"Birds are laying eggs earlier than usual, plants are flowering earlier and mammals are breaking hibernation sooner," said Terry L. Root, a senior fellow with Stanford University's Institute for International Studies (IIS) and lead author of the Jan. 2 Nature study.
"Clearly, if such ecological changes are now being detected when the globe has warmed by an estimated average of only 1 degree F (0.6 C) over the past 100 years, then many more far-reaching effects on species and ecosystems will probably occur by 2100, when temperatures could increase as much as 11 F (6 C)," Root concluded.
Climatic and biological changes
In their Nature paper, Root and her colleagues analyzed 143 scientific studies involving a total of 1,473 species of animals and plants. Each study found a direct correlation between global warming and biological change somewhere in the world. For example, several studies revealed that, as temperatures increased in recent decades, certain species began breeding and migrating earlier than expected. Other studies found that the geographical range of numerous species had shifted poleward or moved to a higher elevation -- indicating that some plants and animals are occupying areas that were previously too cold for survival.
Were these biological and behavioral changes isolated events, or did they reflect a worldwide pattern consistent with global warming? After exhaustive statistical analyses of all 143 studies, Root and her co-authors concluded that global warming is, in fact, having a significant impact on animal and plant populations around the world.
"Our study shows that recent temperature change has apparently already had a marked influence on many species," they wrote, noting that a
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Contact: Klas Bergman
kbergman@stanford.edu
650-723-8490
Stanford University
1-Jan-2003