2.1.2 Longer and more intense heatwaves

internal references to solve:

  • part-5 Drying-soils-and-mega-heatwaves
  • part-5 What-will-our-world-look-like-in-2050-if-we-don%E2%80%99t-take-radical-action-now
  • part-5 What-will-our-world-look-like-by-the-end-of-the-century

"These records will be broken in a few years. What we see with European heatwaves is that all the climate models are underestimating the change that we see."
Friederike Otto, Associate Professor Climate Research Programme, University of Oxford

As global temperatures increase, not only does the average day in many locations become hotter, but the chance of extremely hot days is greater too -- increasing the frequency and intensity of heatwaves. Indeed, studies have shown that human-induced warming has made scorching heatwaves significantly more likelyand also more intense when they hit. There have now been more than 230 attribution studies around the world and these have found that 95% of heatwaves were made more likely or worse by climate change.

Heatwaves are intensified in areas where the land is already dry, as dry soils can’t absorb as much heat. As a result, more heat is radiated back into the atmosphere, leading to even more sustained heating. This worrying feedback loop can trigger ‘mega-heatwave’ events. See section on drying soils and mega-heatwaves.

The mega-heatwave that struck Europe in 2003 was made at least twice as likely due to climate change and approximately 70,000 more people died than usually die in an average year -- the vast majority of these deaths were directly attributable to the extreme temperatures. This record breaking heatwave also had a massive impact on ecosystems across Europe and caused over $15 billion in economic losses. A more recent analysis from 2014 calculated that, due to the warming seen in just the course of a decade, a similarly extreme event is already about ten times more likely than in 2003.

During the Russian mega-heatwave of 2010, made at least three times more likely by man-made climate change, Russia’s wheat harvest declined by 40% -- contributing to a global wheat shortage as well as a 90% increase in international grain prices -- leading to economic losses of more than $15 billion.

In 2017, 157 million more people worldwide were exposed to heatwaves than in 2000, and hotter weather contributed to the loss of 153 billion hours of labour (a 60% increase from 2000) as workers in construction, farming and other industries had to stop work, often reducing the family income. In India, heat caused the number of hours worked to fall by almost 7%, whilst in England and Wales there were 700 more deaths than normal during a 15-day hot spell in June and July.

In 2018, unprecedented heat and wildfires that "could not have occurred without human-induced climate change" swept across the northern hemisphere with at least 224 locations around the world experiencing all-time record-breaking heat. A record 220 million more over 65s were exposed to heatwaves compared with 2000. The sweltering heat that the UK experienced that summer was made 30 times more likely by climate change. The 2018 heatwave in Japan, which led to over 1,000 deaths, was so severe that researchers said that it "could not have happened without global warming."

In 2019 nearly 400 temperature records were broken across 29 countries, with July being the hottest month ever recorded. Studies show that the searing mega-heatwaves that summer would have been extremely unlikely without climate change. Indeed, climate change made the sort of extreme heat felt in France and the Netherlands that summer up to 100 times more likely to occur whilst the record-breaking temperatures in the UK were around 20 times more likely to have occurred. Following record breaking heat that led to the hottest day ever recorded in Australia, Dr Sophie Lewis, a climate scientist at the University of New South Wales, said, "It’s not just the frequency that we’re breaking them [temperature records], it’s the margin... We’re now seeing temperatures that are occurring outside what we’d expect from natural variability alone."

As of July 2020, January 2020 was the warmest January ever recorded in Europe, and Siberia faced a record breaking heatwave, made some 600 times more likely due to climate change, which saw temperatures as high as 38°C in the Arctic Circle. We have just seen the hottest May ever recorded and we now have an 85% chance that 2020 will be the hottest year on record.

What is of particular concern is that the heatwaves hitting Europe havebeen even more frequent and severe than climate models have predicted. Experts say that Europe and the eastern Mediterranean appear more vulnerable to hotter temperatures than Africa and Southeast Asia, largely because so many older people (who are particularly at risk from increasing temperatures) live in cities which trap heat and can therefore be hotter than surrounding areas.

It is not just human health but also infrastructure that suffers under increased heating. Alex Hynes, Managing Director of Scotland’s railway, warned *"Britain’s railways can no longer cope with the effects of the climate crisis."