A new record has been set for the extent of Antarctic sea ice for the third year in a row.
But scientists say the seemingly positive figures are no reason to relax about climate change in the Antarctic continent.
The increase in sea ice goes against what would be expected due to global warming. By contrast NASA figures show the extent of the sea ice in the Arctic is below the 30 year average.
“It’s not a good thing or a bad thing; it is what it is,” CEO of the Antarctic Climate and Ecosystems CRC, Tony Worby, said.
“But it’s no reason to get complacent about climate change.”
The most sea ice area since records began
Two days ago satellite imagery revealed an area of about 20 million square kilometres covered by sea ice around the Antarctic continent.
Jan Lieser from the Antarctic Climate and Ecosystems CRC said the discovery showed an area covered by sea ice which “we’ve never seen from space before”.
“Thirty-five years ago the first satellites went up which were reliably telling us what area, two dimensional area, of sea ice was covered and we’ve never seen that before, that much area.
“That is roughly double the size of the Antarctic continent and about three times, four times the size of Australia.”
Why sea ice is important
The sea ice is a very important habitat for krill in particular and for the reproduction of krill and that forms one of the absolute staples of the diet for many species in the Antarctic
The formation of sea ice around Antarctica every year is one of the biggest seasonal events on Earth.
The ice is generated in what scientists refer to as “sea ice factories” or polynias; areas of the ocean surface where currents and wind patterns combine to generate sea ice.
As soon as sea ice is produced in these polyniers it is actually transported away from that so more sea ice can be produced.
While sea ice can have significant impact on the Antarctic eco-system, Mr Worby said the current increase in the area of sea ice is slight, about 1.5 per cent increase per decade.
“This slight increase really isn’t going to have a significant impact on ecosystem of Antarctica; if there was a dramatic increase that would be a much better story.”
Why is sea ice increasing?
Antarctic Climate and Ecosystems CRC chief executive Mr Worby said unlike in the Arctic, the extent of the southern pole sea ice was increasing.
“The extent of Antarctic sea ice is going in the opposite direction than we’d think as a result of global warming,” he said.
The reason is partly because of the hole in the ozone layer.
The depletion of ozone means temperature is cooler in that part of the atmosphere. At the same time, surface temperatures are increasing due to global warming.
The increase in the disparity between the two is driving a stronger winds – this is the cause of the increase the in extent of sea ice.
But Mr Worby said this is no reason to be complacent about climate change.
As the area covered in sea ice expands the ice on the continent of Antarctica which is not over the ocean continues to deplete.
“If you look at the continental ice, which is the main ice cap, we know there are very significant reductions in the volume of ice.”
– with ABC