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Credit: Alex van Hulsenbeek

Land Use

Temperate Forests

Moss, fern, and southern beech trees in Fiordland National Park on the South Island of New Zealand. The 3-million-acre forested landscape traverses the mountaintops to the seas, with lakes and rainforests in between. It is said that rainfall in Fiordland is measured in meters. The steep inclines, deep ravines, and nonstop moisture kept all but the hardiest from trying to inhabit the land until it became a park in 1952.

A quarter of the world’s forests lie in the temperate zone, mostly in the Northern Hemisphere. Some are deciduous; others are evergreen. Over the course of history, 99 percent of temperate forests have been altered in some way—timbered, converted to agriculture, disrupted by development. However, forests are resilient. They are dynamic systems that constantly recover from impacts, even if regaining their full ecological integrity may require centuries.

The world’s 1.9 billion acres of temperate forests are a net-carbon sink. According to the World Resources Institute, more than 1.4 billion additional acres are candidates for restoration—either large-scale, closed forest or mixed mosaics of forests, more sparsely growing trees, and land uses such as agriculture. With restoration comes additional carbon sequestration.

While temperate forests are not threatened by the same large-scale deforestation that afflicts the tropics, they continue to be fragmented by development. They also are experiencing hotter and more frequent droughts, longer heat waves, and more severe wildfires, as well as worsening insect and pathogen outbreaks. These disturbances can push temperate forests beyond their capacity for resilience. Restoration efforts will need to continue evolving in response, yet restoration is no replacement for protection.

References

A quarter of the world’s forests: Tyrrell, Mary L., Jeffrey Ross, and Matthew Kelty. “Carbon Dynamics in the Temperate Forest.” In Managing Forest Carbon in a Changing Climate, 77-107. Springer Netherlands, 2012.

[once] the epicenter of deforestation: FAO. State of the World’s Forests. Rome: Food and Agriculture Organization of the United Nations, 2016.

99 percent…altered in some way: Tyrrell et al, “Temperate Forest.”

1.9 billion acres…net-carbon sink: Pan, Yude, Richard A. Birdsey, Jingyun Fang, Richard Houghton, Pekka E. Kauppi, Werner A. Kurz, Oliver L. Phillips et al. “A Large and Persistent Carbon Sink in the World’s Forests.” Science 333, no. 6045 (2011): 988-993.

carbon [sequestered] each year: Pan et al, “Carbon Sink.”

1.4 billion…acres are candidates for restoration: Susan Minnemeyer, Lars Laestadius, Nigel Sizer, Carole Saint-Laurent, and Peter Potapov. A World of Opportunity. Global Partnership on Forest Landscape Restoration, 2011.

Atlas of Forest and Landscape Restoration Opportunities: “Atlas of Forest and Landscape Restoration Opportunities.” http://www.wri.org/applications/maps/flr-atlas/#; Laestadius, L., K. Buckingham, S. Maginnis, and C. Saint-Laurent. “Before Bonn and Beyond: The History and Future of Forest Landscape Restoration.” Unasylva 66, no. 245 (2015): 11-18.

Ireland as opportunity area: Reytar, Katie. “7 Unexpected Places for Forest Landscape Restoration.” World Resources Institute. May 30, 2014.

carbon sink provided by U.S. forestland: Birdsey, Richard, Kurt Pregitzer, and Alan Lucier. “Forest Carbon Management in the United States.” Journal of Environmental Quality 35, no. 4 (2006): 1461-1469.

era of “megadisturbance”: Millar, Constance I., and Nathan L. Stephenson. “Temperate Forest Health in an Era of Emerging Megadisturbance.” Science 349, no. 6250 (2015): 823-826.

view all book references

Technical Summary

Temperate Forests

Project Drawdown defines temperate forests as: the restoration and protection of temperate-climate forests on degraded lands. This solution replaces degraded forest.

Young forests sequester carbon in both soils and biomass at impressive rates. Temperate forests include coniferous, broad-leaved evergreen, broad-leaved deciduous, and mixed associations. The primary regions featuring temperate forests are Europe, northeast Asia, southern Chile, New Zealand, the Mediterranean, and North America. Temperate forests hold roughly 10 percent of all terrestrial carbon and 20 percent of global plant biomass (Bonan, 2008). Compared to tropical forests, a greater proportion of the carbon is held in soils (Lal and Lorenz, 2012). Soil carbon stocks account for 60 percent of the carbon in these ecosystems (Lal, 2005). Temperate forest soils typically contain roughly 100 tons of carbon per hectare (Lal and Lorenz, 2012).

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. Compared to tropical forest restoration, this solution is less often discussed and somewhat less powerful in terms of mitigation.

The temperate forests solution models natural regeneration, which has the benefit of being a low-cost strategy. Natural regeneration also offers co-benefits which make it an appealing option. These include: biodiversity conservation, watershed protection, soil protection, and resilience to pests and disease.

It is assumed that all land in this solution is legally protected from deforestation, so that it will not be cleared or degraded again.

Methodology

Total Land Area [1]

The total area allocated to temperate forests is 196 million hectares, comprising degraded temperate and boreal forests. [2] Current adoption [3] is set at 0 hectares, as forests that have already been restored are accounted for as existing forests in Drawdown's Agro-Ecological Zone model.

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

Adoption Scenarios [4]

Nine custom adoption scenarios were developed based on: (a) current 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).

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

  • Plausible Scenario: Analysis of the scenarios under the most conservative approach yields the restoration of 95.2 million hectares of temperate degraded land area by 2050.
  • Drawdown Scenario: Based on the most aggressive adoption approach with a peak adoption by 2030 or later, this scenario yields the restoration of 142.3 million hectares of degraded temperate land.
  • Optimum Scenario: Based on the most aggressive adoption approach with a peak adoption by 2030 or later, this scenario yields the restoration of 144.4 million hectares of degraded temperate land.

Sequestration Model

Sequestration rates of temperate forests are set at 3.0 tons of carbon per hectare per year, based on meta-analysis of 18 data points from 8 sources.

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 [5]

Drawdown’s Agro-Ecological Zone model allocates current and projected adoption of solutions to the planet’s forest, grassland, rainfed cropland, and irrigated cropland areas. Temperate forests is the highest-priority solution for degraded temperate/boreal forest land.

Results

Total adoption in the Plausible Scenario is 95.2 million hectares in 2050, representing 48.5 percent of the total suitable land. Of this, 95.2 million hectares are adopted from 2020-2050. The emissions impact of this scenario is 22.6 gigatons of carbon dioxide-equivalent sequestered by 2050. Financial impacts are not modeled.

Total adoption in the Drawdown Scenario is 142.3 million hectares in 2050, representing 72.6 percent of the total suitable land. Of this, 142.3 million hectares are adopted from 2020-2050. The impact of this scenario is 34.7 gigatons of carbon dioxide-equivalent by 2050.

Total adoption in the Optimum Scenario is 144.4 million hectares in 2050, representing 73.6 percent of the total suitable land. Of this, 144.4 million hectares are adopted from 2020-2050. The impact of this scenario is 42.6 gigatons of carbon dioxide-equivalent by 2050.

Discussion

Benchmarks

Mitigation benchmarks for temperate/boreal 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 sequestered per year by 2030, at carbon prices of US$20, $50, and $100 per ton of carbon dioxide-equivalent (IPCC, 2014).2 Drawdown's temperate forests solution sequesters 1.0-1.6 gigatons of carbon dioxide-equivalent per year by 2030 in the three Scenarios; thus, when considering it as one component of a larger forest strategy that includes afforestation, tropical forests, forest protection, and indigenous peoples' land management, 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. Future upgrades of the Drawdown land model will include this capability. 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

Drawdown considers temperate forest restoration to be a very high priority, given its impressive 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] For more on Project Drawdown’s Land Use integration model, click the Sector Summary: Land Use link below.

Full models and technical reports coming in late 2017.

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