Scientists say this ‘extreme’ weather in the northern hemisphere may soon be the norm
Why is it so hot?
Partly, it’s just the luck of the weather. The jet stream – the west-to-east winds that play a big role in determining Europe’s weather – has been further north than usual for about two months. A stationary high-pressure weather system has left the UK and much of continental Europe sweltering. Iceland, by contrast, has been hit with clouds and storms that would normally come further south.
The jet stream’s northerly position may have been influenced by temperatures in the north of the Atlantic, which have been relatively warm in the subtropics and colder south of Greenland.
“The current hot and dry spell in the UK is partly due a combination of North Atlantic ocean temperatures, climate change and the weather,” said Len Shaffrey, a professor of climate science at the University of Reading.
The influence of climate change on the jet stream is still being explored.
Is climate change to blame?
The heatwaves in the northern hemisphere are undoubtedly linked to global warming, scientists say. “There’s no question human influence on climate is playing a huge role in this heatwave,” said Prof Myles Allen, a climate scientist at the University of Oxford.
On Thursday the university will publish an analysis of how much more likely climate change made Europe’s current heatwave. Similar heatwaves have happened in the past when the planet was cooler – the world was two-thirds of a degree celsius cooler in 1976, a notably hot year in the UK. But climate change made them happen more often, Allen said.
Prof Peter Stott, a science fellow at the Met Office, said global warming of 1C since the industrial revolution was clearly making extreme heat more likely. “It is increasing quite significantly the risk of such a heatwave. The temperatures of 30C (86F) and above this week have gone from being a very rare occurrence to, not a frequent occurrence, but much more likely,” he said.
The wide geographical spread of the heatwave, right across four continents, also points to global warming as the culprit. “That pattern is something we wouldn’t be seeing without climate change,” Stott said.
Is climate change good or bad for Britain?
Britons are only somewhat worried about climate change, according to the British Social Attitudes tracker. Wildfires, such as those that have occurred recently in northern England, are one reason to be more concerned. “The moorland fires is an example of an impact that comes with such prolonged heatwaves,” Stott said.
Older people are vulnerable to extremes of heat, with 20,000 people believed to have died across Europe in the 2003 heatwave. Transport infrastructure suffers, with rail lines buckling. The other major short-term impact is on agriculture. Shaffrey said the hot, dry spell was wreaking havoc on farming. Heatwaves in other countries will probably cut yields of crops that the UK imports, pushing up prices.
Longer-term, the green and pleasant landscape of the UK may vanish if rainfall patterns change because of global warming. “People might like a Mediterranean climate but it will be very different. For wildlife, a change of that magnitude could be very traumatic because it has nowhere to go,” said Allen.
Is this a sign of things to come?
Yes. “It’s a warning of what we will have to deal with,” said Stott. Michael Mann, a US climate scientist, tweeted: “What we call an ‘extreme heatwave’ today we will simply call ‘summer’ in a matter of decades if we do not sharply reduce carbon emissions.”