Conserve and restore forests and other terrestrial ecosystems

Conserving the world’s forests is essential for addressing the interconnected challenges of nature loss and climate change. Forest habitats are home to 80% of terrestrial plant and animal species. Conserving forests also prevents the release of their large carbon stores into the atmosphere, safeguarding their ability to continue sequestering carbon, and for tropical forests, maintaining the biophysical mechanisms that help to cool the planet. To help secure these benefits, the Glasgow Leaders’ Declaration (GLD) has established the collective goal of halting forest loss – which includes reaching zero gross deforestation – by 2030.

The world permanently lost at least 5.4 million hectares (Mha) of forests in 2023, with some estimates suggesting that the loss was a higher 6.4 Mha. Using the higher estimate, global deforestation increased slightly in 2023 compared to 2022. Should current trends continue, the world will fail to halt permanent forest loss by 2030. The annual rate of gross deforestation must instead fall by over 1 Mha each year throughout the rest of this decade to deliver on the GLD’s goal.

Deforestation and the 2030 goal 

Why do we provide two estimates of deforestation?

Deforestation is defined as the permanent conversion of natural forest cover to new, non-forest land uses. Different global data and methods can be used to approximate deforestation, though none perfectly captures trends in permanent forest loss.

Here, we provide two estimates resulting from two different methodologies. Both use a combination of datasets available on Global Forest Watch and estimate deforestation as the areas of tree cover loss where the dominant driver is the production of commodities (namely large-scale agriculture and pastures and mining), urbanization, or the expansion of shifting agriculture in humid tropical primary forests.

However, the two methodologies treat the presence of fires differently. Tree cover loss from fire includes both natural and human-ignited fires where fire was the direct cause of loss (e.g., does not include burning of felled trees). Tree cover loss can be temporary or lead to permanent land use change.

To illustrate this point, one methodology – described in the State of Climate Action 2023 – excludes all tree cover loss due to fire that occurs within areas where the dominant driver is commodity production, urbanization, or shifting agriculture in primary forest. Meanwhile, the other methodology – described in the 2023 Forest Declaration Assessment – does not exclude tree cover loss due to fires.
While neither of the resulting estimates can be considered perfectly accurate, each serves as an effort to present a realistic depiction of global deforestation trends.

Deforestation (including areas of tree cover loss cleared by fires)

When including areas of tree cover loss cleared by fires, the Forest Declaration Assessment finds that deforestation occurred across 6.4 Mha worldwide in 2023. This is a 4% increase compared to 2022.

Deforestation (excluding areas of tree cover loss cleared by fires)

When excluding areas of tree cover loss cleared by fires, following the methodology from the State of Climate Action 2023, 5.4 Mha of deforestation occurred globally in 2023. While this estimate suggests that the global rate of deforestation is trending downward, the rate at which it’s decreasing is still far from what is needed to meet global climate goals or the goals of the GLD.

Gross GHG emissions from deforestation and the 2030 goal

Deforestation remains the primary source of gross emissions from land use, land-use change, and forestry (LULUCF), accounting for almost 10% of global net anthropogenic greenhouse gas (GHG) emissions in 2022.  

In 2023 alone, gross GHG emissions from deforestation reached between 3.2 and 3.8 billion metric tons of carbon dioxide equivalent (GtCO2e) (excluding areas of tree cover loss cleared by fires) – a slight increase compared to 3.6 GtCO2e – the annual average during the baseline period from 2018 to 2020. To put the scale of these emissions in perspective, if deforestation was its own country, it would have been the fourth-highest emitter after China, the United States, and India in 2023.

Humid tropical primary forest loss and the 2030 goal

Humid, tropical primary forests – the bulk of which are found in major forest basins in three main geographies – the Amazon, the Congo Basin, and Southeast Asia – are among the world’s most important ecosystems for carbon storage and biodiversity. Urgent action to conserve these valuable forests is essential for meeting the GLD goal of halting forest loss by 2030.

Yet global progress toward eliminating humid tropical primary forest loss remains woefully inadequate. In 2023, 3.74 million hectares (Mha) of these forests were cleared, which is only slightly below average (3%) for annual losses from the baseline period, 2018 to 2020. To reach zero by 2030, the world now needs to reduce these losses by 0.53 Mha each year through 2030.

Gross GHG emissions from humid tropical primary forest loss and the 2030 goal

Greenhouse gas (GHG) emissions released when the world loses humid tropical primary forests account for a large share of total emissions from deforestation. In 2023, for example, gross emissions from humid tropical primary forest loss totaled 2.4 billion metric tons of carbon dioxide equivalent (GtCO2e) – a slight decrease (4%) relative to average annual GHG emissions from the baseline period, 2018 to 2020. To put the scale of these emissions in perspective, global emissions from humid tropical primary forest loss were greater than emissions from the United States’ energy sector (2.2 GtCO2e) in 2023.  

Stretching across nearly 15 million hectares (Mha) of shoreline globally, mangrove forests are among the world’s most carbon-dense ecosystems, holding at least twice as much carbon per hectare as boreal, temperate, and tropical forests. Due to the carbon density of these ecosystems, the loss of even a small area of mangroves, particularly when their soils are disturbed or dredged, can release an outsized amount of greenhouse gas emissions relative to other ecosystems.

Although average annual rates of global gross mangrove loss have slowed dramatically since the late 20th century, they appear to once again be ticking upward. From 1999 to 2019, the world lost an estimated 560,000 hectares (ha) of mangrove forests, with gross losses of these coastal wetlands increasing by an average of nearly 950 ha per year since 2008. Accordingly, global efforts to halt the conversion of mangrove forests have fallen short, and a sharp reversal in action is needed.

The Forest Landscape Integrity Index (FLII) provides annual estimates of global forest degradation. The index tracks changes in forest extent, forest connectivity, direct pressure from human activities, and inferred pressure from edge effects to estimate forest integrity through an FLII score. Higher scores correspond to higher levels of forest integrity, while lower FLII scores correspond to a decrease in forest integrity. In other words, decreasing FLII scores imply increasing forest degradation. Halting and reversing forest degradation translates into no reduction or an increase in the FLII score at the global and regional levels. 

According to FLII data available through 2022, extensive forest degradation has occurred globally and within all regions, including both tropical and non-tropical regions of Africa, Asia, Latin America, the Caribbean, Europe, and North America. A net total of 62.6 million hectares of forest fell to a lower ecological integrity class in 2022 – 10 times the area that was deforested in the same year.

However, despite this large absolute area of degradation, in 2022, the rate of degradation as measured by the FLII was lower than baseline levels (38% less degradation than the 2018-20 average) and from the year prior (29% less degradation than 2021). These findings signal that degradation due to human-induced factors is declining, which is good news. That said, the FLII does not account for the impact of intensifying forest fires, which could derail other progress on reducing degradation drivers.

Intact forest landscapes are mosaics of forested and naturally treeless ecosystems that show very few signs of human activity or habitat fragmentation. Occupying a minimum area of 50,000 hectares, they are large enough to play a critical role in helping to maintain native biodiversity. Accordingly, these ecosystems are hotspots for biodiversity and contain large carbon stores. Reducing tree cover loss within these natural terrestrial ecosystems is a key part of halting forest loss and land degradation by 2030.

Yet, annual rates of tree cover loss across these intact forest landscapes have been on the rise since 2001. In 2023 alone, 5.7 million hectares were lost – a 39% increase relative to average annual losses from 2018 to 2022. Though not all tree cover loss is permanent, the increasing trend likely indicates more degradation and fragmentation of these ecosystems, as well as a rise in human activity. Efforts to address tree cover loss in intact forest landscapes must be accelerated, urgently and rapidly, to reverse this concerning trend. 

Covering just 3.8% of the planet’s land, peatlands – also known as mires, bogs, fens, and swamp forests – are global hotspots for carbon sequestration and long-term storage. They also hold large stores of organic nitrogen as their water-logged soils slow decomposition, allowing carbon and nitrogen-rich peat to accumulate over millennia. But when these ecosystems’ water tables fall, oxygen enters the upper layers of peat, spurring decomposition and subsequent losses of stored carbon and nitrogen. These degraded peatlands can emit carbon dioxide and nitrous oxide for decades to centuries until all peat is fully lost or their soils are rewetted.

An estimated 57 million hectares (Mha) – nearly 12% of the world’s peatlands – are degrading such that they are no longer actively forming peat, and peat accumulated over centuries to millennia is now disappearing. Collectively, these degraded peatlands emit about 1.9 gigatonnes of carbon dioxide equivalent (GtCO2e) each year – roughly equivalent to Russia’s greenhouse gas (GHG) emissions in 2020. This estimate, however, excludes GHG emissions from peat fires that, while highly variable and difficult to measure, likely occur on an order of magnitude from 0.5 to 1 GtCO2e annually.

Halting peatland degradation by 2030 can help to limit global warming. However, despite recent advances in mapping peatlands, significant data gaps such as incomplete coverage, inconsistent quality, and outdated data inhibit efforts to monitor progress. Data estimating the area of organic soils drained for agriculture provide the best available (though still imperfect) proxy, and they indicate that degradation of the world’s peatlands continues. 

Stretching across roughly 460 million hectares (Mha) as of 2018, forests that are highly significant for biodiversity are disproportionately important for supporting forest-dependent species. Designation of these areas of high significance for forests accounts for both species richness and endemism across forests globally and is complementary to key biodiversity areas, which also include important areas for geographically restricted species. Key biodiversity areas, however, determine important sites for biodiversity according to a broader range of criteria, including ecological integrity, threat status, or irreplaceability.  

Loss of forest habitat in areas with high significance for biodiversity, specifically, may have outsized impacts on the species that inhabit these areas, but tree cover loss in these areas continues to occur. In 2023, for example, the world lost 2.6 Mha of tree cover in areas of high significance for forest biodiversity, an 18% increase from 2022. 

Forest cover loss in key biodiversity areas (KBAs) is particularly concerning, as these areas play an outsized role in conserving biodiversity due to, for example, being ecologically intact or hosting species that live in just a few geographies. 

In 2023, over 1.4 million hectares of forests were lost within forested KBAs. While this is a 16% decline in forest loss relative to the annual average during the baseline period, 2018 to 2020, the year-to-year trend is concerning. Tree cover loss in forested KBAs increased by 10% from 2022 to 2023. This is particularly disappointing given significant strides in reducing tree cover loss in KBAs had been made from 2020 to 2022 and even small amounts of loss within KBAs can significantly harm biodiversity.

Monitoring shifts in species populations offers an important and complementary measure of forest biodiversity because changes in forest cover do not always directly correlate with impacts on species living in these ecosystems. 

The Forest Specialists Index (FSI) tracks changes in vertebrate forest specialist populations. Vertebrate forest specialists are species of birds, mammals, reptiles, and amphibians that rely on forest habitats for their survival or reproduction. In 2022, FSI found that between 1970 and 2018, the abundance of vertebrate forest specialist populations declined an average of 79%. Habitat loss, habitat degradation, overexploitation, and climate change are major threats to forest biodiversity.

All modeled pathways limiting global temperature rise to 1.5°C with no or limited overshoot rely on carbon removal. Reforestation is a relatively cost-effective, readily available approach to carbon removal that, when implemented appropriately (i.e., by focusing on recovering forests’ ecological functions rather than solely on replanting trees), can also generate additional benefits for adaptation, sustainable development, and biodiversity conservation. Restoring terrestrial ecosystems, including forests, is also a standalone goal of the Glasgow Leaders’ Declaration (GLD). 

While data limitations pose significant challenges to monitoring reforestation globally, remotely sensed data on the gross area of tree cover gain offers the best available proxy. However, this data may include tree cover gains that, while potentially beneficial for climate mitigation, do not meet common definitions of reforestation, such as afforestation across historically non-forested lands or regrowth after harvesting within already established plantations. In addition, increases in tree cover occur gradually as these plants grow, making it more challenging to reliably estimate using satellite remote sensing methods over short timescales. 

Still, historical cumulative data suggests that worldwide, a total of 130 million hectares (Mha) experienced tree cover gain from 2000 to 2020. However, this average annual rate of tree cover gain (6.5 Mha per year) will need to accelerate to help limit warming to 1.5°C; reverse forest loss as pledged in the GLD; and deliver the Bonn Challenge pledge to bring 350 Mha of deforested and degraded land into restoration by 2030.  

Critically, while reforestation is needed to meet climate and biodiversity goals, it cannot serve as a substitute for protecting standing forests. For example, it may take decades (if not longer) for these ecosystems to regain species diversity, ecosystem structure, and ecological functions, all of which may impact carbon cycling and greenhouse gas fluxes within these ecosystems.

Even if peatland degradation ended today, degraded peatlands could continue emitting roughly 1.9 gigatonnes of carbon dioxide equivalent (GtCO2e) per year for decades to centuries because, unlike forests, peatlands store carbon primarily within their waterlogged soils rather than in aboveground vegetation. Carbon and nitrogen losses following land-use changes continue until the soil is rewetted or all peat is lost. The efficacy of restoring peatlands to avoid these greenhouse gas (GHG) emissions, however, will depend in part on what form of degradation the wetland ecosystems experienced (e.g., drainage, burning, or cutting). Rewetting peatlands drained by agriculture, for example, can significantly reduce or even halt carbon losses, as well as enable carbon sequestration. Because drained peatlands will emit carbon dioxide and nitrous oxide for up to hundreds of years, restoring these ecosystems’ water tables should occur as quickly as possible to maximize avoided GHG emissions.  

Although data is insufficient to assess global progress made in restoring peatlands, available evidence suggests that current efforts are occurring but likely not at the pace and scale required across many countries. From 2010 to 2013, for example, the Russian government implemented one of the largest-scale peatland rewetting projects in the Northern Hemisphere across more than 73,000 hectares (ha) near Moscow. During the early 2000s, Germany rewetted more than 20,000 ha of peatlands in one of its northeastern states. Likewise, Indonesia reported that it rewetted a total of 1.8 million ha from 2016 to 2023.

Restoring mangrove forests not only enhances their ability to sequester and store carbon but may also reduce greenhouse gas emissions that would have otherwise continued for decades after certain disturbances, such as the loss of soil organic carbon following drainage for aquaculture ponds. Monitoring mangrove restoration, however, remains challenging. Mangroves grow gradually, and therefore, restoration is challenging to monitor on shorter timescales, as gain may not be detected until mangrove trees reach a certain level of maturity. Moreover, the establishment of mangrove trees does not always indicate restoration of the ecological functions of these ecosystems, and in some cases, the addition of mangroves can lead to negative consequences (e.g., the loss of other coastal ecosystems) or only short-lived gains if tree-planting is not implemented appropriately.  

Still, available global estimates indicate that the world gained approximately 180,000 hectares (ha) of mangrove forests from 1999 to 2019, but only 8% of these gains (15,000 ha) can be attributed to direct human interventions, such as mangrove planting or other restoration activities. Although mangrove gain due to direct human interventions does not indicate whether the establishment of these mangroves restored the ecological function of these ecosystems, it does provide the best available proxy for mangrove restoration.