Temperate Forest Restoration

Introduction

Found mainly in Europe, northeast Asia, southern Chile, New Zealand, the Mediterranean, and North America, temperate forests are a net carbon sink, typically containing roughly 100 metric tons of carbon per hectare (Lal and Lorenz, 2012).

Over the course of history, 99 percent have been altered in some way—harvested, converted to agriculture, disrupted by development. According to the World Resources Institute, more than 1.4 billion acres are candidates for restoration. Restoring degraded and deforested temperate lands to forest can offer substantial climate change mitigation opportunities. Temperate forest regrowth is often rapid and results in impressive rates of carbon sequestration.

Project Drawdown’s Temperate Forest Restoration solution involves the restoration and protection of temperate-climate forests on degraded lands using natural regeneration. Natural regeneration is low cost and also offers co-benefits such as biodiversity conservation, watershed protection, soil protection, and resilience to pests and disease.

This solution replaces degraded forest. It assumes that the restored land is legally protected from deforestation so it will not be cleared or degraded again.

Methodology

Total Land Area

To evaluate the extent to which a Food, Agriculture, and Land Use sector solution can reduce greenhouse gas emissions and sequester carbon, we need to identify the total land area available for that solution. To avoid double counting, we use an integration model that allocates land area among all of the sector’s solutions. This involves two steps. First, we classify the global land area into agro-ecological zones (AEZs) based on the land cover, soil quality, and slope and assign AEZs to different thermal moisture regimes. We then classify the AEZs into “degraded” and “nondegraded.” Second, we allocate the solutions to AEZs, with the solution most suited to a given AEZ or sets of AEZs assigned first, followed by the second-most-suited solution, and so on. Because it’s hard to predict future changes, we assume the total land area remains constant. Total land areas represent both the implementation and functional unit.

The total area allocated to the Temperate Forest Restoration solution is 150 million hectares of degraded temperate forests. Current adoption (defined as the amount of functional demand supplied by the solution in 2014) is set at 0 hectares because forests that have already been restored are accounted for as existing forests in our model.

We calculated future restoration of temperate forest using targets from the New York Declaration of Forests, which commits to reforesting 350 million hectares by 2030 (Intergovernmental Panel on Climate Change, 2015), and estimates from the World Resources Institute, which predict that 304 million hectares of land are available for wide-scale restoration.

Adoption Scenarios

We developed nine custom adoption scenarios based on: (a) restoration commitments to date; (b) potential future commitments; (c) the proportion of committed land restored to intact forest; and (d) the year commitments are realized (2030, 2045, or 2060).

​​We calculated impacts of increased adoption of the Temperate Forest Restoration solution from 2020 to 2050 by comparing drawdown scenarios with a reference scenario in which the market share was fixed at current levels.

• Scenario 1: 92.64 million hectares of degraded temperate forest are restored (62 percent of available land area).
• Scenario 2: 128.38 million hectares of degraded temperate forest are restored (86 percent of available land area).

Sequestration Model

We set sequestration rates of temperate forests at 2.7 metric tons of carbon per hectare per year, based on meta-analysis of 20 data points from nine sources.

Financial Model

We assumed that any costs (e.g., carbon payments or payment for ecosystem services) are borne at a government or nongovernmental organization level. Project Drawdown land solutions only model costs that are incurred at the landowner or manager level.

Integration

Project Drawdown’s Agro-Ecological Zone model allocates current and projected adoption of solutions to forest, grassland, rain-fed cropland, and irrigated cropland areas. Temperate Forest Restoration is the highest-priority solution for degraded temperate forest land.

Results

Scenario 1 sequesters 19.42 gigatons of carbon dioxide equivalent greenhouse gases by 2050. We did not model financial impacts due to insufficient data.

Scenario 2 sequesters 27.85 gigatons of carbon dioxide equivalent greenhouse gases by 2050.

Discussion

Benchmarks

Mitigation benchmarks for temperate forest restoration are rare. For global forestry of all types, the Intergovernmental Panel on Climate Change (IPCC) reports ranges of 0.0–1.45, 0.1–9.5, and 0.2–13.8 gigatons of carbon dioxide equivalent greenhouse gases sequestered per year by 2030, at carbon prices of US$20, US$50, and US$100 per metric ton of carbon dioxide equivalent (IPCC, 2014). Griscom et al. (2017) calculate 2.7–17.9 gigatons of carbon dioxide equivalent per year in 2030 for “reforestation” in temperate, boreal, and tropical forests.

When considering the Temperate Forest Restoration solution as one component of a larger forest strategy that also includes Tree Plantation (on Degraded Land), Tropical Forest Restoration, Forest Protection, and Indigenous Peoples’ Forest Tenure solutions, its contribution is in line with the benchmark.

Limitations

This study does not include impacts of albedo from forest growth in temperate and boreal climates, which can substantially offset sequestration. Inclusion of economic impacts (e.g., costs to governments and NGOs) would be a valuable addition to future updates. As benchmarks become available, they should be included in the study as well.

Conclusions

Project Drawdown considers temperate forest restoration to be a very high priority, given its impressive sequestration potential and numerous co-benefits. We assume that these new forests will be legally protected, as in the Forest Protection solution. Reduction of land demand for food through solutions such as Health and Education, Plant-Rich Diets, and Reduced Food Waste will help ease pressure on these new forests. Agroecological intensification due to increased yields from solutions such as Conservation Agriculture, Silvopasture, and Perennial Staple Crops also helps. The Abandoned Farmland Restoration solution also helps make land available by bringing degraded farmland back into production.

References

Griscolm, B. W., Adams, J., Ellis, P. W., Lomax, G., Miteva, D. A., Schlesinger, W. H., Shock, D., Siikamäki, J. V., Smith, P., Woodbury, P., Zganjar, C., Blackman, A., Campari, J., Conant, R. T., Delgado, C., Elias, P., Gopalakrishna, T., Hamsik, M. R., Herrero, M., Kiesecker, J., Landis, E., Laestadius, L., Leavitt, S. M., Minnemeyer, S., Polasky, S., Potapov, P., Putz, F. E., Sanderman, G., Silvius, M., Wollenberg, E., Fargione, J. (2017). Natural Cliamte Solutions. Proceedings of the National Academy of Sciences, 114(44) 11645-11650. DOI: 10.1073/pnas.1710465114

Intergovernmental Panel on Climate Change. (2015). Climate Change 2014: Mitigation of Climate Change: Working Group III Contribution to the IPCC Fifth Assessment Report. Cambridge: Cambridge University Press. doi:10.1017/CBO9781107415416

Lal, R., & Lorenz, K. (2012). Carbon sequestration in temperate forests. In Recarbonization of the Biosphere (pp. 187-201). Springer Netherlands.