Antarctica’s wandering ice shelf

November 18, 2009

GPS markers usually pinpoint a spot on the earth’s surface to help everything from map-making to navigation.

This one (left) spectacularly didn’t.

In fact, it wandered hundreds of miles (km) this year on an iceberg, blown by winds or carried by ocean currents in huge pirouettes off the coast of Antarctica.

When glaciologist David Vaughan (above) of the British Antarctic Survey stuck the pole holding the GPS (global positioning system) tracking device into the Wilkins Ice Shelf in Antarctica in January, the ice felt solid as rock.

Stuart McDill of Reuters TV and I had landed with him in a small plane mounted with skis on a 40-km-long floating ice bridge which had been in place probably for thousands and thousands of years. But it was weakening and about to snap in what Vaughan said was a sign of global warming.

We didn’t stay long.

The GPS marker was meant to transmit its position to satellites to help monitor movements in the ice shelf — up to about 250 metres thick — to measure the strains before it finally cracked up. The ice bridge shattered in April and collapsed into a swarm of icebergs.

But surprisingly, the GPS kept on going for months — broadcasting its position as a lone metal spike that may have puzzled passing penguins or the odd whale. The diagram above shows where it began (near top right by Charcot Island and then southwest until its last transmission on Aug. 30. No one knows its fate – maybe the batteries gave out or its iceberg cracked up.

The GPS did far better than planned. Vaughan had been convinced that the GPS, set up for Michiel van den Broeke of Utrecht University and colleagues, was not going to work at all. After he set it up, it went “beep beep beep” to signal that it was OK but then fell silent.

We all thought it had failed; we didn’t know that it was programmed to beep only briefly to show that it worked — too many beeps would have drained the batteries.

(Picture: REUTERS/Alister Doyle, diagram: Roderik van de Wal, Utrecht University, Matthias Braun, Bonn University






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I feel concerned for the polar bears.

Posted by Camron Barth | Report as abusive

The GPS technology is pretty neat.

Posted by Camron Barth | Report as abusive

Icebergs are so beautiful. It’s sadly ironic that they’re often the result of breakage due to climate change.

Posted by Camron Barth | Report as abusive

I feel for Polar Bears too, Camron … but in this case they are not affected … no Polar Bears in the Antarctic … just the Arctic, at the other side of the globe.

Posted by DB | Report as abusive

Can anyone of these scientists explain why there has been no temp increase in the past ten years? Some even say that the Earth may be getting cooler. I have a funny feeling that ice bergs have alway broke off and drifted out to see. In fact one sunk a ship in 1912. Climatr Change? Fact is the climate is always changing. Here in the midwest were going into winter. Climate change.

Posted by Kyle Stevens | Report as abusive

Mr. Doyle,I think I heard something about some “Climate Scientists” just making up data to fit their political agenda. Perhaps you could report on that. It doesn’t seem to be getting a lot of press. You could be breaking big news. Of course, you might have an agenda too. It would not be very professional to avoid reporting on facts, but then again they were not professional.

Posted by Russ Stringer | Report as abusive

thanks kyle for your obvious sarcasm. with that kind of thinking it is easy to see why some people still don’t believe that cigarettes cause cancer.

Posted by js | Report as abusive

Of course icebergs have existed before; there are just more of them now due to climate change. That isn’t a contention that climate change is only caused by people.

Posted by Camron Barth | Report as abusive

Russ and Kyle,Firstly, if you take 1998 as your starting point it does appear that there has not been warming over the last 10 years. But as you should know that would be cherry picking data and 1998 was also known as the time when the world’s largest el nino occurred which is why it was the warmest ever recorded. In terms of the overall trend it is still on the order of 0.19 C per decade which is consistent with predictions. In fact if you checked out some actual scientific literature instead of internet blogs you might know that. Secondly for Russ, there is no distinct evidence of falsified data. The adding in the real temperatures onto the 1960’s dataset in order to “hide the decline” is simply putting on actual temperature data in place of data which cannot be used. The reason it couldn’t be used was because after 1960 that particular tree ring set diverged from recorded temperatures so the original author advised against using post-1960 tree ring data…. that would also be something you would know if you had any clue about things before you mouthed off. So sick of people who are so quick to jump on bandwagons without actually doing the research themselves. Nowmatter what I say you are going to think you’re right… that’s the difference between actual degrees in climate science and degrees from the University of Google.

Posted by Robert | Report as abusive