NH1.3

EDI
Extreme heat events: processes, impacts and adaptation

Heat extremes are already one of the deadliest meteorological events and they are projected to increase in intensity and frequency due to rising CO2 emissions. The hazard these events pose to society may therefore increase dramatically, and society will need to adapt if the worst impacts are to be avoided. This session therefore welcomes a broad range of new research addressing the challenge of extreme heat. Suitable contributions may: (i) assess the drivers and underlying processes of extreme heat in observations and/or models; (ii) explore the diverse socio-economic impacts of extreme heat events (for example, on aspects relating to human health or economic productivity); (iii) address forecasting of extreme heat at seasonal to sub-seasonal time scales; (iv) focus on societal adaptation to extreme heat, including (but not limited to) the implementation of Heat-Health Early Warning Systems.

Convener: Tom Matthews | Co-conveners: Ana Casanueva, Martha Marie VogelECSECS
vPICO presentations
| Tue, 27 Apr, 15:30–17:00 (CEST)

Session assets

Session materials

vPICO presentations: Tue, 27 Apr

Chairpersons: Tom Matthews, Ana Casanueva, Martha Marie Vogel
15:30–15:35
Observation-based studies
15:35–15:37
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EGU21-2582
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ECS
Joakim Kjellsson, Nils Niebaum, and Robin Pilch Kedzierski

We investigate how European heat waves and their associated heat stress on humans have changed over the 20th century. We find that the heat stress has increased, even in regions where heat waves have not become warmer. As heat stress increases over wide areas of Europe there is also an increase in the total population affected by the heat stress. 

Heat waves pose a serious health risk to humans by reducing our ability to shed heat. We have studied the occurrence and intensity of heat waves as well as a heat stress index based on simplified wet-bulb globe temperature using data from ERA-20C reanalysis 1900-2010. Over the 110 years of data we find an overall warming of the air temperatures and dew point. The 98th percentile of both air temperature has increased by more than 1.5°C over large areas of Europe. 

We find an overall increase in heat wave days per year as well as an increase of air temperature during heat waves over most of Europe. As such, many densely populated areas exhibit increased heat stress during heat waves. For example, the mean heat stress during heat wave days over Paris has increased by one level, from “alert” in 1900-1930 to “caution” in 1980-2010. The fraction of the population exposed to heat waves has increased by 10%/century in central Europe and 25%/century over the Mediterranean. 

We find more heat waves during 1920 - 1950, which may be related to the positive phase of the Atlantic Multidecadal Variation (AMV). This suggests that the heat stress during European heat waves may also be influenced by internal climate variability, and large-ensemble model simulations may be used to disentangle the effects of natural variability and anthropogenic forcing.

How to cite: Kjellsson, J., Niebaum, N., and Pilch Kedzierski, R.: Trends in heat stress over Europe over the 20th century, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2582, https://doi.org/10.5194/egusphere-egu21-2582, 2021.

15:37–15:39
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EGU21-46
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ECS
Chloe Brimicombe, Claudia Di Napoli, Rosalind Cornforth, Florian Pappenberger, Celia Petty, and Hannah Cloke

Heatwaves are increasing in intensity, duration and frequency. One of the impacts of heatwaves is heat stress, which can lead to death and raised morbidity. This project, uses a mixed method approach. Using the ERA5.HEAT reanalysis data of the UTCI – a bio-meteorological heat stress index- and temperature, to study the climatology and trends of heat at a global level and at a regional and country level for African nations. In addition, we review a range of literature from academic papers, international reports and EM-DAT the international disaster database. All of this reveals the extent to which heat risk is communicated. As well as, revealing the growing size of heatwaves. These together provide evidence of whether more preparedness measures are needed.

How to cite: Brimicombe, C., Di Napoli, C., Cornforth, R., Pappenberger, F., Petty, C., and Cloke, H.: Borderless Heat Stress, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-46, https://doi.org/10.5194/egusphere-egu21-46, 2021.

15:39–15:41
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EGU21-9677
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ECS
Lennart Marien, Mahyar Valizadeh, Wolfgang zu Castell, Alexandra Schneider, Kathrin Wolf, Diana Rechid, and Laurens Bouwer

Myocardial infarctions (MI) are a major cause of death worldwide. In addition to well-known individual risk factors, studies have shown that temperature extremes, such as encountered during heat waves, lead to increases in MI. The relationship between health impacts and climate is complex, depending on a multitude of climatic, environmental, sociodemographic and behavioral factors. Machine Learning (ML) is a powerful tool for investigating complex and unknown relationships between extreme environmental conditions and their adverse impacts that has already been applied to other climate extremes, such as in the prediction of flood damages. By combining heterogeneous health, climatic, environmental and socio-economic datasets, this study is a first step in developing an ML model for predicting past and future MI risk due to heat waves.

Here, we present first results of our ML approach for modelling heat-related health effects in Augsburg based on the KORA MI and environmental data. The basis of our data-driven approach is the KORA cohort study and the MI Registry in the Augsburg region of Bavaria, Germany, comprising detailed information on MI and underlying health conditions. Additionally, weather and climate data, air pollution data (e.g., PM10, PM2.5, nitrous oxides, and ozone), as well as socio-economic data (household income, education) are used for this study. One of the key challenges is to assemble and integrate heterogeneous data from various sources and prepare them for the appropriate spatial scales. We outline major challenges in combining these data and deriving quantitative models from them.

Moreover, we present initial results based on both regression and classification models, discussing model performance for the period between 2000 and 2015, with a focus on two major heat wave events in Germany during 2003 and 2006. Ultimately, this research may be useful in better understanding heat-related MI risks, supporting possible adaptation options in urban areas and in identifying high-risk groups within society.

How to cite: Marien, L., Valizadeh, M., zu Castell, W., Schneider, A., Wolf, K., Rechid, D., and Bouwer, L.: Using Machine Learning to investigate Heat Waves and Myocardial Infarctions in Augsburg, Germany, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9677, https://doi.org/10.5194/egusphere-egu21-9677, 2021.

15:41–15:43
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EGU21-10365
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ECS
Olivia Cahill, Andrew Grundstein, Christian Walker, and Earl Cooper

Across the globe, exposure to environmental heat stress may impose increased health and safety hazards to active populations such as athletes and workers. Monitoring heat stress is a key component of a well-designed heat mitigation policy. Yet, the cost of several hand-held heat stress sensors may pose a financial barrier for use in many circumstances. Numerous areas, however, have existing networks of weather stations that could potentially be incorporated into monitoring heat stress. Currently, the Japanese Ministry of the Environment has set up a network of weather stations across the city to monitor environmental conditions in preparation of the 2021 Tokyo Olympic and Paralympic games. Our research question asks how representative are the values recorded at local weather stations (often located over a natural surface) to playing field conditions with various surfaces and microclimate conditions. In the U.S. the WeatherSTEM network has over 600 stations scattered across the country and measures a suite of variables relevant to heat stress including air temperature, humidity, wind speed, solar radiation and models the wet bulb globe temperature (WBGT) values. This study will compare measurements from a local WeatherSTEM station with on-site measurements taken over three different playing surfaces (grass, synthetic turf, and hardcourt tennis) in a humid subtropical climate in Athens, Georgia. U.S. It will also compare WBGT values computed using different models. Our results may provide insight not only for sports but also for the workplace which take place over various surface types and environments.

How to cite: Cahill, O., Grundstein, A., Walker, C., and Cooper, E.: Can a local weather station be used in place of on-site measurements for heat stress assessment in a sports setting?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10365, https://doi.org/10.5194/egusphere-egu21-10365, 2021.

Process understanding
15:43–15:53
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EGU21-11842
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ECS
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solicited
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Highlight
Laura Suarez-Gutierrez, Chao Li, Wolfgang A. Müller, and Jochem Marotzke

We use the 100-member Max Planck Institute Grand Ensemble (MPI-GE) to disentangle the contributions from colocated dynamic atmospheric conditions and local thermodynamic effects of moisture limitation as drivers of variability in European summer heat extremes. Using a novel extreme event definition, we find that heat extremes with respect to the evolving mean climate increase by 70% under a moderate warming scenario during the twenty-first century. With a multiple regression approach, we find that the dynamical mechanisms representing blocking and anticyclonic conditions are the main driver of variability in extreme European summer temperatures, both in past and future climates. By contrast, local thermodynamic drivers play a secondary role in explaining the total variability in extreme temperatures. We also find that considering both dynamical and thermodynamical sources of variability simultaneously is crucial. Assessing only one type of drivers leads to an overestimation of their effect on extreme temperatures, particularly when considering only thermodynamical drivers. Lastly, we find that although most past and future heat extremes occur under favorable dynamical atmospheric conditions; this occurs 10–40% less frequently over Central Europe in the twenty-first century. By contrast, heat extremes over Central Europe occur 40% more frequently under concurrent extreme moisture limitation in the twenty-first Century. Our findings highlight a new type of neutral-atmosphere, dryness-driven heat extremes, and confirm that the increase in European heat extremes and associated variability increase are dominated by the local thermodynamic effect of moisture limitation.

How to cite: Suarez-Gutierrez, L., Li, C., Müller, W. A., and Marotzke, J.: Dynamical and thermodynamical drivers of variability in European summer heat extremes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11842, https://doi.org/10.5194/egusphere-egu21-11842, 2021.

15:53–15:55
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EGU21-566
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ECS
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Highlight
Michael Byrne

Extreme temperatures have warmed substantially over recent decades and are projected to continue warming in response to future climate change. Warming of extreme temperatures is amplified over land where the impacts on human health, wildfire risk and food production are most severe. Using simulations with climate models, I show that hot days over tropical land warm substantially more than the average day. For example, warming of the hottest 1% of land days is 24% larger than the time-mean warming averaged across models. The climate-change response of extreme temperatures over tropical land is interpreted using a theory based on atmospheric dynamics. According to the theory, warming is amplified for hot land days because those days are dry: I term this the "drier get hotter" mechanism. Changes in near-surface relative humidity further increase tropical land warming , with decreases in land relative humidity particularly important. The theory advances physical understanding of the tropical climate and highlights land-surface dryness as a key factor determining how extreme temperatures will respond to future climate change.

How to cite: Byrne, M.: Amplified warming of extreme temperatures over tropical land, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-566, https://doi.org/10.5194/egusphere-egu21-566, 2021.

15:55–15:57
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EGU21-1587
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ECS
Yi Zhang, Isaac Held, and Stephan Fueglistaler

Extreme heat under global warming is a concerning issue for the growing tropical population. However, model projections of extreme temperatures, a widely used metric for extreme heat, are uncertain on regional scales. In addition, humidity also needs to be taken into account in order to estimate the health impact of extreme heat. Here we show that an integrated temperature-humidity metric for the health impact of heat, namely the extreme wet-bulb temperature (TW), is controlled by established atmospheric dynamics and thus can be robustly projected on regional scales. For each 1°C of tropical mean warming, global climate models project extreme TW (the annual maximum of daily-mean or 3-hourly values) to increase roughly uniformly between 20°S and 20°N latitude by about 1°C. This projection is consistent with theoretical expectations based on tropical atmospheric dynamics, and observations over the past 40 years, which gives confidence to the model projection. For a 1.5°C warmer world, the likely (66 per cent confidence interval) increase of regional extreme TW is projected to be 1.33-1.49°C, whereas the uncertainty of projected extreme temperatures is 3.7 times as large. These results suggest that limiting global warming to 1.5°C will prevent most of the tropics from reaching a TW of 35°C, the limit of human adaptation.

How to cite: Zhang, Y., Held, I., and Fueglistaler, S.: Projections of tropical heat stress constrained by atmospheric dynamics, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1587, https://doi.org/10.5194/egusphere-egu21-1587, 2021.

15:57–15:59
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EGU21-12972
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ECS
Ritika Kapoor, Carmen Alvarez-Castro, Enrico Scoccimarro, Stefano Materia, and Silvio Gualdi

Rising global temperatures are a potential cause for increase of extreme climate events, such as heat waves, both in severity and frequency. Under an increasing extreme event scenario, the world population of mid- and low-latitude countries is more vulnerable to heat related mortality and morbidity.

In India, the events occurred in recent years have made this vulnerability clear, since the numbers of heat-related deaths are on a rise, and heat waves can impact various sectors including health, agriculture, ecosystems and the national economy.

Preliminary results show the prevalence of heat events in seven different regions of India during the pre-monsoon (March, April, May) and transitional (May, June, July) months. We consider daily maximum temperatures (Tmax) and the NOAA’s Heat Index (HI), a combination of temperature and relative humidity that gives an insight into the discomfort because of increment in humidity.

We look into various drivers behind the heat events in the seven different clusters, in particular ENSO and the North Atlantic Regimes that have been linked to the generation of heat waves in different parts of India. The preliminary results indicate Nino 3.4 SST anomalies show positive correlation with Tmax anomalies only in the western coast during pre-monsoon season, while in the transitional months positive correlation extends to central and east India. The Tmax composite anomalies for the cold, warm and neutral phases of ENSO show positive anomalies for only warm years and negative anomalies for the cool and neutral years. Heat Index shows similar spatial patterns for correlation analysis and composite anomaly analysis. The Mean Sea Level Pressure (MSLP) composite associated with heat waves (days exceeding 95th percentile=>3 days) show a persistent ridge over the North Atlantic region.

 

How to cite: Kapoor, R., Alvarez-Castro, C., Scoccimarro, E., Materia, S., and Gualdi, S.: Heat Events in the Indian Subcontinent under a warming climate scenario: Detection and its Drivers , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12972, https://doi.org/10.5194/egusphere-egu21-12972, 2021.

Climate change scenarios
15:59–16:01
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EGU21-2596
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Highlight
Cathryn Birch, Lawrence Jackson, Declan Finney, John Marsham, Rachel Stratton, Simon Tucker, Cath Senior, and Richard Keane

Mean temperatures and their extremes have increased over Africa since the latter half of the 20th century and this trend is projected to continue, with very frequent, intense and often deadly heatwaves likely to occur very regularly over much of Africa by 2100. It is crucial that we understand the scale of the future increases in extremes and the driving mechanisms. We diagnose daily maximum wet bulb temperature heatwaves, which allows for both the impact of temperature and humidity, both critical for human health and survivability. During wet bulb heatwaves, humidity and cloud cover increase, which limits the surface shortwave radiation flux but increases longwave warming. It is found from observations and ERA5 reanalysis that approximately 30% of wet bulb heatwaves over Africa are associated with daily rainfall accumulations of more than 1 mm/day on the first day of the heatwave. The first ever pan-African convection-permitting climate model simulations of present-day and RCP8.5 future climate are utilised to illustrate the projected future change in heatwaves, their drivers and their sensitivity to the representation of convection. Compared to ERA5, the convection-permitting model better represents the frequency and magnitude of present-day wet bulb heatwaves than a version of the model with more traditional parameterised convection. The future change in heatwave frequency, duration and magnitude is also larger in the convective-scale simulation, suggesting CMIP-style models may underestimate the future change in wet bulb heat extremes over Africa. The main reason for the larger future change appears to be the ability of the model to produce larger anomalies relative to its climatology in precipitation, cloud and the surface energy balance.

How to cite: Birch, C., Jackson, L., Finney, D., Marsham, J., Stratton, R., Tucker, S., Senior, C., and Keane, R.: Future changes in heatwaves over Africa at the convection-permitting scale, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2596, https://doi.org/10.5194/egusphere-egu21-2596, 2021.

16:01–16:03
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EGU21-3140
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ECS
Athanasios Ntoumos, Panos Hadjinicolaou, George Zittis, and Jos Lelieveld

This study provides an overview of the projected temperature extremes over the MENA region until the end of the 21st century. The main objectives of our analysis are the following: i) analyze the projected changes in temperature extremes using the CMIP5 multi-model ensemble, reveal ii) the warmest model realizations and iii) the “hotspot” locations within MENA with the projected highest temperature extremes. For this purpose, a list of indices of temperature extremes, based on threshold, percentile, heatwave and coldwave characteristics is used, as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). We use daily near-surface air (2-metre) temperature (Tmax and Tmin) to derive the extremes-indices for the period 1980-2100. The data were taken from 18 CMIP5 models combining historical (1980-2005) and scenario runs (2006-2100 under RCP 2.6, RCP4.5 and RCP8.5). Using these datasets, the indices of temperature extremes were derived. The changes of the extremes over the 21st century are analyzed, in space and time, relative to the reference period 1981-2000. Moreover, a model ranking is performed based on the magnitude of the projected changes of the indices and the relation with the model climate sensitivity is explored. A further analysis of model statistics over specific locations/grid points reveals the areas with the projected most intense heat extremes.

How to cite: Ntoumos, A., Hadjinicolaou, P., Zittis, G., and Lelieveld, J.: Assessment of the projected temperature extremes over the MENA region from CIMP5 scenario runs , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3140, https://doi.org/10.5194/egusphere-egu21-3140, 2021.

16:03–16:05
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EGU21-14302
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ECS
Antonio Sánchez Benítez, Thomas Jung, Helge Goessling, Felix Pithan, and Tido Semmler

Under the current global warming trend, heatwaves are becoming more intense, frequent, and longer-lasting; and this trend will continue in the future. In this context, the recent 2019 summer was exceptionally hot in large areas of the Northern Hemisphere, with embedded heatwaves, as for example the June and July 2019 European events, redrawing the temperature record map in western Europe. Large-scale dynamics (associated with blockings or subtropical ridges) play a key role in explaining these-large scale events.

Conceptually, global warming can be split into two different contributions: Dynamic and thermodynamic changes. Whereas dynamic changes remain highly uncertain, some thermodynamic changes can be quantified with higher confidence. We exploit this concept by studying how these recent European heatwaves would have developed in a pre-industrial climate and how it would develop in the future for 1.5, 2 and 4 ºC warmer climates (storyline scenarios). To do so, we employ the spectral nudging technique with AWI-CM (CMIP6 model, a combination of ECHAM6 AGCM + FESOM Sea Ice-Ocean Model). Large-scale dynamics are prescribed by reanalysis data (ERA5). Meanwhile, the model is run for different boundary conditions corresponding to preindustrial and future climates along the SSP370 forcing scenario. This approach can be useful to help understand and communicate what climate change will mean to people’s life and hence facilitate effective decision-making regarding adaptation to climate change, as we are quantifying how recent outstanding events would be modified by our climate action. 

Temperatures during the heatwaves often increase twice as much as global mean temperatures, especially in a future 4 ºC warmer climate. In this future climate, maximum temperatures can locally reach 50ºC in many western Europe countries. Nighttime temperatures would be similar to the daytime temperatures in a preindustrial world. The global warming amplification can be partly explained by a robust soil drying in the future 4 ºC warmer climate (exacerbated due to the June 2019 heatwave) which is transmitted to a robust increase in Bowen ratio. Importantly, by design of our study, this response occurs without any changes in atmospheric circulation.

How to cite: Sánchez Benítez, A., Jung, T., Goessling, H., Pithan, F., and Semmler, T.: Storylines of plausible past and future climates for the July 2019 European heatwave, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14302, https://doi.org/10.5194/egusphere-egu21-14302, 2021.

16:05–16:07
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EGU21-2987
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ECS
Claudia Gessner, Erich Fischer, Urs Beyerle, and Reto Knutti

During the last decades, Europe has experienced intense dry and hot spells, which seriously impact socio-economic sectors and the ecosystem by shortages of water in the summer season. The occurrence of two exceptional consecutive dry summers 2018/2019 let a multi-year drought become a conceivable scenario. In order to implement adaptation strategies for such a natural hazard, stakeholders raise the questions, how dry and hot a worst-case drought scenario would turn out and how long it would take to fully recover from those climate anomalies?

We address these concerns through the generation of storylines, describing the driest plausible multi-year droughts over western Europe. By repeatedly resampling the occurrence of precipitation in the climate simulation, using 100-member ensembles, we inhibit rainfall and dehydrate the soils in western Europe. These storylines and a millennial climate control simulation are carried out with CESM1.2 under pre-industrial forcing.

In doing so, local precipitation is reduced by 80% and local soil moisture falls far below the 1st percentile of the climatology. Even compared to the present and future climate scenarios, still, the number of dry days is very rare in our drought storyline, i.e. we describe a hazardous but unlikely scenario. Moreover, these storylines are associated with the hottest spring, summer and fall temperatures, but also the coldest winter temperatures. Starting large ensembles from each summer of the multi-year drought scenario, i.e. under exceptional dry initial soil conditions, we find that summertime hot and dry spells have a twenty-fold chance to occur plus their persistence extents by about 1.5 days. After strong precipitation deficits in the summer months, the precipitation increases again. Nevertheless, the local soil moisture does not fully recover within the next year so that the following spring and summer season may be affected by re-occurring droughts, aggravating the damage through water deficits for the vegetation growth and the economy.

How to cite: Gessner, C., Fischer, E., Beyerle, U., and Knutti, R.: A multi-year drought scenario for western Europe, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2987, https://doi.org/10.5194/egusphere-egu21-2987, 2021.

Urban focus
16:07–16:09
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EGU21-7972
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ECS
Clemens Schwingshackl, Anne Sophie Daloz, Carley Iles, Nina Schuhen, and Jana Sillmann

Cities are hotspots of human heat stress due to their large number of inhabitants and the urban heat island effect leading to amplified temperatures. Exposure to heat stress in urban areas is projected to further increase in the future, mainly due to climate change and expected increases in the number of people living in cities. The impacts of climate change in cities have been investigated in numerous studies, but rarely using climate models due to their coarse spatial resolution compared to the typical areal extent of cities. Recent advances in regional climate modelling now give access to an ensemble of high-resolution simulations for Europe, allowing for much more detailed analyses of small-scale features, such as city climate.

Focusing on Europe, we compare the evolution of several heat stress indicators for 36 major European cities, based on regional climate model simulations from EURO-CORDEX. The applied EURO-CORDEX ensemble (Vautard et al., 2020) has a spatial resolution of 0.11° (~11 km; comparable to the extent of large cities) and contains over 60 ensemble members, allowing thus for robust multi-model analyses of climate change on city levels. We analyze changes in heat stress both relative to the climatological heat stress variability in each city during 1981-2010 using the Heat Wave Magnitude Index daily (HWMId, Russo et al., 2015) and in absolute terms by counting the yearly number of exceedances of impact-relevant thresholds. Relative and absolute heat stress increase throughout Europe but with distinct patterns. Absolute heat stress increases predominantly in Southern Europe, primarily due to the hotter climate in the South. Relative changes are also highest in Southern Europe but exhibit a secondary maximum in Northern Europe, while being lowest in Central Europe. The main reason for this pattern is that day-to-day variability in heat stress indicators during present climate conditions is highest in Central Europe but lower in Southern and Northern Europe. Large Northern European cities, which are all located at the shore, are further influenced by different heat stress evolutions over land and sea surfaces.

As human vulnerability does not only depend on the absolute heat stress but also on what people are adapted to (i.e., the climatological range), the results of this study highlight that cities in all parts of Europe – including in Northern Europe – must prepare for higher heat stress in the future.

 

References:

Russo, S., et al. (2015). Top ten European heatwaves since 1950 and their occurrence in the coming decades. Environmental Research Letters, 10(12). doi:10.1088/1748-9326/10/12/124003

Vautard, R., et al. (2020). Evaluation of the large EURO‐CORDEX regional climate model ensemble. Journal of Geophysical Research: Atmospheres. doi:10.1029/2019jd032344

How to cite: Schwingshackl, C., Daloz, A. S., Iles, C., Schuhen, N., and Sillmann, J.: Heat stress projections for major European cities from high-resolution regional climate model simulations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7972, https://doi.org/10.5194/egusphere-egu21-7972, 2021.

16:09–16:11
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EGU21-9181
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ECS
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Highlight
Alexia Karwat and Christian L. E. Franzke

Over the last few decades heat waves have intensified, become more common, pose severe health risks, especially in densely populated cities, and have led to excess mortality. While the probability of being adversely affected by heat stress has significantly increased over the last few decades, the risk of heat mortality is rarely quantified. This quantification of heat mortality risk is necessary for systematic adaptation measures. Furthermore, heat mortality records are sparse and short, which presents a challenge for assessing heat mortality risk for future climate projections. It is therefore crucial to derive indicators for a systematic heat mortality risk assessment. Here, risk indicators based on temperature and mortality data are developed and applied to major cities in Germany, France and Spain, using regional climate model simulations. These simulations have biases of up to 3°C with respect to observations and, thus, need to be bias-corrected. Bias-corrected daily maximum, minimum and wet-bulb temperatures show increasing trends in future climate projections for most considered cities. Additionally, we derive a relationship of daily maximum temperatures and mortality for producing future projections of heat mortality risk due to extreme temperatures based on low (Representative Concentration Pathway; RCP2.6) and high (RCP8.5) emission scenario future climate projections. Our results illustrate that heat mortality increases by about 0.9%/decade in Germany, 1.7%/decade in France and 7.9%/decade in Spain for RCP8.5 by 2050. The future climate projections also show that wet-bulb temperatures above 30°C will be reached regularly with maxima above 40°C likely by 2050. Our results suggest a significant increase of heat mortality in the future, especially in Spain. On average, our results indicate that the mortality risk trend is almost twice as high in all three countries for the RCP8.5 scenario compared to RCP2.6.

How to cite: Karwat, A. and Franzke, C. L. E.: Future Projections of Heat Mortality Risk for Major European Cities due to Heat Waves, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9181, https://doi.org/10.5194/egusphere-egu21-9181, 2021.

16:11–16:13
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EGU21-5158
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ECS
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Highlight
Victoria Ramsey and Claire Scannell

Recent extreme heat events in the UK are likely to become more frequent over the 21st Century and exacerbated in cities due to the urban heat island effect. Due to high population densities and a concentration of assets, urban areas are more vulnerable to climatic extremes with impacts that traverse health, infrastructure, built environment and economic activity. Risks to health, well-being and productivity from high temperatures is one of six priority areas from in UK Climate Change Risk Assessment (2017) where more action is needed to manage risks, prompting local authorities to understand heat risks within their city. 
City based climate services are needed for day-to-day operations in cities, emergency response and to inform urban design and development.  Recent advances in high resolution modelling enable better representation of urban processes and provide greater understanding of extreme events.  By exploiting such advances in underpinning science, the Met Office is generating urban climate services for city stakeholders to plan for and manage heat stress in their city.
The Met Office has been engaging with local authorities and city stakeholders in the UK and China to co-produce a prototype, two tier, urban heat climate service to enhance the resilience of urban environments to extreme heat events.  The prototype is based on a strong requirement from several cities to develop an evidence base of the heat hazard and understand current and future hot spots vulnerable to extremes of heat within the city.  Tier 1 uses observations and high-resolution climate data to provide city specific information of the heat hazard in a graphical factsheet format.  This includes information on future changes in temperature, extreme heat indicators, frequency and duration of heatwave events, and spatial distribution of heat across the city.  Tier 2 involves working closely with city stakeholders to combine the hazard information with data on health, built environment and socio-economics, to provide tailored information on heat exposure and vulnerability.  This will allow users to identify highly vulnerable parts of the city network and neighbourhoods for priority action.  This two-tier service can provide an evidence base to inform urban policy, design and adaptation strategies, and prepare authorities and city stakeholders for future demand on city services. 

How to cite: Ramsey, V. and Scannell, C.: An urban climate service to manage heat risks in UK and Chinese cities , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5158, https://doi.org/10.5194/egusphere-egu21-5158, 2021.

16:13–17:00