Carbon stored by fungi in soil could be essential to reach net-zero

London: A new study has quantified the fungi in the soil globally to be storing over 13 gigatons of carbon, roughly 36 per cent of yearly global fossil fuel emissions, a finding it said could prove crucial to reach net-zero goals.

The study is a meta-analysis of hundreds of studies looking at plant-soil processes to understand how much carbon is being stored by the fungi on a global scale, conducted by an international team of scientists including those from University of Sheffield, UK.

Mycorrhizal fungi have been known to support life on land for at least 450 million years and make up vast underground networks all around us - even forming beneath roads, gardens, and houses, on every continent on Earth.

While widely believed to be able to store carbon through symbiosis with land plants and transportation of carbon as sugars and fats into soil, the true extent of the amount of carbon the mycorrhizal fungi were storing was unknown until now, the study said.

Estimating the carbon-dioxide (CO2) being transferred from plants to fungi at 13.12 gigatons annually, the findings transform the soil beneath our feet into a massive carbon pool and the most effective carbon capture storage unit in the world, the study published in the journal Current Biology said.

The study equated the amount of carbon stored to roughly 36 per cent of yearly global fossil fuel emissions - more than what China emits each year.

Given the crucial role of fungi in cutting carbon emissions, researchers are now calling for them to be considered in biodiversity and conservation policies.

"Mycorrhizal fungi represent a blind spot in carbon modelling, conservation, and restoration - the numbers we've uncovered are jaw-dropping, and when we're thinking about solutions for climate we should also be thinking about what we can harness that exists already.

"More needs to be done to protect these underground networks - we already knew that they were essential for biodiversity, and now we have even more evidence that they are crucial to the health of our planet," said Katie Field, Professor of Plant-Soil Processes at the University of Sheffield and co-author of the study.

The researchers are now investigating how long the carbon is stored by the fungi in the soil, and are seeking to further explore the role that fungi plays in Earth's ecosystems.

"We always suspected that we may have been overlooking a major carbon pool.

"A major gap in our knowledge is the permanence of carbon within mycorrhizal structures. We do know that it is a flux, with some being retained in mycorrhizal structures while the fungus lives, and even after it dies.

"Some will be decomposed into small carbon molecules and from there either bind to particles in the soil, or even be reused by plants. And certainly, some carbon will be lost as carbon dioxide gas during respiration by other microbes or the fungus itself," said Heidi Hawkins, lead author of the study from the University of Cape Town, South Africa.