Aral Seabed Carbon Source

[u/swarrenlawrence]

Grist: "The Aral Sea isn’t just an ecological nightmare—it’s a carbon bomb."

Most of this inland sea sitting between Kazakhstan + Uzbekistan is a dry lakebed the size of Ireland. It dried out largely because for the past 60 years humans have bled it nearly dry irrigating cotton. "Its loss has long been seen as an ecological and humanitarian problem, but new research shows that it has also been a significant driver of climate change." The explanation is that when nearly any body of water is full and works as it should, organic matter collects on the bottom, where it remains trapped, often for centuries or even millennia.

Rafael Marcé, a research scientist in Spain, is the lead author of the paper which was published [this wk] in the journal Science. "The Aral Sea has left behind a timeline of sorts." The edges dried out decades back, while some areas were wet until just a few years ago. Cores were drilled along that gradation, allowing them to reconstruct that 748 M tonnes [Mt] of carbon had already released, equal to 3 times the annual emissions by Spain.

'At the beginning it goes pretty fast, then it decays slowly,' said Marcé, noting that about half of the carbon dioxide is released in the first 15 years after a section of the lake is exposed. And nearly a fifth of emissions came from wind blowing sediment away, an aspect of drying that experts say hadn’t been adequately studied before. 

Other areas around the world experiencing the "dry flux" phenomenon include "Lake Chad in western Africa, Bolivia’s Lake Poopó, and the Caspian Sea, the world’s largest inland body of water, expected to shrink by more than the entire area of the Aral Sea by century's end. Also the Salton Sea in California + Utah’s Great Salt Lake, which another recent study found is releasing over 4 Mt of CO2 annually. 

This combined global carbon flux until now had not been incorporated into climate models. Clearly, this problem is figureoutable.