Forest Carbon Coalition – Science Synthesis

What role can forests play in mitigating the climate crisis?

The world’s forest lands have enormous potential to capture and store enough carbon dioxide to slow and eventually reverse the growth of CO2 in the atmosphere back towards the upper limit of 350 parts per million called for by the scientific community. There are three general pathways for mitigating climate change through changes in forest management.

Two of these involve planting tree seedlings to expand the acreage of land growing trees. Reforestation does so on lands where forests have recently been degraded or removed. Afforestation occurs through the planting of seedlings on lands that have not been previously forested. The third pathway, called proforestation, focuses on allowing existing trees to grow bigger. Remaining fragments of native, unlogged forests provide a benchmark for carbon storage targets that could be achieved in each forested region of the world by implementing these climate smart practices.

Key research on the climate mitigation potential of the world’s forests:

Goldstein, A., Turner, W.R., Spawn, S.A., et al., 2020. Protecting irrecoverable carbon in Earth’s ecosystems. Nature Climate Change.

Link: Download PDF here: PDF

Summary: The authors estimate the amount of irrecoverable carbon that will be emitted into the atmosphere if ecosystems with high carbon densities are logged or lost to development pressure. Irrecoverable carbon is the not recoverable on timescales relevant to avoiding dangerous climate impacts.

Key excerpts:

“These three dimensions allow us to identify ecosystems containing high amounts of ‘irrecoverable carbon’, which we define as carbon that (1) can be influenced by direct and local human action, (2) is vulnerable to loss during a land-use conversion and (3), if lost, could not be recovered within specified timeframe (t).”
“Based on estimated, conservative geographic extents (Table 1) and average irrecoverable carbon densities across ecosystems (Fig. 2), ecosystems with carbon that is manageable through direct, localized human actions contain at least 264 Gt C that would not be re-sequestered within 30 years if lost in the near-term.”
“Mechanisms for securing irrecoverable carbon at the national level might include new protected area designations, increased rights and resources to indigenous peoples, land-use planning that specifically incorporates irrecoverable carbon protection, ending or retiring concessions to agriculture, logging or aquaculture within areas of concentrated irrecoverable carbon, and designation of areas as critical biological carbon reserves deserving of a special protected status.”

Boutte, P.C., Law, B.E., Ripple, W.J., Berner, L.T., 2019. Carbon sequestration and biodiversity co-benefits of preserving forests in the western United States. Ecological Applications e02039.

Link: DOI: 10.1002/eap.2039

Summary: The authors use process models and ecological criteria to provide estimates of how much carbon high productivity-low vulnerability forests in the western United States can capture and store by century’s end. These forests are concentrated in the Pacific Northwest. Vulnerability was modeled with respect to fire and drought.

Key excerpts:

“High-productivity, low-vulnerability forests have the potential to sequester up to 5,450 Tg CO2 equivalent (1,485 Tg C) by 2099, which is up to 20% of the global mitigation potential previously identified for all temperate and boreal forests, or up to ~6 yr of current regional fossil fuel emissions.”
“Additionally, these forests currently have high above- and belowground carbon density, high tree species richness, and a high proportion of critical habitat for endangered vertebrate species, indicating a strong potential to support biodiversity into the future and promote ecosystem resilience to climate change.”

Grissom B.W., et al., 2017. Natural climate solutions. PNAS October 31, 2017 114 (44) 11645-11650.

Link: https://doi.org/10.1073/pnas.1710465114

Summary: Reversing the degradation of natural forests can accomplish more than one third of the total climate change mitigation required by 2030. Existing forests will store more carbon only if logged less frequently and less intensely. Planting trees offers the biggest and cheapest way to slow the climate crisis. We must act quickly. It will take decades for seedlings to store carbon at their full potential.

Key excerpts:

“We find that the maximum potential of NCS—when constrained by food security, fiber security, and biodiversity conservation—is 23.8 petagrams of CO₂equivalent (PgCO₂e) y⁻¹ (95% CI 20.3–37.4).”
“Natural climate solutions can provide 37% of cost-effective CO2 mitigation needed through 2030 for a >66% chance of holding warming to below 2 °C.”