Growing‑longer Summers

Growing-longer Summers

Summers in many parts of the world are up to a month longer than they were in the 1960s. While this might sound like good news to fans of swimming and beaches, it's actually a worrying problem.

This finding comes from a study published in Environmental Research Letters. Researchers looked at global temperature data from 1961 to 2023, with a focus on the world's “midlatitudes”—areas away from the poles and the equator. The poles and equator were avoided because they don't have four clearly divided seasons.

The researchers didn't use calendar months to decide when summer begins, however. Instead, they defined summer based on the quarter of the year with the hottest daily average temperatures between 1961 and 1990. When average temperatures in each location entered this range, they defined summer as having begun.

And looking at the data, the researchers found that the midlatitudes have increased five to seven extra days of summer per ten years since 1990.

Newer research that looked at temperatures between the 1950s and early 2010s had suggested an average increase of four summer days per ten years—so the new research suggests that this estimate was actually too low.

Added up, the new data shows that the midlatitudes have added about an extra 30 days of summer compared to the 1960s.

Longer summers can mean longer droughts, as well as longer and more serious wildfire seasons, not to mention greater need for air conditioning.

The researchers also found that the speed at which the seasons change is getting faster, as temperatures are rising more quickly at the beginning of summer and falling more quickly at its end.

So not only is the world getting hotter, but there is also less time to adapt to the changing weather each year. This means some regions may see faster spring snowmelt, which could increase the risk of flooding.