Satellites reveal sudden Greenland ice melt

 
Nasa images reveal the extent of the  surface melt over Greenland’s ice sheet on July 8 (l) and July 12 (r) The first image shows Greenland's ice sheet on 8 July, the second, taken four days later, shows the area where ice has melted at the surface

Related Stories

The surface of Greenland's massive ice sheet has melted this month over an unusually large area, Nasa has said.

Scientists said the "unprecedented" melting took place over a larger area than has been detected in three decades of satellite observation.

Melting even occurred at Greenland's coldest and highest place, Summit station.

The thawed ice area jumped from 40% of the ice sheet to 97% in just four days from 8 July.

Start Quote

Melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time”

End Quote Lora Koenig Nasa Goddard Space Flight Center

Although about half of Greenland's ice sheet normally sees surface melting over the summer months, the speed and scale of this year's thaw surprised scientists, who described the phenomenon as "extraordinary".

Nasa said that nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its centre, which is 3km (two miles) thick, experienced some degree of melting at its surface.

Until now, the most extensive melting seen by satellites in the past three decades was about 55% of the area.

According to ice core records, such pronounced melting at Summit station and across the ice sheet has not occurred since 1889.

"When we see melt in places that we haven't seen before, at least in a long period of time, it makes you sit up and ask what's happening," Nasa chief scientist Waleed Abdalati said.

"It's a big signal, the meaning of which we're going to sort out for years to come."

Watch this space

He said that, because this Greenland-wide melting has happened before - in 1889 - scientists are not yet able to determine whether this is a natural but rare event, or if it has been sparked by man-made climate change.

Start Quote

The observation is in my view much more important than the recently reported break up of a large iceberg from Petermann Glacier”

End Quote Poul Christoffersen Scott Polar Research Institute

"Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time," said Lora Koenig, a glaciologist from Nasa's Goddard Space Flight Center in Maryland and a member of the research team analysing the satellite data.

"But if we continue to observe melting events like this in upcoming years, it will be worrisome."

Prof Eric Wolff, from the British Antarctic Survey (Bas) told BBC News: "There have clearly been some very warm days in Greenland this month. As a result, the surface snow has melted across the whole ice sheet.

"This is confirmed by some of my international colleagues who are on the ground at the NEEM ice core drilling site in north Greenland - they are reporting several days with temperatures above zero, and ice layers forming in the snow.

"While this is very unusual, as always we cannot attribute any individual extreme event to climate change: We will have to wait and see if more such events occur in the next few years to understand its significance for both the climate and the health of the ice sheet."

Dr Poul Christoffersen, a glaciologist and engineer at the Scott Polar Institute in Cambridge, told BBC News: "The melting seen in the satellite data is unprecedented, as it extends all the way across the ice sheet including the summit, which is located 3,200 m above sea level. Melting is usually limited to less than 2000m elevation."

The news comes just days after Nasa satellite imagery revealed that a massive iceberg, twice the size of Manhattan, had broken off the Petermann Glacier in Greenland.

"The observation [from Greenland] is in my view much more important than the recently reported break up of a large iceberg from Petermann Glacier," Dr Christofferson added.

Nasa's Tom Wagner said: "This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story."

Scientists said they believed that much of Greenland's ice was already freezing again.

 

More on This Story

Related Stories

The BBC is not responsible for the content of external Internet sites

Comments

This entry is now closed for comments

Jump to comments pagination
 
  • rate this
    +70

    Comment number 103.

    Whether you believe this is worrying or not, the result of man's activities or not, this is not a green light to carry on ripping up the planet for resources.

    Too often people conflate "no evidence of global warming" with "so everything's tickety boo." Nul points.

    7 billion and growing. Dwindling natural resources. Pressure on commodities prices. Sustainable?

  • rate this
    +65

    Comment number 82.

    'July was the 329th consecutive month in which the temperature of the entire globe exceeded the 20th-century average'.
    Just thought you would like to know.

  • rate this
    +61

    Comment number 155.

    "Whilst the jury is still out whether this is a natural warming or man made..."

    No, the jury made their mind up a long time ago. It's only a controversial topic amongst politicians, the ignorant and people with ulterior motives.

  • rate this
    +55

    Comment number 37.

    @Peter_Sym

    "1000 years ago Greenland WAS a Greenland. It had trees & barley was grown by the Viking settlers. It was only in the 16th century during 'the little ice age' that it froze up again."

    The Greenland ice sheet is estimated at 400,000 to 800,000 years old. Whilst certain parts of it may have been greener in the recent past, e.g. a 1000 years ago, it hasn't been "green" for a long time.

  • rate this
    +50

    Comment number 129.

    88. Someonewhocares

    100% of climate scientists agree that the earth's climate changes naturally: it has in the past and will continue. 98% of them are very certain that the recent climate change is due to the 40% rise in atmospheric CO2 since 1850 due to man's industrialisation. The fact the climate does change naturally is not evidence that man is having no, or little, effect now.

 

Comments 5 of 720

 

More Europe stories

RSS

Features

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.