Restoring and protecting the planet’s soils could remove up to 5.5 billion tonnes of CO2 annually—almost equivalent to the current annual emissions of the United States—while at the same time bolstering soil fertility and water retention, along with broader ecosystem health.

“The top metre of the world’s soils contains three times as much carbon as the entire atmosphere, making it a major carbon sink alongside forests and oceans,” reports Carbon Brief. Carbon gets stored in soil as plants die and decompose into the ground, passing on the atmospheric CO2 they absorbed during photosynthesis.

But that carbon storage is being damaged as deforestation, destruction of peat bogs and wetlands, and industrial agriculture practices cause CO2 to slip out of the soil and back into the atmosphere—though exactly how much soil carbon sequestration loss is happening is unclear. Carbon Brief cites a recent report by the Intergovernmental Panel on Climate Change that highlighted the difficulties of measuring the loss, given that so few countries are tracking this critical determinant of atmospheric (as well as soil) health.

What is clear, says Carbon Brief, is that protecting and restoring soil health—whether that soil is in peat bogs or cornfields—will play a critical role in fighting the climate crisis. A new study recently published in the journal Nature Sustainability concludes that maximum global efforts to restore and protect soil health could remove up to 5.5 billion tonnes of CO2 per year.

Lead author and Nature Conservancy soil scientist Deborah Bossio told Carbon Brief that “around 40% of this carbon offsetting potential would come from protecting existing soil carbon stores in the world’s forests, peatlands, and wetlands,” with forest protection and reforestation showing the “largest greenhouse gas removal potential,” offsetting as much as 1.2 billion tonnes annually.

While peatlands cover just 3% of the world’s surface, the boggy ecosystems contain as much as 33% of its soil carbon, which makes their protection critical in the fight against climate change, the study found. The same is true for wetlands: a recent study flagged by Carbon Brief found the Amazon’s wetlands to be “twice as carbon rich as its rainforests, with soils holding the majority of this carbon.”

The Nature Conservancy study affirms these findings, noting that protecting forests, peat bogs, and wetlands from further degradation “would be the most low-cost way to mitigate greenhouse gas emissions on a global scale.” Bossio and her colleagues are calling for the active replenishment of agricultural soils through such time-honoured techniques as seeding fields with biochar (a carbon-rich charcoal), cover cropping, and agroforestry. Improving soil carbon levels will also boost the fertility of the soil and its capacity to hold (and purify) water, while nurturing broader ecosystem resilience.

While such techniques would be highly cost-effective, Bossio noted, they would also require profound changes to agricultural policies, which now often discourage farmers from taking up soil-based solutions. Policy-makers will also have to address today’s lack of knowledge of such solutions. “We tell farmers ‘just plant cover crops’—but that means a farmer needs to know when to plant them, which to plant, and how to manage them,” she said.

In the UK, a failure to protect soil health is “potentially heightening the risks of flood, food insecurity, and biodiversity loss,” according to a recent report by that country’s Sustainable Soils Alliance (SSA). The SSA found that “just 0.41% of England’s total environmental monitoring budget was spent on soil health monitoring in 2017-18,” Business Green writes. “In contrast, multi-million-pound budgets were assigned to monitoring air and water quality across the UK.”

Condemning the lack of investment in soil monitoring as “staggering but unfortunately not surprising,” SSA Director Ellen Fray urged policy-makers to understand that both water and air quality ultimately depend on soil health. “We could be actually saving money—and the environment—by investing in soil monitoring, because understanding soil would tell us a great deal about the health of our water and air, too,” she told Business Green.

The SSA report “comes amid growing concern about the health of soils both in the UK and worldwide,” the publication notes. Citing a 2014 United Nations study, it adds that “the world may only have an estimated 60 harvests left on average before soils are too degraded to feed the global population.”