Rising carbon dioxide levels have not only resulted in rising global temperatures, but it seems they have also been adding a splash of green to our planet's arid regions.
Carbon dioxide, it turns out, has been having a "fertilization effect," increasing foliage around the globe. Scientists have noticed the greening since the 1980s, but the link to carbon dioxide hasn't been defined until now.
"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 lead author Randall Donohue of the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Canberra, Australia.
"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 team of researchers poured over data from 1982 to 2010, and predicted that there would be a 5 to 10 percent increase in foliage correlating with the 14 percent increase in carbon dioxide. The data showed that there was an 11 percent increase in greenery during that time period, providing "strong support for our hypothesis," as the team put it.
The study focused on the southwestern corner of North America, Australia's outback, the Middle East, and parts of Africa. It also took into account precipitation factors and other outside variables that could have led to the increased vegetation.
"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."
You can read the full published study in the journal Geophysical Research Letters.