Warming and drying cut India’s forest carbon sequestration by 5–12 per cent
IIT Kharagpur study shows greening does not equal healthy forests
Eastern Himalayas, Western Ghats and north-east among hardest hit
Wildfires, deforestation and land-use change compound climate stress
India contributes ~7 per cent to global carbon sinks with just 2 per cent forest cover
India may be gaining tree cover, but its forests are growing weaker. Forests across the country are showing signs of declining health under the stress of a warming climate, reducing their ability to absorb carbon dioxide, according to a new study.
The analysis, the first of its kind, was conducted by researchers at Indian Institute of Technology (IIT), Kharagpur. It found that despite an apparent increase in India’s green cover, there is a mismatch between forest growth and the carbon being sequestered.
The study, published in the journal Resources, Conservation & Recycling, is the first to link increases in forest “greenness” with changes in carbon sequestration. The authors analysed the climate's influence on the forests’ efficiency in using carbon for growth and water for photosynthesis.
It showed a decline in photosynthetic efficiency, carbon absorption and water-use efficiency in forests across India, both under present and projected climate conditions.
The research estimated how greenness translates into carbon sequestration, measured through carbon-use efficiency and water-use efficiency. It found that reduced soil moisture and rising temperatures are adding stress to forest ecosystems, conditions likely to worsen in the future.
Although India accounts for just 2 per cent of the world’s forest cover, it contributes about 7 per cent to global carbon sinks. The country also contains four of the planet’s 36 biodiversity hotspots, including two of the eight most critical.
On average, carbon uptake fell by 5 per cent, with losses reaching 12 per cent in parts of the north-east and the Eastern Ghats, the authors wrote in the paper. “The study shows that despite increasing green cover, it does not mean the forests are healthy. Overall, India’s forests are weak and non-resilient to the impacts of climate change,” study co-author Jayanarayanan Kuttippurath, associate professor at IIT Kharagpur’s Centre for Oceans, Rivers, Atmosphere and Land Science, told Down To Earth.
Drier conditions and climate change are leading to low soil moisture, adding stress to Indian forests and impacting their health, Kuttippurath said. The conditions are likely to worsen in the current and future climate regime.
The study analysed forests in six categories: Western Himalaya, Eastern Himalaya, North East, Indo-Gangetic Plain, Central India, and Western Ghats and Peninsula. While carbon uptake increased in some regions, such as the Western Himalayas, Central India and the North East, there were sharp declines in the Eastern Himalayas, Western Ghats, parts of Central India and the Indo-Gangetic Plain.
Declines were most pronounced in pristine forests of the Eastern Himalayas and the Western Ghats, areas also experiencing high soil moisture stress (-20 to -5 per cent), significant warming (0.2-0.6 degrees Celsius), and greater climatic water deficit (CWD), vapour pressure deficit (VPD) and atmospheric aridity of 10-20 per cent.
The researchers linked the decline in forest health to reduced rainfall (-1.1 per cent), declining soil moisture (-2.2 per cent), and rising aridity (CWD +8.2 per cent, VPD +0.4 per cent).
These stresses are compounded by more frequent wildfires, which increased by 8.7 per cent between 2010 and 2019 compared to the previous decade, and recurring landslides in the Himalayan region.
Forests in the lower Western Himalayas, Eastern Himalayas, Western Ghats, North East and large parts of Central India were found to be especially non-resilient to precipitation deficits, soil drying and wildfire outbreaks.
The study said, “The decline in the health of Indian forests is due to reduced moisture availability with decreased precipitation by 1.1 per cent, reduction of soil moisture by 2.2 per cent and increased aridity measured collectively using parameters CWD and VPD which was found to have increased by 8.2 per cent and 0.4 per cent respectively.”
Human pressures further undermine forest resilience. The study noted that over 50 per cent of forests in the North East and large parts of Central India show moderate to low ecological integrity, with fragmentation driven by land-use change.
For example, the Western Ghats lost 7 per cent of their forest cover between 2001 and 2020, while forested areas across India saw human populations rise by 40-60 per cent between 2000 and 2019.
India’s forests are also relatively young: most are between 30 and 60 years old, concentrated in the foothills of the Himalayas, North East, Central India, and the Western Ghats and Peninsula. Younger forests (under 30 years) dominate parts of the Ghats, eastern Central India and the Indo-Gangetic Plain, while older forests (60-150 years) are found mainly in the higher Himalayas.
The loss of older forests — often to agricultural or urban expansion — has further weakened carbon sequestration. Central India and the Western Ghats recorded the largest losses from 2001 to 2019.
“This explains the decline in carbon sequestration in Indian forests with its peak in the pristine forests of Eastern Himalayas and.Western Ghats and Peninsula Thus, we find declining forest carbon sink potential in India despite greening due to both changing climate and anthropogenic intrusions,” the paper said.
Looking ahead, the researchers warned that accelerated warming could push carbon sequestration down by as much as 15 per cent between 2040 and 2050, while forest biomass could shrink by 23 per cent and leaf carbon-to-nitrogen ratios by 14 per cent.
Future warming, Kuttippurath added, could also trigger additional carbon dioxide release, leading to saturation of carbon uptake and compounding emissions.
“The current carbon sequestration of India’s forests — about 7 per cent of global carbon sinks — may already have been reduced by 1-2 per cent,” he said. “The next step is to assess how much of this loss has already occurred.”