Europe's Rising Heat and Vulnerable Outdoor Workers
Outdoor workers are especially susceptible to the impacts of extreme heat, such as those experienced across the UK and Europe last month.
Although July has just begun, two record-breaking summer heatwaves have already offered the UK and Europe a glimpse of their emerging climate reality.
Following May's intense heat, June witnessed temperature records not only being broken but dramatically surpassed in what the United Nations' weather agency described as an "extraordinary" event across the continent.
After a short break, another heatwave is forecasted to arrive soon.
If these conditions feel unusual, it is because they are. However, this pattern aligns precisely with scientific predictions for a warming world, primarily driven by fossil fuel combustion releasing heat-trapping greenhouse gases into the atmosphere.
"Human-induced climate change has made events like this more likely and more intense," said Prof Stephen Belcher, chief scientist at the UK Met Office.
The severity of these heatwaves is illustrated by how much temperatures exceeded normal levels in May and June averaged across the UK, highlighted here in red.
While the June heatwave was most intense in southern England and south Wales, few regions escaped the elevated temperatures.
Temperatures peaked at 37.7°C in Lingwood, Norfolk, according to provisional data. This was among several stations that exceeded the UK's previous June high of 35.6°C, set in 1957 and matched in 1976.
"To see temperatures like this in the UK in June is sobering," said Belcher.
Not all weather stations have records dating back to the notable summer of 1976, but even some of the longest-running stations observed their previous records broken by 2°C or more.
"We normally expect the records broken by small amounts – tenths, maybe up to a degree or so," said Ed Hawkins, professor of climate science at the University of Reading.
"So to have it shattered by such a large amount is noticeable and extraordinary, and of course this comes after a similar event in May."
June's heatwave may have felt particularly oppressive due to the combination of high temperatures and humidity. Elevated humidity levels reduce the body's ability to cool through sweating.
Additionally, temperatures remained high even after sunset, complicating sleep. The human body relies on cooler nighttime temperatures to recover from daytime heat.
In Cardiff, temperatures did not fall below 23.5°C on the night of Wednesday 24 June into Thursday, marking the warmest June night ever recorded in the UK.
Most of England and Wales experienced at least one tropical night in June, defined as temperatures not dropping below 20°C. Historically, such nights have been very rare in the UK.
"We would definitely expect to see more and more tropical nights, as global temperatures keep rising," said Hawkins.
Heatwaves Across Europe Break Records
The same "heat dome" responsible for the UK's extraordinary June heatwave also caused temperature records to fall across Europe.
The German weather service, Deutscher Wetterdienst, described it as "a heatwave for the history books," while the French weather agency, Météo-France, called it "exceptional" and "historic."
More than a dozen countries across western, central, and eastern Europe broke their June temperature records, with some surpassing previous highs by two or three degrees Celsius.
Several countries recorded temperatures above 40°C and set new records for any time of year, despite June typically being cooler than July.
France and Spain also recorded their hottest June days in terms of national averages, though higher temperatures had been recorded previously at individual weather stations.
"Compared to historical measurements, this was obviously very unusual," said Sonia Seneviratne, professor at the Institute for Atmospheric and Climate Science at ETH Zurich in Switzerland.
The Alpine nation reached 39°C, exceeding the previous June record by more than 2°C.
"[But] I would say as a climate scientist, I was not that surprised to see this happen... when you know that we have a warming climate," she added.
Europe's Rapid Warming and Contributing Factors
Global temperatures have increased over the past century due to human emissions of greenhouse gases, but local and regional geography influence the rate of warming in different areas.
Europe is warming particularly rapidly, making it more vulnerable to frequent and intense heatwaves.
This accelerated warming is partly due to the melting of reflective snow and ice, as well as a reduction in tiny polluting particles in the air. These changes reduce the reflection of the Sun's energy back into space, leaving more energy to heat the Earth's surface.
Some scientists also suggest that climate change may be altering atmospheric circulation patterns over Europe, increasing the frequency of high-pressure systems that contribute to heatwaves, though this remains uncertain.
Exceptional Sea Surface Temperatures and Their Effects
Europe's seas are also experiencing exceptional warmth this summer. Marine heatwave conditions around the UK's coast have intensified partly due to last week's record-breaking air temperatures.
Because water cools more slowly than air, elevated sea temperatures can persist longer. This can amplify future heatwaves on land by diminishing the cooling effect of sea breezes.
Scientific Consensus on Climate Change and Heatwaves
Scientists agree that climate change has already made warm spells like June's heatwave significantly hotter than similar weather systems in the past.
"The only way to explain [such strong heatwaves] is to taking into account this [long-term] warming," said Seneviratne.
"When you have a high-pressure system, this heatwave will tend to be much hotter [now]. This is very well understood."
Experts warn that as average temperatures continue to rise, future hot spells will reach even higher temperatures.
Only a few decades ago, the UK reaching 30°C in June was relatively rare. Now, it has become common.
The long-term warming trend across the UK and Europe does not guarantee that the next heatwave will be hotter than the last, nor that the next summer will surpass the current one in temperature.
However, scientists caution that UK and European summers will inevitably become warmer on average as carbon emissions continue to increase global temperatures.
"Our heatwaves will get hotter and hotter and hotter until we get to global net zero greenhouse gas emissions [and] we stabilise the climate," said Hawkins.
Additional Context and Resources
France recorded 2,025 excess deaths at the peak of the heatwave as Europe prepares for more extreme weather events.
A third heatwave is anticipated for parts of the UK, with temperatures forecasted to reach 30°C.
The UK's summers are becoming hotter, raising questions about preparedness.
For those seeking to understand climate change better, a simple guide is available, along with explanations of how climate change exacerbates heatwaves, droughts, wildfires, and floods.
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