Life on Antarctica moved by warming GLOBAL WARMING

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Scientists monitoring the effects of global warming in Antarctica report that rising temperatures have triggered a chain reaction that is rapidly altering the climate and the lives of plants and animals there.

Marine life is moving from one region to another along West Antarctica's Palmer Peninsula as winds blow harder than they have in 30 years, cloud cover increases and the sea's surface mixes more strongly with deeper water layers.

The sea changes are disrupting the lives and range of microscopic marine plants called phytoplankton, and the tiny animals called krill that feed on those plants are moving, too. And because the krill are moving, the penguins that depend on the krill for food are also moving - and other species are replacing them along parts of the peninsula.

These effects on the food chain are being reported today in the journal Science by a team of oceanographers headed by Martin Montes-Hugo of Rutgers University in New Jersey.

"We're seeing how the entire ecosystem down there is responding to the increasing temperatures," said Sharon Stammerjohn, a UC Santa Cruz oceanographer and member of the team who had just returned from a 54-day scientific cruise along the coasts of Antarctica's Bellinghausen and Amundsen seas.

Data gathered from satellites, from the team's own cruises aboard National Science Foundation icebreakers and from scientists from more than 20 other nations are telling the same story, said Montes-Hugo.

"The evidence tells us there's been a big change in the food web over the last 30 years, and it's happening all along the peninsula," he said.

The long, curving Palmer Peninsula has long been a major focus of oceanography research - and even more so now that major ice shelves there are collapsing, sea ice is disappearing and ecological changes are becoming more evident.

The seas around the peninsula have been warming nearly five times faster than world-wide average temperature over the past 50 years and more rapidly than at any time during the past 500 years, the data show.

While the population of phytoplankton - the basis of the ocean's food web - has decreased along the peninsula's northern shores, its concentrations have increased in what the researchers call the southern "sub-regions, and other living organisms have followed the plankton.

This changing life could be a "harbinger of rapid change" for many other parts of the world, said Andrew Monaghan, a polar expert at the National Center for Atmospheric Research in Boulder, Colo., who is not connected with the research team.

In a phone interview, Monaghan called the report "really important because it ties all the implications of global warming together in a biological chain of events - kind of like the canaries in a coal mine."

A direct cause-and-effect relationship of the team's findings is still unproven, Montes-Hugo said, but it's clear that the changes in phytoplankton, krill and penguin distribution do resemble a chain reaction - much more so than what scientists often describe as a cascade of unrelated events, he said in an interview.

The changes are most marked in the waters of the Amundsen and Bellinghausen seas, where sea ice cover has been diminishing sharply, according to observations from the NASA satellite Sea Star, which has been in orbit surveying the world's oceans for nearly a dozen years.

The shifting populations of penguin species over the past 50 years are linked closely to shifts in the distribution of phytoplankton and krill, the team reports.

Adelie penguin colonies, for example, depend primarily on krill for their food and have moved to where the krill has moved. Meanwhile, Gentoo and Chinstrap penguins, whose diets favor small fish, squid and shrimp but don't require krill, appear to be replacing the Adelie species habitats, according to the scientists' data.

Montes-Hugo said his team is already gathering additional data for another detailed report seeking to understand more clearly each link in the chain of events, which is clearly triggered by what the group calls "a transition from a cold-dry polar-type climate to a warm-humid sub-Antarctic-type climate."