11 July (FORBES BLOGS) - Rising atmospheric carbon dioxide levels are bolstering plant life throughout the world, environmental scientists report in a newly published peer-reviewed study.
by James Taylor
The findings, published in Geophysical Research Letters, are gleaned from satellite measurements of global plant life, and contradict assertions by activists that global warming is causing deserts to expand, along with devastating droughts.
A team of scientists led by environmental physicist Randall Donohue, a research scientist at the Commonwealth Scientific and Industrial Research Organization in Australia, analyzed satellite data from 1982 through 2010. The scientists documented a carbon dioxide “fertilization effect” that has caused a gradual greening of the Earth, and particularly the Earth’s arid regions, since 1982. The satellite data showed rising carbon dioxide levels caused a remarkable 11 percent increase in foliage in arid regions since 1982, versus what would be the case if atmospheric carbon dioxide levels had remained at 1982 levels.
“Lots of papers have shown an average increase in vegetation across the globe, and there is a lot of speculation about what’s causing that,” said Donohue in a press release accompanying the study. “Up until this point, they’ve linked the greening to fairly obvious climatic variables, such as a rise in temperature where it is normally cold or a rise in rainfall where it is normally dry. Lots of those papers speculated about the CO2 effect, but it has been very difficult to prove.”
The study noted that foliage in warm, wet regions such as tropical rainforests are near their maximum capacity. In warm, arid regions there is room for greater increases in foliage and rising carbon dioxide levels are inducing more prevalent plant growth.
Carbon dioxide acts as aerial fertilizer and also helps plants thrive under arid conditions. Although global precipitation has increased during the past century as the Earth has warmed, elevated carbon dioxide levels are assisting plant life in warm, dry regions independent of – and in addition to – increases in global precipitation.
“The effect of higher carbon dioxide levels on plant function is an important process that needs greater consideration,” said Donohue. “Even if nothing else in the climate changes as global CO2 levels rise, we will still see significant environmental changes because of the CO2 fertilization effect.”
Donohue focused special attention on Australia in an additional press release. Although global drought is becoming less frequent and less severe as the Earth modestly warms, activists claim global warming is causing harmful drought in Australia.
“In Australia, our native vegetation is superbly adapted to surviving in arid environments and it consequently uses water every efficiently,” said Donohue. “Australian vegetation seems quite sensitive to CO2 fertilization.”
“On the face of it, elevated CO2 boosting the foliage in dry country is good news and could assist forestry and agriculture in such areas,” Donohue reported, while adding that scientists should still monitor secondary effects.
The satellite data show plant life in the United States has especially benefited from rising atmospheric carbon dioxide levels and gradually warming temperatures. Satellite data show foliage has increased in the vast majority of the United States since 1982, with the western U.S. benefiting the most. Indeed, many western regions experienced a greater than 30 percent increase in foliage since 1982.
Other regions showing particularly strong increases in foliage include the Sahel region of Africa, the Horn of Africa, southern Africa, the Indian subcontinent, and nearly all of Europe.