Climate Change Upped Earth's Vegetation, Study Finds

By John Roach
for National Geographic News
June 5, 2003

For most of the world's plant life, the effect of the pace of climate change over the past two decades has been productive, according to an analysis of climate and satellite data collected between 1982 and 1999.

The research, reported in the June 6 issue of Science, addresses the question of how global vegetation has responded to changes in precipitation, temperature, and cloud cover patterns. Such climate factors determine how vegetation grows.

Previous studies have looked at vegetation's response to climate change at regional scales, but this is the first study to look at it from a global perspective.

"This is the first global representation of climate changes and how they might influence vegetation," said Ramakrishna Nemani, a climate change researcher at the University of Montana in Missoula who led the study.

According to the analysis, global climate change has eased climatic constraints on plant life around the globe, allowing vegetation to increase 6 percent over the study period.

"For example, in the Amazon cloud cover is a major factor for plant growth and in those areas the cloud cover has declined and solar radiation has increased," said Nemani.

Owing to the added sunshine, photosynthesis has been rampant. The Amazon basin accounts for 42 percent of the global increase in vegetation, according to the study.

Dave Schimel, an atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colorado, was not surprised by the findings and said the research adds new perspective to the field of climate change science.

"Most studies of the effects of climate change have addressed temperature effects, some have also addressed water effects. But some of the most robust observed changes in climate have been in cloudiness and almost no studies have examined trends in solar radiation," he said. "So this is a really interesting new perspective."

Easing Off

The most pronounced effect of increased plant growth as a response to global climate change is in the Amazon basin, where increased sunshine combined with no reduction in rainfall allowed the region to flourish.

In other parts of the world such as Australia, India, and southern Africa, water is the primary driver for vegetation growth. In the last few decades these regions have experienced wetter weather, and thus, increased plant production, according to the research.

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