Perilous Times and Climate Change
The Big Heat: Alarming Increase In Flow Of Fresh Water Into Oceans
The evaporation and precipitation cycle taught in grade school is
accelerating dangerously because of greenhouse gas-fueled higher
temperatures, triggering monsoons and hurricanes.
by Staff Writers
Irvine CA (SPX) Oct 13, 2010
Freshwater is flowing into Earth's oceans in greater amounts every
year, a team of researchers has found, thanks to more frequent and
extreme storms linked to global warming. 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.
"That might not sound like much - 1.5 percent a year - but after a few
decades, it's huge," said Jay Famiglietti, UC Irvine Earth system
science professor and principal investigator on the study, which will
be published this week in Proceedings of the National Academy of
Sciences. He noted that while freshwater is essential to humans and
ecosystems, the rain is falling in all the wrong places, for all the
wrong reasons.
"In general, more water is good," Famiglietti said. "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."
In essence, he said, the evaporation and precipitation cycle taught in
grade school is accelerating dangerously because of greenhouse
gas-fueled higher temperatures, triggering 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 rainfall then travels via rivers to the sea in ever-larger
amounts, and the cycle begins again.
The pioneering study, which is ongoing, 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.
"Many scientists and models have suggested that if the water cycle is
intensifying because of climate change, then we should be seeing
increasing river flow. Unfortunately, there is no global discharge
measurement network, so we have not been able to tell," wrote
Famiglietti and lead author Tajdarul Syed of the Indian School of
Mines, formerly of UCI.
"This paper uses satellite records of sea level rise, precipitation and
evaporation to put together a unique 13-year record - the longest and
first of its kind. 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 researchers cautioned that although they had analyzed more than a
decade of data, it was still a relatively short time frame. Natural ups
and downs that appear in climate data make detecting long-term trends
challenging. Further study is needed, they said, and is under way.
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, Calif. Funding is
provided by NASA.