Forests around the world play a major role in curbing or contributing to climate change. Standing, healthy forests sequester more atmospheric carbon than they emit and act as a carbon sink; degraded and deforested areas release stored carbon and are a carbon source.
Forests are a net carbon sink globally, but there’s huge variation locally. Our analysis finds that forests managed by Indigenous people in the Amazon were strong net carbon sinks from 2001-2021, collectively removing a net 340 million tonnes of carbon dioxide (CO2) from the atmosphere each year, equivalent to the U.K.’s annual fossil fuel emissions.
Meanwhile, forests outside of the Amazon’s Indigenous lands were collectively a carbon source, due to significant forest loss. The research underscores the need to help Indigenous people and other local communities safeguard their forest homes and preserve some of the Amazon’s remaining carbon sinks.1
Carbon Flux: How Forests Serve As Carbon Sinks — or Carbon Sources
The world’s forests, which cover about 30% of Earth’s land, absorbed approximately 7.2 billion more tonnes of CO2 per year than they emitted between 2001 and 2021, about twice as much carbon as they released. Deforestation, degradation and other disturbances, however, have already turned some of the world’s most iconic forests into carbon sources and threaten to convert others.
The Amazon, the world’s largest tropical forest, remains a net carbon sink, but it teeters on the edge of becoming a net source. Southeastern Amazonia already emits more carbon than it sequesters. Over the past 40-50 years, an estimated 17% of Amazonian forest has been lost, of which over four-fifths was converted to agricultural land, mainly pastures.
Scientists estimate that deforesting 20% of the Amazon could push it past a tipping point, triggering a large-scale dieback that would release more than 90 billion tonnes of CO2 into the atmosphere (approximately 2.5 times greater than annual global fossil fuel emissions), transform the forest into a savannah and disrupt rainfall across South America.
Indigenous Peoples Are Strong Forest Protectors
For Indigenous people and other communities, their land is a primary source of food, medicine, fuelwood and construction materials, as well as employment, income, welfare, security, culture and spirituality. Community land is also a basis for social identity, status and political relations.
A growing body of research shows that lands managed by Indigenous people — both through legal title and informal, customary ownership — have lower deforestation rates than similar lands managed by other forest users. Lands legally held or titled to Indigenous people exhibit even lower deforestation rates than untitled Indigenous lands, underscoring the importance of tenure security to sustainable land management.
Moreover, research shows that lands held by Indigenous people and other communities — much of which is forested — are rich stores of carbon, and a significant share is held only under customary tenure arrangements, where land is not legally recognized as belonging to the communities or titled to them by the government.
The extent to which these forests are carbon sinks or sources, however, has not been explored in depth until now.2
Here's what our analysis shows:
The Amazon’s Indigenous Forests Are Largely Carbon Sinks, but Strengths Vary
About 1.5 million Indigenous people from 385 different ethnic groups reside in the Amazon bioregion, which includes portions of Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Venezuela.3 Indigenous people hold about 29% of the bioregion, of which almost half is in Brazil. Given that forests make up more than 80% of the bioregion, these collectively managed lands —henceforth referred to as “Indigenous forests” — are vital for halting forest loss.
Our analysis of carbon emissions and removals finds that Indigenous forests in all nine Amazonian countries were net carbon sinks between 2001 and 2021, collectively emitting an average of 120 million tonnes of CO2e per year and removing 460 million tonnes CO2/year, making them a net sink of 340 million tonnes of CO2e/year.4 However, the relative magnitudes of emissions and removals — known as carbon fluxes — varied greatly between countries.
The relative magnitudes of removals and emissions can be considered an indicator of how “secure” a carbon sink is. A higher ratio means that emissions must increase more, or removals must decrease more, to turn the area into a net carbon source.
For example, Indigenous forests in Bolivia and Peru had higher emissions relative to removals — and thus were closer to turning into carbon sources — than Indigenous forests in Brazil, which removed about 4 times more carbon than they emitted.
Outside Indigenous Lands, the Amazon Forest Is a Net Carbon Source
Forests in the Amazon bioregion outside Indigenous lands were collectively a net carbon source between 2001 and 2021. These forests emitted 1.3 billion tonnes CO2e/year due to forest loss and removed about 1 billion tonnes CO2/year, making them a net source of approximately 270 million tonnes CO2e/year, equivalent to the annual fossil fuel emissions from France.
Forest loss in Brazil, which comprises three-quarters of total regional loss, is the driving factor. Forest loss outside Indigenous lands in the Brazilian Amazon was such a significant source of carbon it counteracted the effects of the other Amazonian countries, which were either small carbon sinks or carbon sources. In Brazil, forests outside Indigenous lands are rapidly being lost to commercial farming and cattle ranching, extractive industries, infrastructure and other developments.
Indigenous Forests Produce Far Less Emissions than Other Forests
While Amazonian countries with more Indigenous forest area naturally had larger carbon fluxes, the annual carbon flux per hectare — or the carbon flux density — varied little among the countries’ relatively stable, mature Indigenous forests. From 2001 to 2021, the carbon flux density ranged from a net sink of roughly 0.78 tonnes CO2e/hectare/year in the Bolivian Amazon to 2.0 tonnes CO2e/hectare/year in the Colombian Amazon.
Outside Indigenous lands, however, annual net carbon flux density varied considerably, from forests in the Brazilian Amazon emitting 1.4 tonnes CO2e/hectare/year to forests in French Guyana removing 2.0 tonnes CO2e/hectare/year. This reflects the differences across Amazonian countries in how much forest outside Indigenous lands are being degraded and lost.
The contribution of Indigenous forests to mitigating climate change comes primarily from their lower emissions compared to forests outside Indigenous lands, as opposed to more efficient removals. Our analysis shows that the carbon emissions per hectare of forest inside Indigenous lands were much lower than for outside Indigenous lands (0.60 tonnes CO2e/hectare/year inside and 3.2 tonnes CO2e/hectare/year outside, respectively), while Indigenous forests captured about as much carbon per hectare of forest as forests outside Indigenous lands (2.2 tonnes CO2/hectare/year inside and 2.5 tonnes CO2/hectare/year outside).
Given that forest loss drives carbon emissions, this finding shows that the focus of forest-related climate change mitigation in Indigenous lands should be on keeping emissions low by protecting standing forest.
Other Community Lands Are Also Strong Carbon Sinks
Carbon fluxes in Amazonian Indigenous forests are not alone in their ability to curb climate change. While most communities in the Amazon identify as Indigenous, many Afro-descendent communities — descendants of enslaved Africans — also hold and manage land in a collective manner.
Our analysis of Afro-descendant forests in Brazil found that about 90% were net carbon sinks from 2001 to 2021.5 Removals were about twice as large as emissions (3.5 million tonnes CO2/year vs. 1.6 million tonnes CO2e/year), and their net sinks per hectare were comparable to those of Indigenous forests in Brazil (1.6 tonnes CO2e/hectare/year in Afro-descendent forests vs. 1.7 tonnes CO2e/hectare/year in Indigenous forests).
Further, our analysis of carbon fluxes in Indigenous forests in Mexico and the Philippines as well as community forests in Mexico (peasant communities that do not identify as Indigenous, but hold and manage land in a collective manner) shows that many communities around the world are helping to fight climate change through forest stewardship.6 Collectively held forests in Mexico and the Philippines were net carbon sinks, sequestering 70 million more tonnes of CO2/year than they emitted from 2001 to 2021, comparable to the fossil fuel emissions of Romania. Their net sinks per hectare were also on par with the net sinks per hectare of Amazonian Indigenous and Afro-descendant forests.
Unlike in the Amazon, however, forests outside collective lands in Mexico and the Philippines were carbon sinks.
Indigenous Forests in the Amazon Are Under Threat
Between 2001 and 2021, approximately 94% of Indigenous forest area in the Amazon bioregion was a net sink7, ranging from about 99% of Indigenous forests in Venezuela to about 76% in Bolivia. The remaining 6% of Indigenous forest area was a net carbon source, responsible for 42% of Indigenous forests’ emissions in the Amazon.
This percentage, however, varied by country. In Colombia, for example, 2% of Indigenous forests were responsible for 21% of their emissions, and in Suriname, 11% of Indigenous forests were responsible for half their emissions. While many Indigenous forests in the Amazon are threatened, this finding suggests that the carbon in some Indigenous forests is under much greater pressure than in others.
And while many Indigenous communities have successfully shielded their forests from development and other pressures, threats are mounting. As competition for land intensifies, land disputes between Indigenous people and external actors, especially governments and companies, are becoming more common and growing more dangerous. An increasing number of Indigenous people in the Amazon and elsewhere are being harassed, arrested and murdered for their efforts to protect their land. Latin America is consistently ranked as the region with the most killings of land and environmental defenders.
How to Protect Indigenous Forests and the Carbon They Hold
As more forests are lost and converted to other uses, Indigenous and other community forests stand out as stable carbon sinks that must be secured.
Some of the most pressing strategies to protect Indigenous forests include:
- Recognize community lands in climate strategies: Community forests can play a major role in helping countries meet their international climate action commitments. In Brazil, Colombia, Peru and Mexico, for example, Indigenous forests sequester emissions equivalent to an average 30% of their countries' national emissions-reduction pledges, known as Nationally Determined Contributions (NDCs). The climate community — including international negotiators, national policymakers, donors and civil society leaders — should recognize the mitigation contributions of community forests. Forested countries with large areas of community land should make them a central component of their climate action strategies.
- Secure and protect community lands: Securing community lands is a low-cost, high-benefit investment and a cost-effective carbon mitigation measure when compared to other carbon capture and storage approaches. Governments should support communities in their efforts to protect and sustainably manage their land. Such assistance might include help in monitoring collective lands, apprehending and bringing to justice unlawful intruders, strengthening community organizations, and protecting community land and environment defenders. Governments should also establish accessible and transparent procedures to register community land in a government cadaster and document it with a land certificate or title.
- Increase funding to communities. Official development assistance (ODA) is under-supporting communities for their climate change mitigation contributions. From 2011 to 2020, bilateral, multilateral and private foundation donors disbursed about $2.7 billion for projects supporting community forest management in tropical countries, less than 1% of ODA for climate change and less than 5% of ODA for general environmental protection. Should community forests be degraded or lost, large stocks of carbon would be released into the atmosphere and the lands would no longer be able to sequester the same amount of carbon. Governments and donors should channel more financial resources to communities and their organizations, recognizing that they’re some of the world’s best forest protectors.
There is much that can be done to protect forests and the communities who call them home. At stake is not just the fate of carbon, but people’s lives and lifestyles.
1 Ecosystems of all kinds around the world are being degraded or lost. The loss or degradation of forests, mangroves, peatlands, and other carbon-rich ecosystems are of particular concern given their contribution to climate change and other critical ecosystem services.
2 For this analysis, we overlaid maps of Indigenous and community lands within the Amazon with gross emissions, gross removals, and net greenhouse gas fluxes from forests. Emissions, removals, and net flux maps are from Harris et al. 2021, updated through 2021. Forests were defined as having greater than 30% canopy cover in 2000 or subsequent tree cover gain, as defined by Hansen et al. 2013 and described in Harris et al. 2021. Maps of Indigenous and community lands were sourced from LandMark: The Global Platform of Indigenous and Community Lands as of October 2022. The data from LandMark were compiled from a variety of original sources. For Suriname, “indicative areas of Indigenous and community land rights” (areas where Indigenous and community lands likely exist but the clear delimitation, recognition and/or documentation status of these land rights are not available at this time) were used instead of exact boundaries. The analysis covered 2001-2021 because the removals and net flux estimates from Harris et al. 2021 cannot be disaggregated by sub-period.
3 The Amazon biogeographic region is the area where the fauna and flora have similar or shared characteristics (the biogeographic region is larger than the Amazon River basin). The bioregion is a mosaic of ecosystems, including rainforests, seasonal forests, deciduous forests, flooded forests, and savannas.
4 CO2 equivalent (CO2e) is a measure used to compare the emissions from various greenhouse gases based on their global warming potentials over 100 years. It equates non-CO2 greenhouse gases to the equivalent amount of CO2. For simplicity, we use the terms “net carbon sink”, “net carbon source”, and “net carbon flux” to refer to all forest-related greenhouse gas emissions and CO2 removals, even though emissions and net values are reported in units of CO2e and include methane and nitrous oxide.
5 Afro-descendant lands cover smaller areas than Indigenous lands in the Amazon. Our analysis focused on the Afro-descendant lands in Brazil for which we had maps. The lands covered 1.2 million hectares of forest held by approximately 430 Afro-descendant communities.
6 Maps of Indigenous and community lands for Mexico and the Philippines were sourced from LandMark: The Global Platform of Indigenous and Community Lands as of October 2022. The data from LandMark were compiled from a variety of original sources, including Registro Agrario Nacional (Mexico) and the Philippine Association for Intercultural Development, Inc. (PAFID) and National Commission on Indigenous Peoples (NCIP) (Philippines).
7 The percentage of the area of Indigenous land that was a net sink or source, not the percentage of the number of distinct Indigenous lands.