'Green' Deserts Created with Increased Carbon Dioxide: Climate Change

First Posted: Jul 08, 2013 02:18 PM EDT

As the levels of carbon dioxide increase in the atmosphere, our world is changing. Temperatures are rising and sea chemistry is shifting. Yet there's also another phenomenon that's taking place--the deserts are becoming greener. Scientists have discovered that increased levels of CO2 have helped boost green foliage across the Earth's arid regions over the past 30 years due to a process called CO2 fertilization.

Carbon dioxide fertilization occurs when elevated levels of this gas enable a leaf to extract more carbon from the air, lose less water to the air, or both. This, in turn, causes the plant to be healthier and to be able to overcome harsher conditions. While CO2 fertilization has long been speculated, though, researchers haven't been able to prove its large-scale existence--until now.

In order to examine this phenomenon, researchers used satellite observations. They examined the world's arid regions over the past 30 years, using models to find out exactly how much the areas changed over time. In the end, they found that CO2 fertilization correlated with an 11 percent increase in foliage cover from 1982 to 2010 across parts of Australia, North America, the Middle East and Africa.

"Our work was able to tease-out the CO2 fertilization effect by using mathematical modeling together with satellite data adjusted to take out the observed effects of other influences such as precipitation, air temperature, the amount of light and land-use changes," said Randall Donohue, one of the researchers, in a news release. "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."

The study shows that this CO2 fertilization is certainly occurring in some regions, but it's unknown exactly what implications it will have for the rest of the planet. Studies in the past have shown how weather in one area of the world can have global effects. Dust storms, for example, can affect levels of precipitation elsewhere. This means that scientists will have to keep a close eye on changing conditions.

"Ongoing research is required if we are to fully comprehend the potential extent and severity of such secondary effects," said Donohue.

The findings are published in the journal Geophysical Research Letters.

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