Underground Desert Aquifers Could Hold Missing Carbon

Here’s what we know:  Carbon dioxide is building up in the atmosphere as the result of man-made emissions, trapping more and more heat and warming the planet.  Here’s what we’re still working on:  Of the excess CO2 that doesn’t stick around in the atmosphere — about 60 percent of it — exactly how much gets pulled into various so-called carbon sinks, such as the world’s oceans and forests, and where exactly the main sinks are located.

It’s fairly well established that about 30 percent of atmospheric CO2 is pulled into the oceans, and it is thought that another 30 percent is sucked up by land-based ecosystems.  But the estimates of how much various forests, grasslands and other systems take in doesn’t quite add up — there seem to be some missing sinks.  A new study has a somewhat surprising candidate that could fill at least some of that gap:  large aquifers below the world’s deserts.

Understanding what systems pull in CO2, where they are located and how much they siphon from the atmosphere would help scientists better model the future effects of warming around the globe.  To that end, researchers have been monitoring CO2 uptake and release both from the ground and from space.

The new study looked at how much CO2 was being absorbed by irrigation waters on the fringes of the Tarim Basin desert in the Xinjiang region of China, as it seeped through the soil and into the underground aquifer, where it can be permanently locked away.

“The carbon is stored in these geological structures covered by thick layers of sand, and it may never return to the atmosphere,” study author Yan Li, a desert biogeochemist with the Chinese Academy of Sciences in Urumqi, Xinjiang, said in a statement.  “It is basically a one-way trip.”

Read more at Underground Desert Aquifers Could Hold Missing Carbon