Melting like an ice cube in water: Glaciers surrounded by meltwater lakes lose ice ten times faster than those on dry land, study claims
- Researchers created a new model to consider the impact of lakes on melting ice
- They found that cold lake water significantly speeds up the melting of glaciers
- The lakes are formed as meltwater becomes trapped behind ridges of debris
- As the glaciers melt due to climate change more of these lakes are created
Lakes of meltwater that form at the edges of glaciers can increase the rate at which ice is lost ten-fold – just like an ice cube melts in a bowl of water, study finds.
Researchers from the University of Leeds found a land-terminating glacier took 1,000 years to shrink as much as a lake-terminating glacier did in 100 years.
Climate change has led to a ‘dramatic increase’ in the size and number of these lakes which in turn has resulted in a rapid increase in the speed of ice loss.
Many mountain glaciers now terminate in such lakes, which are formed as meltwater becomes trapped behind ridges of glacier debris, the Leeds team explained.
The effects of these lakes aren’t considered in ice loss models and so the current ‘worst case scenario’ calculations may be wrong, with the team suggesting the rate of ice loss worldwide may be much greater in the coming decades than predicted.
Hooker Lake, New Zealand is an example of a meltwater lake, created as melted ice from a glacier gets trapped behind rocks and ridges
Researchers from the University of Leeds found a land-terminating glacier took 1,000 years to shrink as much as a lake-terminating glacier did in 100 years
For the first time researchers have quantified the influence of the lakes on mountain glaciers using computer simulations.
They found that the presence of a proglacial lake causes a glacier to recede more than four times further and accelerate ice flow by up to eight times when compared to the same glacier terminating on land under the same climate.
Study lead author Dr Jenna Sutherland, from the University of Leeds, compared the effect to an ice cube left in a bowl of water.
Saying the ice cube 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.
Climate change has led to a ‘dramatic increase’ in the size and number of these lakes which in turn has resulted in a rapid increase in the speed of ice loss
For the first time researchers have quantified the influence of the lakes on mountain glaciers using computer simulations based on a glacier in New Zealand
‘The simulations show that the influence of a proglacial lake on a glacier predominantly takes place over decades to centuries rather than over millennia.
Sutherland added that this means ‘the glacier recedes much faster than it ever could from climatic changes alone.’
Using an ice-flow model, the team analysed the effects of a proglacial lake on the Pukaki Glacier in New Zealand, but say the findings apply to all such lakes.
Study co-author Dr Jonathan Carrivick, from the University of Leeds, said the findings suggest that previous simulations ignore the effects of ice-contact lakes.
This means they ‘will likely mis-represent the timing and rate of recession, especially the changes to the timing and rate that will occur once a proglacial lake forms.’
‘These effects need to be included in all future models and simulations if we are to have an accurate global picture of glacial ice loss,’ said Carrivick.
The team used the BISICLES ice-flow model to analyse the effects of the New Zealand lake, during recession from the end of the last ice age.
Study co-author James Shulmeister, from the University of Canterbury in New Zealand, said the results will apply to any proglacial lake.
‘Proglacial lakes are prevalent during glacial retreat worldwide and this paper should therefore be of global interest and importance,’ Shulmeister said.
They found that the presence of a proglacial lake (such as Hooker Lake, New Zealand – pictured) causes a glacier to recede more than four times further and accelerate ice flow by up to eight times when compared to the same glacier terminating on land under the same climate
He added: ‘This study is also critical because the timing of ice retreat is often used to determine the synchrony or lack thereof of 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.’
Findings were published in the journal Geophysical Research Letters.
GLACIERS AND ICE SHEETS MELTING WOULD HAVE A ‘DRAMATIC IMPACT’ ON GLOBAL SEA LEVELS
Global sea levels could rise as much as 10ft (3 metres) if the Thwaites Glacier in West Antarctica collapses.
Sea level rises threaten cities from Shanghai to London, to low-lying swathes of Florida or Bangladesh, and to entire nations such as the Maldives.
In the UK, for instance, a rise of 6.7ft (2 metres) or more may cause areas such as Hull, Peterborough, Portsmouth and parts of east London and the Thames Estuary at risk of becoming submerged.
The collapse of the glacier, which could begin with decades, could also submerge major cities such as New York and Sydney.
Parts of New Orleans, Houston and Miami in the south on the US would also be particularly hard hit.
A 2014 study looked by the union of concerned scientists looked at 52 sea level indicators in communities across the US.
It found tidal flooding will dramatically increase in many East and Gulf Coast locations, based on a conservative estimate of predicted sea level increases based on current data.
The results showed that most of these communities will experience a steep increase in the number and severity of tidal flooding events over the coming decades.
By 2030, more than half of the 52 communities studied are projected to experience, on average, at least 24 tidal floods per year in exposed areas, assuming moderate sea level rise projections. Twenty of these communities could see a tripling or more in tidal flooding events.
The mid-Atlantic coast is expected to see some of the greatest increases in flood frequency. Places such as Annapolis, Maryland and Washington, DC can expect more than 150 tidal floods a year, and several locations in New Jersey could see 80 tidal floods or more.
In the UK, a two metre (6.5 ft) rise by 2040 would see large parts of Kent almost completely submerged, according to the results of a paper published in Proceedings of the National Academy of Science in November 2016.
Areas on the south coast like Portsmouth, as well as Cambridge and Peterborough would also be heavily affected.
Cities and towns around the Humber estuary, such as Hull, Scunthorpe and Grimsby would also experience intense flooding.