Pathway
Forests
Carbon removal potential: 0.5-3.6 GtCO₂/year¹
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Forests are a huge natural carbon sink. Trees inhale carbon through photosynthesis, storing it above ground in their trunks, branches and leaves, and below ground in roots and surrounding soils. As part of the carbon cycle trees release CO₂ when degraded, cleared or burned. Therefore, forests act as both a source and a sink of CO₂. Estimates suggest forests emit around 8.1Gt CO₂ each year from deforestation or forest disturbance2. Deforestation rates of rainforests in the Amazon and Southeast Asia mean they are now a source of CO₂ emissions. However, globally forests still absorb twice as much CO₂ as they emit and provide a net sink of ~8Gt CO₂/year2. Afforestation and reforestation aims to increase forest capacity as a carbon sink.
Responsibly restoring forests yields a variety of co-benefits. Thriving forests with a range of endemic trees sustain incredible biodiversity and are more resilient to environmental change. Tree roots improve the soil's capacity to absorb water, preventing soil erosion and providing flood resistance. Regenerated forests can boost local commerce and carbon credits allocated to reforesting and stewardship can generate flow of capital to the Global South, where many projects are located.
Planting trees requires careful planning to achieve the full carbon sequestration potential and accompanying co-benefits. Forests are vulnerable to environmental stress such as fire, drought, or disease. Just as forests need to be restored, they need to be protected to ensure the carbon is not re-released. And projects should recognize it may take up to a century before forests reach their full carbon carrying potential. There are other risks; planting monocultures, for example, can result in soil degradation and biodiversity loss. Additionally, community governance and the local or indigenous population’s access to forests and its products must be respected during the implementation of any forestry program. Understanding how much carbon is locked within forests, the feasibility of land and forest vulnerability to environmental change are key first steps to execute responsible reforestation and afforestation.
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Practices:
Afforestation: establishment of new forests or trees in places with no previous tree cover
Reforestation: replanting forests or woodlands degraded by deforestation
(Co-)Benefits:
Reduces soil erosion
Improves flooding tolerance
Increases biodiversity
Boosts local economies
Low cost and easily actionable
Risks:
Permanence is not guaranteed due to forest fires and land-use conversion
Increased surface albedo - more tree coverage makes the earth surface darker, potentially absorbing more sunlight and warming the earth
Monocultures deplete soil nutrients and reduce biodiversity
Replacing existing forests with non-native fast-growing trees
Displacing food production with knock-on impacts
Issues We Care About:
Identifying responsible areas that will not compete with land for food.
Engaging local communities in decision making.
Monitoring forests and providing reliable stewardship to ensure CO₂ is not re-released.
Using accurate models to interpret satellite data to provide trustworthy carbon accounting.
Sources
1. Negative emissions -Part 2: Costs, potentials and side effects, Fuss et al. 2018
2. Global maps of twenty-first century forest carbon fluxes, Harris et al. 2021
More pathways
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