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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 the implementation of Heat-Health Early Warning Systems for disaster risk reduction.

Co-organized by AS1
Convener: Martha Marie VogelECSECS | Co-conveners: Ana Casanueva, Tom Matthews
Presentations
| Thu, 26 May, 15:10–18:20 (CEST)
 
Room C

Thu, 26 May, 15:10–16:40

Chairpersons: Ana Casanueva, Laura Suarez-Gutierrez

15:10–15:15
Welcome and introduction

15:15–15:22
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EGU22-1204
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Highlight
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On-site presentation
Hendrik Wouters et al.

Global warming increases the number and severity of deadly heatwaves. Recent heatwaves often coincided with soil droughts that acted to intensify air temperature but lower air humidity. Since lowering air humidity may reduce human heat stress, the net impact of soil desiccation on the morbidity and mortality of heatwaves remains unclear. Combining weather balloon and satellite observations, atmospheric modelling, and meta-analyses of heatwave mortality, we find that soil droughts—despite their warming effect—lead to a mild reduction in heatwave lethality. More specifically, morning dry soils attenuate the afternoon heat stress anomaly by ~5%. This occurs due to reduced surface evaporation and increased entrainment of dry air from aloft. The benefit appears more pronounced during specific events, such as the Chicago 1995 and Northern U.S. 2006 and 2012 heatwaves. Likewise, our findings suggest that irrigated agriculture may intensify lethal heat stress, and question recently proposed heatwave mitigation measures involving surface moistening to increase evaporative cooling.

The manuscript of the findings is in press for Science Advances.

 

 

 

How to cite: Wouters, H., Keune, J., Petrova, I. Y., van Heerwaarden, C. C., Teuling, A. J., Pal, J. S., Vilà-Guerau de Arellano, J., and Miralles, D. G.: Less-deadly heatwaves due to soil drought, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1204, https://doi.org/10.5194/egusphere-egu22-1204, 2022.

15:22–15:29
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EGU22-1538
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ECS
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Highlight
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On-site presentation
Goratz Beobide-Arsuaga et al.

Past case studies have proposed many different spring and early summer sea surface temperature anomalies (SSTA) over the North Atlantic as precursors of European summer heat waves. Negative SSTAs in the Subpolar Gyre and western tropical Atlantic, and positive SSTAs in North Sea and Mediterranean Sea are few of the examples suggested to precede different European summer heat waves. Any robust description of North Atlantic spring SSTA precursors is further complicated by the large spatial heterogeneity of European summer heat waves and the limited number of observed events. Here, we combine the MPI-Grand Ensemble dataset with its 100 historical simulations (1850-2006) with a Neural-Network-based Explainable Artificial Intelligence method. In this unique data set, we systematically investigate the relevance of the North Atlantic spring SSTAs in preceding different types of European summer heat waves. We find that spring European regional seas provide useful information to differentiate and anticipate different types of European summer heat waves. While positive SSTAs in western Iberian Peninsula precede western European summer heat waves, positive SSTAs in the North Sea or Mediterranean Sea precede eastern European summer heat waves. The regional spring SSTAs relate to distinct soil moisture anomaly patterns in June, which resemble the location of the heat waves. These results could potentially improve seasonal prediction of European summer heat waves.

How to cite: Beobide-Arsuaga, G., Düsterhus, A., Müller, W. A., Barnes, E. A., and Baehr, J.: Spring regional sea surface temperature precursors of European summer heat waves, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1538, https://doi.org/10.5194/egusphere-egu22-1538, 2022.

15:29–15:36
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EGU22-7118
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ECS
Yi Zhang and William Boos

 Extreme temperatures have a wide societal impact yet remain a major uncertainty in climate projections. Past studies have identified several drivers of heatwaves, including atmospheric blocking and soil moisture-atmosphere feedback. However, it remains unknown what limits the magnitude of extreme temperatures, and a quantitative understanding of heatwaves is lacking. Here we provide a theory of mid-latitude extreme temperatures based on a convective-instability mechanism. We formulate the upper bound of the surface temperature as a function of the temperature at the 500-hPa pressure level (T500), which is supported by observations and reanalysis data. Based on this theory, we project that the annual hottest daily maximum temperature (TXx) should increase by 1.9 K for each 1 K of increase in T500 over mid-latitude land if there is no evident drying or moistening of surface air on the annual hottest days. The observed TXx trend over the past four decades between 40°N-65°N is consistent with our projection. With T500 within 40°N-65°N increasing slightly faster than the global warming, the warming rate of TXx of this region will be on average around twice of the global warming if specific humidity does not change on the hottest days. However, TXx will increase at a faster rate over regions with a decrease in specific humidity on the hottest days, and vice versa.

How to cite: Zhang, Y. and Boos, W.: The upper bound of mid-latitude extreme temperatures, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7118, https://doi.org/10.5194/egusphere-egu22-7118, 2022.

15:36–15:43
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EGU22-237
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ECS
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Virtual presentation
Rani Devi and Krushna Chandra Gouda

India witnessed the second longest recorded heat wave during May-June 2019 causing more human deaths with the maximum temperature recorded was about 51.8oC in a place called Churu in the state of Rajasthan. The present study investigated the spatio-temporal pattern of the maximum temperature and the associate heat waves in the country. The relationship of the heat wave spread and the variables like temperature, humidity, soil moisture as well as the land use and land cover is explored. The dynamics of large scale oceanic and atmospheric features resulting advection and local heating mechanism is found to be the reason of such high intense heat wave in 2019 summer season. The anomaly of all the related weather parameters are linked with the intense maximum temperature and resultant heat wave and the hot spots are identified. The impacts of ENSO (including 'El Niño Modoki') and MJO on the longest and highest heat wave phenomena are also quantified for the year 2019. The role of soil moisture and the evapotranspiration also observed in the analysis which clearly shows lack of these parameters also triggers the intense heat wave events. This study will help in better understanding of the local heat wave dynamics and these informations can be useful for the public health interventions against the intense heat wave situations.

 

How to cite: Devi, R. and Gouda, K. C.: Investigating the associated dynamics of 2019 Heat wave over India, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-237, https://doi.org/10.5194/egusphere-egu22-237, 2022.

15:43–15:50
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EGU22-6827
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ECS
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Virtual presentation
Ye-Won Seo et al.

Summer heatwave events have exhibited increasing trends, with sudden increases occurring since the early 2000s over northeastern China and along the northern boundary of Mongolia. However, the mechanism behind heatwaves remains unexplored. To quantitatively examine the feedback attribution of concurrent events related to surface temperature anomalies, the coupled atmosphere–surface climate feedback-response analysis method based on the total energy balance within the atmosphere–surface column was applied. The results demonstrate that the contributions of the latent heat flux and surface dynamic processes served as positive feedback for surface warming by reducing the heat release from the surface to the atmosphere because of deficient soil moisture based on dry conditions. Cloud feedback also led to warm temperature anomalies through increasing solar insolation caused by decreasing cloud amounts associated with anomalous high-pressure systems. In contrast, the sensible heat flux played a role in reducing the warm temperature anomalies by the emission of heat from the surface. Atmospheric dynamic feedback led to cold anomalies. The influence of ozone, surface albedo, and water vapor processes is very weak. This study provides a better understanding of combined extreme climate events in the context of radiative and dynamic feedback processes.

How to cite: Seo, Y.-W., Ha, K.-J., and Park, T.-W.: Feedback attribution to dry heatwaves over East Asia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6827, https://doi.org/10.5194/egusphere-egu22-6827, 2022.

15:50–15:57
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EGU22-6693
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On-site presentation
Jieun Wie and Byung-Kwon Moon

Heatwaves are meteorological disasters that can damage human health and reduce agricultural production when extremely high temperatures are involved. A heatwave over the Korean Peninsula in 2018 broke the temperature and duration records kept since observations began. This event caused significant socio-economic damage. High pressure in the upper atmosphere over Eastern Europe and strong convection over the western North Pacific subtropical region are major fluctuations known to strengthen heatwaves over the Korean Peninsula. This study analyzed how these factors affected predictions of the 2018 heatwave over the Korean Peninsula using the sub-seasonal to seasonal (S2S) prediction model. Of the 11 models used in the S2S prediction project, 6 were selected: CMA, ECCC, ECMWF, KMA, NCEP, and UKMO. These models underestimated the daily surface temperature from July to August 2018 compared with observations, and the prediction errors gradually increased as lead-time increased. The model that simulated significant upper-level high pressure events in Eastern Europe and convection activities in the western North Pacific subtropical region predicted surface temperatures for the Korean Peninsula that were similar to the observed values. The increase in air pressure in the upper atmosphere over Eastern Europe is related to the recent expansion of areas affected by heatwaves in Europe. Even in the S2S models, the model that accurately predicted the characteristics of the heatwave showed excellent prediction performance for the Korean Peninsula. The increase in convection activities in the western North Pacific subtropical region increased when the amplitude of phases 4–6 of the Madden–Julian Oscillation (MJO) was large and they included many days. If the S2S model simulates the characteristics of the MJO accurately, the surface temperature prediction performance for the Korean Peninsula will increase. Therefore, it is very important for the S2S model to predict these two factors accurately, particularly when predicting heatwaves similar to that which occurred over the Korean Peninsula in 2018.

This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI2020-01212.

How to cite: Wie, J. and Moon, B.-K.: Effect of Upper-Level High Pressure in Eastern Europe and Convection Activities in the Western North Pacific Subtropical Region on the Prediction of Heatwaves over the Korean Peninsula, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6693, https://doi.org/10.5194/egusphere-egu22-6693, 2022.

15:57–16:04
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EGU22-3750
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ECS
Sebastian Buschow et al.

The driving mechanisms of extreme heat events are known to live on a range of spatio-temporal scales. The occurrence and severity of a heatwave can be influenced by (a) slow variations in the ocean and sub-surface, (b) planetary tele-connections, (c) variations in the jet-stream and synoptic weather systems, as well as (d) local-scale feedbacks.

While important progress has been made on each of these individual contributions, fewer studies have attempted to draw a unified picture including them all. We approach this task with tools from classic statistical modeling, as well as image processing machine learning. With the help of wavelet-transforms, predictor variables can be separated into individual scales. Together with local variables and global principal component time-series, these potential drivers are supplied to a statistical learner with the task of reconstructing the field of heatwave occurrences. Contributions from individual scales can then directly be identified, either via variable selection before or during learning, or by measures of feature importance applied to the trained models.

We demonstrate this approach for the case of summer heatwaves in the ERA5 reanalysis. If successful, our  framework can also be transferred to other extreme events such as droughts, cold spells or wind storms.

How to cite: Buschow, S., Keller, J., and Wahl, S.: Identifying drivers for heat waves using wavelets and machine learning approaches, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3750, https://doi.org/10.5194/egusphere-egu22-3750, 2022.

16:04–16:11
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EGU22-2397
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ECS
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On-site presentation
Christoph Sauter et al.

Research on heatwave-related impacts typically focusses on risks to health or critical infrastructure. However, since high temperatures are an important element of convection-driven extreme rainfall events that can trigger flash floods, heatwave-induced extreme rainfall events are also important when considering heatwave impacts. Heavy rainfall events following heatwaves might alleviate the direct impacts of the heat but introduce other risks related to flash floods.

Using sub-daily rainfall observations on a global scale, we show that short duration rainfall extremes are indeed more likely to occur if preceded by a heatwave than compared to non-heatwave events. In addition, these rainfall events are more intense as well. However, this link is dependent on the region, with some locations, especially arid regions, showing no relationship between the two phenomena at all. We also investigate if hotter heatwaves are more likely to be followed by rainfall extremes. This could have implications for future heatwaves which are projected to become more intense.

How to cite: Sauter, C., White, C., Fowler, H., and Westra, S.: Heatwave-related extreme rainfall events, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2397, https://doi.org/10.5194/egusphere-egu22-2397, 2022.

16:11–16:18
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EGU22-7778
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On-site presentation
Wei Chen et al.

Extremes in temperatures not only directly affect the marine environment and ecosystems but also have indirect impacts on hydrodynamics and marine life. The role of heatwave events responsible for the occurrence and persistence of thermal stratification was analysed using a fully coupled hydrodynamic and wave model within the framework of the Geesthacht Coupled cOAstal model SysTem (GCOAST) for the North Sea. The model results were assessed against satellite reprocessed data and in situ observations from field campaigns and fixed MARNET stations. To quantify the degree of stratification, a potential energy anomaly over the water column was calculated. A linear correlation existed between the air temperatures and the potential energy anomaly in the North Sea excluding the Norwegian Trench and the area south of 54◦N latitude. Contrary to the northern part of the North Sea, where the water column is stratified in the warming season each year, the southern North Sea is seasonally stratified in years when a heatwave occurs. The influences of heatwaves on the occurrence of summer stratification in the southern North Sea are mainly in the form of two aspects, i.e., a rapid rise in sea surface temperature at the early stage of the heatwave period and a relatively higher water temperature during summer than the multiyear mean. Another factor that enhances the thermal stratification in summer is the memory of the water column to cold spells earlier in the year. Differences between the seasonally stratified northern North Sea and the heatwave-induced stratified southern North Sea were attributed to changes in water depth.

How to cite: Chen, W., Staneva, J., Grayek, S., Schulz-Stellenfleth, J., and Greinert, J.: The role of heatwave events on the occurrence and persistence of thermal stratification in the southern North Sea, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7778, https://doi.org/10.5194/egusphere-egu22-7778, 2022.

16:18–16:25
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EGU22-2728
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ECS
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On-site presentation
Laura Hövel et al.

Over the past century there was a significant increase in heatwaves in several regions around the globe. This increase is projected to continue with ongoing global warming and forms a serious risk for various ecosystems as well as human health. Changes in the occurrence and the characteristics of heatwaves since the middle of the 20th century are extensively studied in observational datasets and model simulations. However, there is a research gap concerning preindustrial (1850-1900) heatwaves and heatwaves in the early 20th century and their relation to forcings and large-scale variability modes.

In this study we analyse the occurrence of heatwaves and the spatial and temporal distribution of different heatwave characteristics since 1850 using different observational datasets (20CRv3 reanalysis, EUSTACE gridded temperature, HadEX3 and station data) and a 36-member ensemble of atmospheric model simulations. We compare preindustrial heatwaves to recent and projected heatwaves and analyse how global or local heatwave hotspots change over time.

We use a new approach, a 30-year running baseline climatology, which allows us to analyse heatwave characteristics across different centuries. Our analysis shows that the different observational datasets show a comparable distribution of heatwave characteristics. Furthermore, the atmospheric model based on observed volcanic forcings can also be used to analyse preindustrial and early 20th century heatwaves.  The agreement of the model simulations with the observational datasets allows to use the atmospheric model to analyse earlier preindustrial time periods that are not covered by observations. With our on-going analysis of preindustrial heatwaves, we consequently contribute to a better understanding of past climate extremes.

 

How to cite: Hövel, L., Hand, R., and Brönnimann, S.: A global assessment of heatwaves since 1850 in different datasets, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2728, https://doi.org/10.5194/egusphere-egu22-2728, 2022.

16:25–16:32
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EGU22-10642
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ECS
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Virtual presentation
Julia Hellmig et al.

Mainly caused by anthropogenic climate change occurring heatwaves have become more frequent and extreme throughout the 21th century. Summer heatwaves over Europe are mainly caused by positive phases of the North Atlantic Oscillation (NAO) and jet stream anomalies, subsequently causing atmospheric blocking over different parts of Europe. With this work we aim to define families of European heatwaves caused by different atmospheric regimes. In the long run this could help predicting European heatwaves and their length, intensity and spatial extend. To identify European heatwaves and their spatial extend we use the graph framework DeepGraphs. Within this framework every extreme heat day isconsidered a node and a heatwave is defined as the union of all nearest neighbour nodes (which are connected by edges). 

Two clustering steps are applied to cluster the heatwave into families depending on their length, season and spatial extend. 

Our results reveal a promising way to classify European heatwaves based on their atmospheric cause which could help forecasting heatwaves in the future.

How to cite: Hellmig, J., Strnad, F., and Goswami, B.: Identification of European heatwave families , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10642, https://doi.org/10.5194/egusphere-egu22-10642, 2022.

16:32–16:39
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EGU22-3666
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ECS
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Highlight
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Virtual presentation
Ondřej Lhotka and Jan Kyselý

Climate change-induced rise in global temperatures is linked to changes in hot extremes. The recent summer of 2021 was marked by extremely high temperatures over the Mediterranean, which together with numerous wildfires considerably affected human society and natural environment. Using daily maximum temperatures from the ERA-5 reanalysis, we aim to assess the severity of heat waves in 2021 in the context of past major European heat waves (since 1950) through analysing their length, spatial extent, intensity, and overall magnitude. We show that the summer of 2021 was record-breaking in terms of total duration of heat waves and their magnitude was comparable to those in 2003 and 2010. The past two decades (2002–2021) almost completely redraw the spatial pattern of the occurrence of the historically most severe heat wave in European regions. Before 2002, heat waves of 1955, 1972, and 1994 were the most severe in many parts of Europe. Considering the whole 1950–2021 period, however, those heat waves remain as historically the most severe only over a small portion of their original area, and the map is dominated by the 2003, 2010, 2018, and 2021 events. This documents a rapid change in heat wave characteristics in Europe over the last two decades.

How to cite: Lhotka, O. and Kyselý, J.: European heat waves of summer 2021 in the context of past major heat waves, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3666, https://doi.org/10.5194/egusphere-egu22-3666, 2022.

Thu, 26 May, 17:00–18:30

Chairpersons: Ana Casanueva, Laura Suarez-Gutierrez

17:00–17:07
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EGU22-10558
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ECS
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On-site presentation
Laura Suarez-Gutierrez et al.

We evaluate the contribution of the decadal to multidecadal variability in the North Atlantic climate system to impact-relevant extreme heat metrics over Europe, and how this contribution evolves in a warming world. To do this, we use the largest existing ensemble of a comprehensive, fully-coupled climate model: the 100-member Max Planck Institute Grand Ensemble (MPI-GE). MPI-GE has been shown to have one of the most adequate representations of the variability and forced response in observed temperatures in the historical record. Furthermore, the large ensemble size of MPI-GE provides the robust sampling of internal variability that is required to evaluate the contribution of variability on decadal to multidecadal timescales to low-probability, high-impact extreme events.

In our evaluation, we go beyond common metrics defining heatwave intensity or duration, and employ heat excess metrics that account for the cumulative intensity and persistence of heat per Summer beyond given thresholds. We use these cumulative heat metrics to assess excess dry heat as well as other impact-relevant aspects of heatwaves, such as hot and humid conditions and lack of night time cooling. Our preliminary results indicate that the contribution of the decadal variability in the North Atlantic, represented by the Atlantic Multidecadal Variability (AMV), contributes to differences in these metrics between positive versus negative AMV phases that are comparable to the forced changes due to anthropogenic global warming in parts of Europe. This potential for the exacerbation of such extreme conditions under positive AMV phases highlights the necessity for considering these decadal variations both in the attribution of past events as well as in our projections of future extreme heat.

How to cite: Suarez-Gutierrez, L., Müller, W. A., and Marotzke, J.: The Decadal Variability of Extreme European Heat, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10558, https://doi.org/10.5194/egusphere-egu22-10558, 2022.

17:07–17:14
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EGU22-4042
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On-site presentation
Chloe Brimicombe et al.

Extreme heat is a growing risk to both human and planetary health. It is an area of research with many mathematical models that attempt to capture mostly human responses to thermal conditions. However, like many science fields software is often not developed in a reproducible manner, which adheres to the shared principles of open science, software and research. Here, we present thermofeel which is a python thermal comfort library that was developed at the European Centre for Medium-Range Weather Forecasts (ECMWF) with the dual purpose of being able to be integrated into their operational forecasting systems and allowing users of ECMWF products to be able to use the same methods with their data. In addition, hosting thermofeel on GitHub allows for future growth through open research software process in line with the fast-moving extreme heat field and gives the potential for collaboration between the ECMWF with many other user groups. Further, the development here could lead to a global heat hazard early warning system and the first forecasting results will be presented demonstrating the skill of thermal indices. Finally, thermofeel is currently in pre-operational forecasting at ECMWF and is available for everybody through pip and GitHub. This work has been funded by the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement no 824115. 

How to cite: Brimicombe, C., Quintino, T., Di Napoli, C., Pappenberger, F., Cornforth, R., and Cloke, H.: thermofeel: developing an open research software project for heat stress and thermal comfort. , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4042, https://doi.org/10.5194/egusphere-egu22-4042, 2022.

17:14–17:21
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EGU22-11189
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Highlight
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On-site presentation
Erich Fischer et al.

The Pacific Northwest heat wave is one of a series of record-shattering heat extremes that, based on the previous observational record, may have been deemed impossible. Here we address the question of whether the potential for such an extreme heat wave could have been foreseen using simulated physical climate storylines.

We use a novel approach, called ensemble boosting, in which a fully-coupled free-running climate model (CESM2) is used to develop physical storylines of very rare heat extremes under present-day conditions. In ensemble boosting, the most extreme events in an initial-condition large ensemble for the near future are re-initialized with slightly perturbed atmospheric initial conditions to efficiently generate events that are even more extreme, with the goal of sampling events with magnitudes that have not been seen before.

We demonstrate that, with this approach, CESM2 can efficiently simulate events that reach or even exceed the magnitude and duration of the 2021 Pacific Northwest heatwave anomaly. The atmospheric circulation anomalies associated with the most extreme simulated heat waves in the boosted ensemble are remarkably similar to the observed event. We further evaluate the anomalies in the surface energy and water budgets that contribute to the most intense simulated events. We conclude that based on this approach, heat waves unseen in the observational record can be simulated in models, at least in some regions. After probing this approach for the Pacific Northwest heatwave, we apply it to other mid-latitude regions where extreme heat events of much higher magnitude than has been observed are plausible in the near future.

The ensemble boosting approach is computationally efficient, and it preserves physical consistency both in time, in space and across variables. This has the major advantages that the drivers can be directly evaluated against observed events and the generated storylines can be used in impact studies that require physical consistency, e.g. for the evaluation of humid heatwaves or compound events, for assessing wildfire risks or for ecosystem modelling.

How to cite: Fischer, E., Beyerle, U., Gessner, C., Lehner, F., Pendergrass, A., Sippel, S., Zeder, J., and Knutti, R.: Probing the unfathomable: ensemble boosting for physical climate storylines of unseen heat extremes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11189, https://doi.org/10.5194/egusphere-egu22-11189, 2022.

17:21–17:28
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EGU22-2671
Cathryn Birch et al.

The future change in dry and humid heatwaves is assessed in 10 year pan-African convective scale (4.5km) and parameterised convection (25km) climate model simulations. Compared to reanalysis, the convective scale simulation is better able to represent humid heatwaves than the parameterised simulation. Model performance for dry heatwaves is much more similar. Both model configurations simulate large increases in the intensity, duration and frequency of heatwaves by 2100 under RCP8.5. Present day conditions that occur on 3 to 6 heatwave days per year will be normal by 2100, occurring on 150-180 days per year. The future change in dry heatwaves is similar in both climate model configurations, whereas the future change in humid heatwaves is 56% higher in intensity and 20% higher in frequency in the convective scale model. Dry heatwaves are associated with low rainfall, reduced cloud, increased surface shortwave heating and increased sensible heat flux. In contrast, humid heatwaves are predominately controlled by increased humidity, which is associated with increased rainfall, cloud, longwave heating and evaporation, with dry bulb temperature gaining more significance in the most humid regions. Approximately one third (32%) of present day humid heatwaves commence on wet days, suggesting the potential for compound flood-humid heat climate extremes. Moist processes are known to be better represented in convective scale models. Climate models with parameterised convection, such as those in CMIP, may underestimate the future change in humid heatwaves, which heightens the need for mitigation and adaptation strategies and indicates there may be less time available to implement them to avoid future catastrophic heat stress conditions than previously thought.

How to cite: Birch, C., Jackson, L., Finney, D., Marsham, J., Stratton, R., Tucker, S., Chapman, S., Senior, C., Keane, R., Guichard, F., and Kendon, E.: Future changes in African heatwaves and their drivers at the convective scale, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2671, https://doi.org/10.5194/egusphere-egu22-2671, 2022.

17:28–17:35
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EGU22-2473
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On-site presentation
Lidija Srnec et al.

Introduction: Last IPCC AR6 reported with very high confidence that more frequent hot extremes will increase for the severity of heatwaves all-round the globe. It is known that heat and hot weather that can last for several days (so called heatwaves) can significantly influence human health as well as rise in heat-related deaths.

Design and methods: In this work, climate simulations obtained by regional climate model RegCM4 over Croatia are used. RegCM4 was forced by four different global climate models on 12.5 km horizontal resolution. Historical climate simulated by model is compared with observed daily data measured at Croatian meteorological stations in order to evaluate simulations. Future climate is considered by three different IPCC scenarios: the lowest RCP2.6, the middle RCP4.5 and the highest RCP8.5 emission scenario. We considered three future time slices: 2021-2050 (P1), 2031-2060 (P2) and 2041-2070 (P3).

Results: The range of climate change for maximum temperature during summer will be examined in the future time slices. We will also look into duration and number of heat waves in different parts of Croatia. Knowledge of the current situation as well as possible change in the future can help in the planning future adaptation and mitigation measures.

How to cite: Srnec, L., Magjarević, V., and Güttler, I.: Historical and projected heat waves in Croatia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2473, https://doi.org/10.5194/egusphere-egu22-2473, 2022.

17:35–17:42
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EGU22-4390
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ECS
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On-site presentation
Théo Mandonnet et al.

There is high confidence that heatwaves will become more frequent and more intense under the influence of climate change. Different definitions of heatwaves exist based on the statistical distribution of temperature, in general using thresholds and duration and extension criteria.
If one observes the overlap between these definitions and the actual human and material damage produced by heatwaves, it appears that there is low consistency between the two. In other terms, a large amplitude heatwave in the physical climatological sense may not be equivalently as large in terms of impacts.
By crossing meteorological (E-OBS), demographic (WorldPop, GHS-POP), and impact (EM-DAT) databases at the European scale, we developed indices to classify heatwaves and select extreme ones in terms of impacts. We also proposed a method to evaluate the classification abilities of these indices. Including demographic data in the indices seems central to understand the links between meteorological conditions and observed impacts.

How to cite: Mandonnet, T., Jézéquel, A., D'Andrea, F., Vallet, A., and Guivarch, C.: Extreme heatwaves in Europe 1950-2020: analysis of the links between meteorology, population, and impacts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4390, https://doi.org/10.5194/egusphere-egu22-4390, 2022.

17:42–17:52
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EGU22-13479
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ECS
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solicited
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Highlight
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On-site presentation
Jeetendra Sahani et al.

With ongoing climate change, the number, frequency, and intensity of events of extremely hot days during summers called heatwaves are progressing. Vulnerability of the population is one aspect responsible for the risk induced by such heatwaves. In society, certain characteristics make one group of people more vulnerable to heatwaves than others, such as poverty, access to cooling facilities, age, gender etc. The current research identifies such vulnerability factors or indicators of population to help in devising heat management strategies. This research focuses on a small bucolic region (Guildford) in Surrey county of the United Kingdom as mostly risk or vulnerability factors are underestimated and ignored in such regions compared to city population. Twelve heat vulnerability factors or indicators (house type, sex, age, ethnicity, place density, access to central heating, residence type: communal, health condition, household composition, disability, accommodation tenure i.e. rented or owned, and education level) were selected after reviewing several literatures to include in the study based on their data availability. Census data on such vulnerability indicators at lower output scale were collected. Principal component analysis was performed, and four major principal components were identified from these 12 factors which explained most of the variance (82 %) in the data. The corresponding loading value of each of these factors were utilised to find heat vulnerability indices for each lower output area and these indices were mapped using QGIS. It was noted that not only people living in town centre which is generally considered hotter and so are highly vulnerable, but outskirt regions were also significantly vulnerable compared to other lesser vulnerable regions. Such a vulnerability map can help authorities for site focused heat mitigation strategies application, early warnings, and preparation during summers, particularly during excessively hot days i.e., heatwaves. Nature-based permanent solution can be encouraged in regions of such highly vulnerable identified regions. 

How to cite: Sahani, J., Debele, S. E., and Kumar, P.: Heat vulnerability assessment and mapping for a bucolic town in the UK , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13479, https://doi.org/10.5194/egusphere-egu22-13479, 2022.

17:52–17:59
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EGU22-4129
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ECS
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Virtual presentation
Eunice Lo et al.

Extreme high temperatures are associated with elevated human mortality risks. This is evidenced by a typically U- or J-shaped relationship between daily temperature and mortality found for most places in the world where data exist. However, high temperature is not the only contributor to heat stress. Humidity is also an important factor because it affects evaporation of sweat, which is crucial for cooling the human body in hot environments. Although various heat stress metrics, many of which are a combination of atmospheric temperature and humidity based on different physiological assumptions, have been developed to estimate heat stress, the relationship between these metrics and mortality remains unclear.

In this study, the relationships between seven heat stress metrics — wet bulb temperature, apparent temperature, discomfort index and swamp cooler temperatures at four different efficiencies [1] — and mortality are systematically assessed using well-established Distributed Lag Non-linear Models (DLNMs) [2]. The predictive powers of these metrics, as well as that of daily mean temperature, are compared for the summer season at global locations in 39 countries, where sufficient meteorological and health data are available [3]. The results of this study provide new information as to which of these metrics are most indicative of summer mortality in different locations, and whether the ‘best-fit’ heat stress metric for a location gives a substantially different mortality estimate compared to the commonly used daily mean temperature. These results have important implications for heat-health impact monitoring, developing national and international heat-health action plans, as well as for projecting future heat-related mortality under different climate change scenarios.

References:

[1] Buzan, J. R. et al.: Implementation and comparison of a suite of heat stress metrics within the Community Land Model version 4.5. Geosci. Model Dev., 8, 151–170, 2015.

[2] Gasparrini and Armstrong: Reducing and meta-analysing estimates from distributed lag non-linear models. BMC Medical Research Methodology, 13:1, 2013.

[3] Vicedo-Cabrera, A. M. et al.: The burden of heat-related mortality attributable to recent human-induced climate change. Nature Climate Change, 11, 492–500, 2021.

How to cite: Lo, E., Vicedo-Cabrera, A. M., Mitchell, D., Buzan, J., and Zscheischler, J.: Is heat stress more indicative of summer mortality than temperature alone?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4129, https://doi.org/10.5194/egusphere-egu22-4129, 2022.

17:59–18:06
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EGU22-2046
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On-site presentation
Anastasia Paschalidou et al.

It is well-established that exposure to extreme ambient temperatures is linked to adverse health effects associated with cardiovascular and respiratory diseases. Epidemiological studies demonstrate that the relationship between air temperature and mortality is depicted as a “U”, “V” or “J” shaped curve where the lower extrema reflect the comfort zone and mortality rises beyond a temperature threshold that is region- and population-specific and depends on various socioeconomic factors. However, temperature is not the only parameter determining thermal stress, as relative humidity, wind speed and other meteorological parameters are also known to play an important role which is often ignored. This study investigated the relationship between mortality and thermal conditions in the region of Northern Greece, using several bioclimatic indices as indicators. The data used included mean daily values of air temperature, relative humidity and wind speed and daily mortality counts due to cardiovascular diseases for the time-period 2010-2018. The following 3 thermal indices were estimated: (a) Effective Temperature (ET), (b) Normal Effective Temperature (NET) and (c) Apparent Temperature (AT). These indices were selected as they depend on typically measured variables and they can describe thermal comfort in both warm and cold environments. The association between each thermal index and mortality was studied by fitting a Poisson regression model for over-dispersed data, combined with a distributed lag non-linear model. In order to detect delayed adverse effects of low temperatures, the lag period was extended to 21 days. A “U” shape curve was found to describe the relationship between each thermal index examined and mortality, indicating the existence of a cold and a hot threshold. Thresholds were identified at 16.6oC and 31.3oC for AT, at 16.1oC and 25.5oC for ET and at 13.7oC and 24.3oC for NET. Exposure to high temperatures was found to be more hazardous compared to low temperatures. The cardiovascular mortality risk increased by 8%, 14% and 10% for each additional degree above the AT, NET and ET hot threshold, respectively. On the other hand, a degree below the AT cold threshold resulted in 1% rise in the mortality risk and 2% rise for the case of ET and NET. Furthermore, the thresholds identified for the bioclimatic indices were used to identify temperature thresholds. In all cases the cold temperature threshold lied between 18.1oC and 20.7oC, confirming that cold-mortality is not necessarily linked to the lowest temperatures. The hot temperature threshold was almost the same in all cases; 27.6oC for AT and ΝET and 27.7 for ET. On the whole, this study confirms the complexity of climate-health associations and highlights the importance of bioclimatic indices as tools to evaluate thermal stress and to feed adverse health effect prevention strategies.

ACKNOWLEDGEMENT: We acknowledge support of this work by the project “Risk and Resilience Assessment Center –Prefecture of East Macedonia and Thrace -Greece.” (MIS 5047293) which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund). 

How to cite: Paschalidou, A., Psistaki, K., Begou, P., Petrou, I., and Dokas, I. M.: Exploring the association between bioclimatic indices and cardiovascular mortality: Preliminary results from Northern Greece, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2046, https://doi.org/10.5194/egusphere-egu22-2046, 2022.

18:06–18:13
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EGU22-4219
Steffen Lohrey et al.

Extreme heat is an increasing climate threat, most pronounced in urban areaswhere poor populations are at particular risk.Weanalyzed heat impacts and vulnerabilities of 1027 outdoorworkerswho participated in a KAP survey in Hanoi, Vietnam in 2018, and the influence of their mitigation actions, their knowledge of heat-risks, and access to early warnings.
We grouped respondents by their main income (vendors, builders, shippers, others, multiple jobs, and nonworking) and analyzed their reported heat-health impacts, taking into consideration socioeconomics, knowledge of heat impacts and preventive measures, actions taken, access to air-conditioning, drinking amounts and use of weather forecasts. We applied linear and logistic regression analyses using R.
Construction workers were younger and had less knowledge of heat-health impacts, but also reported fewer symptoms. Older females were more likely to report symptoms and visit a doctor. Access to air-conditioning in the bedroom depended on age and house ownership, but did not influence heat impacts as cooling was too expensive. Respondents who knew more heat exhaustion symptomswere more likely to report impacts (p< 0.01) or consult a doctor (p<0.05). Similarly, thosewho checkedweather updateswere more likely to report heat impacts (p< 0.01) and experienced about 0.6 more symptoms (p< 0.01). Even though occupation type did not explain heat illness, builders knewconsiderably less (40%; p<0.05) about heat than other groups butwere twice as likely to consult a doctor than street vendors (p < 0.01). Knowledge of preventive actions and taking these actions both correlated positively with reporting of heat-health symptoms, while drinking water did not reduce these symptoms (p < 0.01). Child carers and homeowners experienced income losses in heatwaves (p < 0.01). The differences support directed actions, such as dissemination of educational materials and weather forecasts for construction workers. The Red Cross assisted all groups with cooling tents, provision of drinks and health advice.

How to cite: Lohrey, S., Chua, M., Gros, C., Faucet, J., and Lee, J. K. W.: Perceptions of heat-health impacts and the effects of knowledge andpreventive actions by outdoor workers in Hanoi, Vietnam, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4219, https://doi.org/10.5194/egusphere-egu22-4219, 2022.

18:13–18:20
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EGU22-4753
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ECS
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Nicole van Maanen et al.

Climate change and increasing heat stress reduces labour productivity and supply all across the globe. In a global warming scenario of 3°C, effective labour (i.e., the combination of productivity and supply) is expected to decrease by up to 50 percentage points relative to the period 1986-2005. Central Africa, Southeast Asia and Latin America will be most affected. In these regions, the agricultural sector is still of paramount importance for livelihoods and food security and outdoor work is more common. When heat stress further increases, the capability for physical activity will reduce across a wide range of working places, primarily outdoors. Especially in low- and middle-income countries the effects of climate change will lead to a reduction in economic activity and decrease the capacity for economic growth.

 

Automation and mechanization of outdoor work could greatly reduce the economic costs of heat stress and counts as the most effective adaptation strategy in the agricultural- and construction sectors to climate change, but scenarios of potential future deployment of mechanization are in their infancy. Here we propose a Mechanization Deployment Index (MDI), which builds on the concept of constrained adaptative capacity reflecting a level of mechanization under the presence of socio-economic constraints compared to the maximum mechanization potential in the absence of constraints to adaptive capacity. By identifying socioeconomic variables within the framework of the Shared Socioeconomic Pathways (SSPs) that correlate with the current level of mechanization deployment, we are able to project five scenarios for future mechanization implementation alongside the SSPs. For the first time, we will be able to show how different socio-economic trajectories strongly modulate future heat stress impacts in the agriculture sector. These scenarios can be included in integrated assessments of climate change and improve the economic risk assessment in the 21st century.

How to cite: van Maanen, N., Orlov, A., and Schleussner, C.-F.: Adaptation to extreme heat in the agricultural sector – SSP-dependent scenarios for mechanization deployment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4753, https://doi.org/10.5194/egusphere-egu22-4753, 2022.