The Underground Trade That Moves 13 Billion Tons of Carbon a Year

Quanta Magazine describes the network beneath our feet as a trading system rather than a one-way giveaway: mycorrhizal fungi swap minerals with plant roots. That exchange does two jobs at once. It enriches the soil, and, on the magazine's accounting, it sequesters roughly 13 billion tons of atmospheric carbon dioxide a year — about a third of the world's fossil-fuel emissions. The trading framing is what makes the number interesting. If the relationship is an exchange, the carbon held in soil is a byproduct of a deal both sides have reason to keep, not a favour the fungi perform for the climate. Which invites the obvious follow-up question: what happens to the stored carbon when the terms of the deal change?