Why is it so hot? The heat wave in Europe explained – POLITICO

Europe is in the grip of a fierce heatwave, with temperatures set to hit new records this week, possibly leading to thousands more deaths.

The heat set to hit Western Europe on Monday and Tuesday follows days of intense weather on the Iberian Peninsula, where hundreds of people have already died as a result of scorching heat which experts say has been aggravated by climate change.

Britain’s Met Office issued its first-ever red warning for extreme heat in England – indicating ‘danger to life’ – with temperatures reaching 43C on Tuesday.

Meanwhile, in France, temperatures are also above 40C and in the south-west of the country thousands of people have been evacuated after wildfires scorched more than 10,000 hectares.

Parts of Germany could also reach 40C by the middle of the week, while Eastern European countries will suffer the most on Thursday.

If there’s one thing politicians want to avoid, it’s a repeat of 2003, when a heat wave in Europe killed more than 70,000 people. So far more than 1,000 people have died from the heat in Spain and Portugal.

Here’s what you need to know about the latest heat wave in Europe.

How can extreme heat be deadly?

The most immediate risks are heatstroke and heat exhaustion, which in some cases can be fatal, especially in the elderly and people who exercise or work in high temperatures.

As the temperature rises, perspiration increases to cool the body through evaporation. Additionally, the blood vessels near the skin dilate, allowing blood to flow out of the core of the body to its extremities. Without rehydration, this can put extra strain on the heart and lead to a dangerous drop in blood pressure, leading to organ failure in extreme cases.

In addition, when the ambient temperature exceeds the 37.5°C of the body, sweating itself becomes less effective. « Sweat is evaporated by the heat in the air, not by the body. Therefore, sweating is not as effective at cooling you down, » said Dr Simon Cork, lecturer in physiology at the University Anglia Ruskin,

Heat stroke occurs when the body can no longer maintain its temperature and can lead to brain and organ damage without prompt emergency treatment.

But the true death toll from a heat wave tends to be much higher than expected. Because heat puts the body’s cells and organs under stress, it tends to exacerbate existing conditions and vulnerabilities. Particularly in the sick, the elderly and the very young, the pressure of dealing with high temperatures can take its toll days or even weeks later.

« Heat waves really do kill a surprising number of people, » said Hannah Cloke, a natural hazards researcher at the University of Reading.

Temperatures as low as 25 degrees can aggravate cardiovascular problems, the leading cause of deaths in those over 65, said Mike Tipton, professor of human and applied physiology at the University of Portsmouth.

High temperatures also reduce air circulation and lead to increased air pollution, worsening respiratory problems like asthma with life-threatening consequences.

40C is normal elsewhere in the world – why are we worried?

In many European countries, buildings are not designed to withstand temperatures even 5 degrees above 20C, according to Mariam Zachariah, a climatologist at Imperial College London.

It’s a serious problem in northern Europe, where most homes are built to trap heat to help residents better withstand the cold, driving up indoor temperatures during a heat wave. Only a tiny fraction of these houses are air-conditioned.

Cities that weren’t built to withstand high temperatures also don’t, in many cases, have the right infrastructure to keep people cool – think lots of shade and access to spaces green and water – or emergency response measures to help the most vulnerable.

Is it climate change?

Yes. The buildup of CO2 from the burning of fossil fuels has made heat waves more intense and more frequent across the world, including in Europe.

« The chances of seeing 40C days in the UK could be up to 10 times more likely in the current climate than in a natural climate unaffected by human influence, » said award scientist Nikos Christidis. climate at the UK Met Office.

Climate change causes heat waves in two ways, Zachariah said. One is simply to trap more heat in the global system. « A warmer atmosphere means more extreme heat, » she said.

The second impact is ‘dynamic’ – that is, changing weather patterns, which can bring heat and rain to areas that do not normally experience them. In the case of Europe, this year an area of ​​slow high pressure brought in scorching air from North Africa.

These types of heat waves will become more frequent in the coming decades, even if governments keep their promises to reduce emissions, which is far from certain.

“Even with current emission reduction pledges, such extremes could occur every 15 years in the climate of 2100,” Christidis said.

How should policy makers react?

In France, town halls have made museums and other air-conditioned places free, and extended the opening hours of swimming pools. Municipal authorities also have registers for vulnerable people and check those who live alone and may be at risk.

London this week set up free water points and announced emergency arrangements for the homeless.

But beyond immediate measures, countries need long-term heat action plans, said Sjoukje Philip of the Royal Netherlands Meteorological Institute. This means planting more trees in cities, building heat-resistant houses, retrofitting buildings and establishing robust early warning systems.

The EU urges municipal and government authorities to take these steps. “Adaptation to climate change is fundamental and must become faster, smarter and more systemic,” a European Commission spokesperson told POLITICO.

Is Europe a special case?

Although heat waves affect most parts of the world, there are regional differences, according to Philip.

« Heat waves in Western Europe are warming up faster than in some other regions, » he said. « Various factors can influence this: drying out of the ground, changes in the jet stream, [or] high pressure areas that often stay in one place for a long time.

Research by the Intergovernmental Panel on Climate Change shows that temperatures across Europe will increase at a rate greater than average global temperature changes in coming years, while the frequency and intensity of temperatures extremes will also increase.

Douglas Busvine contributed reporting.