Times Atlas Ice Error Was A Lesson In How Scientists Should Mobilize

By Poul Christoffersen, TheGuardian

Over the past few days, climate scientists and polar researchers from across the world have rallied, mobilised and responded to a massively incorrect press statement by HarperCollins, the publisher of the Times Comprehensive Atlas of the World. According to HarperCollins, the atlas is “turning Greenland 'green' because the new edition has had to erase 15% of Greenland's once permanent ice cover”.

Recent years have seen record melting at Greenland's ice cap. However, scientists say that a newly published map of Greenland in the Times Comprehensive Atlas of the World has overstated how much ice sheet has shrunk. Credit: NASA Goddard.

The press release issued last Thursday quickly spread across the global news, leaving many scientists flabbergasted. How on earth could the Times Atlas obtain such high number? The Greenland Ice Sheet contains 2.9m cubic kilometres of ice – enough to raise the sea level by 7 metres if it were to melt. A 15% reduction in size would be about a 1-metre rise – enough to cause flooding over a third of the Netherlands.

Since flooding of this magnitude has not taken place in recent years, scepticism was immediate in the glaciological community. Something must have gone seriously wrong when the new map of Greenland was compared against the previous version from 1999.

What happened next is something new. Scientists from around the world quickly expressed their frustration with the questionable claim.

Jeffrey Kargel from the University of Arizona wrote on the cryolist, an email distribution list used by many students, researchers and academics, that “a number like 15% ice loss … is simply a killer mistake. This is not a scientific error, but it could be perceived as one.”

Graham Cogley, a professor of geography at Trent University in Ontario, Canada, replied “the claims here are simply not backed up by science”, and concluded “this pig can't fly”.

At the Scott Polar Research Institute, seven scientists including myself issued a press statement on the University of Cambridge website explaining “a 15% decrease in permanent ice cover since the publication of the previous atlas 12 years ago is both incorrect and misleading. A sizable portion of the area mapped as ice-free in the atlas is clearly still ice-covered.” Journalists at the Guardian and many other news outlets immediately picked up these concerns.

Meanwhile, scientists from across the world continued the exchange of emails via the cryolist. Ted Scambos, a senior scientist at the National Snow and Ice Data Centre, said: “I'm worried that the importance of the changes that are going on will be lost on the public, because the true value of what the ice sheet has lost compared to this 15% number sounds very small.”

And he is right, because the true loss of permanent ice in Greenland from 1999-2011 is about 0.1%. This sounds miniscule. Why worry?

The answer is that it is a small fraction of a very large number. The current annual loss of ice from Greenland is about 200 cubic kilometres per year. This is about 0.007% of the total ice volume, but the same as 6mm/decade in terms of sea level rise. This is a substantial number which excludes losses from other ice sheets and ice caps, and mountain glaciers, which tend to melt faster.

So we should worry about climate change and its impact, not only on the Greenland Ice Sheet, but ice masses across the world as a whole. A recent study published in Nature shows a rapid decline of glaciers and ice caps in the Canadian Arctic. In Antarctica, a number of ice shelves have collapsed, exposing glaciers to the marine environment and causing them to flow much faster than their original pace. Many readers will probably already be familiar with the continuing decline of European glaciers.

Yet in recent years, Greenland has been on the top of the list when it comes to large and sudden glacier change. The past ten years have seen record melt year after year. The margin of the ice sheet is clearly thinning. Numerous glaciers have retreated abruptly, exposing new lands and causing faster transfer of ice from ice sheet interior to the ocean. For glaciologists working in Greenland, climate change is very real.

Atlases such as the Times Comprehensive Atlas of the World can and probably will play an important role in the communication of climate change, but it is absolutely essential that the communication is based on facts and scientific evidence.

The substantial consequences of making inaccurate or exaggerated claims in the climate change debate came to light after the Intergovernmental Panel on Climate Change incorrectly stated in their last assessment report, that Himalayan glaciers could vanish before 2035. Although this mistake was not made within the actual assessment of the physical science basis of climate change, the unravelling of this mistake nonetheless lasted more than a year and was damaging not just to the IPCC, but the wider scientific community.

In the aftermath of what is often referred to as 'Himalayagate', scientists are well aware that one big error can cloud a thousand truths. This is why the science community tackled the Times Atlas mistake swiftly and effectively.

Yesterday, HarperCollins issued a press statement retracting the claimed magnitude of ice loss, but maintained that they stand by their maps. But to scientists, the representation of the Greenland Ice Sheet in the latest atlas, without explanatory text, will continue to be misleading.

Dr. Poul Christoffersen is a lecturer at the Scott Polar Research Institute, Cambridge