Forest dieback in the northeastern United States and neighboring areas in Canada has been more frequent, more persistent, and more severe during recent decades, research has shown. Now scientists have found springtime temperature swings have intensified in that region during the same period. A new study links these escalating freeze-thaw episodes, which are known to harm trees, to an atmospheric pressure imbalance over the North Atlantic.
Scientists have shown, for the first time, that changes in a large-scale climate system can synchronize population fluctuations in multiple mammal species across a continent-scale region. The study, to be published in the 14 November 2002 issue of the journal Nature, compares long-term data on the climate system known as the North Atlantic Oscillation with long-term data from Greenland on the population dynamics of caribou and muskoxen, which are large mammals adapted to breeding in the Arctic.