[Mb-civic] New Data Point to Man-Made Global Warming, Severe Climate Change

[ean at sbcglobal.net]

http://www.commondreams.org/headlines05/0218-04.htm

Published on Friday, February 18, 2005 by Knight Ridder
New Data Point to Man-Made Global Warming, 
Severe Climate Change
by Seth Borenstein
 

WASHINGTON - New measurements from the world's oceans, 
announced Thursday, give the most compelling evidence yet that 
man-made global warming is under way and hint at a more dramatic 
and sudden climate change in the future.

Two different sets of ocean readings presented at the annual 
meeting of the prestigious American Association for the Advance of 
Science solidify the scientific underpinnings of global warming and 
point to an increased chance for a much-feared side effect that was 
popularized and fictionalized in last year's movie "The Day After 
Tomorrow," in which global warming triggers a new ice age in the 
Northern Hemisphere.

"The debate is no longer whether there is a global warming signal," 
Tim Barnett, a marine physicist at Scripps Institution of 
Oceanography who analyzed 9 million ocean-temperature and 
salinity readings. "The debate is what are we going to do about it."

The new data show that the world's oceans have heated up just as 
predicted in global-warming computer models, and, more 
ominously, that massive amounts of fresh water from melting Arctic 
ice are seeping into the Atlantic Ocean, threatening to trigger a 
climate crisis.

What scientists have found could cause parts of the Eastern United 
States to cool by several degrees, according to new calculations 
announced by Ruth Curry, a scientist at the Woods Hole 
Oceanographic Institute. The same worst-case "Day After 
Tomorrow"-type scenario is one that a 2003 Pentagon analysis said 
"would challenge United States' national security in ways that should 
be considered immediately." A 2002 National Academy of Sciences 
study worried about it, too.

Curry found that between 1965 and 1995, about 4,800 cubic miles 
of fresh water - more water than is in Lake Superior, Lake Erie, 
Lake Ontario and Lake Huron combined - melted from the Arctic 
region and poured into the normally salty northern Atlantic.

If it continues, the increased influx of fresh water eventually could 
shut down the great ocean conveyor belt, which helps regulate air 
and water temperatures, abruptly changing the climate around the 
Atlantic and elsewhere.

The conveyor belt, which is a system of currents, moves water in 
multiple directions from the Greenland coast all the way to Australia 
and back. It depends on heavier salt water sinking to pull warm 
water from the tropics to higher latitudes.

Climate scientists fear that if polar ice continues to melt, the 
resulting lower salinity in the Atlantic would shut down the conveyor 
belt, something that happened once about 8,200 years ago, Curry 
said.

Early calculations show that it would take another 4,300 cubic miles 
of fresh water from the Arctic to trigger a shutdown of the conveyer 
belt, Curry said.

If the thaw continues at current rates, the shutdown scenario would 
occur in about two decades. What's worrisome, Curry said, is that 
the Greenland ice, which hadn't been melting with the rest of the 
Arctic, is starting to thaw.

"We are taking the first steps" toward this scenario, Curry said in a 
news conference. "The system is moving in that direction."

Curry said abrupt climate change was "just possible" but not 
necessarily likely.

While Curry was speculating on the future, the new ocean data from 
Scripps reveal how global warming already has changed the Earth.

Seven million temperature readings and 2 million salinity readings 
collected by the National Oceanic and Atmospheric Administration 
created the best "fingerprint" of man-made global warming ever, 
Scripps' Barnett said.

>From 1969 to 1999, surface ocean temperatures rose about two-
thirds of a degree Fahrenheit, while temperatures hundreds of feet 
deeper hadn't warmed as much. The readings are nearly exactly 
what computer models of global warming say they should be, 
Barnett said.

If the global warming were the result of natural variability or 
increased sun activity, the temperature and salinity changes would 
be very different from the ones seen in the NOAA data, Barnett 
said.

"The evidence really is overwhelming," Barnett said.

© 2005 KR Washington Bureau and wire service source

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