Forests as Carbon Sinks: Climate Heroes Under Threat

Every breath you take connects you to a global climate system where forests play a starring role. Through photosynthesis, trees absorb carbon dioxide from the atmosphere, transforming it into wood, leaves, and roots while releasing oxygen. This natural process makes forests one of our most powerful climate allies. Yet as deforestation accelerates and forest fires intensify, these carbon sinks face mounting threats that could reverse their climate benefits entirely.

How forests capture and store carbon
Young versus old forests
The scale of global forest carbon storage
When carbon sinks become carbon sources
India’s carbon sink potential and challenges
Implementation obstacles
Controversies in carbon sink projects
Equity and access concerns
Ecosystem disruption risks

How forests capture and store carbon

Trees use photosynthesis to extract carbon dioxide from the air, combining it with water to produce sugars. The carbon from these sugars becomes integrated throughout the entire tree structure, from the deepest roots to the newest buds. This process, known as carbon sequestration, removes carbon from the atmosphere and locks it away in living biomass.

Carbon storage extends beyond just the standing trees. Forest ecosystems accumulate carbon in multiple pools: above-ground woody biomass, deadwood, leaf litter, and forest soils. When leaves fall each autumn and trees eventually die, much of their carbon remains stored in soil rather than returning immediately to the atmosphere. Research shows that approximately half of soil carbon storage in certain forests occurs in roots and associated microorganisms.

Young versus old forests

Different forest ages contribute to carbon management in distinct ways. Young forests between 20 and 70 years old demonstrate the highest carbon sequestration rates because they grow rapidly. Middle-aged forests show the greatest carbon sequestration capacity per acre. Meanwhile, old-growth forests contain vast carbon stores accumulated over centuries. This stored carbon is considered largely irrecoverable on timescales relevant to climate action, making the protection of mature forests critical for climate stability.

The scale of global forest carbon storage

The numbers are staggering. Globally, forests currently hold 861 gigatonnes of carbon in their branches, leaves, roots, and soils. This represents more than double the amount of carbon currently in the atmosphere. Each year, forests absorb approximately 16 billion metric tonnes of carbon dioxide from the atmosphere through photosynthesis.

Tropical rainforests shoulder the heaviest burden in this global carbon cycle. Studies estimate that these forests alone prevent more than 1 degree Celsius of atmospheric warming. About 75 percent of this cooling effect comes directly from carbon storage, while the remaining 25 percent results from shading, water cycling, and airflow disruption.

When carbon sinks become carbon sources

The relationship between forests and carbon is bidirectional. While healthy forests absorb carbon, disturbances release it back into the atmosphere. Between 2001 and 2019, deforestation, fires, and other disturbances released an average of 8.1 billion metric tonnes of carbon dioxide annually. When trees are cut and burned or left to decompose, direct emissions occur. Forest clearing also disturbs soil carbon, accelerating decomposition and releasing additional carbon dioxide.

Recent data shows concerning trends. In 2023 and 2024, extreme fires caused forests to absorb only a quarter of the carbon dioxide they typically capture in an average year. This marked the lowest forest carbon sink in over two decades. Some regions have transitioned from net carbon sinks to net carbon sources entirely, with fires contributing 60 percent of forest emissions in affected areas.

India’s carbon sink potential and challenges

India presents both opportunities and obstacles in expanding forest carbon sinks. The country has approximately 98 million hectares of severely degraded land with extremely low soil organic carbon levels. This degradation stems from unsustainable cultivation practices, deforestation, and overgrazing that have depleted soil carbon by 30 to 60 percent compared to undisturbed ecosystems.

India committed under the Paris Agreement to create an additional carbon sink capable of absorbing 2.5 to 3 billion tonnes of carbon dioxide equivalent by 2030. The Green India Mission aims to restore 25 million hectares of degraded forest and non-forest land by the same deadline. Current progress shows India has already achieved 2.29 billion tonnes of additional carbon sink capacity since 2005.

Implementation obstacles

Despite policy frameworks and financial mechanisms, the current afforestation rate of 35 million tonnes of carbon dioxide equivalent per year falls short of what’s needed to meet targets. Funding gaps present a major hurdle, with estimates suggesting a shortfall of 82 percent between money spent annually and the total required to achieve carbon sink goals through additional forest and tree cover.

Quality issues also plague afforestation efforts. Many compensatory afforestation programs focus on monoculture plantations of commercial species like eucalyptus and teak on non-forest land. Unlike natural forests that host 30 to 40 different native species, these monoculture plantations lack biodiversity and ecological value. They hold relatively little carbon, and when harvested, that carbon returns to the atmosphere.

Controversies in carbon sink projects

Forest carbon initiatives face significant criticism, particularly regarding their impacts on indigenous communities and local populations. Many carbon credit projects operate on indigenous lands without proper consultation or benefit-sharing arrangements. Indigenous leaders report encountering secretive contracts written in inaccessible language and inadequate participation in decision-making processes.

Equity and access concerns

Current carbon accounting frameworks create perverse incentives. By basing rewards on recent historic emissions reductions, the system effectively channels more funding to areas with high past deforestation rather than to communities that have successfully protected forests for generations. This approach excludes indigenous peoples and local communities in high forest, low deforestation regions from accessing climate finance, despite their proven track record as forest stewards.

Cases of displacement and rights violations have emerged globally. Indigenous communities face eviction to make way for carbon credit conservation projects, pressure to abandon sustainable traditional practices, and intrusion by brokers offering unfair long-term agreements. These “carbon cowboys” exploit weak legal frameworks around indigenous land rights and collective carbon ownership.

Ecosystem disruption risks

Beyond social justice concerns, some carbon sink projects disrupt ecosystems through inappropriate species selection or conversion of non-forest ecosystems. Planting trees in naturally treeless areas like grasslands, peatlands, and wetlands undermines biodiversity and can reduce those ecosystems’ own carbon storage capabilities. Responsible forest restoration must protect natural biodiversity across all ecosystem types, not just focus narrowly on tree cover.

What do you think? How can we balance the urgent need for carbon sequestration with the rights of communities who have protected forests for generations? What role should indigenous knowledge play in designing future forest carbon projects?

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Table of Contents

How forests capture and store carbon 🔗

Young versus old forests 🔗

The scale of global forest carbon storage 🔗

When carbon sinks become carbon sources 🔗

India’s carbon sink potential and challenges 🔗

Implementation obstacles 🔗

Controversies in carbon sink projects 🔗

Equity and access concerns 🔗

Ecosystem disruption risks 🔗