Uttarakhand green cover sees slow rupture over two decades, satellite data shows

Uttarakhand's green cover stretches across its forests and valleys and the state remains under the country's top tourist destinations. However, its beauty remains in danger today with an analysis of two-decade data of the state's vegetation shows how the region responds to climate change more horrificly and how its rhythms are starting to falter.

Mountain ecosystems respond more quickly than most landscapes to shifts in temperature and rainfall. Moreover, the debate over development in Uttarakhand continues to resurface as the hill state faces recurring flash floods and landslides almost every year, raising questions over the sustainability of infrastructure projects in ecologically fragile zones and the balance between growth and environmental safety.

To map these changes, researchers from the Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital — an autonomous institute under the department of science and technology — collaborated with Indian and international partners using Google Earth Engine (GEE), a cloud-based platform designed to process massive volumes of satellite data.


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GEE allows scientists to analyse land degradation, urban expansion, dust transport, and temperature trends without the logistical burden of storing and managing raw satellite imagery.

The team examined records spanning 2001 to 2022, focusing on a widely used indicator of plant health known as the Normalised Difference Vegetation Index (NDVI).

The index tracks how vegetation reflects light: low values indicate rock, sand, water, or snow, while higher readings point to dense forests, croplands, and wetlands. Researchers also analysed the Enhanced Vegetation Index (EVI), which offers greater accuracy in regions with thick biomass.

Green Patters

Findings from the study, led by Umesh Dumka of ARIES and published in Environmental Monitoring and Assessment, reveal pronounced seasonal cycles. NDVI and EVI values peak after the monsoon, when the hills turn lush and green, and drop to their lowest levels in the dry months before the rains.

While monthly and annual variations follow familiar patterns, long-term trends show a gradual but steady decline.

The researchers attribute this erosion of greenery to deforestation, the expansion of agriculture, illegal logging, and rising pollution from growing towns and industrial activity.

Pollution, they note, does not spread evenly. Certain pockets endure heavier damage, compounding the stress caused by warming temperatures and increasingly erratic rainfall. Together, these pressures threaten wildlife habitats, river systems, and the livelihoods of millions who depend on the Himalayan ecosystem downstream.

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Using time-series maps generated through GEE, the scientists compared vegetation trends with climate data and applied Pearson’s correlation to identify how closely the two are linked. This approach enabled them to pinpoint districts where vegetation loss has been most severe.

Distressed Himalayas

The authors argue that satellite-based monitoring can function as an early-warning system. By identifying vulnerable zones in advance, authorities can guide afforestation efforts, regulate construction, and curb emissions before ecological losses become irreversible.

The Himalayas, they suggest, are signalling distress in a language of pixels and numbers. Whether policymakers choose to listen may determine how resilient the region remains in the decades ahead.