Frequent and extreme storms tied to global warming are causing more freshwater to flow into the Earth's oceans and sea levels to rise, concludes a team of researchers led by Jay Famiglietti, a UC Irvine Earth system science professor.
“All told, 18 percent more water fed into the world's oceans from rivers
and melting polar ice sheets in 2006 than in 1994, with an average
annual rise of 1.5 percent,” reads a UCI statement on the research.
“That might not sound like much–1.5 percent a year–but after a few decades, it's huge,” Famiglietti is quoted as saying.
“In general, more water is good,” he added. “But here's the
problem: Not everybody is getting more rainfall, and those who are may
not need it. What we're seeing is exactly what the Intergovernmental
Panel on Climate Change predicted–that precipitation is increasing in
the tropics and the Arctic Circle with heavier, more punishing storms.
Meanwhile, hundreds of millions of people live in semiarid regions, and
those are drying up.”
Famiglietti was the principal investigator on the study that will be published this week in Proceedings of the National Academy of Sciences. It is based on ongoing research that employs NASA and other world-scale satellite observations rather than
computer models to track total water volume each month flowing from the
continents into the oceans.
The NASA-funded study's lead author is Tajdarul Syed of the Indian School of Mines and formerly of UCI. Other authors are: Don Chambers of the University of South Florida;
Joshua Willis of the Jet Propulsion Laboratory in Pasadena; and Kyle
Hilburn of Remote Sensing Systems in Santa Rosa.
To dumb it down for us, Famiglietti says to think about the evaporation and precipitation cycle taught in grade school. Now, think of that cycle on steroids. The research indicates it is accelerating dangerously because of greenhouse gas-fueled higher temperatures that trigger monsoons and hurricanes. Or, as the UCI statement puts it:
Hotter weather above the oceans causes freshwater to evaporate faster, which leads to thicker clouds unleashing more powerful storms over land. The rainfall then travels via rivers to the sea in ever-larger amounts, and the cycle begins again.
The researchers do caution that although they had analyzed more than a decade of data, it was still a relatively short time frame and that natural ups and downs that appear in climate data make detecting long-term trends challenging.
The answer: more study.