The elderly and children under 1 year of age faced 3.7 billion more life-threatening heatwave days in 2021 than annually in 1986-2005.1 12022 Global Report of the Lancet Countdown
Heat stress is the leading cause of weather-related death and can exacerbate underlying illnesses including cardiovascular disease, diabetes, psychological distress, asthma, and high temperatures can also increase the risk of accidents and infectious disease.
Both extreme heat and human exposure to it are on the rise. There is robust evidence that climate change is increasing the frequency, intensity, and duration of heatwaves. These trends are projected to continue for the foreseeable future without rapid mitigation of climate change, particularly as the numbers of vulnerable and exposed individuals increase.
Fortunately, nearly all adverse health outcomes of extreme heat are preventable with targeted and informed interventions.
The elderly and children under 1 year of age faced 3.7 billion more life-threatening heatwave days in 2021 than annually in 1986-2005.1 12022 Global Report of the Lancet Countdown
Heat stress will reduce total working hours worldwide by 2.2 per cent and global GDP by US$2,400 billion in 2030 - a productivity loss equivalent to 80 million jobs.2 2TITLE
The number of reported heat-related deaths is likely a vast underestimation, as deaths are routinely attributed to specific heat-related illnesses and not connected to heat itself.
A heatwave is a marked unusual period of hot weather over a region persisting for at least two consecutive days during the hot period of the year based on local climatological conditions, with thermal conditions recorded above given thresholds.3 3WMO 2020 via UNDRR/ISC Hazard Information Profiles: Supplement to UNDRR-ISC Hazard Definition & Classification Review: Technical Report
Approximately 30% of the world’s population is exposed to catastrophic heat events every year.4 4WHO, 2018. COP24 Special Report: Health and Climate Change In all world regions the characteristics of extreme temperatures are changing in similar ways, including longer heat seasons, more frequent heat waves, and more intense heat days. 5 5Changes in regional heatwave characteristics as a function of increasing global temperature. Perkins-Kirkpatrick and Gibson, 2017
Due to the Urban Heat Island (UHI) effect, people in urban environments face magnified exposure to heat stress. This exposure can be compounded by other vulnerability factors such as poor housing and inadequate access to clean drinking water or cool spaces.
Hot environments can overwhelm the body’s heat-dissipating mechanisms. At high temperatures, the body increases blood flow to the skin and starts to sweat to increase evaporation, cool down and maintain a safe body temperature. This physiological response can strain the body’s circulatory system and lead to its collapse, causing negative health impacts or even death in people with pre-existing health conditions. High humidity can limit evaporation of sweat, limiting the effectiveness of this mechanism for cooling.
Negative health effects of heat often occur early in the heat season, before people have acclimatized to the heat.
No population can avoid exposure to rising ambient temperatures, but some populations are more exposed to or more vulnerable to physiological stress, exacerbated illness, and an increased risk of death from exposure to excess heat than others.
Populations in Europe and the Eastern Mediterranean are among the most vulnerable to the health effects of heat as a result of ageing populations, the high prevalence of chronic disease, and rising levels of urbanisation. However, the Western Pacific, South-East Asian and African Regions have all seen a dramatic increase in vulnerability of >10% since 1990.6 6Lancet Countdown: Vulnerability to Extremes of Heat; The 2020 Report of the Lancet Countdown on Health and Climate
Especially vulnerable populations include the elderly, infants and children, pregnant women, physical labourers, athletes and attendees of outdoor events (e.g. music festivals), and the poor. Gender can also play an important role in determining heat exposure.
Other determinants of vulnerability include:
Practical, feasible, and often low-cost measures can save lives. Some of these measures include:
Heat risk management requires organization and coordination of many actors. Heat Health Action Plans are an important mechanism to strategically coordinate planning, preparedness, and action. They provide a portfolio of measures that can be taken over different time scales to increase preparedness and reduce heat health impacts. The core elements of a heat plan include:
Heat Health Warning Systems are an integral part of Heat Health Action Plans, and are provided by National Meteorological Services. They provide heat advisories, warnings, and watches to alert decision-makers and the public so that timely action can be taken.
Research
EN
Research
EN
Research
EN