LOS ANGELES – The volume of fresh water pouring from the world’s rivers has risen rapidly since 1994 in what researchers say is further evidence of global warming.
The study, led by a team at the University of California, Irvine, is the first to estimate global freshwater flow into the world’s oceans using observations from new satellite technology rather than through computer models.
Published this week in the Proceedings of the National Academy of Sciences, the study found that annual freshwater flow increased 18 percent from 1994 to 2006, suggesting an acceleration in the global water cycle of evaporation and rainfall, which influences the intensity of storms, floods and droughts.
UC Irvine Earth system science professor Jay Famiglietti, a principal investigator, said that the data have major implications for California, where warmer temperatures are already triggering earlier snowmelt. Rising sea levels are expected to alter the state’s coastline significantly.
“Until now, we have had no continuous record of global-scale river discharge,” said Famiglietti.
The study “is additional clear evidence that the hydrologic cycle is accelerating,” said hydrologist Peter Gleick, editor of the biannual “World’s Water” survey and director of the Pacific Institute think tank. “This is exactly what climate modelers have said would happen from climate change, and now we see it happening. How much more evidence do we need before we take action against climate change?”