India’s Fading Lungs

By all accounts, green vegetation is a quiet, tireless ally in the global struggle against climate change. Trees, crops, and forests inhale carbon dioxide, temper the planet’s fever, and exhale the oxygen that sustains life. Yet, the effectiveness of this natural carbon sink is not static but bends under the weight of climate extremes, sometimes releasing more than it sequesters. In India, a country whose vast landscapes have historically absorbed more carbon than they emitted, scientists are now watching an unsettling trend - a slow but steady weakening of this once-reliable buffer.

A team of researchers from the Indian Institute of Science Education and Research Bhopal (IISERB), working with experts from Germany, the United Kingdom, and India’s National Remote Sensing Centre, has devised an innovative method to track how well the country’s greenery is coping. The technology, which links plant fluorescence - an almost imperceptible glow - to carbon uptake, offers unprecedented insights into India’s ecosystem dynamics. Plants, it turns out, emit a faint, measurable radiance during photosynthesis, a spectral whisper of their metabolic activity. By analysing these emissions with high-resolution satellite instruments such as the Sentinel-2’s TROPOMI sensor, scientists can determine how efficiently vegetation is pulling carbon from the air.

India’s vegetation has long acted as a natural carbon sink, absorbing more CO₂ than it emits. The overall balance between this uptake and release of CO₂ is known as the net ecosystem exchange (NEE). When the NEE is positive, it means vegetation is releasing more carbon than it absorbs, and when it’s negative, it indicates that the vegetation is effectively storing carbon. For the last decade, India’s ecosystems absorbed more carbon than they emitted annually, with annual NEE estimates ranging from -380 to -530 million tonnes of carbon annually. This level of carbon sequestration is presently impressive but tends to show declining in response to climate extremes, underscoring the critical role of vegetation in the context of climate change mitigation and adaptation.

Evergreen forests are India’s most efficient carbon sinks, capturing vast amounts of CO₂ through photosynthesis. Croplands, though less effective per hectare, contribute significantly due to their sheer expanse. But Central India’s deciduous forests tell a different story. Each year, they release 210m tonnes of carbon, as respiration outpaces absorption, making them net emitters rather than absorbers. These findings are crucial for shaping climate policies and ensuring that India’s green cover remains an asset in its net-zero ambitions.

Agricultural lands, sprawling across the subcontinent, contribute to carbon capture, albeit less efficiently than forests. Yet, their sheer scale makes them crucial players in India’s broader climate strategy. The ability to fine-tune policies around such findings is where this research proves invaluable. Understanding which ecosystems are underperforming and why allows policymakers to intervene strategically, whether through afforestation projects, conservation efforts, or sustainable agricultural practices.

The IISERB team’s approach also brings a necessary precision to a field that has long relied on broad-stroke global models, often lacking localized ground data. Their ten-year analysis, integrating thousands of observational records, offers a more responsive and sensitive metric for measuring India’s carbon flux. The work, part of an Indo-German collaboration supported by the Max Planck Society and India’s Anusandhan National Research Foundation, aligns with India’s commitment to achieving net-zero emissions by 2070. But commitment alone does not guarantee results.

The fundamental question remains whether the country’s natural carbon sinks will hold the line against accelerating climate change? Forests are resilient, but not invincible. Without decisive intervention, the nation’s green lungs will continue to falter, shifting from allies in carbon sequestration to unwilling accomplices in its release.

(The author is an Associate Professor and Head of the Max Planck Partner Group at IISER Bhopal.)