Trees, trees, trees. Everyone is crazy about trees. Okay, I get it. They’re these big, green, leafy things that look pretty, create shade and attract birds and picnickers. They grow fruit — it’s like a vending machine provided by Mother Nature! — and even their blood can be tasty on pancakes. They’re also often affectionately cited as an effective Band-Aid for global climate change, as trees — provided they’re in the right location, such as the equator — sponge up carbon emissions and generate moisture, which in turn helps spawn clouds that act like big reflective windowshades, making for an overall cooling effect. You go, trees.
Intuitively, you might think it follows that desert — really, if you think about it, the anti-tree — has nothing positive whatsoever to contribute to putting the brakes on global climate change. Deserts just kind of sit around and be all hot and dusty, right? Not necessarily. A new study that considers some research done in our own backyard has found that arid deserts act as sinks or traps for carbon emissions, absorbing a significant amount of carbon dioxide from the atmosphere. From an NBC story on the study:
The findings indicate that these arid ecosystems are "significant, previously unrecognized sinks" for atmospheric carbon dioxide, Evans and colleagues write in a paper published Sunday in the journal Nature Climate Change. Analysis of the data indicates that desert ecosystems may increase their carbon uptake in the future to account for 15 to 28 percent of the carbon currently being absorbed by land surfaces. Overall, according to the paper, rising carbon dioxide levels may increase the uptake by arid land enough to account for 4 to 8 percent of current emissions. The team found that most of the carbon was being taken up by soil microbes that surround the roots of plants. In contrast, forest ecosystems tend to store carbon in the plants themselves.
That’s the good news — that is, uh, if there is any good news in this. The bad news, of course, is that the rapidly accelerating rate of carbon emissions almost renders the sponging effect of deserts — and perhaps even trees — largely moot.
The effect is "unlikely to ever be as large with gradually increasing carbon dioxide," noted Field, who runs a project where similar enrichment experiments are conducted on a grassland ecosystem. Field is also the lead author of a new Intergovernmental Panel for Climate Change report warning that the risks of climate change are rapidly accelerating. "It is worth noting that, although the sink in this experiment is significant, it is … about tenfold less than typical sinks in young forested ecosystems not exposed to elevated carbon dioxide," Field said, adding that "the bottom line is that deserts will not save us from climate change."