Heat Wave Risk Research Articles

Heatwaves in Southeast Asia and Their Changes in a Warmer World

AbstractBased on the observational dataset SA‐OBS and model outputs from the Community Earth System Model Large Ensemble project, this study investigates heatwaves in Southeast Asia in the current and future warmer climate. A heatwave is detected when the daily maximum temperature exceeds the 90th percentile threshold at each grid for at least three consecutive days. Three characteristics describing the frequency, duration, and amplitude of heatwaves are examined, including the sum of heatwave days per year (HWF) satisfying the heatwave definition, the length of the longest yearly heatwave event (HWD), and the hottest amplitude of the hottest yearly heatwave event (HWA). Results indicate that increased global warming is associated with substantial changes in heatwave characteristics over Southeast Asia, with more frequent heatwaves, longer heatwave duration, and higher extreme temperatures. The increase in HWA has a linear growth against global warming levels with distinct regional differences between the Maritime Continent and the Indochina Peninsula due to their different heat content of lower atmospheric boundaries. In contrast, those in HWF and HWD have nonlinear growth characteristics. The projected warmer future tends to be associated with a higher risk ratio value with the occurrence of rarer extreme heatwaves relative to the current climate. These results reiterate the potential risks of extreme regional heatwaves if global warming is unrestricted.

A New Operational Seasonal Thermal Stress Prediction Tool for Coral Reefs Around Australia

Seasonal forecasts of sea surface temperature (SST) have become increasingly important tools in recent years for reef managers to help inform and coordinate management responses to mass coral bleaching events. This manuscript presents new operational thermal stress forecast products for prediction of coral bleaching risk, based on the seasonal ensemble prediction system ACCESS-S1 (Australian Community Climate and Earth System Simulator–Seasonal Version 1). These accumulated thermal stress products form critical tools for reef management, providing advance warning of high thermal stress, and increased risk of coral bleaching in the coming season. Degree Heating Months (DHM) consider both the magnitude and duration of thermal stress, both of which are important in determining reef impacts. Both hindcast and operational realtime DHM forecasts are assessed for past bleaching events across Australia, and the impacts of different drivers and local forcings between regions compared. Generally, the model has the highest skill when forecasting events driven by large scale climate drivers such as the El Niño Southern Oscillation (ENSO) which impacts coral reefs on all sides of Australia. ACCESS-S1 hindcasts indicate higher skill on the west Australian coast than the Great Barrier Reef for summer months, except for the North West Shelf. Realtime forecasts of the 2020 Great Barrier Reef coral bleaching event, used operationally by reef managers throughout this event, are also presented. This work advances our understanding of the 2020 event, provides skill assessments for the new DHM products, and discusses the use of a stationary baseline in a changing climate. High DHM values can indicate an increased risk of marine heatwaves, which are likely to have increasing impacts on Australia’s reef systems in the future under a warming climate.

Present and future projections of heatwave hazard-risk over India: A regional earth system model assessment

The heatwave is a disastrous hazard having significant impacts on health and society. This study analyses the heatwave hazards and risk for India's current and future scenarios using socioeconomic vulnerability and temperature datasets during the summer (April–June) season. The Census of India (CoI) 2011 datasets were considered to assess current vulnerability and projected from the SocioEconomic Data And Application Center (SEDAC) population at Shared Socioeconomic Pathway (SSP) 4 for future vulnerability. Whereas IMD temperature data used for hazard assessment for the present scenario (1958–2005) while projected temperature data from regional earth system model REMO-OASIS-MPIOM (ROM) were used for the future (2006–2099) scenario. The study exhibited the most hazardous, vulnerable, and risk-prone regions identified as the south-eastern coast and Indo-Gangetic plains and some populous districts with metropolitan regions (Mumbai, Delhi, and Kolkata) under the current scenario. The coupled model ROM has efficiently captured the critical districts with higher and lower risk, showing its future projection capability. The study highlighted that the heatwave hazard-risk would significantly worsen in future scenarios in all districts under enhanced global warming and largely affecting the districts in the eastern and middle Indo-Gangetic plains and Malabar region. The present study will provide sufficient insights into designing mitigation strategies and future adaptive planning for the heatwave risk, which is one of the targets under Sustainable Development Goal 13 (Goal 13: Climate Action).

RMetS Meteorological Masterclass Series: Anticipating floods, droughts and heatwaves

<scp>RMetS M</scp>eteorological <scp>M</scp>asterclass <scp>S</scp>eries: Anticipating floods, droughts and heatwaves

Compound Climate and Infrastructure Events: How Electrical Grid Failure Alters Heat Wave Risk.

The potential for critical infrastructure failures during extreme weather events is rising. Major electrical grid failure or "blackout" events in the United States, those with a duration of at least 1 h and impacting 50,000 or more utility customers, increased by more than 60% over the most recent 5 year reporting period. When such blackout events coincide in time with heat wave conditions, population exposures to extreme heat both outside and within buildings can reach dangerously high levels as mechanical air conditioning systems become inoperable. Here, we combine the Weather Research and Forecasting regional climate model with an advanced building energy model to simulate building-interior temperatures in response to concurrent heat wave and blackout conditions for more than 2.8 million residents across Atlanta, Georgia; Detroit, Michigan; and Phoenix, Arizona. Study results find simulated compound heat wave and grid failure events of recent intensity and duration to expose between 68 and 100% of the urban population to an elevated risk of heat exhaustion and/or heat stroke.

Impact of different heat wave definitions on daily mortality in Bandafassi, Senegal.

The aim of this study is to find the most suitable heat wave definition among 15 different ones and to evaluate its impact on total, age-, and gender-specific mortality for Bandafassi, Senegal. Daily weather station data were obtained from Kedougou situated at 17 km from Bandafassi from 1973 to 2012. Poisson generalized additive model (GAM) and distributed lag non-linear model (DLNM) are used to investigate the effect of heat wave on mortality and to evaluate the nonlinear association of heat wave definitions at different lag days, respectively. Heat wave definitions, based on three or more consecutive days with both daily minimum and maximum temperatures greater than the 90th percentile, provided the best model fit. A statistically significant increase in the relative risk (RRs 1.4 (95% Confidence Interval (CI): 1.2-1.6), 1.7 (95% CI: 1.5-1.9), 1.21 (95% CI: 1.08-1.3), 1.2 (95% CI: 1.04-1.5), 1.5 (95% CI: 1.3-1.8), 1.4 (95% CI: 1.2-1.5), 1.5 (95% CI: 1.07-1.6), and 1.5 (95% CI: 1.3-1.8)) of total mortality was observed for eight definitions. By using the definition based on the 90th percentile of minimum and maximum temperature with a 3-day duration, we also found that females and people aged ≥ 55 years old were at higher risks than males and other different age groups to heat wave related mortality. The impact of heat waves was associated with total-, age-, gender-mortality. These results are expected to be useful for decision makers who conceive of public health policies in Senegal and elsewhere. Climate parameters, including temperatures and humidity, could be used to forecast heat wave risks as an early warning system in the area where we conduct this research. More broadly, our findings should be highly beneficial to climate services, researchers, clinicians, end-users and decision-makers.

Multi-decadal convection-permitting climate projections for China’s Greater Bay Area and surroundings

The Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is the world’s largest bay area in terms of land area and population, which has been increasingly suffering from weather and climate extremes under global warming. It is thus desired to produce reliable high-resolution climate information at a regional scale in order to enhance resilience to climate change over the GBA. For the first time, this study develops the multi-decadal nested-grid climate projections at a convection-permitting scale for the GBA, and assesses the abilities of the Weather Research and Forecasting (WRF) model with 36-, 12- and 4 km resolutions in representing precipitation, temperature and their extremes. Our findings indicate the added value of the convection-permitting WRF model for simulating the spring and summertime precipitation as well as extreme heavy rainfall events with daily amounts larger than 30 mm over the GBA. Increasing the spatial resolution of the WRF model does not necessarily lead to a significant improvement on temperature simulations. In addition, our findings reveal that the GBA is expected to have an increasing number of heavy and extreme heavy rainfall events by the end of the twenty-first century. Moreover, the GBA is projected to have a large temperature change across different seasons, and an enhanced warming will appear in autumn. The GBA is also expected to have more summer days with longer durations, thereby leading to an increasing risk of heatwaves and heat stress.

Projected changes in risk of heat waves throughout Belt and Road Region in the 21st century

<p indent="0mm">The “Belt and Road Initiative”, an important national measure undertaken during the reform and opening-up policy of China, includes the Silk Road Economic Belt and 21st Century Maritime Silk Road. The Belt and Road Initiative involves over four billion people from more than 60 countries; therefore, it is imperative to make accurate projections of future climate changes for improved mitigation planning at the national level. Extreme heat waves may have significant impacts on several aspects of natural ecosystems and society, prompting considerable concern; thus, research is necessary with respect to potential changes in the frequency and intensity of heat waves in the context of global warming. Increasing heat wave related disasters in a potentially warmer future may pose threats to the sustainable development of the Belt and Road Region (BRR)—A region with various complex climates and a weak economic foundation. Heat wave disasters that are accompanied by high temperatures and humidity can threaten human health. Traditional research on heat waves focuses on the effects of temperature; however, taking the comprehensive effect of temperature-humidity into consideration can better explain heat stress on the human body in a high-temperature environment and better measure the intensity of heat waves. Therefore, we adopted a heat wave index (a widely used indicator for the synergistic effect of temperature and humidity) developed by the National Oceanic and Atmospheric Administration to characterize the health risks associated with heat waves, as well as to further project the changes in areal and population exposure to heat waves in the 21st century at different risk levels throughout the BRR under two typical climatic-socioeconomical scenarios (SSP2-4.5 and SSP3-8.5). Our analysis was based on state-of-the-art global climate models that are a part of the Inter-Sectoral Impact Model Intercomparison Project and a population projection dataset developed by the National Center for Atmospheric Research and the City University of New York’s Institute for Demographic Research. Our results indicated that the intensity and frequency of heat waves in most areas throughout the BRR showed various increasing trends. Under the SSP2-4.5 and SSP3-8.5 scenarios, the sum of the population exposure to all levels of extreme heat waves in the BRR will increase to 2.0 and 3.3 times, respectively, by the end of the 21st century compared with that of the reference period (1986–2005). Furthermore, the relative increase in population exposure will be more remarkable for heat waves associated with higher risk levels; namely, the population exposure to heat waves at low, medium, and high risk levels will increase to 1.3, 2.1, and 8.9, respectively, under SSP2-4.5 and 1.5, 2.9, and 28.2 times, respectively, under SSP3-8.5 compared with that of the reference period. Developing countries in South Asia and Southeast Asia with large populations will suffer the most prominent increase in population exposure to heat waves. Typically, climatic factors play a major role in the increase of overall population exposure and dominate the increase in population exposure to heat waves at higher risk levels. However, the relative magnitude of the contribution of climatic and demographic factors varied across the regions. Our results indicated that unlike the air temperature, changes in the heat-humidity indices were significantly greater at lower latitudes, where only slight increases in the mean may be required to substantially enhance the frequency of dangerous conditions. Future construction of the Belt and Road must establish an early warning system for high-risk areas based on risk evaluations for extreme heat wave events. Additionally, it will be necessary to strengthen the vulnerability assessments for different areas and industries in the BRR and to establish an effective technical system to cope with extreme events.

Atmospheric tropical modes are important drivers of Sahelian springtime heatwaves

Heatwaves pose a serious threat to human health worldwide but remain poorly documented over Africa. This study uses mainly the ERA5 dataset to investigate their large-scale drivers over the Sahel region during boreal spring, with a focus on the role of tropical modes of variability including the Madden–Julian Oscillation (MJO) and the equatorial Rossby and Kelvin waves. Heatwaves were defined from daily minimum and maximum temperatures using a methodology that retains only intraseasonal scale events of large spatial extent. The results show that tropical modes have a large influence on the occurrence of Sahelian heatwaves, and, to a lesser extent, on their intensity. Depending on their convective phase, they can either increase or inhibit heatwave occurrence, with the MJO being the most important of the investigated drivers. A certain sensitivity to the geographic location and the diurnal cycle is observed, with nighttime heatwaves more impacted by the modes over the eastern Sahel and daytime heatwaves more affected over the western Sahel. The examination of the physical mechanisms shows that the modulation is made possible through the perturbation of regional circulation. Tropical modes thus exert a control on moisture and the subsequent longwave radiation, as well as on the advection of hot air. A detailed case study of a major event, which took place in April 2003, further supports these findings. Given the potential predictability offered by tropical modes at the intraseasonal scale, this study has key implications for heatwave risk management in the Sahel.

Climate Change Risk Assessment for Kurunegala, Sri Lanka: Water and Heat Waves

Sri Lanka is experiencing various social and environmental challenges, including drought, storms, floods, and landslides, due to climate change. One of Sri Lanka’s biggest cities, Kurunegala, is a densely populated city that is gradually turning into an economic revitalization area. This fast-growing city needs to establish an integrated urban plan that takes into account the risks of climate change. Thus, a climate change risk assessment was conducted for both the water and heat wave risks via discussions with key stakeholders. The risk assessment was conducted as a survey based on expert assessment of local conditions, with awareness surveys taken by residents, especially women. The assessment determined that the lack of drinking water was the biggest issue, a problem that has become more serious due to recent droughts caused by climate change and insufficient water management. In addition, the outbreak of diseases caused by heat waves was identified as a serious concern. Risk assessment is integral to developing an action plan for minimizing the damage from climate change. It is necessary to support education and awareness in developing countries so that they can perform risk assessment well and develop both problem-solving and policy-making abilities to adapt to a changing climate.

The effects of heat wave warning system on mortality in urban and rural populations in South Korea through 2001-2016

Significant threats to public health are posed as climate change is expected to continuously increase global ambient temperature. Many counties have implemented heat wave warning systems to reduce the health impacts of extreme heat but little is known about whether these systems actually reduce heat-related mortality. We assessed changes in the mortality risk of heat waves over time between 2001-2016 in urban and rural regions in South Korea. Mortality, weather monitoring, and air pollution data were collected for 7 urban cities and 8 rural regions. A difference-in-differences analysis combined with propensity score weighting was applied to estimate changes in mortality risks between before and after the implementation of the heat wave warning system (2001-2007, 2008-2016). Results showed evidence of decreased all-cause mortality (-0.611 deaths / 1,000,000 people, 95% CI: -0.974, -0.248) during heat waves in urban populations after the implementation of the warnings. The reduction in mortality was larger in persons aged 65+ (-6.097 deaths / 1,000,000 people, 95% CI: -9.067, -3.127), compared to persons aged 20-64 (-0.715 deaths / 1,000,000 people, 95% CI: -1.101, -0.328). However, decreased mortality was larger in young adult males (age 20-64) than older males, whereas risk reduction in older females was larger than young adult females. Decreased mortality was found for cardiovascular deaths of persons aged 75+ and for respiratory deaths of all-age males. No evidence was found for decreased all-cause mortality in rural populations although decreased mortality was found for respiratory mortality (age 0-19). In conclusion, we found different effects of the national warning system for reducing heat-related mortality among urban and rural populations, which was more effective in urban regions. Further work needs to examine heterogeneity in social resources or perception of high temperature between urban and rural regions that may explain the different mortality effects of heat wave warning system.

Spatio-Temporal Analysis of Urban Heatwaves Using Tukey g-and-h Random Field Models

Real-time heatwave risk management with fine-grained spatial resolution is important for analysis of urban heat island (UHI) effects and local heatwaves. This study analyzed the spatio-temporal behavior of ground temperatures and developed methods for modeling them. The developed models consider two higher-order stochastic spatial properties (skewness and kurtosis), which are key to understanding and describing local temperature fluctuations and UHI effects. Application of the developed models to the greater Tokyo metropolitan area demonstrated the feasibility of statistically incorporating a variety of real datasets. Remotely sensed imagery and data from a variety of ground-based monitoring sites were used to build models linking urban covariates to air temperature. Air temperature models were used to capture high-resolution spatial emulator outputs for modeling ground surface temperatures. The main processes studied were the Tukey g-and-h processes for capturing spatial and temporal aspects of heat processes in urban environments. The main finding is that consideration of not only the mean temperature but also the variance, skewness, and kurtosis parameters can reveal hidden heatwave structures.

COVID-19 and heatwaves: a double whammy for Indian cities

COVID-19 and heatwaves: a double whammy for Indian cities

Early adaptation to heat waves and future reduction of air-conditioning energy use in Paris

Some actions intended to adapt to climate change may do more harm than good, especially when they consume energy, making it more difficult to shift to decarbonized energy, or when, in meeting the needs of one group of people, they increase the vulnerability of others. Heat wave risk provides a typical example: air conditioning (AC) equipment may trigger large energy consumption and worsen outdoor heat stress. Alternative adaptation strategies exist, but it is not clear whether they can prevent the massive use of AC. Here, with an interdisciplinary modeling platform, taking Paris as a case study, we provide a first quantified analysis of the efficiency of adaptation strategies (large scale urban greening, building insulation policy, and generalized behavioral changes in AC use) in reducing future potential AC need. We find that even ambitious strategies do not appear sufficient to totally replace AC and ensure thermal comfort, under a median climate change scenario. They can, however, reduce AC energy use by half during heat waves and compensate for the heat released to the outdoor environment. Our results show that adaptation actions, implemented early, may play a key role if we are to remain on a low-carbon pathway.

Developing a GIS tool for emergency urban cooling in case of heat-waves

Many cities are expected to face a strong increase in the frequency and intensity of heat-waves by the end of the 21st Century due to climate change. In Paris, the frequency of heat-waves could rise from an average of one day per year to 14–26 days per year, with temperatures reaching up to 50 °C. Since 2012, pavement-watering is viewed as a potential tool for emergency cooling by the city while scientific work on the technique has found its application to be best suited to densely built urban areas, compared for example to urban greening whose impact may be hindered by lack of available planting space.This paper proposes an interdisciplinary approach combining urban physics with social sciences to develop such a GIS model for pavement-watering as an emergency response to heat-waves in Paris. It is built on performance criteria derived from previous work are input into a Geographic Information System to identify urban areas where pavement-watering would be most effective. In addition, a heat-related health risk assessment is conducted, using microclimatic, urban and socio-economic layers, to single out areas where heat-wave risk is highest in public spaces, combining high temperatures, pedestrian traffic and local population vulnerability. The microclimatic hazard dataset includes a physical model of park and water body cool islands assuming they are driven by thermal diffusion.The resulting tool has significant flexibility in defining the thresholds of the different indicators. The mapping scheme identified a total of 50 to 200 km of high priority areas for pavement-watering, requiring between 1400 and 5800 m3/day of non-potable water, equivalent to 0.6 to 2.6 L/day per capita. Limitations due to data quality or resolution are discussed as well as paths for further improvement.

Heat Vulnerability and Heat Island Mitigation in the United States

Heat waves are the deadliest type of natural hazard among all weather extremes in the United States. Given the observed and anticipated increase in heat risks associated with ongoing climate change, this study examines community vulnerability to extreme heat and the degree to which heat island mitigation (HIM) actions by state/local governments reduce heat-induced fatalities. The analysis uses all heat events that occurred over the 1996–2011 period for all United States counties to model heat vulnerability. Results show that: (1) Higher income reduces extreme heat vulnerability, while poverty intensifies it; (2) living in mobile homes or rental homes heightens susceptibility to extreme heat; (3) increased heat vulnerability due to the growth of the elderly population is predicted to result in a two-fold increase in heat-related fatalities by 2030; and (4) community heat island mitigation measures reduce heat intensities and thus heat-related fatalities. Findings also show that an additional locally implemented measure reduces the annual death rate by 15%. A falsification test rules out the possibility of spurious inference on the life-saving role of heat island mitigation measures. Overall, these findings inform efforts to protect the most vulnerable population subgroups and guide future policies to counteract the growing risk of deadly heat waves.

Local actions to health risks of heatwaves and dengue fever under climate change: Strategies and barriers among primary healthcare professionals in southern China

Climate change and extreme weather poses significant threats to community health, which need to be addressed by local health workforce. This study investigated the perceptions of primary healthcare professionals in Southern China on individual and institutional strategies for actions on health impacts of climate change and the related barriers. A mixed methodological approach was adopted, involving a cross-sectional questionnaire survey of 733 primary healthcare professionals (including medical doctors, nurses, public health practitioners, allied health workers and managers) selected through a multistage cluster randomized sampling strategy, and in-depth interviews of 25 key informants in Guangdong Province, China. The questionnaire survey investigated the perceptions of respondents on the health impacts of climate change and the individual and institutional actions that need to be taken in response to climate change. Multivariate logistic regression models were established to determine sociodemographic factors associated with the perceptions. The interviews tapped into coping strategies and perceived barriers in primary health care to adapt to tackle challenges of climate change. Contents analyses were performed to extract important themes. The majority (64%) of respondents agreed that climate change is happening, but only 53.6% believed in its human causes. Heat waves and infectious diseases were highly recognized as health problems associated with climate change. There was a strong consensus on the need to strengthen individual and institutional capacities in response to health impacts of climate change. The respondents believed that it is important to educate the public, take active efforts to control infectious vectors, and pay increased attention to the health care of vulnerable populations. The lack of funding and limited local workforce capacity is a major barrier for taking actions. Climate change should be integrated into primary health care development through sustainable governmental funding and resource support.

Spatiotemporal Distribution and Risk Assessment of Heat Waves Based on Apparent Temperature in the One Belt and One Road Region

Heat waves seriously affect the productivity and daily life of human beings. Therefore, they bring great risks and uncertainties for the further development of countries in the One Belt and One Road (OBOR) region. In this study, we used daily meteorological monitoring data to calculate the daily apparent temperature and annual heat wave dataset for 1989–2018 in the OBOR region. Then, we studied their spatiotemporal distribution patterns. Additionally, multi-source data were used to assess heat wave risk in the OBOR region. The main results are as follows: (1) The daily apparent temperature dataset and annual heat wave dataset for 1989–2018 in the OBOR region at 0.1° × 0.1° gridded resolution were calculated. China, South Asia and Southeast Asia are suffering the most serious heat waves in the OBOR region, with an average of more than six heat waves, lasting for more than 60 days and the extreme apparent temperature has reached over 40 °C. Additionally, the frequency, duration and intensity of heat waves have been confirmed to increase continuously. (2) The heat wave risk in the OBOR region was assessed. Results show that the high heat wave risk areas are distributed in eastern China, northern South Asia and some cities. The main conclusion is that the heat wave risk in most areas along the OBOR route is relatively high. In the process of deepening the development of countries in the OBOR region, heat wave risk should be fully considered.

An Experimental Analysis of Emergency Equipment for Heat-related Injuries

A growing risk of heat wave has forced the countries to come up with realistic and viable solutions. Despite a lack of on-site treatment tools to deal with heat-related diseases, few studies have examined this issue. We aim to examine the literature related to thermal damage to find out solutions to this problem. The literature related to heat-related diseases suggested five methods for rapid treatment and analyzed the effects of each treatment option. It is found that the average temperature of the surface of the terrain is about 7.9°C lower with heat shield. As for the method of clothing removal, the use of scissors was faster than the use of knives in the absence of a helper (scissor 2.8±1.7 min. vs. knife 4.1±2.3 min., p<0.05). Overall, ion drinks or water was found to provide a higher satisfaction than salt water according to the water intake satisfaction survey (94±10 vs. 86±9 vs. 28±19, p<0.05).

Predictors Associated with Health-Related Heat Risk Perception of Urban Citizens in Germany.

The rising probability of extremely high temperatures and an increasing number of consecutive hot days caused by climate change—combined with the impact of these high temperatures on human health—is widely discussed in the literature. There are calls for the development of heatwave adaptation measures by governmental and scientific institutions. In this research, the predictors of health-related heat risk perception of urban citizens in Augsburg, Germany, were investigated. An online survey was conducted with 468 citizens, asking about their heat risk perception, knowledge about heat risks, and demographic data and health information. Statistical methods (Spearman correlation, unpaired t-test, ANOVA and multiple regression) were used to determine which factors were significant and relevant. The results show that the knowledge of heat risks, heat risk sensitivity and an external locus of control are the most important factors for heat risk perception. The health implication score and chronic disease show significant effects in descriptive statistics. Furthermore, younger people showed the highest heat risk perception of all age groups. Surprisingly, income, education, living alone and gender did not play a role in heat risk perception. The findings imply a need for better and intensified heat risk communication in urban areas—especially among elderly people—and thus are important for creating acceptance towards heat wave risks, which is a prerequisite of willingness to adapt.