Climate change is “undeniably” to blame for the intensity of the heatwave affecting western Europe, according to a new study by scientists from World Weather Attribution (WWA), published today.

The exceptionally high daytime and night-time temperatures recorded during the current heatwave would have been “virtually impossible” in the same period in 1976 – a year also remembered for severe heat in Europe – according to the researchers, who examine the role of human-driven climate change in extreme weather events.

A similar heatwave in 1976 would have brought temperatures 3.5C lower during the day and 2.4C lower at night, the scientists estimated.

“We conclude that over the past 50 years, during which global temperatures have risen by 1.1 Celsius, the likelihood of a heatwave like this has changed dramatically,” said Theodore Keeping of Imperial College London, one of the study’s authors.

“This heatwave episode could not have happened in June without climate change,” he added.

Western Europe has been experiencing extreme temperatures for more than a week, driven by a vast mass of hot air from Africa, compressed by high pressure at altitude.

“This weather pattern is not particularly unusual, but the temperatures are – or at least they were before human-induced climate change,” said Friederike Otto of Imperial College London.

Why is this happening?

Human-caused climate change is driven mainly by the widespread use of fossil fuels – coal, oil and natural gas – and, to a lesser extent, by deforestation.

For their report, the scientists, who are based in several European countries, compared current meteorological observations and forecasts for the coming days with data from 2003 and 1976.

The study was published rapidly and has not yet been peer-reviewed, as is usually the case with scientific publications. However, its authors said the methodology used has already been validated by the scientific community.

In terms of probability, hot nights have become 100 times more likely today compared with the 2003 heatwave, while peak daytime heat has become around 10 times more likely, the researchers calculated.