Polar opposites


in Science, The environment

By now, everybody knows that the Arctic summer sea ice is at an all-time low. What I only learned recently is that the extent of Antarctic ice is the greatest since satellite observation began in 1979. At the same time, it is undergoing “unprecedented collapses” like the much-discussed Larsen B collapse. Such realities hint at the complexities of the climate system.

Whereas the Arctic doesn’t have any effect on sea level, because it floats, the Antarctic rests on land. As such, changes in its ice mass do affect the depth of the world’s oceans. Antarctica is also the continent for which the least data is available, making it hard to incorporate into global climate models. As with all complex dynamic systems, there are non-linear effects to contend with. That makes it dangerous to extrapolate from present trends, especially when it comes to local conditions.

All this makes you appreciate why scientists frequently sound less certain about the details of climate change than politicians do. The harder you look at systems like the Earth’s climate, the more inter-relationships you discover, and the more puzzles there are to occupy your attention.

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{ 8 comments… read them below or add one }

Milan October 2, 2007 at 1:29 pm

Characteristics: Arctic vs. Antarctic

Because the Arctic and Antarctic are cold, dark, and remote, we often think these two places are nearly the same. However, they are quite different. One notable difference is that polar bears live only in the Arctic, and penguins live only in the Antarctic. But what about the differences in sea ice between the two regions?

From the U.S. National Snow and Ice Data Center

Rob October 3, 2007 at 9:02 am

This made me realise, or possibly remember, that the volume of water displaced by a floating object must have the same mass as that floating object; thank you.

. October 31, 2007 at 12:45 pm

Southern snowmelt
Harvey Leifert
Geophys. Res. Lett. 34, L18504 (2007)
Antarctic snowmelt is occurring farther inland and at higher altitude than previously observed, according to a new analysis of satellite observations.
A team led by Marco Tedesco at the University of Maryland, US, and NASA mapped the extent and duration of Antarctic melting continent-wide over 20 years using microwave satellite imagery. Unlike other satellite instruments that use visible or infrared data, the sensors can measure the microwave radiation naturally emitted by snow and ice, can see through clouds, and can even detect subsurface melting, day and night.
The data show that from 1987 to 2006, Antarctica, as a whole, cooled, but in some years, coastal areas became warmer. The greatest extent and duration of melting was observed at the Ross Ice Shelf — the continent’s largest ice shelf — where the researchers detected episodes of persistent melting lasting three or more days, starting in 1991–1992. In early 2005, the persistent melt reached nearly 900 kilometres from the coast and an altitude of 2 kilometres in the Transantarctic Mountains — farther inland and higher than ever before recorded. Ice shelves slow the flow of glaciers, and a weakened Ross Ice Shelf could allow much greater quantities of inland ice to reach the ocean, potentially resulting in a significant rise in sea level.

. November 5, 2007 at 9:48 am

Climate shift ‘poles apart’

By Richard Gray
Last Updated: 12:01am GMT 04/11/2007

The Antarctic will be spared the worst of global warming and its ice mass could even grow, but the Arctic will be devastated by rising temperatures, a major new scientific report will claim.

In contrast to earlier fears that ice around the South Pole will suffer widespread melting, the United Nations intergovernmental panel on climate change says that Antarctica’s ice sheets will remain too cold for widespread melting before the end of the century and are expected to get bigger as more snow falls.

The Arctic, by comparison, will suffer widespread loss of sea ice while the Greenland ice sheet will have almost completely disappeared by the end of the century. Up to half of the Arctic tundra will be replaced by forests as temperatures rise by 4degC.

Anon November 8, 2007 at 12:21 am

Ice expedition tests ‘successful’
By Rebecca Morelle
Science reporter, BBC News

In 2008, explorer Pen Hadow will trek 2,000km across the North Pole, dragging a radar that will probe the thickness of the ever-shrinking ice-cap.

In advance of the expedition, the team headed to Eureka, north Canada, to test whether the instruments could perform in the tough Arctic conditions.

Mr Hadow said that the team’s “planning and hard work had paid off”.

The radar, known as Sprite, was able to make accurate ice measurements in temperatures of -35C, the team said.

. November 27, 2007 at 2:08 pm

White Continent in its full glory

Scientists have produced the most detailed map yet of Antarctica.

US and UK researchers have stitched together more than 1,000 views of the White Continent to make a stunning new high-definition polar panorama.

. December 3, 2007 at 9:45 am

The true North strong and free – but not cheap

Canada’s premier Arctic scientific support facility is open for only half the year and has just eight people working for it.

Anon February 13, 2008 at 10:58 am

12 February 2008
Antarctica is Cold? Yeah, We Knew That

Despite the recent announcement that the discharge from some Antarctic glaciers is accelerating, we often hear people remarking that parts of Antarctica are getting colder, and indeed the ice pack in the Southern Ocean around Antarctica has actually been getting bigger. Doesn’t this contradict the calculations that greenhouse gases are warming the globe? Not at all, because a cold Antarctica is just what calculations predict… and have predicted for the past quarter century.

It’s not just that Antarctica is covered with a gazillion tons of ice, although that certainly helps keep it cold. The ocean also plays a role, which is doubly important because of the way it has delayed the world’s recognition of global warming.

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