Is climate change causing this week's hot weather?

By the end of this week, parts of the UK will bake in temperatures of up to 34C, far hotter than normal June weather – but is climate change behind the soaring temperatures?

Met Office deputy chief meteorologist Dan Rudman, said: “Temperatures will continue to rise as we go through the week, becoming well above-average by Friday when many parts of the southern half of the UK are likely to exceed 30C and may even reach 34C in some places.”

“This is the first spell of hot weather this year and it is unusual for temperature to exceed these values in June."

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The Met Office says that the unseasonal warmth is due to ‘home-grown warming during the day’ due to high pressure, plus a southerly airflow which is bringing warm air from the continent to Britain.

This week’s temperature doesn’t – quite – qualify as a heatwave, the Met Office says, due to the short-lived nature of the hot temperatures.

But is climate change behind this week’s blistering temperatures?

Is climate change causing the UK heatwave?

Dr Mark McCarthy, who looks after UK climate records at the Met Office, has said that temperatures in England are getting warmer, and in some areas of England the rise is up to 1C.

McCarthy said: “A scientific study by the Met Office into the summer 2018 heatwave in the UK showed that it was 30 times more likely to occur now than in 1750 because of the higher concentration of carbon dioxide in the atmosphere."

“As greenhouse gas concentrations increase, heatwaves of similar intensity are projected to become even more frequent, perhaps occurring as regularly as every other year.”

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Our warming climate meant that last year’s summer heatwave was 30 times more likely and, by mid-century, such summers could happen about 50% of the time.

The study, based on computer models, found that carbon dioxide in the atmosphere is behind the rising temperatures, Met Office scientists said.

Levels of carbon dioxide in the atmosphere hit 416 parts per million last year, the Met Office said, compared to the pre-industrial era (before 1750), when the atmospheric concentration was about 280 parts per million.”

In 2018, Met Office scientist Dr Nikolaos Christidis who was ainvolved in the study said: “Our models show that there is now about a 12% chance of summer average temperatures being as high as the UK experienced in summer 2018. This compares with a less than half per cent chance we’d expect in a natural climate.”

Are heatwaves getting worse?

Other research has shown that climate change is linked to heatwaves and extreme weather events around the world.

Matt Williams, co-founder of Greenspark, which works with businesses to improve their environmental impact, said: “Extremely hot days are a natural part of our weather cycle, but recently we’re experiencing more intense heat waves at often unusual times in the year.

“These extreme weather events are becoming more common, and it’s expected that they will continue to become more frequent as time goes by.

“There is evidence to suggest that human activity is increasing the frequency and magnitude of these events. A great deal of evidence suggests that human behaviour is impacting the severity and frequency of heatwaves, flooding, wildfires and other extreme weather events.”

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Last year’s UN climate change report warned that extreme weather events like heatwaves and droughts which previously would have happened every 50 years could soon happen every four.

Speaking about the UN report, Dr Robert Rohde, lead scientist of Berkeley Earth, said: “What were once-in-50-year heat extremes are now occurring every 10 years.

“By a rise of two degrees celsius, those same extremes will occur every 3.5 years.”

The report found that (for example) once-in-a-decade heavy rain events are already 1.3 times more likely and 6.7% wetter, compared with the 50 years leading up to 1900 when human-driven warning began to occur.

Droughts that previously happened once a decade now happen every five or six years.

Xuebin Zhang, a climatologist with Environment Canada in Toronto, warned that as the world warms, such extreme weather events will not just become more frequent, they will become more severe.

Zhang said that the world should also expect more compound events, such as heat waves and long-term droughts occurring simultaneously.

Zhang said: “We are not going to be hit just by one thing, we are going to be hit by multiple things at the same time.”

What impact do heatwaves have on the planet?

Researchers at UCL warned in a recent study that heatwaves will have a direct impact on mortality in Britain.

Deaths directly related to temperature will soar by 42% if the world’s climate warms by 2C above pre-industrial levels, scientists have warned.

The rate of increase particularly speeds up at 2C of warming, with a much higher risk appearing beyond 2.5°C.

The researchers say that 3C warming could lead to a 75% increase in mortality risk during heatwaves.

Lead author Dr Katty Huang, from University College London's Civil, Environmental & Geomatic Engineering team, said: "The increase in mortality risk under current warming levels is mainly notable during heatwaves, but with further warming, we would see risk rise on average summer days in addition to escalating risks during heatwaves.

“What this means is that we shouldn't expect past trends of impact per degree of warming to apply in the future.

“One degree of global warming beyond 2C would have a much more severe impact on health in England and Wales than one degree warming from pre-industrial levels, with implications for how the NHS can cope."

“The heat is a result of a mix of home-grown warming in the day due to high pressure, as well as a southerly airflow introducing some of the warm air from the continent to UK shores.”

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