
© NASA
The Greenland ice sheet on July 8, left, and four days later on the right. In the image, the areas classified as 'probable melt' (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as 'melt' (dark pink) correspond to sites where two or three satellites detected surface melting.
The Greenland ice sheet melted at a faster rate this month than at any other time in recorded history, with virtually the entire ice sheet showing signs of thaw.
The rapid melting over just four days was captured by three satellites. It has stunned and alarmed scientists, and deepened fears about the pace and future consequences of climate change.
In a statement posted on Nasa's website on Tuesday, scientists
admitted the satellite data was so striking they thought at first there had to be a mistake.
"This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?" Son Nghiem of Nasa's jet propulsion laboratory in Pasadena said in the release.
He consulted with several colleagues, who confirmed his findings. Dorothy Hall, who studies the surface temperature of Greenland at Nasa's space flight centre in Greenbelt, Maryland, confirmed that the area experienced unusually high temperatures in mid-July, and that there was widespread melting over the surface of the ice sheet.
Climatologists Thomas Mote, at the University of Georgia, and Marco Tedesco, of the City University of New York, also confirmed the melt recorded by the satellites.
Comment: Forget rising sea levels, what we should be worrying about is fresh meltwater diluting the salty North Atlantic, interfering with or even shutting down the conveyor belt cold-warm water mechanism of the Gulf Stream, which keeps the East coast of the US and Canada and the Northwestern Europe relatively warm. If that goes, we will enter an ice age.
Essential reading: Fire and Ice: The Day After Tomorrow

© unknown
A diagram of the Gulf Stream conveyor and related currents.
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| This image shows how the British Isles, Western Europe and Scandinavia are bathed in the heat of the Gulf Stream
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Comment: Forget rising sea levels, what we should be worrying about is fresh meltwater diluting the salty North Atlantic, interfering with or even shutting down the conveyor belt cold-warm water mechanism of the Gulf Stream, which keeps the East coast of the US and Canada and the Northwestern Europe relatively warm. If that goes, we will enter an ice age.
Essential reading: Fire and Ice: The Day After Tomorrow
A diagram of the Gulf Stream conveyor and related currents.