A vast array of physical and biological systems across the earth are being affected by warming temperatures caused by humans, says a new 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, North America and Australia; and shifting of the oceans’ plankton and fish from cold- to warm-adapted communities. The study appears in the May 15 issue of the leading scientific journal Nature.
“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,” said lead author Cynthia Rosenzweig, a scientist at the NASA Goddard Institute for Space Studies and the Columbia Center for Climate Systems Research. Both are affiliates of The Earth Institute at Columbia University.
Rosenzweig and researchers from 10 other institutions across 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 of revealed a picture of changes on continental scales; previous studies had looked mainly at single phenomena, or smaller areas. In physical systems, 95% of observed changes are consistent with warming trends. These include wastage of glaciers on all continents; melting permafrost; earlier spring river runoff; and warming of water bodies. Among living creatures inhabiting such systems, 90% of changes are consistent with warming. The researchers say it is unlikely that any force but human-influenced climate change could be driving all this; factors like deforestation or natural climate variations could not explain it. Their work builds upon the consensus of the Intergovernmental Panel on Climate Change, which in 2007 declared manmade climate warming “likely” to have discernible effects on biological and physical systems.
“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.
KEY OBSERVED IMPACTS BY CONTINENT
North America
- Earlier spring plant flowering 89 species (examples: American holly, sassafras, box elder maple) in Washington, D.C. area; earlier flowering in Boston, Massachusetts.
- Cannibalism and declining populations among polar bears in southern Beaufort Sea.
- Rapid melting of Alaska glaciers.
- Earlier breeding and earlier arrival dates of birds (American robins are arriving 14 days earlier in Colorado).
- Shoreline retreat in southern Gulf of St. Lawrence.
- Advancing spring flight of butterflies in lowa and California.
- Change in mollusk poulations in Monterey, California.
- Earlier high river flows in New England.
- Earlier peak migration of Atlantic salmon in New England.
- Earlier breakup and later freezing dates in lake and rive ice over wide areas.
- Declining mountain snowpack in the West.
- Earlier streamflow timing across the West.
- Changes in diatoms in northern Canadian lakes.
- Genetic shift in pitcher plant mosquito to more warm-adapted type in Eastern U.S.
- Marmots are emerging 38 days earlier in the Rockies.
- Frogs (including the bullfrog and the American toad) are calling earlier in Ithaca, N.Y
Europe
- Changes in leaf-unfolding and flowering and animal growing phases in 19 European countries. Plant examples: hazel, lilac, apple, linden, birch.
- Earlier egg-laying by birds; earlier migration by birds (for example, flycatchers).
- Long-term changes within fish communities in Upper Rhone River.
- Glacier melting in the Alps.
- Rapid advance of spring arrival of long-distance migratory birds, continentwide.
- Mountain birches growing at increasing elevations in Sweden.
- Changes in lake diatoms to warmer-adapted species in Finnish Lapland.
- Earlier pollen release in the Netherlands.
- Apple trees are leafing out 35 days earlier in Spain.
Asia
- Greater growth of Siberian pines in Mongolia.
- Earlier breakup and thinning of river and lake ice in Mongolia.
- Change in freeze depth of permafrost in Russia.
- Earlier flowering of ginkgo in Japan.
South America
- Glacier wastage in Peru and Bolivia.
- Melting Patagonia icefields are contributing to sea-level rise.
Africa
- Decreasing aquatic ecosystem productivity of Lake Tanganyika.
Australia
- Early arrival of Australian migratory birds, including flycatchers and fantails.
- Declining water levels in Western Victoria.
Antarctica
- Emperor penguins have declined by 50% on Antarctic Peninsula.
- Retreating glacier fronts.
Ocean
- Long-term decline in krill stock in Southern Ocean.
- Increasing abundance of tropical/subtropical species and decreasing abundances of temperate/subpolar species in California current.
- Increasing plankton abundance in cooler regions and decreasing plankton in warmer regions in Northeast Atlantic.
