The climate crisis is making the water cycle spin faster and faster.
New research published in Scientific Reports last month found satellite evidence that the water cycle is speeding up, as fresh ocean water becomes fresher and salty ocean water becomes saltier.
“The acceleration of the water cycle has implications both at the ocean and on the continent, where storms could become increasingly intense,” study lead author Estrella Olmedo of the Institute of Marine Sciences (ICM) in Barcelona said in a press release.
The water cycle is the term for how water first evaporates from the Earth, rises into the atmosphere to form clouds and then falls again as rain or snow, as NASA explains. The climate crisis is naturally speeding this process because warmer temperatures cause water to evaporate faster, the press release explained.
It is possible to tell if this process is accelerating by measuring the salinity of surface ocean water. This is because some ocean water turns saltier as the fresh water evaporates, while already fresher water is further diluted by heavy rainfall, ScienceAlert explained. However, it’s hard to measure this with ocean buoys because they tend to measure water slightly below the surface. Satellites, however, measure at the surface and can provide a steady stream of data from all parts of the ocean regardless of location or condition, according to the study and the press release.
“These results highlight the crucial importance of using satellites to unveil critical changes on ocean–atmosphere fluxes,” the study authors wrote.
Climate models have predicted that the water cycle could intensify by as much as seven percent for every degree Celsius of global warming, which means that wet areas would get seven percent wetter and dry areas seven percent drier, ScienceAlert said.
In addition to raising the risk of extreme weather events like heavy rainstorms and drought, a faster water cycle could contribute to the melting of polar ice.
“This higher amount of water circulating in the atmosphere could also explain the increase in rainfall that is being detected in some polar areas, where the fact that it is raining instead of snowing is speeding up the melting,” Olmedo said in the press release.
The changes in the water cycle could also be influenced by a decrease in wind in some parts of the ocean.
“Where the wind is no longer so strong, the surface water warms up, but does not exchange heat with the water below, allowing the surface to become more saline than the lower layers and enabling the effect of evaporation to be observed with satellite measurements,” study co-author Antonio Turiel, also of ICM, said in the press release.