Arid areas absorb unexpectedly high amounts of atmospheric carbon

A new research, conducted over a period of ten years in Mojave Desert, has found that arid areas absorb an unexpectedly large amount of carbon as levels of carbon dioxide increase in the atmosphere.

The findings give scientists a better handle on the earth's carbon budget-how much carbon remains in the atmosphere as CO2, contributing to global warming, and how much gets stored in the land or ocean in other carbon-containing forms.

R. Dave Evans, a Washington State University professor of biological sciences specializing in ecology and global change, said that the study has pointed out the importance of these arid ecosystems.

They are a major sink for atmospheric carbon dioxide, so as CO2 levels go up, they'll increase their uptake of CO2 from the atmosphere and help take up some of that excess CO2 going into the atmosphere, he said.

The findings come after a novel 10-year experiment in which researchers exposed plots in the Mojave Desert to elevated carbon-dioxide levels similar to those expected in 2050.

The researchers then removed soil and plants down to a meter deep and measured how much carbon was absorbed.

The analysis, done by Benjamin Harlow in WSU's Stable Isotope Core Laboratory, suggests that arid lands may increase their carbon uptake enough in the future to account for 15 to 28 percent of the amount currently being absorbed by land surfaces.

Overall, said Evans, rising CO2 levels may increase the uptake by arid lands enough to account for 4 to 8 percent of current emissions.

The experiment did not account for other possible changes stemming from climate change, like varying precipitation and warming temperatures.

Still Evans said that he was surprised at the magnitude of the carbon gain, that we were able to detect it after 10 years because 10 years isn't very long in the life of an ecosystem.

While forest ecosystems tend to store carbon in plant matter, the Mojave researchers found most carbon was being taken up by increased activity in the rhizosphere, a microorganism-rich area around the roots.

From an optimistic point of view, the research suggests that, come 2050, arid ecosystems will be doing more than their fair share of taking earth-warming carbon out of the atmosphere.

But a potential cause for concern is what happens to these ecosystems as the planet's population grows and people look for places to develop and live.

The study is published in the journal Nature Climate Change.