Technical Summary

Tropical Forest Restoration

Project Drawdown defines tropical forest restoration as: the restoration and protection of tropical-climate forests. This solution replaces degraded forest in the tropics.

Tropical forest restoration is widely considered to offer substantial climate change mitigation opportunities, if conducted at large spatial scales. Despite this assertion, estimates of how much carbon could be sequestered from the atmosphere as a result of large-scale restoration are largely lacking. The international community has pledged to restore 350 million hectares of degraded forest land by 2030. Thus, efforts to quantify carbon storage over large spatial scales are timely.

Tropical forest regrowth is often rapid, and results in impressive rates of carbon sequestration. The tropical forests solution models natural regeneration of tropical forests on degraded lands. This has the benefit of being a low-cost strategy. It is assumed that forest regrowth will be legally protected so that it will not be cleared or degraded again.

Natural regeneration also offers co-benefits which make it an appealing option, including: biodiversity conservation, watershed protection, soil protection, and resilience to pests and disease.

Methodology

Total Land Area[1]

The total area allocated for tropical forest restoration is 287 million hectares, representing degraded tropical forests.[2] Current adoption[3] is set at 0 hectares, as forests that have already been restored are accounted for as existing forest in the Drawdown Agro-Ecological Zone model.

Future restoration of tropical forests was calculated using the targets from the New York Declaration of Forests, which commits to reforesting 350 million hectares by 2030 (United National Framework Convention on Climate Change, 2014), and estimates from the World Resources Institute, which predict 304 million hectares of land are available for wide-scale restoration

Adoption Scenarios[4]

Ten custom adoption scenarios were developed based on: (i) current restoration commitments to date; (ii) potential future commitments; (iii) the proportion of committed land restored to intact forest; and (iv) the year commitments are realized (2030, 2045 or 2060).

Impacts of increased adoption of tropical forests from 2020-2050 were generated based on two growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.

  • Scenario 1: Analysis of these scenarios under the most conservative approach yields the restoration of 161.4million hectares of degraded land area by 2050.
  • Scenario 2: Based on a more aggressive adoption approach with peak adoption by 2030 or later, this scenario yields the restoration of 2230.8  million hectares of degraded tropical forest.

Sequestration Model

Sequestration rates are set at 4.4 tons of carbon per hectare per year,[5] based on meta-analysis of 18 data points from 10 sources. Note that data on soil carbon sequestration was unavailable.

Financial Model

It is assumed that any costs (e.g. carbon payments or payment for ecosystem services) are borne at a government or non-governmental organization (NGO) level. Drawdown land solutions only model costs that are incurred at the landowner or manager level.

Integration[6]

Drawdown’s Agro-Ecological Zone model allocates current and projected adoption of solutions to the planet’s forest, grassland, rainfed cropland, irrigated cropland, arid, and arctic areas. Tropical forest restoration is the highest-priority solution for degraded tropical forest land.

Results

Total adoption in the Scenario 1 is 161.4million hectares in 2050, representing 56 percent of the total suitable land. Of this, 161.4 million hectares are adopted from 2020-2050. The emissions impact of this scenario is 54.45gigatons of carbon dioxide-equivalent sequestered by 2050. Financial impacts are not modeled.

Total adoption in the Scenario 2 is 230.8 million hectares in 2050, representing 80 percent of the total suitable land. Of this, 230.8 million hectares are adopted from 2020-2050. The impact of this scenario is 85.14 gigatons of carbon dioxide-equivalent by 2050.

Discussion

Benchmarks

Griscom et al (2017)’s “Natural climate solutions” calculate 2.7-17.9 gigatons of carbon dioxide equivalent per year in 2030 for “reforestation”, in all climate, temperate, boreal, and tropical. The Drawdown model shows 1.7-2.9 gigatons carbon dioxide-equivalent per year by 2030 for tropical forest restoration and 0.6-0.9 for temperate forest restoration, for a combined 2.3-3.8 gigatons carbon dioxide-equivalent per year in 2030.

As more data on soil carbon sequestration in tropical forest restoration becomes available, the sequestration rate of this solution, and thus its mitigation impact, will likely increase. Inclusion of economic impacts, e.g. costs to governments and NGOs, would be a valuable addition to future updates. As more benchmarks become available, they should be included in the study as well.

Conclusions

Drawdown considers tropical forest restoration to be an extremely high priority, given its massive sequestration potential and numerous co-benefits. It is assumed that these new forests will be legally protected, as in the forest protection solution. Reduction of land demand for food helps ease pressure on these new forests. Solutions like family planning, educating girls, plant-rich diet, and reduced food waste reduce demand. Agroecological intensification due to increased yields from solutions like conservation agriculture, silvopasture, and tropical staple trees also makes room for these new forests. Farmland restoration also helps make land available by bringing degraded farmland back in to production.

 

[1] To learn more about the Total Land Area for the Land Use Sector, click the Sector Summary: Land Use link below.

[2] Determining the total available land for a solution is a two-part process. The technical potential is based on the suitability of climate, soils, and slopes, and on degraded or non-degraded status. In the second stage, land is allocated using the Drawdown Agro-Ecological Zone model, based on priorities for each class of land. The total land allocated for each solution is capped at the solution’s maximum adoption in the Optimum Scenario. Thus, in most cases the total available land is less than the technical potential.

[3] Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.

[4] To learn more about Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Land Use Sector-specific scenarios, click the Sector Summary: Land Use link.

[5] This includes above-ground biomass and roots, but not soil organic carbon.

[6] For more on Project Drawdown’s Land Use integration model, click the Sector Summary: Land Use link below.