losses. These heat extremes are expected to continue increasing in frequency and intensity, necessitating a deeper understanding and close monitoring of these events.
The primary objective of this study is to quantify and compare the sectoral impacts of 1.5 °C and 2.0 °C global warming scenarios on human health, agriculture, and wildfire risks using high-resolution climate simulations. Health impacts were assessed using the Health Heat Index (HHI), while wildfire risk was analyzed using the Forest Fire Danger Index (FFDI), which evaluates the duration and frequency of fire seasons in terrestrial ecosystems. Agricultural impacts were quantified by estimating crop heat stress during thermal-sensitive periods, calculating anthesis heat stress (AHS), and normalizing production damage indices.
These analysis reveals a significant increase in areas exposed to critical levels of heat stress, affecting human health, ecosystems, and food security. Our results show a significant rise in risks measured by the HHI And the analysis of the FFDI reveals also an extension in the duration and frequency of fire-prone seasons. In agriculture, the assessment of heat stress during sensitive periods, particularly through the Anthesis Heat Stress Index (AHS), highlights worsening production losses.
These findings highlight the urgency of adopting ambitious mitigation strategies to minimize risks to vulnerable populations and preserve ecosystems and food security.
How to cite: Essoussi, S., El Morjani, Z. E. A., and Sadiq, A.: Assessing the Effects of Extreme Heat on Health, Agriculture, and Ecosystemsin Morocco under different levels of climate warming, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16229, https://doi.org/10.5194/egusphere-egu25-16229, 2025.
The extent to which changes in labour force outcomes can be attributed to historic climate change is currently unknown. Here, we combine robust estimates of the impact of climatic stressors on labour supply, labour productivity, and a combined metric of the two - effective labour, with novel historic climate forcing data to quantify the effect of historic climate change on labour. We do this at the global and regional level, taking explicit account of heterogeneity of working conditions. Glob- ally, effective labour in outdoor working conditions was 1.8 percentage points lower in 1901-2019 than it would have been without climate change. The attributable declines have increased over time, rising to 3.6 percentage points between 2001 and 2019. The highest declines have been in the relatively lower-income regions of Western Africa, South-Eastern Asia, and Middle Africa, where climate change has increased workforce inequalities. We also estimate the economic effects through impacts on GDP and find up to a 12% GDP loss for some regions. Our findings can help improve the design of better labour protections, improve worker health, enhance productivity and economic growth, and inform better climate adaptation and resilience.
How to cite: Dasgupta, S.: Attribution of historical changes in labour outcomes to climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20600, https://doi.org/10.5194/egusphere-egu25-20600, 2025.
Extreme heat can substantially impact worker productivity, causing fatigue, loss of focus, and illness in the workplace. As extreme heat increases under climate change, substantial reductions in labour productivity are expected. According to some models, economic costs from decreased worker productivity will be larger than any other climate related impacts, and corporations are therefore interested in understanding their potential exposure and vulnerability to heat stress in the future. Workplace regulations (e.g. ISO) and epidemiological studies have previously been combined to develop continuous functions relating workplace heat stress to labour productivity. In this work, we utilise productivity loss functions with climate model projections for future extreme heat exposure to assess changes in labour productivity loss. We present a new modelling framework for providing labour productivity loss projections for several scenarios (SSPs), work intensities (low, moderate, and high), and regions, specifically designed for financial services. We include a model of air conditioning availability, with which the productivity loss estimates can be scaled according to the likely adoption and use of cooling systems in the workplace.
How to cite: Starr, A., Woodhouse, S., Leach, N., Brennan, J., Reveley, G., Woodcock, C., Ramesh, K., Stables, J., Ramsamy, L., Sullivan, P., and Padilha, V. L.: Estimates of labour productivity loss from climate model projections of extreme heat: Implications for financial services , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6084, https://doi.org/10.5194/egusphere-egu25-6084, 2025.
Heatwaves and prolonged periods of extremely high temperatures are increasingly recognized for their significant impact across various regions and societal sectors, such as energy resources management, human health or agriculture. So far, the scientific community has focused on better understanding summer heatwaves with the use of various definitions and climatic indices. In this context, we introduce the Warm Spell Magnitude Index daily (WSMId) for extending beyond the warm period. This index is designed to capture the characteristics of consecutive days with anomalous high temperatures throughout the year, ultimately allowing us to investigate the various drivers behind prolonged periods of extreme heat.
WSMId builds upon the Heat Wave Magnitude Index daily (HWMId) by Russo et al. (2015), adapting a similar mathematical framework to identify heatwave-like events across multiple seasons. Calibration is based on the ERA5 reanalysis, focusing on the most intense summer European heatwaves of the past decades. Through this exercise, we aim in ensuring that the new index can meaningfully quantify episodes of anomalous warmth in non-summer periods, such as “false spring effects,” “extended summer periods,” and clustering of heatwaves.
This work could allow us to explore the underlying drivers behind these phenomena, aiming at enhancing our understanding of regional heatwave dynamics and their broader implications. We envision that WSMId will offer as a valuable tool for climate scientists, with potential applications in seasonal forecasting, development of climate adaptation strategies, and impact studies.
References
Russo, S., Sillmann, J., & Fischer, E. M. (2015). Top ten European heatwaves since 1950 and their occurrence in the coming decades. Environmental Research Letters, 10(12), 124003. https://doi.org/10.1088/1748-9326/10/12/124003
How to cite: Liakakos, A., Zittis, G., Tyrlis, E., and Hadjinicolaou, P.: Development and Application of the Warm Spell Magnitude Index daily (WSMId) in historical European heatwaves, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8843, https://doi.org/10.5194/egusphere-egu25-8843, 2025.
Mass gatherings in India, encompassing religious and cultural events, draw millions of participants annually and are increasingly vulnerable to the impacts of climate change, particularly intensifying heat stress during summer months. This study evaluates the projected risks of heat stress at six prominent locations: Ajmer, Amritsar, Delhi, Haridwar, Prayagraj, and Ujjain. Wet-bulb temperature (Tw), a reliable indicator of heat stress, is used to assess the impacts of rising temperature and humidity levels. Simulations from dynamically downscaled bias-corrected Coupled Model Intercomparison Project Phase 6 (CMIP6) datasets, under SSP2-4.5 and SSP5-8.5 scenarios, are used from to capture the spatiotemporal variability of heat stress throughout the 21st century. Results indicate a substantial increase in maximum Tw during the summer months (March to June) across all sites. By mid-century, Tw is projected to reach or exceed “danger” levels, with Prayagraj and Delhi identified as high-risk zones. Extreme danger thresholds are anticipated at these locations by the late 21st century under the SSP5-8.5 scenario. Haridwar, while showing the lowest risk among the study sites, is not immune to the impacts of heat stress. Focusing on the intersection of climate change and public health in densely populated regions, the findings highlight the urgent need for adaptation and mitigation strategies to protect public health during future mass gatherings in India.
How to cite: Dutta, S., Samanta, D., and Deb, P.: Intensified Heat Stress Risks at Indian Mass Gathering Sites Due to Climate Change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12636, https://doi.org/10.5194/egusphere-egu25-12636, 2025.
How to cite: Popov, H. and Stepanyuk, O.: Heat Waves over the Balkans: A statistical analysis, towards a predictive ML model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20371, https://doi.org/10.5194/egusphere-egu25-20371, 2025.
In this study we assess the occurrence of summertime heatwaves (HW) and their underlaying atmospheric drivers under current and past climate conditions for Sweden using a weather regime classification based on optimized fuzzy rules. It uses daily mean 500hPa geopotential height of ERA5 reanalysis at 0.5° spatial resolution as atmospheric input data for the period of 1940 to 2022. Daily anomalies of 500hPa geopotential height at each grid over the Euro-Atlantic region have been computed as daily deviations from the long-term climatology of 1981-2010. Daily mean temperature from station data over the same 30-year period, distributed in the whole of Sweden, serve as predictand to reflect the variability of local climate. They help to optimize pre-defined fuzzy rules describing individual weather regimes (WRs). A set of twelve temperature-induced WRs are classified as daily timeseries for the years of 1940 to 2022.
HWs are investigated using the Excess Heat Factor (EHF) and the NDQ90 index when daily maximum temperature exceeds the 90th percentile over the reference period based on ERA5 reanalysis data. The EHF is a measure of heatwave intensity related to human health impacts and consists of two indices describing the deviation of the three-day mean air temperature from the long-term 95th percentile-based climatology and the short-term anomaly of the previous 30 days. The Chi-square test is used to study the significance of the classified WR along with the co-occurrence of a HW.
For the case-study of Stockholm, 985 HW events are detected by the NDQ90 index from 1940 to 2022 during May to August. Nearly 83% of detected HWs is found to coincide with the occurrence of four types of anticyclonic WRs. One type of anticyclone explains nearly 40% of the detected summertime HW events. During August, it particularly explains 47% of detected HWs. It is likely because of the strong high-pressure system situated over the North Sea and southern Scandinavia that caused the warmer-than-average temperatures over northern Europe. Similar results are found when using the EHF. In addition, we present how this approach can be extended to investigate the linkages of leading WRs and the occurrence of detected HWs in major European cities.
How to cite: Klehmet, K. and Yang, W.: Current and past atmospheric heat wave precursors for Sweden: A Machine Learning-based weather regime approach, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13141, https://doi.org/10.5194/egusphere-egu25-13141, 2025.
Amidst unprecedented rising global temperatures, this study investigates the historical context of heatwave (HW) events in Eastern Europe. The record-breaking 2023 summer, featuring a HW lasting for 19 days in the south-eastern part of Romania, extending up to Ukraine, necessitates a deeper understanding of past extreme events. Utilizing statistical methods on long-term station data spanning from 1885 to 2023, we aim to detect and analyze historical HWs, particularly focusing on events predating 1960. This extended timeframe allows for a more comprehensive assessment of noteworthy extremes compared to recent decades. We used both a percentile-based threshold and a fixed absolute temperature threshold to identify HW events. Our analysis identifies two critical periods with increased HW frequency and intensity: 1920–1965 and 1980–2023, respectively, highlighting the most extreme events in August 1946, August 1952, July 2012, June 2019, and August 2023. Furthermore, reanalysis data shows that historical HWs, similar to the 2023 event, were associated with large-scale European heat extremes linked to high-pressure systems and they were accompanied by extreme drought, thus leading to compound extreme events. We find that while a clear trend emerges towards more frequent HWs from the 1980s onward, the analysis also uncovers substantial HW activity on daily timescales throughout the 1885-1960 period. Moreover, we highlight the intertwined impacts of climate change and multidecadal internal variability on HW patterns, with evidence suggesting that both contribute to the increasing frequency and intensity of these extreme events. Attribution analysis reveals that the extreme summer temperatures observed in 2023, would not have been possible in the absence of anthropogenic climate change. Regardless of future warming levels, such temperatures will occur every year by the end of the century. Our research highlights the value of extending the historical record for a more nuanced understanding of HW behavior and suggests that extreme heat events, comparable to those experienced in recent decades, have occurred throughout the analyzed period.
How to cite: Ionita-Scholz, M., Vaideanu, P., Antonescu, B., Roibu, C., Ma, Q., and Nagavciuc, V.: Examining the Eastern European extreme summer temperatures of 2023 from a long-term perspective: the role of natural variability vs. anthropogenic factors , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15014, https://doi.org/10.5194/egusphere-egu25-15014, 2025.
There is mounting evidence that heatwaves are increasing in frequency and duration around the world. South Asia is highly vulnerable to heatwaves due to its high heat exposure and limited adaptive capacity. Besides, South Asia is also a global aerosol hotspot. Many governments in South Asia plan to reduce aerosol emissions. However, any change to aerosol concentrations may also modify heatwave characteristics through ‘direct’ influences on the radiation budget and surface heat fluxes, and through ‘indirect’ impacts, such as on cloud formation and atmospheric circulation. Hence, lowering aerosol concentrations – while good for human respiratory health – may increase heat stress.
Previous studies have shown that aerosols can affect heat stress by influencing temperature, humidity, wind speed and radiation. However, the process of how aerosols affect heat stress has not been explained in detail. Our research intends to reveal the specific process of aerosols affecting heat stress from the perspective of surface energy balance, using WRF model as the initial methods. Improving understanding of the mechanisms of aerosol influence on heatwaves will help improve the long-range prediction capability for extreme heat. The results from the research will also be of interest to policy makers and disaster risk reduction communities, as it will help characterize the evolving public health burden to expect as temperature rises and aerosol loadings change in the future.
Our preliminary results show that the presence or absence of aerosol emissions affects surface temperature, 2-m temperature, and sensible heat flux in South Asia, with different patterns being observed during the daytime and nighttime.
How to cite: Meng, Y., Matthews, T., Sun, T., and Irvine, P.: Aerosol Modulated Heat Stress in South Asia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9670, https://doi.org/10.5194/egusphere-egu25-9670, 2025.
The frequency, intensity and duration of heatwaves are expected to increase in Toronto, Canada due to both climate change and the urban heat island effect. This poses a greater health risk to those who are most vulnerable to heat among a population of almost three million residents. Therefore, designing and implementing appropriate heat management measures requires information about how heat vulnerability is distributed across the city. To fill the knowledge gap, two distinct methods are examined in this study to quantitatively measure the spatial distribution of heat vulnerability in Toronto. Both heat vulnerability indices (HVIs) consist of three dimensions, exposure, sensitivity and adaptive capacity, that are aggregated from remotely sensed land surface temperature measurements and socio-economic census data. The first method uses principal component analysis to derive an HVI, while the second, simpler method assigns equal weight to each input variable to derive an HVI. The HVIs display a similar U-shaped pattern of high heat vulnerability across Toronto, with low heat vulnerability areas primarily located along the Lake Ontario shoreline and throughout the fluvial ravine system. Further cluster analysis reinforces this spatial pattern. Notably, this study highlights that low-income tower block communities are significantly more vulnerable to heat than the city average. The qualitative consistency between the two HVI methods allows for ease of adoption of the simpler, equal-weight method for future use by the city. Integration of HVI updates into municipal operations can allow city planners and managers to monitor and visualize heat vulnerability consistently over time, develop decision-support tools for heat emergency preparedness and response and assess the effectiveness of heat adaptation strategies.
How to cite: Smith, K., Bu, S., Masoud, F., and Sheinbaum, A.: Spatial distribution of heat vulnerability in Toronto, Canada, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6795, https://doi.org/10.5194/egusphere-egu25-6795, 2025.
