A multinational team of researchers has catalogued data on 773 subglacial lakes — repositories of ancient climate conditions, provide habitats for life and modulate ice flow — including 675 subglacial lakes from Antarctica (59 newly-identified), 64 from Greenland, two beneath the Devon Ice Cap, six beneath Iceland’s ice caps and 26 from valley glaciers.
Global inventory of subglacial lakes: (a) inventory of northern hemisphere subglacial lakes (SGLs); the top right inset shows the location of part a (red box) in the northern hemisphere; (b) inventory of SGLs beneath the Antarctic Ice Sheet; the extents of larger lakes (such as PEL Lake and Lake Vostok) are defined by blue polygons; red circles represent stable lakes identified from radio-echo sounding (RES), and blue triangles represent active lakes that have been observed to drain at least once during the observation period; lakes labeled in green have been accessed and cleanly sampled with the exception of Glacier de Tête Rousse, which was monitored using boreholes (water level) and sonar (cavity geometry), and Lake Vostok. MIC – Mýrdalsjökull Ice Cap, VIC – Vatnajökull Ice Cap. Image credit: Livingstone et al., doi: 10.1038/s43017-021-00246-9.
Subglacial lakes under ice sheets and glaciers affect multiple components of the Earth system.
They provide viable habitats for microbial communities that might have followed unique evolutionary trajectories and serve as analogues for putative extraterrestrial ecosystems.
They can play a critical role in the speed at which ice flows into oceans and, when on land in mountainous regions, could pose a major risk to populations downstream if they were to drain and cause flooding and landslides.
It is believed that there are many thousands of subglacial lakes worldwide but, until now, their details were not collectively held and there was no clear picture on the size, stability and characteristics of the lakes.
“Subglacial lakes are fascinating,” said Dr. Kate Winter, a researcher in the Department of Geography and Environmental Sciences at Northumbria University.
“They can occur due to meltwater from the surface of the glacier traveling to the base and lying in in hollow areas or cavities, or they can occur due to geothermal heating from the earth below, warming the ice above and causing it to melt.”
“The lakes are protected by a layer of thick overlying ice which insulates it from the cold air above, preventing them from re-freezing and can exist alone for millions of years, harboring unique life forms, or they can fill and drain over hourly timescales.”
“These lakes can lubricate the base of the glacier or ice sheet and make ice flow faster, contributing to global sea level rise. In populated regions such as the Alps, the sudden release of subglacial lake water can cause catastrophic damage to life and infrastructure.”
“It is therefore important to study where subglacial lakes are, how much water they contain, how stable or active they may be and how they might be changing over time so we can learn more about why they form and what influence they may have on the local area.”
The 773 lakes catalogued in the inventory include 59 which have been newly-identified in Antarctica — some of which measure up to six miles in length and are under 3,000 m of ice.
While 80% of the lakes were found to be stable — meaning they have no addition or removal of water at all, or they have a balanced inflow and outflow — the researchers also observed that 20% of lakes are active.
This means they can drain suddenly and catastrophically, posing a hazard to human populations and infrastructure downstream.
“Innovations in radio-echo sounding, swath radar technology, satellite altimetry and high-resolution time-stamped digital surface models have confirmed the widespread existence of subglacial lakes over the last five decades,” said Dr. Stephen Livingstone, a researcher in the Department of Geography at the University of Sheffield.
“Our inventory will enable researchers to evaluate subglacial lake environments and their dynamics across different regions.”
“As the ice above subglacial lakes responds to climate change, lakes which were once stable may become unstable, and vice versa.”
“Now we have a better understanding of how many lakes are currently stable, we can monitor how this changes with time.”
“These changes are not just important for water and ice flow, but also for the lifeforms that exist in the lakes.”
The results were published in the journal Nature Earth & Environment.
_____
S.J. Livingstone et al. Subglacial lakes and their changing role in a warming climate. Nat Rev Earth Environ, published online January 4, 2022; doi: 10.1038/s43017-021-00246-9
