28 years of Earth’s surface changes on Google

Watch a city expand or a glacier shrink through a series of satellite images; see the altering landscape at four spots in India  

By Kundan Pandey, Anupam Chakravartty
Published: Tuesday 21 May 2013

It is now possible to track how the landscape across the world has changed in the recent past. Google has released a new environment monitoring platform, Google Earth Engine, which brings satellite images of the planet’s surface over the past 28 years on to viewers’ screens, giving people the opportunity to look at land surface changes at any place on the earth.

Platforms like Google Maps and Google Earth show only current views of different areas, but the new viewer shows images of a region from 1984 to 2012 in quick succession like a slide show. One can watch a city expand, or a rainforest shrink.

The tool has exciting potential applications—detecting deforestation, classifying land cover, estimating forest biomass and carbon, and mapping the world’s road-less areas.

The tool released on May 16 relies on US space agency NASA’s archive of images from Landsat. Google Earth Engine available online is an invaluable tool for researchers to detect changes, map trends and quantify differences on the Earth's surface


Must see spots in India


Take for instance the Gangotri glacier in the Himalaya. Satellite images from Google released now show the extent of snow melting at the glacier since 1984 (see images below).The Gangotri glacier in the Himalaya is the source of water for the Ganga, the major perennial river which supplies water to the fertile agricultural plains of North India. Studies show the glacier is retreating rapidly at a speed of about 30 metre every year. If warming continues, it will melt rapidly, releasing large volumes of water, but once this source begins to dry, there may be dry periods with very little water flowing in the river

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Google's Earth Engine
Source: Google Earth Engine

You could go to the Google Earth Engine to explore changes in landscape in any part of the world. Down To Earth has picked these five must-see locations in India for readers

Kevadia, Gujarat
The Sardar Sarovar Dam is on the Narmada River in Gujarat state, 170 km upstream from where the river flows into the Gulf of Khambhat in the Arabian Sea. According to Narmada Bachao Andolan, about 12,000 local residents face submergence of their land and homes during the monsoons as the water levels in the reservoir increase. The Union government has allowed Sardar Sarovar Narmada Nigam Limited to increase the dam height to 90 metre. The canal network supported by the dam only covers 30 per cent of the network.
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Majuli, Brahmaputra river, Assam
Majuli, the world’s largest river island, faces the challenge of erosion as the mighty and turbulent Brahmaputra washes away the soil at its boundaries during the monsoon season. The Brahmaputra Board claims that the anti-erosion measures it has put in place have been able to reclaim 20 sq km of land in 2013. Since 2001, the island has lost about 410 sq km of its area.
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Sundarbans, West Bengal
The 20,000 sq km Sundarban mangroves are spread across the Ganga delta in coastal Bangladesh and south eastern West Bengal of India. The precious mangroves support many endangered flora and fauna and a large number of people in what is one of the world's most densely populated pockets. Climate change characterised by cyclones have caused extensive damage to the mangroves, while sea level in the Sundarbans has risen at an average rate of 3.14 cm a year over the past two decades - much higher than the global average of 2 mm a year 
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Yamunotri glacier, Uttarakhand
Along with Gangotri, this glacier faces a similar challenge due to climate change. Yamunotri glacier is the source of Yamuna river, another major river in north India which unites with the Ganga at Allahabad. Like the Gangotri, this glacier, too, faces the threat of climate change
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Loktak Lake Manipur
Loktak Lake is a freshwater lake near Imphal in the north-eastern state of Manipur. It supports a fishing community. The Manipur government sanctioned the Loktak Lake project in 2010 to clear "encroachments" from the lake. The clearing up has lead to destruction of the floating reed islands inside the lake
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