Where, scientists wondered. The Aleutians are a dynamic place, ever-changing. Fog shrouds the islands one instant and retreats the next. Hurricane-force squalls descend with little warning. The environment of the Aleutians, however, isn't supposed to be as capricious as its weather.
Ecosystems normally evolve slowly.
Ecological shifts as sudden and sweeping as the ones in the Aleutians usually can come only from human interference, said David Lindberg, an evolutionary biologist at the University of California, Berkeley. If the shift were natural, animals and plants of the Aleutians would have evolved with some defensive strategies, he said. Scientists are exploring many factors global warming, overfishing, pollution that might have played a role in the Aleutians misfortunes. Looking back, they theorize that the key event may have come in 1977, when a sudden warming just two degrees Celsius in the average temperature of the Gulf of Alaska was recorded. The Arctic has been especially vulnerable to climate change, which many scientists believe is caused in part by worldwide burning of fossil fuels and production of greenhouse gases.