A toned beach body will become a matter of life and death in the Northern Hemisphere by the end of the century, judging by a new study; but likely, so will a good air conditioning unit. According to the authors, a business as usual scenario will mean that, by 2100, half of the Earth will experience summers spanning almost six months every year.

Longer summers definitely hold some promise for fun, but the changes predicted in this study are quite worrying. The disruptions to natural systems caused by longer summers would have a significant impact on human health, agriculture and the environment, according to the team.

Times are a-changin’

“Summers are getting longer and hotter while winters shorter and warmer due to global warming,” said Yuping Guan, a physical oceanographer at South China Sea Institute of Oceanology, Chinese Academy of Sciences, the lead author of the study.

We’re used to a world with four seasons, each arriving at roughly the same time every year, in a known order. That, however, is likely going to be a bit of interesting historical trivia by the end of the century in the Northern Hemisphere. the driver, unsurprisingly, is climate change.

Under a business-as-usual scenario, the authors note, both the start dates and length of individual seasons are going to see significant, and irregular, changes by the end of the century. Overall, however, past recordings show that summers have become longer and warmer while winters got shorter over the last 50 to 70 years, suggesting this trend will keep going (or ramp up) in the future.

The authors say their study was spurred by observed changes in the cycle of the seasons, pointing to unseasonable weather reports “for example false spring, or May snow, and the like,” Guan said.

They used daily weather recordings from 1952 to 2011 in the Northern Hemisphere to chart how each season varied in length and onset in this area. Summer was defined as the time with the top 25% hottest temperatures of each year, while winter was defined as the time where temperatures hit the year’s 25% coldest days.

On average, between 1952 and 2011, summer grew from 78 to 95 days (an extra 17 days overall) and winter shrank from 76 to 73 days. Spring and autumn went from 124 to 115 days and 87 to 82 days respectively. Spring and summer also saw a shift to earlier onset, while autumn and winter started later. The greatest overall changes to seasonal cycles seen in this study were concentrated in the Mediterranean and Tibetan Plateau regions.

Armed with these historic trends, the researchers used climate change models to chart how seasons will shift in the future. If measures are not taken to slow down or reverse climate change, by 2100, the models show, spring and autumn will keep shrinking, and winters will last for under two months.

These findings are particularly troubling from an environmental point of view. Humans can adapt more easily to changes in seasonal cycles, but natural ecosystems are deeply tied to them. Changes such as the ones predicted in this paper would have enormous implications for phenomena such as bird migration patterns or the timing of plant emergence and flowering periods. Essentially, changes in seasons can mean that animals may become disconnected from their environment, particularly their food sources. The same instincts that kept wildlife fed and alive all this time will become liabilities, as they won’t match with the world around them any longer.

On our end, agriculture is likely the area where seasonal changes will impact us the most. False springs or late snows can destroy whole crops even today, and these events are only going to become more common. Longer summers also mean longer growing seasons, and if you have a pollen allergy, or if you simply hate mosquitoes, you aren’t going to have a good time at all.

Lastly, freak weather events, including wildfires, heatwaves, or cold surges like the recent one in Texas, will also become more common and more intense. Hurricanes and typhoons will also become more violent, as their energy is directly tied to how hot the oceans are, and they’re hotter in summer.

All in all, this is the extent of the threat that we can see right now — as things progress, new elements may start factoring into making the eventual situation even worse. Ideally, we’ll never get to find out. For that to happen, however, meaningful change and action is needed — and it’s needed now.

The paper “Changing Lengths of the Four Seasons by Global Warming” has been published in the journal Geophysical Research Letters.