Meltwater lakes at glacier margins cause ice to recede much further and faster, according to a new international study published in the journal Geophysical Research Letters.
Due to climate change, many more mountain glaciers now terminate in lakes, formed as meltwater becomes trapped behind ridges of glacier debris.
In order to fully understand the impact that these lakes are having on glacier behaviour, the researchers used the BISICLES ice-flow model to analyse the effects of a lake on the Pukaki Glacier, New Zealand during the recession from the end of the last ice-age.
The researchers found that the presence of a lake at the end of a glacier causes the glacier to recede four times further and accelerates ice flow by up to eight times when compared to the same glacier ending on land.
A land-terminating glacier took 1,000 years to succumb to the same amount of recession as a lake-terminating glacier experienced in 100 years.
Based on these findings the researchers have said that current estimates of glacier recession rates are likely to be under-estimated.
Lead author of the study, Dr Jenna Sutherland from the University of Leeds said: ‘An ice cube in a bowl of water is going to melt much more quickly than an ice cube sitting on a table, and the effect proglacial lakes have on glacier ice is roughly the same.
‘The simulations show that the influence of a proglacial lake on a glacier predominantly takes place over decades to centuries rather than over millennia, meaning the glacier recedes much faster than it ever could from climatic changes alone.’
Study co-author James Shulmeister, from the University of Canterbury, New Zealand, said: ‘This study is critical because the timing of ice retreat is often used to determine the synchrony or lack thereof in climate events globally.
‘Major inferences have been made about the roles of phenomena like oceanic circulation in affecting the global climate system from glacial retreat timings. If the timings are wrong, the relationship between these processes may need to be re-examined.’
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