What is extreme heat stress? Inside the deadly phenomenon surging across Europe
The world is grappling with a “sharp rise” in dangerous heat stress, as our reliance on fossil fuels continues to bake the planet. According to the EU’s Copernicus Climate Change Service (C3S), temperatures...
The world is grappling with a “sharp rise” in dangerous heat stress, as our reliance on fossil fuels continues to bake the planet.
According to the EU’s Copernicus Climate Change Service (C3S), temperatures in Europe have increased by an estimated 2.5°C compared to pre-industrial levels despite efforts to stop global warming, making it the fastest-warming continent on Earth.
But researchers have now gone beyond analysing just the outside air temperature and have started to study ‘feels-like temperatures’ to understand more of the impact on people.
‘Feels like’ temperatures measure how hot or cold the weather feels to bare human skin. Rather than just using the standard air temperature, which you often see on forecasts, ‘feels like’ temperatures adjust for environmental factors like wind speed, humidity, as well as experts’ understanding of how heat is lost from the human body.
A new study, published in the science journal Nature, warns that extreme ‘feels-like’ temperatures, heat stress days and tropical nights – where the temperature doesn’t drop below 20°C during a 24-hour period – have all become “dramatically more frequent”.
Even regions previously untouched by heat stress are now feeling it too.
What is heat stress?
Heat stress refers to the build-up of body heat generated either internally by muscle use or externally by the environment. This occurs when the heat the body absorbs from the environment exceeds the body’s ability to dissipate it.
“Heat stress generally results from a combination of factors, such as high ambient temperatures, humidity, physical activity and inadequate fluid intake,” says C3S.
“Various factors influence the human body’s ability to keep its core temperature within certain boundaries.”
The heat produced by the human body can be balanced with heat exchanged with the surrounding environment through our thermoregulatory system (which is why we sweat when we’re hot). Behavioural factors can also play a part, such as staying hydrated, wearing baggy clothing, and not exercising during the hottest part of the day.
When our bodies are unable to balance this heat, we can experience a slew of symptoms such as elevated core body temperature, increased heart rate, rapid breathing, excessive sweating, nausea, and dizziness.
In severe cases, heat-related illnesses such as heat exhaustion or heat stroke can be deadly.
Where is heat stress hitting Europe the most?
Researchers looked at heat stress at three levels: strong (index temperatures of greater than or equal to 32°C); very strong (index temperatures of greater than or equal to 38°C); and extreme (index temperatures of greater than or equal to 46°C).
They found that in southern Spain, Italy, Greece and Turkey some areas will see up to 40 additional days with strong heat stress compared with the 1970s. Much of southern Europe is seeing almost a full month of additional strong heat stress days from decades ago.
The study’s lead author Rebecca Emerton, says it is striking “to see heat stress not only intensifying in those places that we already consider as being hot or used to experiencing heat waves ... but also to see this, we call it, expanding footprint of heat stress expanding into regions where it’s historically been rare or non-existent.”
Places that might see around 50 more days per year of at least strong heat stress compared with the 1970s include parts of Southern Africa, such as in Namibia and Angola; Eastern Africa, including parts of Tanzania, Kenya and Uganda; and parts of Mexico and Central America.
‘Feels-like’ temperatures are on the rise
According to the study, the feels-like temperatures on the ten warmest nights of each year have also increased faster — 0.32°C per decade — than the ten warmest days, 0.27°C per decade.
High nighttime temperatures can have a significant impact on human health, as the body relies on cooler temperatures during the night to regulate its core temperature and recover from daytime heat. This can lead to increased cardiovascular stress and sleep disturbance.
“Nighttime heat is often underestimated, but it can be particularly dangerous because people are typically at home and may not have access to cool, air-conditioned spaces,” Ruth Engel, a data scientist on environmental health and extreme heat at the World Resources Institute (WRI) tells Euronews Earth.
“In Europe, where air conditioning (AC) remains relatively uncommon and temperatures are rising faster than in any other region, tropical nights are becoming a major public health concern.”
Studies have shown that high nighttime temperatures are linked to increased mortality, particularly among older adults and those with pre-existing health conditions.
There are plenty of ways to cool down your home without air conditioning.
