Global Warming Evident in Antarctic

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Antarctic Island Called a Unique Climate-Change Lab

(see Photos at

http://dailynews./h/nm/20020124/sc/science_antarctica_dc_1.html )

Reuters Photo

By Will Dunham

WASHINGTON (Reuters) - An unexpectedly rapid warming of lakes on a desolate

Antarctic island provides compelling evidence of the environmental impact

wrought by rising global temperatures, scientists said on Thursday.

Writing in the journal Science, British and Canadian scientists said a

20-year study has revealed dramatic changes in Signy Island's lakes caused

by a 1.8-degree Fahrenheit rise in air temperature.

This increase has triggered a series of changes in the lakes on the island,

located 435 miles northeast of the Antarctic Peninsula. The scientists

consider polar lakes to be early detectors of change wrought by global

warming.

The gain in winter lake temperatures was three times higher than that of

local air temperatures, the scientists said. The amount of time during a

given year that the lakes were completely frozen over declined by more than

four weeks.

This decline allowed the lake water and sediments to absorb solar energy

that normally would be reflected away by the ice.

Nutrient levels in the lakes rose, most likely because streams ran over

thawed ground rather than ice. Algae and phytoplankton in the lakes also

increased.

'ALMOST A BEACON GOING OFF'

``This is almost a beacon going off saying, 'Look, we've gone through this

threshold at this point on the planet, and it's an indicator that the

environment is changing rapidly,''' researcher Lloyd Peck of the British

Antarctic Survey in Cambridge said in a telephone interview.

``The main finding of our work is that the ecology and the ecosystem in the

lakes that we've looked at have changed really dramatically fast. ... What

we're seeing is an amplification of the larger-scale environmental change

signal,'' Peck added.

Signy Island, in the South Orkney Islands, is named for the wife of a

whaling ship captain who had a station there in the early 20th century. It

is about four miles long and three miles wide. There is permanent ice cover

over a large part of the island.

But in summer, extensive areas of moss and some grasses are exposed, and

there are numerous freshwater pools and lakes.

Researchers say the island's isolation allowed them to come up with

measurements not affected by local pollution or heating associated with

cities.

``In the Northern Hemisphere, where they're seeing fast changes in lakes,

they've often been associated with large human centers of population,'' Peck

said.

``So it's hard to say whether it's a global change ... or whether it's

something to do with extra heating and pollution from big cities, like

Chicago and the Great Lakes. Whereas here, we're in an island that is

several thousand miles away from the nearest big city,'' Peck added.

CONTRADICTORY FINDINGS?

The study was published just two weeks after other researchers reported in

the journal Nature that temperatures had dropped since the mid-1980s in

Antarctica's arid and inhospitable desert valleys. Those researchers noted

that the climate is warming up on average globally, and that Antarctica's

Dry Valleys region represented an exception.

Peck said his team's findings and the seemingly contradictory results from

the Dry Valleys illustrate that regional variations exist in the global

warming phenomenon.

He also noted that the Dry Valleys are about 4,000 miles from Signy Island.

``You would not expect to get the same message from every point on the

planet of warming, or whatever, during a changing environmental scenario. It

just doesn't work that way,'' he said.

, also of the British Antarctic Survey, said a complex picture

has emerged of temperature change over the whole Antarctic continent. He

noted that while the Antarctic Peninsula region experienced one of the

largest temperature increases on Earth over the last 50 years, the South

Pole has experienced a modest cooling.

``However, what we can say with certainty is that Antarctica is extremely

sensitive to environmental change,'' said.