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India's Forests Are Greener—but Storing Less Carbon: New Study Reveals a Sequestration Crisis
Published : Aug 04, 2025 17:30 IST - 5 MINS READ
Through photosynthesis, trees and plants absorb carbon dioxide and turn it into energy needed for growing trunks and roots. This process of removing carbon dioxide from the atmosphere and storing it as biomass is called carbon sequestration. It is this ability of trees and plants that can help mitigate the impacts of climate change.
The Indian government, much like many other governments and private companies around the world, is banking on forests and plantations to tackle climate change.
As part of climate commitments under the Paris Agreement, the Indian government has pledged to create an additional carbon sink of 2.5 to 3 billion tonnes of CO2 (carbon dioxide) through additional forest and tree cover by 2030. There are ongoing efforts by the Ministry of Environment, Forest and Climate Change, such as the National Afforestation Programme (NAP) and the Green India Mission (GIM), aimed at afforestation and plantation activities. GIM is one of eight 'National Missions' under the National Action Plan on Climate Change.
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Over the past few years, India has experienced significant greening, driven by irrigated agriculture and plantations. But to be an effective climate mitigation tool, the greening should translate to effective carbon sequestration. A new scientific study says this is not happening.
Published in the journal Resources, Conservation & Recycling last month by two scientists from IIT-Kharagpur, the study shows that in the last decade (2010-2019), carbon stock capacity declined by 5 per cent compared to the decade before (2000-2009). In some regions like the eastern Himalaya and the Western Ghats, the decline in forest carbon stock is as high as 17-20 per cent.
'Green-ness is on the outside. It is structural. And carbon uptake is a functional quality,' said Rahul Kashyap, the lead author of the study and Prime Minister's Research Fellow (PMRF) at CORAL, IIT Kharagpur. 'For Indian forests, the outer green-ness is increasing, but functional health, of which a key aspect is the ability to act as carbon sinks, is declining,' he added.
The study notes how greening is translating to biomass production at lower rates than before. And the reason is reduced soil moisture due to climate change-driven warming and activities like deforestation and plantations. And this trend is set to continue till 2100.
Jayanarayanan Kuttippurath, the other author of the study and an Assistant Professor at IIT Kharagpur, said, 'The atmosphere is continuously warming. The mitigation action the world is taking [to reduce the usage of fossil fuels] is not enough. And we are continuously emitting carbon dioxide and other greenhouse gases. On top of this, we have forest fires and deforestation. This is why the translation from green-ness to biomass is also decreasing.'
Plants under stress
Temperatures are rising and soil moisture is decreasing, causing heat stress in plants, which are unable to produce biomass and sequester carbon dioxide at rates they used to earlier. 'There are forest-dwellers and their livelihood. We have a big forest economy, and this will also be compromised. In addition to this, we have a net-zero target by 2070. The declining carbon stock capacity is a big concern,' Kuttippurath said.
The study is first-of-its-kind to estimate Ecosystem Photosynthetic Efficiency (EPE), which is a measure of translation of greenness to carbon uptake, across Indian forests. It finds that the largest declines in EPE are in the Eastern Himalaya, the Western Ghats, and the Indo-Gangetic Plain, which, interestingly, have the highest EPE in the country.
'We are losing quality forests'
Over the last two decades, reports by the Forest Survey of India have shown how green cover and forest cover in India are increasing. But this includes lots of areas outside historical forests, such as plantations and agroforestry.
'Day by day, we are losing quality forests. We have different kinds of forests with different species and different kinds of disturbances like infrastructure development and invasive species. And climate change exacerbates the impacts of disturbances,' said Purabi Saikia, Associate Professor at the Department of Botany in Banaras Hindu University. As an ecologist, Saikia has conducted ground studies of forests across the country in States like Arunachal Pradesh, Madhya Pradesh, Jharkhand, and Tamil Nadu.
'Invasive species like lantana and parthenium are also part of the green cover, but they have low carbon sequestration compared to native trees,' Saikia explained. 'So, yes. We have increasing green cover but not in terms of forest productivity or ecosystem productivity,' she added.
However, since the study is based purely on remote-sensing and predictions, Saikia called for more analysis based on ground-truthing. 'It is an important finding and the paper presents a good idea to carry forward with ground work in forests,' she added.
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In the paper, too, the authors note that India needs more studies on forest carbon dynamics that integrate remote sensing observations and ground-based measurements.
Declining forest sink capacity is a global issue, too. A study published last month showed that forest sink capacity in Europe, too, is 'rapidly declining'. And yet another study from July showed that tropical forests the world over are losing drought resilience.
On the issue of declining forest carbon stock in India, the authors warn that it is 'imperative' not to misconstrue forest-based mitigation as a solution to climate change and that forest protection and afforestation measures should be done more scientifically to secure historical natural forests.
Rishika Pardikar is an environment reporter based in Bengaluru who covers science, law, and policy.
