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Warming oceans and rising atmospheric dryness are intensifying ecological droughts across India’s forests and croplands.
Forests in the Himalayas, Northeast, Central India and the Western Ghats are showing clear signs of vegetation stress and browning.
Human pressures such as deforestation and rapid population growth are compounding drought risks.
IIT Kharagpur scientists warn that India’s key carbon sink regions may turn into carbon sources if trends continue.
The study urges policymakers to integrate ecological drought adaptation into sustainability planning.
Ecologically fragile forests in the Western Ghats, the Himalayas, and the Northeast, along with croplands in central India, are increasingly facing ecological droughts, scientists from the Indian Institute of Technology (IIT) Kharagpur have warned.
Ecological droughts are defined as prolonged periods of water deficit that push ecosystems beyond critical thresholds, disrupting their structure, functioning, biodiversity and services, according to a new study published in the journal Nature Communications Earth & Environment.
The researchers found that warming oceans and increasing atmospheric dryness, compounded by human disturbances such as deforestation, are driving these droughts. Between 2000 and 2019, meteorological aridity and ocean warming contributed 23.9 per cent and 18.2 per cent respectively to ecological droughts across India, while land evaporative aridity and atmospheric aridity added a further 14 per cent and 12.4 per cent. Soil moisture, temperature and precipitation were also found to affect vegetation stress.
The increase in ecological droughts has led to widespread browning — a decline in vegetation health — during the monsoon, particularly in croplands of the eastern Indo-Gangetic Plains (IGP) and southern India, and in forested regions of the Himalayas, Northeast and central India. The browning of croplands in eastern IGP and southern India, the study notes, is driven by warming-induced soil moisture stress.
Forests in the south-western and eastern Himalayas, Northeast India, central India and the Western Ghats show significant evidence of ecological droughts. Many of these forest areas have experienced extensive human modification, including deforestation and changing land use.
The study highlighted that forest landscape integrity is particularly low in southern parts of the Northeast, sections of the western Himalayas, central India and the Western Ghats. Among all regions, the Indo-Gangetic Plains show the weakest forest integrity.
Population pressure has also intensified these vulnerabilities. Between 2000 and 2019, forest regions such as the Himalayas, Northeast, IGP, central India and Western Ghats saw population growth of 40-60 per cent, leading to further fragmentation and degradation, the report said.
The authors also observed a potential westward shift in the summer monsoon system, which could exacerbate ecological droughts and vegetation browning in eastern and southern India. “The rising ecological droughts due to enhanced aridity, ocean warming and human interventions drives browning during the Indian Summer Monsoon (ISM) season in India,” said Rahul Kashyap, the lead author of the study.
At least half the total area across 16 of India’s 24 major river basins is now at high risk of vegetation droughts due to a weakening monsoon, the study warned. “More than half of the total area for each vegetation type exhibits a lack of resilience to vegetation droughts. This highlights the vulnerable state of terrestrial ecosystems in India to moisture stress,” it said.
Vegetation droughts, the authors explained, refer to reduced vigour in both natural and cultivated vegetation due to decreased moisture availability. Even regions that once had ample water and warmth to support plant life are now facing drought-like ecological stress.
The researchers warned that browning in key carbon sink regions such as the Himalayas and the Northeast is particularly concerning. “Ecological droughts weaken forest carbon sinks, reduce crop yields, and threaten the health and functioning of terrestrial ecosystems,” they wrote. “Tree mortality may also increase due to carbon starvation and hydraulic failure.”
If unchecked, rising ecological droughts could destabilise India’s forests, transforming them from carbon sinks into carbon sources. The study cautioned that ecological droughts and vegetation browning reinforce each other in a dangerous feedback loop.
Given that the monsoon season is critical for agriculture and forest growth, the authors warned that ecological droughts during this period pose a major threat to India’s socio-economic stability. They called for urgent action to integrate ecological drought adaptation strategies and regional planning with national sustainability policies.
“It is high time to consider the ecological ramifications of moisture stress on ecosystems, into policy making to attain sustainability,” Kashyap said.
The study recommended further research on forecasting, adaptation and mitigation strategies for ecological droughts, particularly in India, where a large population depends on agriculture and forest-based livelihoods.