Melting glaciers caused by climate change are responsible for a 48 per cent surge in the amount of water trapped in unstable glacial lakes over 30 years, scientists have discovered.
Researchers tracked glacial lake volume since 1990 using more than a quarter of a million NASA satellite images to create a ‘near-global database’ of glacial lakes,
The study also reveals the number of lakes and the total area covered by lakes has increased by 53 and 51 per cent, respectively.
Researchers hope that by understanding how water from glaciers ends up in these lakes they can predict when and how it will reach the ocean, its final destination.
Currently, the amount of water trapped in glacial lakes, 156.5 cubic km, would cause a sea level rise of 0.43 mm if it was released into the oceans, the study reveals.
Pitured: a map compiled from 254,795 satellite images of glacial lakes. This map shows the size and location of glacial lakes according to the latest study. Each dot represents a single glacial lake. Yellow dots are larger than green, which are larger than blue dots
Pictured: the retreating Barry Glacier, which has succumbed to the effects of climate change. new study found melting glaciers has caused by climate change is responsible for a 48 per cent surge in the amount of water trapped in unstable glacial lakes over 30 years
‘We have known that not all meltwater is making it into the oceans immediately,’ lead author Dan Shugar, a geomorphologist at the University of Calgary, said.
‘But until now there were no data to estimate how much was being stored in lakes or groundwater.’
The findings, published Monday in Nature Climate Change, will help identify potential hazards to communities downstream of these often unstable lakes, he said.
They will also improve the accuracy of sea level rise estimates through better understanding of how quickly water from glaciers makes it to the sea.
Between 1994 and 2017, the world’s glaciers, especially in high-mountain regions, shed about 6.5 trillion tonnes in mass, according to earlier research.
‘In the past 100 years, 35 per cent of global sea-level rises came from glacier melting,’ Anders Levermann, climate professor at the Potsdam Institute for Climate Change Impact, told AFP.
Pictured, the disappearance of two St. Patrick Bay ice caps this summer. Images taken by NASA in 2015 and 2020 reveal how the polar ice caps have vanished in half a decade due to global warming. Left, one of the caps in 2015. Right, the same location on July 14, 2020
The other main sources of sea level rise are ice sheets and the expansion of ocean water as it warms.
Earth’s average surface temperature has risen one degree Celsius since preindustrial times, but high-mountain regions around the world have warmed at twice that pace, accelerating glacier melt.
Unlike normal lakes, glacier lakes are unstable because they are often dammed by ice or sediment composed of loose rock and debris.
When accumulating water bursts through these accidental barriers, massive flooding can occur downstream.
Known as glacial lake outbursts, this kind of flooding has been responsible for thousands of deaths in the last century, as well as the destruction of villages, infrastructure and livestock, according to the study, published in Nature Climate Change.
The most recent recorded incident was a glacial lake outburst that washed through the Hunza Valley in Pakistan in May.
In January, the UN Development Programme estimated that more than 3,000 glacial lakes have formed in the Hindu Kush-Himalayan region, with 33 posing an imminent threat that could impact as many as seven million people.
The new study, based on 250,000 scenes from NASA’s Landsat satellite missions, estimates current glacial lake volume at more than 150 cubic kilometres (37 cubic miles), equivalent to one-third the volume of Lake Erie in the United States or twice the volume of Lake Geneva.
A decade ago, it would have not been possible to process and analyse that volume of data, said Shugar.