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Archive for the ‘Antarctic’ Category

Earth’s poles are shifting because of climate change

“Climate change is causing the North Pole’s location to drift, owing to subtle changes in Earth’s rotation that result from the melting of glaciers and ice sheets.

Computer simulations had suggested that the melting of ice sheets and the consequent rise in sea level could affect the distribution of mass on the Earth’s surface. This would in turn cause the Earth’s axis to shift, an effect that has been confirmed by measurements of the positions of the poles.

Jianli Chen of the University of Texas at Austin and colleagues have shown that melting due to our greenhouse-gas emissions is making its own contribution to the shift. …”Ice melting and sea level change can explain 90 per cent of the [eastward shift],” says Chen. “The driving force for the sudden change is climate change.””

http://www.newscientist.com/article/dn24755-earths-poles-are-shifting-because-of-climate-change.html

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New threat to Antarctic ice shelf emerges

“German researchers have found evidence that areas in Antarctica, previously thought relatively safe from the direct influence of climate change, are melting rapidly. An Antarctic area previously thought stable is at risk of melting rapidly within the next century, new research suggests.”

http://www.dw.de/dw/article/0,,15948265,00.html?maca=en-rss_en_nr_ecol-7439-xml-mrss

Video: Ancient climates and the uniqueness of current climate change (Ron Dunbar)

Video: Ancient climates and the uniqueness of current climate change –  [TED Air]
http://www.ted.com/talks/rob_dunbar.html

Ocean Currents Speed Melting of Antarctic Ice, as “Seawater Appear[s] to Boil on the Surface Like a Kettle on the Stove”

http://thinkprogress.org/romm/2011/06/27/254996/melting-antarctic-ice/?utm_medium=twitter&utm_source=twitterfeed

Ice Loss Accelerates in Greenland, Antarctica, NASA Study Finds

March 9, 2011 – Original Source: Bloomberg

Greenland and Antarctica’s ice sheets are shrinking more quickly, suggesting United Nations projections for sea-level rise are too conservative, a U.S. National Aeronautics and Space Administration-funded study said.

From 1992 to 2009, the two regions lost on average 36.3 billion tons more ice every year than the previous year, scientists led by Eric Rignot at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a study in the Geophysical Research Letters journal. The researchers said they linked two independent sets of measurements to validate them.

Continuing the trend may raise oceans 15 centimeters (6 inches) from 2010 to 2050, and by 56 centimeters by 2100, the study said. That’s more than what was factored into the 2007 projection by the UN’s Intergovernmental Panel on Climate Change for seas to rise 18 to 59 centimeters by 2100.

“If present trends continue, sea level is likely to be significantly higher than levels projected by the United Nations,” Rignot said in a statement e-mailed late yesterday by NASA. “Our study helps reduce uncertainties.”

The UN prediction also includes the expansion of water with warmer temperatures and the melting of mountain glaciers and smaller ice caps.

The researchers said their 2050 forecast has a margin of error of 2 centimeters. Melting from mountain glaciers and smaller ice caps would add 8 centimeters to the sea level increase. The expansion of water as temperatures rise would add 9 centimeters, the researchers said.

They warned their 2100 figure can’t be considered a projection because of “considerable uncertainty in future acceleration of ice sheet mass loss.”

‘Surprising’ Acceleration

The IPCC in 2007 said Greenland and Antarctica contributed a combined 0.42 millimeters a year to sea level rise from 1993 through 2003. That’s just over half the 0.77-millimeter contribution from mountain glaciers and smaller ice caps, and a quarter of the 1.6-millimeter rise as a result of water expanding with warmer temperatures.

The North Atlantic island and southern continent now contribute more than mountain glaciers and ice caps, according to the NASA study. The researchers cited another paper that put the ice loss of the glaciers and ice caps at 402 billion tons in 2006, compared with the 475 billion tons from Greenland and Antarctica in the same year — equivalent to 1.3 millimeters of sea level rise. The acceleration in ice loss is three times greater than for mountain glaciers, they wrote.

“That ice sheets will dominate future sea level rise is not surprising — they hold a lot more ice mass than mountain glaciers,” said Rignot, also a researcher at the University of California, Irvine. “What is surprising is this increased contribution by the ice sheets is already happening.”

Utrecht University in the Netherlands and the National Center for Atmospheric Research in Boulder, Colorado, also contributed to the research. The scientists correlated different sets of satellite, radar and climate modeling data to produce the study.

Antarctic Sea Ice Increase Not Linked to Ozone Hole, New Research Shows

October 6, 2010 – Original Source: ScienceDaily

While sea ice extent has declined dramatically in the Arctic in recent years, it has increased slightly in the Antarctic. Some scientists have suggested that increased Antarctic sea ice extent can be explained by the ozone hole over Antarctica. Previous simulations have indicated that the ozone hole induces a large change in atmospheric circulation in austral summer and that this change in circulation could contribute to the changing Antarctic sea extent.

To learn more, M. Sigmond, of the Department of Physics at the University of Toronto, and J. C. Fyfe, of the Canadian Centre for Climate Modelling and Analysis, Environment Canada, used a climate model, forced by monthly varying observed stratospheric ozone changes from 1979 to 2005, to simulate the effects of stratospheric ozone depletion on Antarctic sea ice extent.

Contrary to predictions of previous studies, their model finds that ozone depletion would lead to a year-round decrease in Antarctic sea ice extent rather than the increase that was observed. The results suggest that processes other than ozone depletion must be causing the observed increase in Antarctic sea ice extent.

It remains unclear why Southern Hemisphere sea ice trends differ so greatly from Northern Hemisphere trends.

The research appears in the journal Geophysical Research Letters.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Geophysical Union, via EurekAlert!, a service of AAAS.


Journal Reference:

  1. M. Sigmond, J. C. Fyfe. Has the ozone hole contributed to increased Antarctic sea ice extent? Geophysical Research Letters, 2010; 37 (18) DOI: 10.1029/2010GL044301

How a 2-degree climate change would hit Canada

October 5, 2010 – Original Source: CBC News

Ongoing climate change means that summer Arctic sea ice could be halved, runoff in the South Saskatchewan River basin reduced and the cost of shipping through the Great Lakes and St. Lawrence Seaway could rise due to lower water levels, according to a compilation of research published Tuesday.

Billed as the first comprehensive illustration of expected climate impacts in Canada, the report is a joint project of the National Round Table on the Environment and the Economy (NRTEE) and the Royal Canadian Geographical Society (RCGS), which publishes Canadian Geographic and Géographica magazines.

The October issue of the magazines feature the compiled research, including a diagram outlining 60 effects of climate change at increasing levels of warming.

“I think it’s important to get the correct science information in Canadian hands,” NRTEE chair Robert Page said Tuesday at an Ottawa news conference called to release the data. “What I like about this (report) is it’s an attempt to bring it back to an accepted factual base.”

The scenarios about Arctic sea ice, the South Saskatchewan River and the Great Lakes are premised on a temperature increase of 2 C over pre-industrial levels.

That temperature rise is significant because the United Nations climate change summit in Copenhagen last December ended with a non-binding document aiming to limit world temperature increases to no more than 2 C. Globally, temperatures have already risen by 0.8 C over the past century.

But as Page pointed out, the increase in temperature in Canada is expected to be twice the world average, and parts of the Canadian North are expected to experience a rise in temperature that is twice the Canadian average.

Yet as the compiled research shows, not all impacts in Canada are negative. For example, a 2 C increase could bring increased timber yields from faster-growing trees in the North and more Atlantic cod north of the 60th parallel. The ski industry might struggle, but golfers could benefit from warmer temperatures.

The society and roundtable have also produced an education package based on the compiled research, which will be distributed to 12,000 schools across Canada.

On Tuesday evening, the two groups hosted a reception at the Canadian Museum of Nature where Canada’s new Gov. Gen. David Johnston spoke.

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