Increasing Carbon Dioxide Levels Causing the Desert to Bloom: A Study
Rising levels of carbon dioxide are causing the desert to bloom, according to a new study published in the journal U.S. Geophysical Research Letters.
In all, the researchers found that the increase of CO2 between the years 1982 and 2010 correlated with an 11 percent increase in foliage cover across parts of arid areas under examination in Australia, North America, the Middle East and Africa.
The fertilization effect occurs where elevated CO2 enables a leaf during photosynthesis to extract more carbon from the air or lose less water to the air, or both. In the case that elevated CO2 causes the water use of individual leaves to drop, plants in arid environments respond by increasing their total numbers of leaves. These changes in leaf cover can be detected by satellite, particularly in deserts and savannas where the cover is more sparse than in wet locations, according to the scientists.
"While a CO2 effect on foliage response has long been speculated, until now it has been difficult to demonstrate," Randall Donohue, a scientist at Australia's Commonwealth Scientific and Industrial research Organization (CSIRO), said in a press release.
According to Donohue, their study was able to "tease out" the CO2 fertilization effect by using mathematical models along with satellite data adjusted to take into account other factors, including precipitation, temperature, light exposure and land-use changes.
"In Australia, our native vegetation is superbly adapted to surviving in arid environments and it consequently uses water very efficiently," he explained. "Australian vegetation seems quite sensitive to CO2 fertilization. This, along with the vast extents of arid landscapes, means Australia featured prominently in our results."
In regards to the impacts of this increase of foliage, Donohue says the effects are mixed.
"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; however there will be secondary effects that are likely to influence water availability, the carbon cycle, fire regimes and biodiversity, for example," he said.
However, more research is needed in order to fully discover the extent of these secondary effects, Donohue said.