It was a real challenge to separate the influence of human-caused temperature increases from natural climate variations or other confounding factors, such as land-use changes or pollution, said coauthor David Karoly, a climate scientist at the University of Melbourne in Victoria, Australia. This was possible only through the combined efforts of our multi-disciplinary team, which examined observed changes in many different systems around the globe, as well as global climate model simulations of temperature changes.
The data showing the patterns of change are strongest in North America, Asia and Europe--mainly because far more studies have been done there, said Rosenzweig. On the other continents, including South America, Australia and Africa, documentation of changes in physical and biological systems is sparse, even though there is good evidence there of human-influenced warming itself. The authors say that there is an urgent need to study these environmental systems, especially in tropical and subtropical areas.
|Contact: Kevin Krajick|
The Earth Institute at Columbia University