The purpose of this working paper is to explore the potential for carbon removal in forests and farms in the United States, to identify needs likely to arise on the pathway to large-scale deployment, and to consider ways to begin addressing those needs. This working paper is part of a World Resources Institute (WRI) publication series CarbonShot: Creating Options for Carbon Removal at Scale in the United States. The series presents findings from a WRI-led assessment of needs for scaling candidate carbon removal approaches in the United States, drawing on a synthesis of available scientific literature. This paper focuses on carbon removal in forests and farms.
There is untapped potential to increase carbon removal in America’s forests and farms. However, realizing this potential will require navigating challenging dynamics related to competition for land to supply global food and fiber markets, diffuse landownership over expansive areas, persistent scientific and technological challenges related to measurement and monitoring, and still limited public funding for carbon-beneficial land management.
Carbon removal in forests and farms can be achieved through several different practices. These practices interact differently with global land-use trade-offs that affect food and fiber security as well as net climate benefits. Some practices, like restoring croplands to grassland or forestland, or extending timber harvest rotation lengths, reduce the supply of food or fiber and may lead to indirect land-use change. While these measures have potential, unlocking that potential would require increasing food and fiber yields on existing agricultural lands and reducing growth in demand for land-intensive agricultural products—for example by reducing food loss and waste. The following other measures do not reduce the supply of food or fiber:
Reforestation on nonagricultural lands such as post-disturbance forest areas, abandoned mine lands, abandoned farmland,4 roadsides, parks, and urban areas.
Forest carbon management practices such as restocking understocked stands, reducing the risk of catastrophic wildfire, reduced impact logging, active replanting post-harvest, and silvicultural practices that improve growth rates.
Agricultural practices that boost yields and build soil carbon without shifting land uses.
Integration of trees into agricultural lands while maintaining or increasing farm productivity.
The potential scale of carbon removal in forests and farms in the United States alone appears to be on the order of hundreds of millions of metric tons of CO2 per year. Estimates of the global need for carbon removal reach into the gigatons (billion metric tons) per year by 2050 in scenarios consistent with both 1.5˚C and a likely chance of 2˚C temperature rise above pre-industrial levels. The majority of the estimated potential in the U.S. land sector is linked to reforestation on nonagricultural lands. Additional potential may be available from soil carbon management measures that are excluded from estimates of technical potential in the literature due to lack of field data.
Achieving this potential would require addressing needs related to scientific uncertainty, measurement, and monitoring; mechanisms to drive adoption by landowners at large scale; and public funding. Government agencies (federal, state, and local), the private sector, and individual landowners and producers all have a role to play in addressing these needs.
The ambitious emissions reduction measures modeled in most global emissions pathways are not enough to achieve the Paris Agreement targets for limiting temperature rise. In these pathways, it is also necessary to undertake efforts to remove carbon dioxide (CO2) from the atmosphere at the gigaton scale—billions of metric tons per year globally.
There is untapped potential to increase carbon removal in America’s forests and farms. However, although marginal costs of implementation are generally below US$50/tCO2, deploying these approaches at large scale will require addressing a set of needs related to scientific uncertainty, measurement, and monitoring; mechanisms to drive landowner adoption at large scale; and public funding.
If these needs can be addressed, the potential scale of deployment in the United States is likely on the order of hundreds of millions of metric tons (MtCO2) per year.
Heightened abatement of greenhouse gas (GHG) emissions is needed to achieve the goals of the Paris Agreement to limit warming to well below 2˚C, with efforts to limit warming to 1.5˚C, to avoid the most dangerous climate impacts. Furthermore, most scientific estimates show that to keep these goals within reach, the global emissions trajectory needs to not only reach net-zero by the second half of this century but continue downward into net-negative emissions. Global climate models therefore illustrate the need to pursue both aggressive emissions reductions and significant deployment of carbon removal. They rely upon carbon removal approaches to offset the last remaining GHG-emitting activities that are too challenging or expensive to eliminate, and to compensate for any temporary overshoot of temperature goals.
Carbon removal is the process of removing CO2 from the atmosphere and storing it. It is distinct both from solar radiation management, which seeks to reflect sunlight to reduce warming rather than remove carbon from the atmosphere, and from carbon capture and storage (CCS) from point sources of emissions such as fossil-fueled power plants or other industrial facilities. Approaches to carbon removal traverse a spectrum from land management approaches to technological options, including carbon management in agricultural soils, forests, and agroforestry; bioenergy with carbon capture and storage (BECCS); direct air capture and storage (DACS); and frontier technologies such as biochar, plant breeding or engineering, enhanced weathering, and seawater capture. The intention of carbon removal is to store CO2 in plants, soils, and oceans, as well as nonbiologically in geological formations and products (e.g., building materials), augmenting the net transfer of carbon from the atmosphere that naturally takes place as part of the carbon cycle (Minx et al. 2018). In some cases, storage is permanent; in others the CO2 may return to the atmosphere over time.
To date, a gap exists between the need for rapid emissions reductions to stabilize the climate at the temperature targets established in the Paris Agreement, and the availability of cost-effective measures that can provide those reductions (UNEP 2017). Advancements in carbon removal can help close that gap. However, each carbon removal approach available today faces its own challenges, potential pitfalls, and limitations. The full potential of each remains uncertain. Given this uncertainty, a portfolio of approaches and technologies could yield greater opportunities for achieving large-scale carbon removal (Minx et al. 2018; Fuss et al. 2018).