Summers in the Northern Hemisphere may last nearly half of the year by 2100, according to a new study published in the journal Geophysical Research Letters.
In the 1950s in the Northern Hemisphere, the four seasons arrived in a predictable and fairly even pattern. However, climate change is now driving dramatic and irregular changes to the length and start dates of the seasons.
In order to assess these changes, researchers at the American Geophysical Union looked at historical daily climate data from 1952 to 2011 in order to measure changes in the four seasons’ length and onset in the Northern Hemisphere.
They defined the start of summer as the onset of temperatures in the hottest 25% during that time period, while winter began with temperatures in the coldest 25%.
They found that, on average, summer grew from 78 to 95 days between 1952 and 2011, while winter days shrank from 76 to 73 days.
Spring and autumn also contracted from 124 to 115 days, and 87 to 82 days, respectively.
The researchers have warned that if these trends continue without any effort to mitigate climate change, by 2100, winter will last less than two months, and the transitional spring and autumn seasons will shrink further as well.
Yuping Guan, the lead author of the study, said: ‘Summers are getting longer and hotter while winters shorter and warmer due to global warming.
‘Numerous studies have already shown that the changing seasons cause significant environmental and health risks.
‘A hotter and longer summer will suffer more frequent and intensified high-temperature events — heatwaves and wildfires. Zhu said. Additionally, warmer, shorter winters may cause instability that leads to cold surges and winter storms, much like the recent snowstorms in Texas and Israel.’
Scott Sheridan, a climate scientist at Kent State University added: ‘This is a good overarching starting point for understanding the implications of seasonal change.
‘It is difficult to conceptualise a 2- or 5-degree average temperature increase, but I think realising that these changes will force potentially dramatic shifts in seasons probably has a much greater impact on how you perceive what climate change is doing.’