Is global warming natural or manmade?

• Position: Climate

A vast array of physical and biological systems across the Earth are being affected by warming temperatures caused by humans, says an analysis of information not previously assembled all in one spot. The effects on living things include earlier leafing of trees and plants over many regions; movements of species to higher latitudes and altitudes in the Northern Hemisphere; changes in bird migrations in Europe, Australia, and North America; and shifting of the oceans' plankton and fish from cold- to warm-adapted communities.

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"Humans are influencing climate through increasing greenhouse gas emissions, and the warming world is causing impacts on physical and biological systems attributable at the global scale," comments lead author Cynthia Rosenzweig, a scientist at the NASA Goddard Institute for Space Studies and the Center for Climate Systems Research. Both are affiliates of The Earth Institute at Columbia University, New York.

Rosenzweig and researchers from 10 other institutions around the world analyzed data from published papers on 829 physical systems and some 28,800 plant and animal systems, stretching back to 1970. Their analysis revealed a picture of changes on continental scales; previous studies mainly had looked at single phenomena, or smaller areas.

In physical systems, 95% of observed changes are consistent with warming...