Extreme heat and humidity cause 47,000 deaths in Europe – here’s what it does to the human body

What makes extreme heat so dangerous?

There are many reasons. People are more likely to become dehydrated in high temperatures, increasing the risk of heart attack and stroke. Heat can make breathing problems worse, especially in places with high levels of pollution. Heat stress makes it harder for people to work and increases the likelihood of injury. It’s hard to know exactly how many people die from heat each year; most remain uncounted. Europe likely had 61,672 heat-related deaths in 2022, although this number may underestimate the true total, according to a study led by the Barcelona Institute for Global Health. Emerging economies suffer more than developed ones because there tends to be little respite from the sun; most people work outside and few have effective cooling at home. Concrete and asphalt in urban environments can trap heat, raising overnight temperatures and contributing to heat stress. Studies have found that women and the elderly are the populations most affected by extremely hot weather.

How is extreme heat measured?

Meteorologists are increasingly using measures of heat stress and discomfort – such as humidex, heat index or apparent temperature – to understand the health risks posed by high temperatures. “Wet-bulb” is one such measure. It takes into account the effects of humidity, which makes it harder for the human body to cool down through sweat. For example, 42C with 40% humidity – think Phoenix, Arizona in July – has a wet bulb temperature of around 30C. A lower temperature eg 38C but with humidity greater than 80% will give a wet bulb reading of around 35C. It’s big enough to trigger heatstroke even for healthy people with unlimited shade and water, and it’s already starting to show up in coastal subtropical regions. In reality, shade and water are often limited, and heat can kill at much lower wet bulb temperatures. A 2020 study published in the journal Science found that regions affected by the 2003 heatwaves in Europe and Russia in 2010, which proved deadly for thousands, experienced wet-bulb values ​​no higher than 28°C .

How are wet bulb temperatures measured?

Initially, by wrapping a damp cloth around the bulb of a thermometer. Scientists would record the level after the evaporation of moisture cools it, the way the body cools itself by sweating. Now, wet bulb temperatures are measured using electronic instruments at weather stations, with additional hot spot studies aided by satellite data from sources such as NASA and the International Space Station. The US National Oceanic and Atmospheric Administration has also developed a tool to forecast a more advanced measure of heat stress, the wet globe temperature, which takes into account wind speed, sun angle and cloud cover.

Where is this problem?

Traditionally, heat and humidity were highest in South Asia and subtropical climates. Some places in India recorded wet-bulb temperatures in excess of 32C; The UN predicts it will be one of the first countries to exceed a wet-bulb temperature of 35C. Global warming and the impact of the El Nino weather pattern mean there is a good chance that temperature and humidity records will be set this year in a number of regions straddling the equator, including Florida, Texas, much of Africa, India , Australia and Central and South America, according to the University of California, Berkeley. Increasingly, usually temperate places are also seeing incredibly hot days. The UK recorded a record high of 40.3C in July 2022, although relatively low humidity kept the wet bulb temperature around 25C. Barcelona experienced its hottest day on record at the end of July. In the US, heat alerts covered about half the population on August 1, the World Meteorological Organization said. Japan, Greece, Hungary and Croatia were among the countries that experienced the warmest July on record.

What is the economic impact of heat?

In places with extreme heat, every aspect of life becomes more challenging and inequalities become more acute, especially in cities. But even colder places are feeling the effects, usually through higher food and energy prices. Coffee prices have risen this year to a 45-year high as persistent heat and drought have exacerbated a supply crunch in Vietnam, the world’s biggest producer of robusta. Dry conditions in Russia this year have prompted analysts to cut forecasts for wheat production, and supply of crops including canola and chickpeas also remains susceptible to the impact of the heat. Previous El Niños have resulted in a significant impact on global inflation, adding 3.9 percentage points to non-energy commodity prices and 3.5 points to oil, according to Bloomberg Economics models. Energy consumption also increases during heat peaks, straining the grid and consumers’ pockets as prices rise. Natural gas prices rose this summer as consumers faced risks of outages; Egypt, usually a fuel exporter, resorted to buying LNG amid higher demand. The heat is also exacerbating the drought, adding further stress on hydroelectric and nuclear power generation. Extreme temperatures pose a growing threat to outdoor activities, disrupting events including concerts, religious gatherings and sporting events.

How is extreme heat linked to climate change?

A new branch of science, extreme event attribution, connects global warming to severe weather episodes with a degree of specificity. Heat waves are most directly linked to humanity’s greenhouse gas pollution. And the heat, along with dryness and wind, is fueling wildfires, which is why scientists are now confident that climate change is exacerbating wildfires in the western US, Australia and elsewhere. (The U.S. fire season is two months longer than it was in the 1970s and 1980s.) Global warming is making tropical cyclones — also called hurricanes or typhoons — more intense. Warmer water and wetter air – two results of global warming – provide extra fuel for such storms as July’s record-breaking Hurricane Beryl, which tore through parts of the Caribbean and the US. In India and Pakistan, extreme heat is 30 times more likely due to climate change.

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