published in the journal Nature Climate Change<\/a>, will aid researchers assessing the potential hazards to communities downstream of these often-unstable lakes and help improve the accuracy of sea level rise estimates by advancing our understanding of how glacial meltwater is transported to the oceans.<\/p>\nGlaciers 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.<\/p>\n
\u201cWe have known that not all meltwater is making it into the oceans immediately,\u201d said lead author Dan Shugar of the University of Calgary in Canada. \u201cBut until now there were no data to estimate how much was being stored in lakes or groundwater.\u201d The study estimates current glacial lake volumes total about 37.4 cubic miles (156 cubic kilometres) of water, the equivalent of about one-third the volume of Lake Erie.<\/p>\n
Shugar and his collaborators from governments and universities in Canada, the United States and the United Kingdom, working under a grant from NASA\u2019s High Mountain Asia programme, 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.<\/p>\n
\u201cWe wrote scripts in Google Earth Engine, an online platform for very large analyses of geospatial data, to look only at High Mountain Asia, and then decided to look at all glacial lakes in the world,\u201d Shugar said. \u201cFrom there, we were able to build a scaling relationship to estimate the volume of the world\u2019s glacial lakes based on the area of this large population of lakes.\u201d<\/p>\n
The team ultimately analysed more than 250,000 scenes from the Landsat satellite missions, a joint NASA\/U.S. Geological Survey programme. A decade ago it would not have been possible to process and analyse this volume of data. The team looked at the data in five time-steps beginning with 1990 to examine all the glaciated regions of the world except Antarctica and analyse how glacial lakes changed over that period.<\/p>\n
Shugar pointed out that 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.<\/p>\n