Within the largest-ever examine of glacial lakes, researchers utilizing 30 years of NASA satellite information have discovered that the quantity of these lakes worldwide has elevated by about 50% since 1990 as glaciers soften and retreat on account of local weather change.
The findings, revealed in the journal Nature Local weather Change, will support researchers assessing the potential hazards to communities downstream of these typically unstable lakes and assist enhance the accuracy of sea degree rise estimates by advancing our understanding of how glacial meltwater is transported to the oceans.
Glaciers are retreating on a near-global scale and this examine offers scientists with a clearer image of how a lot of this water has been saved in lakes.
“We now have recognized that not all meltwater is making it into the oceans instantly,” stated lead writer Dan Shugar of the College of Calgary in Canada. “However till now there have been no information to estimate how a lot was being saved in lakes or groundwater.” The examine estimates present glacial lake volumes complete about 37.4 cubic miles (156 cubic kilometers) of water, the equal of about one-third the quantity of Lake Erie.
Within the largest-ever examine of glacial lakes, researchers utilizing a 30-year satellite information document have discovered that the quantity of these lakes worldwide has elevated by about 50% since 1990. Credit score: NASA
Shugar and his collaborators from governments and universities in Canada, the USA, and the UK, working beneath a grant from NASA’s Excessive Mountain Asia Program, initially deliberate to make use of satellite imaging and different remote-sensing information to check two dozen glacial lakes in Excessive Mountain Asia, the geographic area that features the Tibetan Plateau and surrounding mountain ranges, together with the Himalaya.
“We wrote scripts in Google Earth Engine, a web based platform for very massive analyses of geospatial information, to look solely at Excessive Mountain Asia, after which determined to have a look at all glacial lakes in the world,” Shugar stated. “From there, we had been capable of construct a scaling relationship to estimate the quantity of the world’s glacial lakes based mostly on the realm of this massive inhabitants of lakes.”
The crew in the end analyzed greater than 250,000 scenes from the Landsat satellite missions, a joint NASA/U.S. Geological Survey program. A decade in the past it could not have been potential to course of and analyze this quantity of information. The crew regarded on the information in 5 time-steps starting with 1990 to look at all of the glaciated areas of the world besides Antarctica and analyze how glacial lakes modified over that interval.
Shugar factors out that whereas water from melting glaciers saved in glacial lakes is a comparatively small contributor to general sea degree rise, it may have a serious affect on mountain communities downstream of these glacial lakes.
Glacial lakes should not steady just like the lakes in which most individuals are used to swimming or boating as a result of they’re typically dammed by ice or glacial sediment known as a moraine, which consists of free rock and particles that’s pushed to the entrance and sides of glaciers. Slightly, they are often fairly unstable and might burst their banks or dams, inflicting large floods downstream. These varieties of floods from glacial lakes, generally known as glacial lake outburst floods, have been accountable for 1000’s of deaths over the previous century, in addition to the destruction of villages, infrastructure, and livestock. A glacial lake outburst flood affected the Hunza Valley in Pakistan in Could 2020.
“This is a matter for a lot of elements of the world the place folks dwell downstream from these hazardous lakes, largely in the Andes and in locations like Bhutan and Nepal, the place these floods will be devastating,” Shugar stated. “Thankfully, organizations just like the United Nations are facilitating quite a bit of monitoring and a few mitigation work the place they’re reducing the lakes to attempt to lower the dangers.”
In North America, the dangers posed by a glacial lake outburst flood are decrease.
“We don’t have a lot in the way in which of infrastructure or communities which can be downstream,” Shugar stated. “However we’re not proof against it.”
Reference: “Rapid worldwide progress of glacial lakes since 1990” by Dan H. Shugar, Aaron Burr, Umesh Ok. Haritashya, Jeffrey S. Kargel, C. Scott Watson, Maureen C. Kennedy, Alexandre R. Bevington, Richard A. Betts, Stephan Harrison and Katherine Strattman, 31 August 2020, Nature Local weather Change.