Point To Man-Made
Severe Climate Change
By Seth Borenstein
19 February , 2005
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.
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.
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
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.
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.
really is overwhelming," Barnett said.
© 2005 KR Washington
Bureau and wire service source