If emissions continue unchecked, summers in the Northern Hemisphere could last nearly six months by 2100, according to a new study published in the journal Geophysical Research Letters. Scientists say the shift in seasons will likely have significant impacts on agriculture, the environment, human health, and the timing of species’ activities such as breeding, feeding, and migration.
The research, led by scientists at the State Key Laboratory of Tropical Oceanography in China, analyzed six decades of historical daily climate records, and used climate models to project future trends. It defined summer as the “onset of temperatures in the hottest 25 percent during that time period, while winter began with temperatures in the coldest 25 percent.”
On average, the study found, the number of summer days in the Northern Hemisphere jumped from 78 to 95 between 1952 and 2011. Winter, meanwhile, shrank from 76 to 73 days over the same period. Spring contracted from 124 to 115 days, and autumn from 87 to 82 days.
The scientists projected that if these trends continue, summer will last almost six months out of the year, winter will shrink by two months, and spring and autumn will shrink as well. With the extension of summer comes more intense heat waves and extreme weather events like droughts and wildfires.
“Summers are getting longer and hotter while winters shorter and warmer due to global warming,” Yuping Guan, a physical oceanographer at the State Key Laboratory of Tropical Oceanography and lead author of the new study, said in a statement. “Numerous studies have already shown that the changing seasons cause significant environmental and health risks.”
