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:
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.
- “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.”
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.
- “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.”
Houghton, R.A., Nassikas, A.A., 2017. Negative emissions from stopping deforestation and forest degradation, globally. Global Change Biology 24(1)
Summary: Avoiding further loss and degradation of primary forests and intact forest landscapes, and allowing degraded forests to naturally regrow, would reduce global carbon emissions annually by about one gigatonne or 1 Gt, and reduce another two to four Gt of carbon emissions through just allowing natural regrowth.
If greater negative emissions are to be realized, they will require an expansion of forest area, greater efficiencies in converting harvested wood to long‐lasting products and sources of energy, and novel approaches for sequestering carbon in soils.
- “…we estimate that stopping deforestation and allowing secondary forests to grow would yield cumulative negative emissions between 2016 and 2100 of about 120 PgC, globally.”
- “Extending the lifetimes of wood products could potentially remove another 10 PgC from the atmosphere, for a total of approximately 130 PgC, or about 13 years of fossil fuel use at today’s rate.”