Global survey using NASA data shows 50% increase in glacial lakes since 1990

NASA's photo of Lake Imja (As per NASA, Lake Imja near Mount Everest in the Himalaya is a glacier lake that has grown to three times its length since 1990)

Washington: The global climate change has reportedly resulted in melting and retreating glaciers across the world which has led to the increase of the glacial lakes by 50 per cent since 1990, shows a global survey using National Aeronautics and Space Administration (NASA) data.

"In the largest-ever study of glacial lakes, researchers using 30 years of NASA satellite data have found that the volume of these lakes worldwide has increased by about 50% since 1990 as glaciers melt and retreat due to climate change," said NASA on Monday (August 31, 2020).

As per NASA, the findings which are published in the journal Nature Climate Change will aid researchers to assess the potential hazards to communities downstream of these often unstable lakes and will also help improve the accuracy of sea-level rise estimates by advancing the understanding of how glacial meltwater is transported to the oceans.

"Glaciers are retreating on a near-global scale and this study provides scientists with a clearer picture of how much of this water has been stored in lakes," said NASA.

NASA also quoted lead author Dan Shugar of the University of Calgary in Canada as saying, "We have known that not all meltwater is making it into the oceans immediately. But until now there were no data to estimate how much was being stored in lakes or groundwater." 

Shugar and his collaborators from governments and universities in Canada, the United States, and the United Kingdom, working under a grant from NASA’s High Mountain Asia Program, initially planned to use satellite imaging and other remote-sensing data to study two dozen glacial lakes in High Mountain Asia, the geographic region that includes the Tibetan Plateau and surrounding mountain ranges, including the Himalaya.

Shugar added that they wrote scripts in Google Earth Engine to look only at High Mountain Asia, and then decided to look at all glacial lakes around the world.

"From there, we were able to build a scaling relationship to estimate the volume of the world’s glacial lakes based on the area of this large population of lakes," stated Shugar.

The team reportedly analyzed more than 2.5 lakh scenes from the Landsat satellite missions and looked at the data in five time-steps beginning with 1990 to examine all the glaciated regions of the world except Antarctica and analyze how glacial lakes changed over that period.

"While water from melting glaciers stored in glacial lakes is a relatively small contributor to overall sea-level rise, it can have a major impact on mountain communities downstream of these glacial lakes," opined Shugar.

Notably, the glacial lakes are not stable like the lakes in which people are used to swimming or boating and these are often dammed by ice or glacial sediment called a moraine, which is composed of loose rock and debris that is pushed to the front and sides of glaciers.

The glacial lakes can also burst their banks or dams which may result in causing massive floods downstream. These floods from glacial lakes are known as glacial lake outburst floods and have been responsible for thousands of deaths over the past century, as well as the destruction of villages, infrastructure, and livestock. 

Earlier in May 2020, a glacial lake outburst flood affected the Hunza Valley in Pakistan.

"This is an issue for many parts of the world where people live downstream from these hazardous lakes, mostly in the Andes and in places like Bhutan and Nepal, where these floods can be devastating," said Shugar. 

"Fortunately, organizations like the United Nations are facilitating a lot of monitoring and some mitigation work where they’re lowering the lakes to try and decrease the risks," added Shugar.

The study estimates current glacial lake volumes total about 37.4 cubic miles (156 cubic kilometers) of water which is the equivalent of about one-third the volume of Lake Erie.