Later On

A blog written for those whose interests more or less match mine.

Warming is accelerating global water cycle

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More problems arising as global warming continues with no significant action by any government, especially not the US. Janet Raloff reports for Science News:

Fresh water evaporates from the oceans, rains out over land and then runs back into the seas. A new study finds evidence that global warming has been speeding up this hydrological cycle recently, a change that could lead to more violent storms. It could also alter where precipitation falls — drying temperate areas, those places where most people now live.

Among the new study’s more dramatic calculations: River runoff into the seas has been increasing by some 540 cubic kilometers per year, or about 1.5 percent annually over the period analyzed (1994 to 2006). While that may not sound like much, “over 20 or 30 years it would really add up,” notes study author James S. Famiglietti, a hydrologist at the University of California, Irvine.

Global annual precipitation also appears to be on the rise, but at only half the increase seen in river runoff. If prolonged, this differential would suggest that major terrestrial stores of water — such as ground aquifers and glaciers — are drying up (a trend that other studies have been chronicling). This would also be expected to eventually raise sea levels and generally dry temperate regions that depend on rivers to slake their thirsts.

Famiglietti and his colleagues reported their findings October 4, early online in the Proceedings of the National Academy of Sciences.

Scientists have been predicting climate change would intensify the global water cycle, Famiglietti says — “increasing the amount of precipitation and evaporation, globally, and stream flows from the continents.”

Computer models indicated that if this happened, there should also be “a redistribution of precipitation,” he adds. Driven by changes in atmospheric circulation patterns, rains and snowfall would increasingly ignore temperate regions in favor of zones nearer to the poles and tropics. Another feature of an intensifying water cycle: Storm intensity would also tend to increase.

With climate warming, long-frozen stores of water — glaciers and permafrost — could be gushing into the seas from regions largely out of humanity’s view. So fitting their contribution into the global tally would offer important clues to changes in water cycling, Famiglietti explains. But until now, calculating this has proven difficult.

In theory, one of the easiest ways to gauge ice and permafrost melting would be to tally stream flows around the world. Except that stream monitoring programs — never ubiquitous — have been diminishing in recent decades. So a large share of the water flowing over land escapes any accounting.

To estimate global stream flows . . .

Continue reading.

I don’t believe any action will be undertaken until it is way, way too late. Thank the GOP for the US paralysis.

Written by Leisureguy

20 October 2010 at 1:29 pm

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