"Species on land and at sea are suffering adverse consequences of human behavior at latitudes thousands of miles away," said lead author and biologist Eric Post of Penn State University.

"It seems no matter where you look -- on the ground, in the air, or in the water -- we're seeing signs of rapid change."

The study published in the journal Science reviewed recent ecosystem-wide studies of the biological responses to Arctic warming.

They found the effects of a one-degree Celsius warming over the past 150 years were dramatic and cautioned that it is difficult to predict the consequences of an expected six-degree warming over the next century.

"The Arctic as we know it may soon be a thing of the past," Post said.

Sea ice cover has shrunk by a staggering 45,000 kilometers a year over the past 20 to 30 years, causing a rapid decline in the gulls, walruses, seals, horned narwhal whales and polar bears which rely upon it.

Snow cover on land also has declined and is melting faster.

Polar bears and ringed seals -- already in danger of extinction -- are losing cubs when early spring rains collapse the lairs they build under the snow.

Arctic fox populations are down as red foxes move north.

Fewer caribou calves are surviving because their mothers have been unable to adjust the calving season to changes in plant growth and are not getting enough to eat. Warmer summers also have increased the number of insects and parasites which prey on the migratory animals.

Moths are moving north and affecting the dynamics of trace gas exchange by defoliating mountain birch forests and low Arctic trees and shrubs.

That could have a significant impact on the Arctic's ability to act as a carbon sink, Post warned, noting that one study found an unexpectedly large release of methane in Greenland at the onset of autumn soil freezing.

Warming temperatures are allowing shrubs and trees to expand their range and also are damaging native vegetation.

One winter warming episode led to vegetation damage so extensive that plant product was cut by 26 percent over an area of at least 1,400 square kilometers.

"There is little functional redundancy among species in Arctic ecosystems," Post said.

"Therefore, relatively small shifts in species ranges or abundances may cause fundamental changes in a unique ecosystem that also is important for tourism and traditional cultures."

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