Can Soil Save the Climate? Exploring the Promise (and Limits) of Soil Carbon Storage

Soils play a central role in the global carbon cycle – storing more carbon than all vegetation and the atmosphere combined. This massive natural reservoir not only supports plant growth, but has the potential to sequester carbon over meaningful timescales.

Despite its potential, soil carbon storage is dynamic – meaning its permanence, or how long carbon remains stored, can be uncertain. Land management practices like tilling or environmental disturbances such as drought or rising temperatures can reduce carbon stocks, even releasing previously stored carbon back into the atmosphere. In this way, soil can become a source of carbon emission depending on conditions and stewardship.

So how scalable and viable is soil carbon as a CDR method? 

In theory, soil carbon sequestration is extraordinarily scalable — virtually every terrestrial landscape contains soil capable of storing carbon. This makes it one of the few carbon dioxide removal (CDR) approaches with truly global reach. However, in practice, viability is more complicated.

Soil carbon estimates vary widely depending on how and where samples are taken. For instance, the Intergovernmental Panel on Climate Change (IPCC) recommends sampling at 30 cm depths. However, crop roots – that deposit the carbon in the soil – have the potential to extend deeper. This means that using a uniform depth can make comparisons easier for policymakers, but may not reflect true carbon storage potential. In contrast, some science has shown that samples of 15cm to 30cm can risk an overestimation of carbon benefits, especially if no-till agriculture practices are in place. This practice is thought to increase the surface level carbon captured, while potentially decreasing deeper soil carbon depths, causing a bias with the carbon accounting. These findings have created controversy around the effectiveness of no-till agriculture as a management practice to increase soil carbon storage. More scientific monitoring and experimentation needs to be conducted to parse out these discrepancies. 

Connections across Science, Policy, & Community 

In addition to accurate science, community support is essential to effectively implementing the adoption of any management practices. 

For example, in the United States, a little over 50% of land is agricultural. The US Department of Agriculture (USDA), is the primary federal agency leading research, development, demonstration, and deployment (RDD&D) efforts involved in soil carbon storage. Currently 35% of US agricultural land has reduced tillage practices and almost 37% have implemented no-tillage practices. 

This widespread adoption likely could not have been possible without the farming community’s support. Farmers are critical sources of knowledge with years of hands-on experience working with soils. From my experience working in consulting, having community voices in the same room with both the science and policy decision makers can exponentially increase the long term viability of that project. In contrast, when community involvement was minimal or nonexistent, a project would break down or run into resistance that only the community could have identified as barriers from their hands-on experience. 

Bottom Line 

Soil carbon sequestration holds tremendous promise as a nature-based CDR solution, but its long-term effectiveness depends on:

• rigorous measurement protocols (science)

• durable management commitments (community)

• strong verification systems that prevent over-crediting (policy)

If developed with scientific rigor, careful governance, and in collaboration with farmers, soil carbon can be a powerful component of the climate solution portfolio, especially when paired with ecosystem health co-benefits such as improved soil structure and increased water filtration. 

Additionally, consistency and accuracy is critical for soil carbon crediting purposes, as even small inaccuracies can compound significantly when scaled to millions of hectares. 

If you’re interested in diving deeper into soil carbon pathways, I highly recommend exploring some of the educational resources provided through the AirMiners BootUp program.

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