Climate change will lead to more unpredictable water levels in snow-dominated regions in the Northern Hemisphere as snow melts at accelerated paces because of warming temperatures, according to a study published in PNAS on Monday, a finding researchers warned could significantly disturb the management of freshwater resources in the future.
Several regions of the world use snow-related metrics, including the accumulation of snow during the winter and resulting runoff and streamflow from the melting of snow in the spring and summer to help inform management of water resources, according to the study.
But rising global temperatures—which will reduce winter snow accumulation and increase the amount of snow that melts during the winter—will blur this seasonal pattern, leading to “pervasive” changes in water flows and water storage by the end of the century, according to the study, which used a simulation database known as the Community Earth System Model to compare snowpack and water resources from 1940 to 1969 with a future period of 2070 to 2099.
These changes will force those involved in water management to be “at the whim of individual precipitation events” instead of having four to six months in advance to anticipate snowmelt and runoff, National Center for Atmospheric Research scientist Will Wieder said in a statement.
Regions that rely most heavily on seasonal patterns of snowpack and melting to predict water resources, including the Rocky Mountains, the Canadian Arctic, Eastern North America and Eastern Europe, will suffer the most as rising temperatures affect this trend, researchers suggested.
Scientists are “in a race with predictability,” trying to improve forecasts through better data and modeling, but such efforts are complicated by the “rapid disappearance” of the best predictor: snow, Flavio Lehner, study co-author and professor of earth and atmospheric science at Cornell University, said in a statement.
By 2100, on average, there will be 45 more snow-free days a year in the Northern Hemisphere if greenhouse gasses remain as high as predicted, with the biggest increases in snow-free days occurring in mid-latitude regions and more northern maritime regions that are greatly affected by changes to sea ice, according to researchers.
Seasonal snow melting serves as a critical freshwater resource that “sustains ecosystems, agriculture, recreation and livelihoods,” according to researchers. But snow accumulation is expected to decline significantly in the 21st century, sparking concerns about water security and larger effects to the ecosystem. Earlier snow melting, which has been linked with longer plant growing seasons, may dry out soil, put more stress on water resources and increase the risk of wildfires along with other “cascading” effects on ecosystems as a whole, researchers said. Taking actions to reduce greenhouse gas emissions could help prevent some of the most severe impacts, Wieder said.
Climate change: Why is the world seeing more record-breaking floods? (World Economic Forum)