Climate change is increasing the number of days of extreme heat and decreasing the number of days of extreme cold in Europe, finds a study published by the Institute for Atmosphere and Climate (IAC) at ETH Zurich.
The number of summer days with extreme heat has tripled since 1950 and summers have become hotter overall, while the number of winter days with extreme cold decreased in frequency by at least half and winters have become warmer overall. This is confirmed by Ruth Lorenz from the Institute for Atmosphere and Climate (IAC) at ETH Zurich in a study published in the AGU journal Geophysical Research Letters.
Lorenz and her colleagues analyzed trends in the 1% days with high heat stress and the 1% coldest days observed at hundreds of weather stations across Europe from 1950-2018. For each year, they further focused on the hottest day or coldest night per year and looked how these changed over time.
A distinct signal of climate change
Extremely hot days have become hotter by an average of 2.3 degrees Celsius, while extremely cold days have warmed by 3 degrees Celsius on average. Especially in Central and Northern Europe, the hottest days respectively the coldest nights warmed significantly more than their corresponding summer and winter mean temperatures.
“Even at this regional scale over Europe, we can see that these trends are much larger than what we would expect from natural variability. That’s really a signal of climate change,” said Ruth Lorenz, a climate scientist at ETH Zurich and lead author of the new study.