Carbon dioxide 'fertilization' is greening deserts

One suspected side effect of global warming is lusher vegetation, and a new study shows that leaf cover on plants rose by 11 percent in arid areas between 1982 and 2010.

During photosynthesis -- the process by which plants make food -- plants pull carbon dioxide from the air. More carbon dioxide should mean more plant food, and studies in recent decades have confirmed increased plant life, but did not control for increased rainfall or changing temperatures.

Researchers in Australia looked at desert plants and adjusted for precipitation and temperature to weed out other effects. They first created a computer model to estimate the global "fertilization effect" of atmospheric carbon dioxide.

The model estimated that during the study period foliage would increase by 5 to 10 percent, affected by a 14 percent rise in atmospheric carbon dioxide over the same period. The team then used satellite imagery to view the greening from 1982 to 2010.

Arid regions including the southwestern United States, Australia's Outback, the Middle East and parts of Africa experienced an 11 percent increase in leaf cover on plants, according to results published in the journal Geophysical Research Letters.

But lead study author Randall Donohue of the Commonwealth Scientific and Industrial Research Organization in Canberra warns that rising carbon dioxide won't impact all vegetation the same, and new species could dominate in dry areas.

"Trees are reinvading grasslands, and this could quite possibly be related to the carbon dioxide effect," Donohue said in a statement. "Long lived woody plants are deep rooted and are likely to benefit more than grasses from an increase in carbon dioxide."