Everything about these volcanic islands seems eternal, as if you could return every year and nothing would ever change. But 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 UC Berkeley. If the shift were natural, animals and plants of the Aleutians would have evolved with some defensive strategies, he said. 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. Tiny copepods and krill probably followed quickly. The shrimp and crab, along with smelt fishes such as capelin and herring, would have vanished afterward, deprived of their food, to be replaced by an explosion of cod and pollock.