Mycorrhizal fungi have been supporting life on land for at least 450 million years by helping to supply plants with soil nutrients essential for growth. In recent years, scientists have found that in addition to forming symbiotic relationships with nearly all land plants, these fungi are important conduits to transport carbon into soil ecosystems.

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In a meta-analysis published June 5 in the journal Current Biology, scientists estimate that as much as 13.12 gigatons of carbon dioxide equivalents (CO2e) fixed by terrestrial plants is allocated to mycorrhizal fungi annually—roughly equivalent to 36% of yearly global fossil fuel emissions.

Because 70% to 90% of land plants form symbiotic relationships with mycorrhizal fungi, researchers have long surmised that there must be a large amount of carbon moving into the soil through their networks.

“We always suspected that we may have been overlooking a major carbon pool,” says author Heidi Hawkins, research lead at Conservation South Africa and research associate on plant-soil-microbe interactions at the University of Cape Town. “Understandably, much focus has been placed on protecting and restoring forests as a natural way to mitigate climate change. But little attention has been paid to the fate of the vast amounts of carbon dioxide that are moved from the atmosphere during photosynthesis by those plants and sent below ground to mycorrhizal fungi.”

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