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Could the ultimate climate solution be right under our feet? Science makes the case for dirt

red dirt with leaves growing
Image Credit: paul mocan // Unsplash
  • Forests are a huge carbon sink, but when it comes to planetary restoration and nature-based carbon capture methods, the dirt on the forest floor is often ignored.

  • This summer, three studies came out, each of which presents research that make the case for dirt as a secret weapon in the climate fight.

  • One shows how enhanced rock weathering, a process that speeds up a natural carbon capture process already deployed across millions of farmland acres, can be even more impactful and transform cropland into net carbon sinks.

  • Another shows how fungi and bacteria play a pivotal role in the carbon storage of soil, meaning that understanding fungal relationships are integral to emerging programs that aim to restore forests.

  • Lastly, one more study shows how fungi alone store more carbon than China emits in a year, storing over a third of carbon emitted by fossil fuels, even further underscoring the importance of the forest floor in conservation efforts.

For the first time ever a study has quantified the climate benefits of a secret weapon already deployed across Midwestern farming fields: enhanced rock weathering, or ERW. The results of the “breakthrough” study show that when taken a small step further, ERW, which builds on a natural carbon-capturing process rocks perform, can morph crop fields into carbon sinks that absorb more carbon than they release.

This isn’t the only piece of dirt news making the rounds in the news cycle recently. Elsewhere, another study in the June issue of Nature showed that microbes, such as bacteria and fungi, are the primary drivers of carbon capture in soil, multiplying soil’s carbon capture ability fourfold.

Speaking of fungi, news broke earlier this summer that these tiny yeast, mold, and mushroom microorganisms store more than a third of carbon from fossil fuel emissions, making them one of the biggest classes of organisms to be a climate change-fighting carbon sink on the planet in addition to the monumental role they already play in sustaining biodiversity.

These three pieces of dirt news are huge because they open new avenues for conservation and carbon storage that were otherwise ignored.

The fungi story, which was published in June in Current Biology, found that around the world, fungi alone store more carbon than what China emits in a year, making up an underground network of climate-fighting secret weapons in grasslands, forests, savannahs, jungles, and under human-made roads, gardens, and houses. When added to the potential of microbe-riddled soil, and rock-sprinkled crop fields, it makes us wonder… is dirt the climate solution we’ve been looking for all along?

Of course, while scientists have highlighted time and time again that nothing is a silver bullet when it comes to climate change — which last month sparked the hottest July on record — as Katie Field, a professor of plant-soil processes at the University of Sheffield in the United Kingdom said via the university’s news, microbial fungi “represent a blind spot in carbon modeling, conservation, and restoration.”

“The numbers we’ve uncovered are jaw-dropping,” she added, “and when we’re thinking about solutions for climate we should also be thinking about what we can harness that exists already.”

mushrooms in forest
Image Credit: Jesse Bauer // Unsplash

As these studies show, microbes in fungi aren't the only “blind spot” in carbon modeling.

ERW, for example, is a well-studied method of natural carbon capture, such as that researched by InPlanet, an early-stage rock weathering startup that partnered with the FootPrint Coalition Science Engine earlier this year. However, the ERW study, which was published in Global Change Biology Bioenergy, shows that when another rock called basalt is added to the traditional silicate rock recipe, carbon sequestration is even further optimized, underscoring harnessing resources already in existence, as Field said.

“In addition to reducing emissions, we desperately need effective ways to draw down atmospheric carbon dioxide,” Evan DeLucia a director at the University of Illinois-Urbana Institute for Sustainability, Energy, and Environment who co-authored the ERW study said. Aside from improving the ability of crop fields to draw down CO2, DeLucia described the basalt method as a “win-win” for the climate and for farmers because it improves yields as well.

The work the University of Illinois is researching was done in partnership with the University of Sheffield, in which they investigated enhanced weathering for carbon dioxide removal in field sites all around the world including Malaysia, Australia, the U.K., and the United States.

Being able to accelerate the ERW process, which already accelerates a century-long carbon capture process occurring in rocks, means it may be able to play a bigger role in climate mitigation than once thought, taking the reduced carbon loss from 42% at one site to net zero.

In addition to the potential these findings have for carbon reduction strategies and conservation efforts, the researchers also underscored the potential it has for carbon offsets to incentive farmers, for example, to deploy the basalt ERW method.

“As we look for new ways to offset carbon emissions, we need to be able to quantify those carbon savings to better compare our options,” Ilsa Kantola a research scientist and co-author on the EWR study said.

tractors on cropland
Image Credit: Johny Goerend // Unsplash

Whether it be with ground-up rocks, bacteria, fungi, or soil, it’s clear that dirt is emerging from under our feet as potentially a vital option in climate mitigation strategies, and according to the researchers across the studies, the hope is not only to expand the body of scientific knowledge but give dirt the attention it needs as policy, especially in the U.S., pays more attention to climate mitigation, adaptation, and planetary restoration than ever.

“Soil ecosystems are being destroyed at an alarming rate through agriculture, development, and other industry, but the wider impacts of disruption of soil communities are poorly understood. When we disrupt the ancient life support systems in the soil, we sabotage our efforts to limit global heating and undermine the ecosystems on which we depend,” Field said.

“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.”

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