80-year-old photo plates from Danish polar explorer
Prove that Greenland's glaciers melted faster in 30s than they did today
Brief cooling period mid-century re-froze ice
Pre-satellite images of ice shelves are extremely rare
By Rob Waugh
A stash of 80-year-old photo plates in a Danish basement has proved that Greenland's ice was melting even faster then that it is now.
In the thirties, Greenland's ice was melting rapidly, then there was a cooling period in the middle part of the twentieth century, and now it is melting again, accelerating in the 2000s.
Images of ice shelves from the pre-satellite era are extremely rare, so it's often difficult to assess the scale and speed of Arctic ice melting today.
Researchers at the National Survey and Cadastre of Denmark had been storing the glass plates since explorer Knud Rasmussen's expedition to the southeast coast of Greenland in the early 1930s.
In this week's online edition of Nature Geoscience, Ohio State University researchers and colleagues in Denmark describe how they analyzed ice loss in the region by comparing the images on the plates to aerial photographs and satellite images taken from World War II to today.
Taken together, the imagery shows that glaciers in the region were melting even faster in the 1930s than they are today, said Jason Box, associate professor of geography and researcher at the Byrd Polar Research Center at Ohio State.
A brief cooling period starting in the mid-20th century allowed new ice to form, and then the melting began to accelerate again in the 2000s.
‘Because of this study, we now have a detailed historical analogue for more recent glacier loss,’ Box said. ‘And we've confirmed that glaciers are very sensitive indicators of climate.’
Pre-satellite observations of Greenland glaciers are rare - but some are available...
Read more: http://www.dailymail.co.uk/sciencetech/article-2152004/Lost-photos-prove-Greenlands-ice-melting-FASTER-80-years-ago-today.html#ixzz1wNlK4CiZ
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