The Tip of the Iceberg

25 April 2005 | 12:20 Code : 4985 Geoscience events
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Last week on Earth Day, AP newswire led with a real scare story: "Study Shows Antarctic Glaciers Shrinking." In doing so, the press, yet again, predictably distorted a global warming story.
Last week on Earth Day, AP newswire led with a real scare story: "Study Shows Antarctic Glaciers Shrinking." In doing so, the press, yet again, predictably distorted a global warming story.
By "Antarctica" they actually meant the Antarctic Peninsula, which comprises about 2% of the continent. It's warming there and has been for decades. But every scientist (or for that matter, everyone who has read Michael Crichton's "State of Fear") knows that the temperature averaged over the entire continent has been declining for decades.
The underlying science behind the AP story was published in the April 22, 2005 issue of Science magazine, under the more appropriate (and accurate) title, "Retreating Glacier Fronts on the Antarctic Peninsula over the Past Half-Century." A research team led by Alison Cook of the British Antarctic Survey carefully measured the historical position of 244 glaciers as determined from a 60-year collection of images including aerial photographs and satellite pictures. By comparing the position of glacier termini over time, the researchers were able to determine the timing and speed of glacial changes.
 
The results presented in Science weren't even based on the entire Peninsula, but rather the northern portion. While a more comprehensive continent-wide investigation of coastal glacier changes is underway, only the results from the Peninsula were written up.
 
Figure 1 shows the temperature trends from 1966-2000 over Antarctica as reported in a study by Peter Doran and colleagues and published in Nature magazine in 2002. The region that encompasses all 244 of the glaciers in the Science study is highlighted. While it is clear the there has been warming in the localized region around where the Antarctic Peninsula glaciers are located, it is also clear that the majority of the rest of the continent has been cooling. Just how much has been cooling was also calculated by Doran (Figure 2), and shows that about 2/3rds of the continent outside of the Peninsula has been cooling over the past 35 years or so.

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