Solved: mystery of the disappearing lake

view gallery VIEW GALLERY

The sudden and dramatic disappearance of a large lake which had formed on the surface of a melting ice sheet in Greenland has been documented for the first time by scientists who estimated that its outflow was greater than that of Niagara Falls.

Rising temperatures in the Arctic are causing more meltwater lakes to form on top of the Greenland ice sheet and satellite pictures have shown that they can disappear almost overnight for no apparent reason.

Thousands of the "supra-glacial" lakes form each summer – and last year was one of the warmest on record in the region – but scientists have little understanding of how the lakes can suddenly disappear or how far down the water flows into the 3,200ft (975m) deep ice sheet.

Now scientists have seen how they fall through the ice as a result of giant cracks that suddenly open up under the lake bottom, causing millions of tons of water to flow down to the base of the thick ice sheet where it grinds against the bedrock.

Instruments placed around the lake, which covered an area of 2.2sq miles and was up to 40ft deep, found that a huge crack or "moulin" (from the French for mill) opened up in the ice which allowed about 11.6 billion gallons of water to flow down to the bedrock in under 24 hours.

The pressure of the liquid water flowing between the ice sheet and the bedrock lifted the surface of the ice sheet by up to 20 feet at the point where the lake had formed in the summer of 2006, according to the findings of the study published in the journal Science.

The research is important because one of the questions scientists want answered is whether these huge volumes of water falling to the base of the ice sheet can lubricate its movement, so sending it faster towards the coast, where icebergs break off and contribute to a rise in global sea levels.

"We found clear evidence that supraglacial lakes – the pools of meltwater that form on the surface in summer – can drive a crack through the ice sheet in a process called hydrofracture," said Sarah Das of the Woods Hole Oceanographic Institution in Massachusetts.

"If there is a crack or defect in the surface that is large enough, and a sufficient reservoir of water to keep that crack filled, it can create a conduit all the way down the bed of the ice sheet," Ms Das said.

"It's hard to envision how a trickle or a pool of meltwater from the surface could cut through thick, cold ice all the way to the bed. For that reason, there has been a debate as to whether such processes could exist, even though some theoretical work has hypothesised this for decades," she said.

The scientists believe that the lake emptied like a bathtub once the crack had formed, with much of the water disappearing in a cataclysmic outflow lasting about 90 minutes – a flow rate greater than the average flow rate of Niagara Falls.

Global positioning instruments recording the horizontal movements over the ice sheet found that the ice in the region of the lake began to move faster towards the ocean at about double the normal speed.

However, the scientists also found that the speed of movement of the ice sheet nearer the coastline was not affected significantly, indicating that the disappearance of the summer meltwater lakes may not influence the more complex dynamics that determine the rate at which icebergs "calve" from the ice sheet.

"We set out to examine whether the melting at the surface – which is sensitive to climate change – could influence how fast the ice can flow... if the ice sheet is frozen to the bedrock or has very little water available, then it will flow much more slowly than if it has a lubricating and pressurised layer of water underneath to reduce friction," Ms Das said.

Ian Jouglin, of Washington University, said: "Considered together, the new findings indicate that, while surface melt plays a substantial role in ice-sheet dynamics, it may not produce large instabilities leading to sea level rise."

News
The surrealist comedian at the Q Awards in 2010
people
News
Russell Brand arriving for the book launch in East London
peopleRussell Brand cancels his book launch debate due to concerns about the make-up of the panel
Sport
Christiano Ronaldo enjoys his opening goal
champions leagueLiverpool 0 Real Madrid 3: Ronaldo and Benzema run Reds ragged to avenge thrashing from their last visit to Anfield
Arts and Entertainment
Awesome foursome: Sam Smith shows off his awards
music22-year-old confirms he is 2014’s breakout British music success
PROMOTED VIDEO
Life and Style
Six of the 76 Goats' cheese samples contained a significant amount of sheep's cheese
food + drink
Arts and Entertainment
Contestants during this summer's Celebrity Big Brother grand finale
tvBroadcaster attempts to change its image following sale to American media group
Extras
indybest
News
Wilko Johnson is currently on his farewell tour
people
Arts and Entertainment
Sarah Dales attempts to sell British Breeze in the luxury scent task
tvReview: 'Apprentice' candidate on the verge of tears as they were ejected from the boardroom
News
Call me Superman: one of many unusual names chosen by Chinese students
newsChinese state TV offers advice for citizens picking a Western moniker
News
ebooksAn unforgettable anthology of contemporary reportage
Voices
New look: Zellweger at Elle's Women in Hollywood awards on Monday
voicesRenée Zellweger's real crime has been to age in an industry that prizes women's youth over humanity, says Amanda Hess
Arts and Entertainment
Julianne Moore and Ellen Page are starring together in civil rights drama Freeheld
film
Voices
'Irritatingly Disneyfied': fashion vlogger Zoella
voicesVicky Chandler: Zoella shows us that feminism can come in all forms
Life and Style
health
Arts and Entertainment
Pink Floyd on stage at Live 8 in 2005. From left to right: David Gilmour, Roger Waters, Nick Mason and Rick Wright
music New album The Endless River set to overtake boyband for most pre-ordered of all-time
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Solutions Architect - Permanent - London - £70k DOE

£60000 - £70000 Per Annum Excellent benefits: Clearwater People Solutions Ltd:...

General Cover Teacher

£110 - £130 per day: Randstad Education Reading: Great opportunities for Cover...

Maths Teacher

£110 - £130 per day: Randstad Education Reading: QTS Maths Teachers needed for...

Maths Teacher

£110 - £130 per day: Randstad Education Reading: QTS Maths Teachers needed for...

Day In a Page

How could three tourists have been battered within an inch of their lives by a burglar in a plush London hotel?

A crime that reveals London's dark heart

How could three tourists have been battered within an inch of their lives by a burglar in a plush London hotel?
Meet 'Porridge' and 'Vampire': Chinese state TV is offering advice for citizens picking a Western moniker

Lost in translation: Western monikers

Chinese state TV is offering advice for citizens picking a Western moniker. Simon Usborne, who met a 'Porridge' and a 'Vampire' while in China, can see the problem
Handy hacks that make life easier: New book reveals how to rid your inbox of spam, protect your passwords and amplify your iPhone

Handy hacks that make life easier

New book reveals how to rid your email inbox of spam, protect your passwords and amplify your iPhone with a loo-roll
KidZania lets children try their hands at being a firefighter, doctor or factory worker for the day

KidZania: It's a small world

The new 'educational entertainment experience' in London's Shepherd's Bush will allow children to try out the jobs that are usually undertaken by adults, including firefighter, doctor or factory worker
Renée Zellweger's real crime has been to age in an industry that prizes women's youth over humanity

'Renée Zellweger's real crime was to age'

The actress's altered appearance raised eyebrows at Elle's Women in Hollywood awards on Monday
The 10 best smartphone accessories

Make the most of your mobile: 10 best smartphone accessories

Try these add-ons for everything from secret charging to making sure you never lose your keys again
Mario Balotelli substituted at half-time against Real Madrid: Was this shirt swapping the real reason?

Liverpool v Real Madrid

Mario Balotelli substituted at half-time. Was shirt swapping the real reason?
West Indies tour of India: Hurricane set to sweep Windies into the shadows

Hurricane set to sweep Windies into the shadows

Decision to pull out of India tour leaves the WICB fighting for its existence with an off-field storm building
Indiana serial killer? Man arrested for murdering teenage prostitute confesses to six other murders - and police fear there could be many more

A new American serial killer?

Police fear man arrested for murder of teen prostitute could be responsible for killing spree dating back 20 years
Sweetie, the fake 10-year-old girl designed to catch online predators, claims her first scalp

Sting to trap paedophiles may not carry weight in UK courts

Computer image of ‘Sweetie’ represented entrapment, experts say
Fukushima nuclear crisis: Evacuees still stuck in cramped emergency housing three years on - and may never return home

Return to Fukushima – a land they will never call home again

Evacuees still stuck in cramped emergency housing three years on from nuclear disaster
Wildlife Photographer of the Year: Intimate image of resting lions claims top prize

Wildlife Photographer of the Year

Intimate image of resting lions claims top prize
Online petitions: Sign here to change the world

Want to change the world? Just sign here

The proliferation of online petitions allows us to register our protests at the touch of a button. But do they change anything?
Ed Sheeran hits back after being labelled too boring to headline festivals

'You need me, I don’t need you'

Ed Sheeran hits back after being labelled too boring to headline festivals
How to Get Away with Murder: Shonda Rhimes reinvents the legal drama

How to Get Away with Murder

Shonda Rhimes reinvents the legal drama