New Delhi, Feb. 5 -- When it comes to climate change, cars, factory chimneys, and power plants burning massive amounts of biomass are often blamed, and they are indeed major contributors to this issue. However, other contributors are mostly ignored, such as livestock, land-use change, fertilisers, abandoned oil or gas wells, etc. Among them, the most important factor is the retrogressive change of our natural carbon sinks into carbon sources. A carbon sink, alternatively called a carbon sponge, is any system-mostly natural-that absorbs more CO2 than it emits and keeps it stored in living plant biomass and in the soil. Forests, grasslands, soils, wetlands, and oceans are examples of such systems, and alarmingly, they have started betraying us-not by absorbing carbon, but by releasing it back into the atmosphere.
Weakening carbon absorption amid increasing forest cover
Forests in India are estimated to absorb around 15 crore metric tonnes of CO2 every year and rank among the top 10 global carbon sinks, as per recent analysis by the UN's Food and Agriculture Organisation (FAO). Yet, beneath these numbers, there is a worrying trend. Recent scientific studies show that although tree cover has increased partly in the country (30,193 sq km from 2014 to 2024), the health and carbon-absorbing ability of these forests are constantly weakening under the stresses produced by climate change. Drying soils and warming climatic conditions have reduced carbon intake by around 12 per cent, even though tree cover has increased in some parts of the country, according to a 2025 study published by IIT Kharagpur. The scenario is even worse in cities. A study published in the Journal of Sustainable Futures in 2025 revealed that between 2013 and 2022, due to uneven expansion of built-up areas and wetlands, carbon capture had reduced to 34 per cent in Pune city.
Impacts of carbon-emitting ecosystems
The urgent concern for an ordinary citizen arises when a carbon sink becomes a carbon emitter: it releases more carbon than it absorbs, and the consequences are direct and everyday. As a result, summers are marked by extremely high temperatures, leading to excessive evaporation and more erratic rainfall during the monsoon, unwanted flash floods in cities, and declining soil health, which affects cultivation. This is not a distant climate warning-it is a present-day crisis unfolding in our fields, streets, and homes.
Land-use change impacting carbon storage
Land-use change is one of the major reasons for this retrogressive shift. When natural vegetation, fertile soils, and wetlands are converted for development, infrastructure, or even agriculture, the carbon stored in these systems is emitted back into the air. Often ignored, soil is a massive reservoir of CO2 (2,430 crore metric tonnes) and is the largest carbon storehouse among land-based ecosystems. Studies suggest that Indian soils contain significant amounts of organic carbon, and when disturbed through heavy tilling, burning, or land-use change, they begin emitting CO2 instead of storing it. Wetlands cover only 5.12 per cent of the country's landmass, yet they can store more carbon than many forests. For example, some wetlands in Northeast India store more than six per cent carbon compared to just one per cent in nearby farmland soils in the top layers. When wetlands are drained, dried, or filled due to land-use change, the carbon stored deep within these systems is released into the atmosphere.
Measures to protect and restore carbon sinks
Naturally, the question arises: how do we maintain these accumulated carbon stocks? Some practical solutions coexist with this concern:
* Reducing soil disturbance to enhance soil carbon: Farming techniques with minimal tillage, retention of crop residues, and increased organic matter content can help soil sequester more carbon from the atmosphere.
* Protection and restoration of wetlands and floodplains: These systems must be recognised as natural carbon and water buffers rather than being drained or filled for short-term development. Restoring even small wetlands around towns can help stabilise the local climate, improve water availability, and preserve stored carbon.
* Valuation of mature trees and diverse vegetation: Mature trees and native plant communities store far more carbon over their lifetimes than cutting them down and compensating with plantations.
* Promoting agroforestry and mixed land use: Combining trees with crops and pastures enhances a landscape's carbon-absorbing capacity while also supporting farmers' livelihoods.
India's natural ecosystems are not merely scenic beauty or environmental add-ons; they are active partners in climate regulation. Once disturbed, they shift from carbon sinks to carbon sources, intensifying climate challenges. If carbon sinks continue to collapse, no amount of emission reduction alone will be sufficient to protect us. But when cared for and conserved, these systems collectively strengthen nature's carbon reservoir and our resilience to climate change.
Views expressed are personal. The writer is a Research Associate at the Mobius Foundation and holds a PhD degree in Ecology & Environmental Science from Assam University, Silchar
Published by HT Digital Content Services with permission from Millennium Post.