Earth's Water Cycle Is Changing Rapidly
Water cycle seems out of whack, experts find
18 percent more water fed into oceans in 2006 than in 1994, satellite data show
msnbc.com, Oct. 4, 2010
Researchers
who set out to create a baseline for future research on water cycle
trends on Monday reported an alarming discovery: 18 percent more water
was fed into the oceans from rivers and melting polar ice sheets in 2006
than in 1994.
“That
might not sound like much — 1.5 percent a year — but after a few
decades, it's huge," researcher Jay Famiglietti said in a statement
released with the report in the peer-reviewed Proceedings of the
National Academy of Sciences.
"In
general, more water is good," said Famiglietti, an earth system
professor at the University of California-Irvine. "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 (U.N.) Intergovernmental Panel on
Climate Change predicted, that precipitation is increasing in the
tropics and the Arctic Circle with heavier, more punishing storms," he
added. "Meanwhile, hundreds of millions of people live in semi-arid
regions, and those are drying up."
The
experts suspect that the evaporation and precipitation cycle of water
is accelerating dangerously because of greenhouse gas-fueled higher
temperatures. That, in turn, would trigger more severe monsoons and
hurricanes.
"Hotter
weather above the oceans causes freshwater to evaporate faster, which
leads to thicker clouds unleashing more powerful storms over land," the
statement said. "The rainfall then travels via rivers to the sea in
ever-larger amounts, and the cycle begins again."
The
researchers said they used satellite data on sea level rise,
precipitation and evaporation to create what they called the "longest
and first of its kind" record on global water discharge.
Over
the 13 years studied, they added, "the trends were all the same:
increased evaporation from the ocean that led to increased precipitation
on land and more flow back into the ocean."
The experts cautioned, however, that 13 years is a relatively short time frame and that longer-term studies are under way.
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