Plant Roots are Melting Permafrost and Unearthing Vast Stores of Carbon Emissions
upstart writes in with an IRC submission:
Plant Roots Are Melting Permafrost And Unearthing Vast Stores of Carbon Emissions:
As plants begin to spread across melting permafrost, scientists are growing ever more worried their roots will stir microbes into unleashing vast stores of carbon.
To scientists, roots are known as rhizomes, and when these tendrils extend deeper into the soil, it accelerates microbial decomposition by up to fourfold, potentially 'priming' the frozen ground for further thawing.
This mechanism, known as the rhizosphere priming effect (RPE), has been known since the 1950s, and it could have a huge impact on one of Earth's most troubling carbon feedback loops.
Yet today, no climate models include rhizomes as a risk factor for melting permafrost - in large part because the data simply doesn't exist.
[...] For the first time, researchers have now combined high-resolution data on both the spread and depth of key plants growing in Arctic permafrost to determine how much carbon they are actually releasing.
As rising temperatures stimulate further plant growth, the researchers estimate that rhizome priming alone enhances the overall respiration of soil microbes by roughly 12 percent. By 2100, that means an absolute loss of around 40 billion tonnes of carbon from northern permafrost.
[...] To keep global warming under the 1.5C threshold, scientists have estimated that at a minimum we must keep our carbon emissions to 200 billion tonnes, and currently, 50 to 100 billion tonnes is put aside for thawing permafrost.
These new figures make up a quarter of that budget, which means there are minute and overlooked ecological interactions that we are clearly not taking into account.
Journal Reference:
Frida Keuper, Birgit Wild, Matti Kummu, et al. Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming, Nature Geoscience (DOI: 10.1038/s41561-020-0607-0)
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