Original article by Dr. David Vaughan, British Antarctic Survey Follow the dramatic story of the breaking up of an Antarctic ice shelf in 2002, from which scientists are learning about what may happen in the future in our polar regions.

Introduction

Alerted by satellite images, scientists announced on Tuesday 19^th March 2002 that a section of Antarctic ice shelf, nearly the size of Cambridgeshire, had collapsed into thousands of small icebergs. One of those whose research has been predicting this event is glaciologist, Dr David Vaughan.  After helping joint editor, Susan Ballard to assess its significance he has kindly contributed an article he had published in the journal, "Science" last year for those who want to understand more.

Photograph taken from BAS ship RRS James Clark Ross on March 08, 2002 showing the iceberg debris from the collapse of Larsen Ice Shelf B.  The iceberg contains layering from successive years of snowfall.

Sections in this article

• Concerns voiced in the press
• What the records are telling us
• What have we still to learn?
• Where Next?

Concerns voiced in the press

The break up of the Larsen B section of ice shelf was confirmed by the British Antarctic Survey's RRS James Clark Ross which navigated her way through the armada of icebergs to obtain photographs and samples. Subsequent press reports have spawned questions about rapid global warming and sea level rise. The Director of the British Antarctic Survey, Chris Rapley has used the opportunity to publicise his concerns in a letter published in the Daily Telegraph, Thursday 21^st March 2002:

"The recent collapse of the 500-billion ton Larsen B ice shelf (report Mar. 20) is a sharp reminder that all is not well with our planet. We cannot say for certain that the event was a result of human activities, but the circumstantial evidence is strong.

British Antarctic Survey studies of sediment from the nearby seafloor show that the Larsen B had been in place for nearly 2,000 years. Both simple climate theory and sophisticated computer models indicate that human-induced global warming will be amplified in the polar regions, and the United Nations Intergovernmental Panel on Climate Change has concluded that climate change is a reality.

As for the case of the ozone hole, the Antarctic has once again proved remote but relevant. At the opening of the Science Museum's new exhibit on climate change Michael Meacher, environment minister, pointed out that while "Puffing Billy" and other British Victorian engineering on display had led to a revolution in the human condition through the burning of fossil fuels, we may be on the verge of paying a heavy and long-term price.

With America ambivalent about the issue, Britain has the opportunity to take another international lead, this time in the underpinning science technology and the political action to achieve a sustainable future."

What the records are telling us

Progression of the collapse of Larsen B from 1995 to the present.  Back ground image acquired March 5, 2002 by the MODIS sensor on NASA's Terra Satellite.  (Image is approximately 300 x 300 km).

Temperature rises on the Antarctic Peninsula have been five times faster than the global mean, that's 2.5C since records began in the 1940s. Geographically this is unusual and it is also unusual in historical terms. There has been no similar warming in the last five hundred years but I am not alarmed about any immediate impact on the rest of the world from the Larsen B collapse. It is still too small in size to cause a rise in sea level or affect the amount of radiation reflected back into the atmosphere (albedo). However, the event gives scientists like us an indicator of which processes to look at in order to predict what's going on over the next hundred years. This will be relevant to sea level rise.

What have we still to learn?

What particularly interests me is that the rate of climate change differs so radically from one region to another as exemplified not just in the Antarctic Peninsula but also in Alaska and on the Siberian Plateau. This is the reality, some areas will warm more rapidly, some areas will be cooler. Some areas will change differently. Regional climate change will be more profound for people than global mean warming. Yet we have no mechanism for predicting regional climate change. The output from the models we use do not produce accurate regional forecasts. I would say we are ten years away from the measurements we need in order to produce the information necessary to adapt to climate change.

Where Next?

On ClimateX.org

For a first hand account of an oceanographer's trip to the Antarctic to carry out vital ocean temperature and salinity measurements, see 'Antarctic Diary'.

External links

To stay up to date with what is happening in Antarctica and for some fantastic photographs it is worth visiting the British Antarctic Survey website.