Conflicting views on Ice melt

Last updated 00:00 25/09/2007

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Conflicting research about Antarctica has seen climate activists and sceptics each claiming support for their predictions for the world's biggest ice sheets.

The east and west Antarctic ice sheets contain 90 per cent of the world's fresh water and have the potential to raise sea levels by 60m if they melt.

Climate activists urging drastic action on greenhouse gases have cited a Nasa study released on Saturday showing that over the past 20 years melting has occurred in Antarctica further inland and at higher altitudes than before.

But rival climate groups urging a more cautious response to the issue have cited other research showing that for the bulk of Antarctica temperatures have grown progressively cooler and the ice sheets have increased in bulk over the past 40 years.

Glaciologist Wolfgang Rack, from Gateway Antarctica at the University of Canterbury, said the research was not necessarily contradictory but too little was known about the dynamics of Antarctica to make definitive predictions.

"I think global warming is real and this (cooling trend) doesn't mean we should go on with business as usual," Rack said.

"For some reason the climate signals cannot be seen in Antarctica."

The paucity of information about the ice sheets led the United Nations-sponsored Intergovernmental Panel on Climate Change (IPCC) to exclude the impact of Antarctica from its most recent predictions for sea-level rise.

Professor Berry Lyons, of the Byrd Polar Research Institute in the United States, said although parts of Antarctica were cooling and snow was building up rather than melting, all the models for the future were for the opposite.

"If you look at the IPCC models for the next century, it's very apparent that Antarctica is much warmer and if you believe these models and projections, there is no doubt that the terrestrial ecosystem will change dramatically," he said.

"In Antarctica we can see that loss of sea ice will lead to warming. We'll increase precipitation and increase snowfall and glaciers. There will be glacial advance and a decrease in the area of land."

The co-chair of the IPCC, Susan Solomon, said the cooling of Antarctica appeared to be because air circulation patterns over the pole had become more stable than before.

"Basically what's happened is the circulations around Antarctica have changed, so that the cold air sits bottled up over the pole more than it used to be.

"There is cooling over the Antarctic plateau and it's warming in the Antarctic peninsula.

"The world has certainly warmed but we also see a few places where cooling has happened but, overwhelmingly, the ... change has been for warming almost everywhere."

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A group self-described as independent and non-political, called the International Climate and Environmental Change Assessment Project (Icecap), said that while the Arctic sea ice was at its lowest levels since satellite measuring began in 1979, the Antarctic icecap had set a new record for the amount of snow and ice.

- © Fairfax NZ News

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