Brief overview
In this post, I am going to focus on a particular type of lake that is directly related and affected by glacier retreat, "proglacial lake".
But first, you may wonder what is a "proglacial lake"? Those are water masses found at the edge of glaciers and are strong indicators of glaciers retreat and climate change.
Proglacial lakes have increased in number and sizes over the past 45 years, according to many quantitative and qualitative study cases run all over the world:
But how do proglacial lakes tell us about Climate Change?
Climate, glaciers and proglacial lakes are part of a cycle:
From glaciers to lakes: sediment flux have increased in proglacial lakes due to glacier retreat, enhancing phenomenons such as river piracy which I talked about in my last post. Sometimes too much sediment accumulation in the proglacial lake can interrupt the transport of sediment and water to the ocean.
From lakes to glaciers: the increased level of proglacial lakes enhances glacier terminus retreat and thinning by erosion and thermal melting.
Climate Change has both impact on glacier retreat and proglacial lake: increased heat from the sun lead to ice mass loss from one hand. On the other hand, lakes act as a heat trap by absorbing solar radiation on the water surface. This heat can affect the glacier ice margin.
Study of sediment deposits coverage tell us about glacier retreat:
A case study from six glaciers of the Caucasus mountains shows that overall, the sediment coverage has increased over 25 years. Glaciers have been subjected to ice loss, and weathering of surrounding rocks occurred.
The use of satellite images helped to retrace the development of proglacial lakes over 3 years:
The grey colour shows the area covered by 2 proglacial lakes on 2002; white dash shows how those lakes have expanded in 1 year only; black line shows another increase in surface on 2004. Those lakes expanded due to ice mass loss.
How will proglacial lakes change in the future?
Those may increase in size and number in the near future as we expect the temperature to rise.
A better study of past proglacial lakes would help understanding their link with the ocean circulation patterns as freshwater is delivered directly into the ocean.
Also, increased erosion and flux of sedimentation must lead to bigger hazardous phenomenons.
Finally, the increased availability of fresh melted water from the glaciers will probably have a large impact on the water resource available for human societies.
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