Strategies that can deliver wedges

Tropical forests store huge amounts of carbon in trees and soils. When forests are cleared or degraded, that carbon is released quickly if trees are burned, and more slowly as vegetation and disturbed soils decay. Reducing deforestation and forest degradation therefore avoids emissions that would have happened otherwise, and it keeps forests standing so they can continue absorbing some CO₂ as they grow.

Achieving one wedge requires avoiding 75 million hectares of forest loss over 30 years, an area about the size of Pakistan (1). By 2050, 5 million hectares of tropical forest must be avoided annually – an area about the size of Costa Rica (2). This is roughly a 40% reduction relative to the historical rate (13 million hectares) (3), which is a similar order to that achieved in the Brazilian Amazon: deforestation fell about 34% in the first half of 2023 versus the same period in 2022 (4).

Reducing deforestation can deliver up to 2 wedges in total.

Peatlands are waterlogged wetlands that build up decaying plant material (peat) over centuries, and store vast amounts of carbon. Peatlands cover only ~3–4% of Earth’s land but contain about twice the carbon found in the world’s forests (1). When peatlands are drained the water table is lowered and oxygen can reach the peat, so it decomposes and releases the stored carbon to the atmosphere. Rewetting reverses this drainage, which slows decomposition and can also reduce the risk of severe peat fires.

Achieving one wedge requires both stopping the roughly half a million hectares of new drainage that occurs in the tropics each year (2), and rewetting an area of tropical peatland roughly the size of Cambodia (0.2 million km²) (3). Around 50 million hectares of peatlands have been drained across all biomes globally, so a wedge would restore roughly one-third of this (4).

Rewetting peatlands and preventing further drainage can deliver 1 wedge in total.

Forests cover around 50% of global land area in the tropical biome (1, 2). Reforesting the tropics means bringing forests back to places that have been cleared or degraded. As new forests grow, they remove CO₂ from the air and store it in trunks, roots, leaf litter and soils – a form of “carbon dioxide removal”. The climate benefit builds up over decades, and it lasts only if the forests are protected from future loss (for example from logging, fires, pests or drought) (3).

Achieving one wedge requires creating new forest about the size of Colombia (1.1 million km²) (4). Put another way, it’s about 2.6% of today’s total global forest area (4.06 billion hectares) (5). For comparison, the Bonn Challenge aimed to bring 12 million hectares of degraded and deforested land into restoration each year, so a wedge is roughly 30% of that global target (6).

Tropical reforestation can deliver up to 2 wedges in total.

Forests cover 37% of global land area in the temperate biome (1, 2). Reforesting the temperate zone means bringing forests back to places that have been cleared or degraded. As new forests grow, they remove CO₂ from the air and store it in trunks, roots, leaf litter and soils – a form of “carbon dioxide removal”. The climate benefit builds up over decades, and it lasts only if the forests are protected from future loss (for example from logging, fires, pests or drought) (3).

Achieving one wedge requires creating new forest that spans roughly the land area of Mongolia (1.6 million km²) (4). Put another way, it’s about 3.5% of today’s total global forest area (4.06 billion hectares) (5). For comparison, the Bonn Challenge aimed to bring 12 million hectares of degraded and deforested land into restoration each year, so a wedge is roughly 40% of that global target (6).

Temperate reforestation can deliver 1 wedge in total.

Silvopasture involves grazing livestock among trees and shrubs, rather than on open grassland. The trees store carbon in wood and help build soil carbon through roots and leaf litter, so the land can remove CO₂ from the air over time. Trees can also improve pasture conditions (shade, shelter, sometimes fodder), which can raise productivity per hectare and reduce pressure to clear additional land elsewhere, but the climate benefit depends on trees being maintained for decades (1).

Achieving one wedge requires adding trees across a grazing area roughly the size of Peru (1.3 million km²) (2). All forms of agroforestry combined are practised on around 1 billion hectares globally, so this wedge implies expanding tree-on-farm systems by roughly 13% from today’s footprint (3).

Tropical silvopasture can deliver 1 wedge in total.

Silvopasture involves grazing livestock among trees and shrubs, rather than on open grassland. The trees store carbon in wood and help build soil carbon through roots and leaf litter, so the land can remove CO₂ from the air over time. Trees can also improve pasture conditions (shade, shelter, sometimes fodder), which can raise productivity per hectare and reduce pressure to clear additional land elsewhere, but the climate benefit depends on trees being maintained for decades (1).

Achieving one wedge requires adding trees across a grazing area roughly the size of Iran (1.6 million km²) (2). All forms of agroforestry combined are practiced on around 1 billion hectares globally, so this wedge implies expanding tree-on-farm systems by roughly 18% from today’s footprint (3).

Temperate silvopasture can deliver 1 wedge in total.

Adding trees to tropical cropland is a form of agroforestry, where farmers grow crops alongside trees or shrubs (for example, shelterbelts, hedgerows, or “alley cropping”). The trees store carbon in wood and help build soil carbon through roots and leaf litter, so the land can remove CO₂ from the air over time. Tree cover can also protect soils (for example by reducing erosion) and create microclimates that help crops cope with heat and drought, but the climate benefit depends on trees being maintained for decades.

Achieving one wedge requires adding trees to croplands roughly the combined size of Thailand (0.5 million km²) and Tanzania (0. 9 million km²) combined (1). All forms of agroforestry combined are practised on around 1 billion hectares globally, so this wedge implies expanding tree-on-farm systems by roughly 15% from today’s footprint (2).

Tropical intercropping can deliver 1 wedge in total.

Adding trees to temperate cropland is a form of agroforestry, where farmers grow crops alongside trees or shrubs (for example, shelterbelts, hedgerows, or “alley cropping”). The trees store carbon in wood and help build soil carbon through roots and leaf litter, so the land can remove CO₂ from the air over time. Tree cover can also protect soils (for example by reducing erosion) and create microclimates that help crops cope with heat and drought, but the climate benefit depends on trees being maintained for decades.

Achieving one wedge requires adding trees to cropland roughly the combined size of Mexico (2.0 million km²) and Mongolia (1.6 million km²) (1). All forms of agroforestry combined are practised on around 1 billion hectares globally, so this wedge implies expanding tree-on-farm systems by roughly 34% from today’s footprint (2).

Temperate intercropping can deliver 1 wedge in total.

Around one third of all food produced globally does not get eaten. Losses happen “upstream” when crops spoil during harvesting, storage and transport, especially where cooling, roads and storage are limited, while waste happens “downstream” in shops, restaurants and homes when food is thrown out. Producing food requires land, fertiliser, energy, and transport which all produce emissions. Cutting food loss and waste reduces the need to produce extra food in the first place and avoids all associated emissions.

Achieving one wedge requires avoiding just over half of the 2.5 billion tonnes of food that is lost or wasted globally today (1). For perspective, this is roughly 8 times the amount of food consumed in the US in 2024 (169 million tonnes) (2).

Reducing food loss and waste can deliver up to 2 wedges in total.

Eating meat causes more emissions than other diets because livestock production (especially for cattle and sheep) releases large amounts of greenhouse gases and uses a lot of energy and land to grow feed. Eating less meat cuts emissions mainly by reducing demand for these animals, and thus the amount of energy and land devoted to rearing them. People in many parts of the world eat more meat than is healthy (1), so shifting diets can have a meaningful climate impact while improving public health.

Achieving one wedge requires people to reduce their meat consumption by about 6% of a 2,000-calorie diet each day (2). This must be adopted by 5.2 billion people by 2050. In food terms, it’s like skipping about half of a typical 100 g beef burger patty each day (about 270 calories) (3). If those calories are avoided rather than replaced diets move closer to health-focused benchmarks, which suggest around 92 kcal of meat per day total (4). If calories are instead replaced with meat-free alternatives, emissions savings are lower.

Reducing meat consumption can deliver up to 3 wedges in total.

Earth’s soils store roughly two trillion tonnes of organic carbon, which is equivalent to 7,300 GtCO₂ (1). Changing how cropland is farmed can allow more carbon to stay in the soil instead of returning to the air as CO₂ when oxidised. Often referred to as “conservation agriculture”, practices include reducing or avoiding ploughing, keeping the soil covered (for example with crop residues or cover crops), and using more diverse rotations (2). Results vary a lot by climate and soil: some “no-till” gains near the surface can be offset deeper down, while cover crops tend to show more consistent increases in soil carbon (3).

Achieving one wedge requires applying these kinds of practices across roughly the land area of the United States (9.1 million km²) (4). This is around 4 times larger than the estimated global area currently under conservation agriculture: 205 million hectares in 2019 (about 15% of global cropland) (5).

Soil carbon management can deliver 1 wedge in total.

Spreading finely crushed silicate rocks (such as basalt) over farmland speeds up natural chemical reactions that remove CO₂ from the air. As the rock dust dissolves in rainwater and soils, it forms carbonates that wash into rivers and eventually the ocean, where the carbon can be stored in long-lived, stable forms. Many farmers already spread crushed limestone on fields to reduce soil acidity, so the machinery and know-how for large-scale spreading is already familiar (1).

Achieving one wedge requires treating a total cropland across an area of roughly the size of India (3.2 million km²), if applied to regions with the greatest potential (2). The twelve countries with the greatest potential, including China and the US, would need to apply weathering materials across 35-55% of their croplands. This requires 13 billion tonnes of crushed rock to be distributed each year, which is roughly 1.5× the world’s coal demand in 2024 (8.8 billion tonnes) (3). The energy consumed for rock crushing along would consume up to 3% of current electricity supply in each country (4).

Enhanced weathering can deliver 1 wedge in total.