Environment & Energy
Related: About this forumCollapse Of Antarctic Ice Sheet Would Likely Put Washington, D.C. Largely Underwater
University of Toronto and Oregon State University geophysicists have shown that should the West Antarctic Ice Sheet collapse and melt in a warming world as many scientists are concerned it will it is the coastlines of North America and of nations in the southern Indian Ocean that will face the greatest threats from rising sea levels.
The catastrophic increase in sea level, already projected to average between 16 and 17 feet around the world, would be almost 21 feet in such places as Washington, D.C., scientists say, putting it largely underwater. Many coastal areas would be devastated. Much of Southern Florida would disappear, according to researchers at Oregon State University.
There is widespread concern that the West Antarctic Ice Sheet may be prone to collapse, resulting in a rise in global sea levels, says geophysicist Jerry X. Mitrovica, who, along with physics graduate student Natalya Gomez and Oregon State University geoscientist Peter Clark, are the authors of a new study to be published in the February 6 issue of the journal Science. Weve been able to calculate that not only will the rise in sea levels at most coastal sites be significantly higher than previously expected, but that the sea-level change will be highly variable around the globe, adds Gomez.
Scientists are particularly worried about the ice sheet because it is largely marine-based, which means that the bedrock underneath most of the ice sits under sea level, says Mitrovica, director of the Earth System Evolution Program at the Canadian Institute for Advanced Research. The West Antarctic is fringed by ice shelves which act to stabilize the ice sheet these shelves are sensitive to global warming, and if they break up, the ice sheet will have a lot less impediment to collapse. This concern was reinforced further in a recent study led by Eric Steig of the University of Washington that showed that the entire region is indeed warming.
http://www.sciencedaily.com/releases/2009/02/090205142132.htm
See this post for more recent information on Antartica
http://www.democraticunderground.com/101724320
Downwinder
(12,869 posts)sharp_stick
(14,400 posts)camping out on your front lawn.
DJ13
(23,671 posts)I guess its payback time.
truebrit71
(20,805 posts)...
Downwinder
(12,869 posts)above projected sea level.
Scuba
(53,475 posts)No jet flights back to home districts for them.
The Republicans would like to see them treated like Katrina victims, only more so.
joshcryer
(62,270 posts)man4allcats
(4,026 posts)freshwest
(53,661 posts)Edit:
Looking at the responses before mine, it appears I was offtopic, since D.C. is focus of thread, not sea level.
MindMover
(5,016 posts)the answer I believe is yes....
grasswire
(50,130 posts)....if you think like a disaster capitalist.
MindMover
(5,016 posts)bananas
(27,509 posts)joshcryer
(62,270 posts)bananas
(27,509 posts)"But
Pollard's study indicates that the West
Antarctic Ice Sheet won't melt away too
rapidly. He figures that will take at least 1,000
years, and more likely 2,000 to 3,000 years."
joshcryer
(62,270 posts)It was "only" 300-400 billion tons of ice melting ... just a short 3 years ago: http://www.agu.org/pubs/crossref/2009/2009GL040222.shtml
Up to half a trillion and showing no signs of slowing down.
bananas
(27,509 posts)bananas
(27,509 posts)happyslug was answering our questions, read his answers:
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=63301&mesg_id=63496
joshcryer
(62,270 posts)The fact is the latest data is far beyond predictions and far worse than anyone could have imagined.
See my other posts which show that 300k people a year will be affected by the turn of the century. A mind boggling number.
bananas
(27,509 posts)and your other post about this century refers to thermal expansion, not ice sheet collapse.
This thread is about ice sheet collapse.
When the Antarctic ice sheets collapse, there will be a large sea level rise in a matter of hours,
according to the discussion from a few years ago.
happyslug (1000+ posts) Thu Aug-10-06 03:46 PM
Response to Reply #20
22. I suspect it will be a gradual raise within a 24 hour period.
Edited on Thu Aug-10-06 03:48 PM by happyslug
Remember a Tsunami is the product of a rapid change in sea floor levels that acts like an agitator on a washing machine. If the WAIS just starts to move into the Southern Ocean (The technical name for th ocean around Antarctica) you may NOT have a rapid agitation but a gradual but rapid raise.
Now I have read about the Azores' Volcano. Every so often (In geological terms which can means once every couple of thousand years) the side of the Island falls into the Atlantic and causes a Tsunami in the direction of New York City. This Tsunami is caused by a rapid fall into he ocean o a huge amount of Earth. While I do NOT see the WAIS doing the same, it might very while act the same way, no one nows and from i have read there is no evidence of such a Tsunami the last time the WAIS collapsed.
Now, what may happen is the Collapse of the WAIS leads to a Tsunami but directed straight alone the International date line Ross sea, so that any resulting Tsunami will not hit anything till the Aleutian islands and then Alaska and Siberia. The same with the Ronne Ice Shelf, it may direct any Tsunami to the "gold coast" of Africa (Nigeria, Liberia etc). Either way no direct affect on Europe or America (Both North and South America). This is complicated by the existence of the Ross and Ronne Ice Shelves, which may act as a barrier to any Tsunami from forming (i.e. The Tsunami expends its energy moving the Ross and Ronne Ice Sheets out to sea to permit the Ice Sheets to follow.
Thus what I suspect will happen is just a steady increase in sea level as opposed to a Tsunami, but since I have no records from 100,000 years ago when this last may have happen your guess may be as good as mine.
Here is a map of Antarctica, the West Antarctic Ice Sheet is between the Ross and Ronne Ice Shelves on the Map (just South of South America):
joshcryer
(62,270 posts)I found the actual paper and it doesn't say "thousands of years" in the abstract. Does it say as such in the paper itself?
bananas
(27,509 posts)In post #16, you linked to another thread: http://www.democraticunderground.com/11279821
and the OP of that thread says thousands of years:
Future generations could face sea levels 20 metres higher
Published 20 March 2012
<snip>
Professor Ken Miller, who led the study, says that sea-level rise would take time.
"You dont need to sell your beach real estate yet, because melting of these large ice sheets will take from centuries to a few thousand years," he says.
"The current trajectory for the 21st century global rise of sea level is 2 to 3 feet (0.8 to 1 metre) due to warming of the oceans, partial melting of mountain glaciers, and partial melting of Greenland and Antarctica."
Still, says Professor Naish, the study calls into question the sensitivity of the earths large ice sheets to temperature change and shows that the natural state of the earth under carbon dioxide already attained in the atmosphere is one with sea levels around 20 metres above present.
"If the present levels of carbon dioxide in the atmosphere are not abated, and humans were to disappear from the planet and return in 2000 years, they would find a world where the oceans have risen 20 metres," says Professor Naish.
bananas
(27,509 posts)The judges finding: This is distinctly alarmist and part of Mr Gores wake-up call. It was common ground that if Greenland melted it would release this amount of water but only after, and over, millennia.
October 10, 2007, 5:26 pm
British Judge Bruises Al Gores Movie
By MIKE NIZZA
Critics of An Inconvenient Truth include Al Gores political opponents, global warming skeptics and even rank-and-file scientists. But the former vice president waited until today for a detailed review from a high court in Britain.
Asked to ban the film from secondary schools, Judge Michael Burton refused, as long as serious scientific inaccuracies, political propaganda and sentimental mush were explained at screenings, Agence France-Presse reported.
The bill of particulars that he issued, posted to the Web site of the plaintiffs political party, had 11 points. Heres the first and possibly most stinging, courtesy of The Times of London:
The judges finding: This is distinctly alarmist and part of Mr Gores wake-up call. It was common ground that if Greenland melted it would release this amount of water but only after, and over, millennia.
<snip>
arachadillo
(123 posts)The news story sounds like a variation on a theme that's been around for quite some time.
NASA continues to move its comparative Antarctic Ice Sheet maps around, so finding the exact link can be difficult.
"That scenario is actually a toned down dramatic version of events. Scientists also estimate that the West Antarctic Ice Sheet has lost two-thirds of its total mass since its most recent glacial maximum (the largest ice mass it achieved) some 20,000 years ago. If the West Antarctic Ice Sheet were at its glacial maximum today, and experienced a sudden collapse, the sea level changes to follow might chase populations somewhere past the Appalachian Mountains to avoid the flooding." West Antarctic Ice Sheet
The probability of ice loss in the Arctic and entire circumpolar north still exceeds to probability of ice loss in the Antarctic and Southern Ocean areas, especially with the increased interest in hydrocarbon extraction throughout the area.
joshcryer
(62,270 posts)OKIsItJustMe
(19,938 posts)And heres a better source for the recent news (Please note, NASA publication, copyright concerns are nil):
http://www.nasa.gov/topics/earth/features/currents-ice-loss.html
04.25.12
[font size=3]WASHINGTON -- Warm ocean currents attacking the underside of ice shelves are the dominant cause of recent ice loss from Antarctica, a new study using measurements from NASA's Ice, Cloud, and land Elevation Satellite (ICESat) revealed.
An international team of scientists used a combination of satellite measurements and models to differentiate between the two known causes of melting ice shelves: warm ocean currents thawing the underbelly of the floating extensions of ice sheets and warm air melting them from above. The finding, published today in the journal Nature, brings scientists a step closer to providing reliable projections of future sea level rise.
The researchers concluded that 20 of the 54 ice shelves studied are being melted by warm ocean currents. Most of these are in West Antarctica, where inland glaciers flowing down to the coast and feeding into these thinning ice shelves have accelerated, draining more ice into the sea and contributing to sea-level rise. This ocean-driven thinning is responsible for the most widespread and rapid ice losses in West Antarctica, and for the majority of Antarctic ice sheet loss during the study period.
"We can lose an awful lot of ice to the sea without ever having summers warm enough to make the snow on top of the glaciers melt," said the study's lead author Hamish Pritchard of the British Antarctic Survey in Cambridge, United Kingdom. "The oceans can do all the work from below."
The new research also links the observed increase in melting that occurs on the underside of a glacier or ice shelf, called basal melt, and glacier acceleration with changes in wind patterns.
"Studies have shown Antarctic winds have changed because of changes in climate," Pritchard said. "This has affected the strength and direction of ocean currents. As a result warm water is funnelled beneath the floating ice. These studies and our new results suggest Antarctica's glaciers are responding rapidly to a changing climate."
A different picture is seen on the Antarctic Peninsula, the long stretch of land pointing towards South America. The study found thinning of the largest ice shelf on the peninsula can be explained by warm summer winds directly melting the snow on the ice shelf surfaces. The patterns of widespread ocean-driven melting and summer melting on the Antarctic Peninsula can be attributed to changing wind patterns.
[/font][/font]
joshcryer
(62,270 posts)RobertEarl
(13,685 posts)Ok, the font you are using in your posts are hard on the eyes.
Can you please not put a font declaration in your posts? I have my computer set to show a certain font and your posts look awful on my screen. Thanks. Here is the code you are using....
<font times="" new="" roman,="" serif="" face="Times,">
arachadillo
(123 posts)A case can certainly be made that warmer oceans are contributing to ice shelf loss around Antarctica.
However, the Scientific Committee on Antarctic Research (SCAR) research adds to the known Antarctica data.
According to SCAR, the ozone hole over Antarctica serves as the most important factor inhibiting the predicted warming effects across the continent, to date. As the use of ozone depleting chemicals are phased out, and the ozone hole repairs itself, scientists expect to see more pronounced warming effects across the continent.
The Bush administration used a similar ten year time frame on changing ice patterns to support the position that climate change is not affecting continental weather patterns.
Therefore following the research of SCAR, along with others such as the British Antarctic survey, variations in Antarctic ice measurements are better understood in longer time frames than the ten year time frame posted on the graph.
bananas
(27,509 posts)arachadillo
(123 posts)Last edited Wed May 2, 2012, 01:43 AM - Edit history (10)
"So that graph is primarily due to the ozone layer repairing itself?"
At first glance, the way I read the graph and the story about loss of ice shelves, my hypothesis is no, ice shelf loss is not a function (at least a statistically significant function) of changes in the size of the Antarctic ozone hole.
Discussions of changes in Antarctic ice normally divide into the three types of ice, sea ice, ice shelves, and ice sheets.
The ice shelves are the ice patches attached to the continent. At first glance, the NASA story on ice shelf loss correlates strongly with increased ocean temperatures around the continent.
The General Circulation Models (GCMs) currently used (and refined over the past three and one half decades) generally predict the "warming" associated with the concept "global warming" will be most significant in the polar regions, with the amount of warming (as measured in temperature days or something like that) diminishing as one moves to the equator.
Now, when one considers the topic as climate change, rather than global warming, it sounds reasonable to suggest that even absent the extreme temperature changes predicted for the polar regions, the climate variations attached to changing temperatures will either adversely or positively affect different areas of the globe.
As far as polar climate comparisons, the increased warming trends predicted by the GCMs appear to fit the Arctic and circumpolar north better than the fit the Antarctic and Southern Ocean areas.
Part of the reason for the less than perfect fit between the GCM predictions and the Antarctic, at least as I read the scientific literature, is that the ozone hole over Antarctica provides an endogenous environmental factors that acts as a stumbling block for increased warming and melting of the Antarctic ice sheets.
Nonetheless, again, as I read the scientific literature, Southern Ocean warming trends, also predicted by the GCMs, are being experienced, and do provide a reasonable explanation of the melting of the ice shelves.
Addendum: Thought it might be helpful to link to the British Antarctic Survey position Antarctica and Climate Change
"The majority of long-term measurements from Antarctic research stations show no significant warming or cooling trends, and temperatures over most of the continent have been relatively stable over the past few decades. The effects of the ozone hole have shielded much of the Antarctic continent from the impact of global warming."
I recognize the original post of this thread focused on the ice sheets, specifically the West Antarctic Ice Sheet. For one reason or another, the discussion drifted to the issue of ice shelves, and, at first glance, it looked to me as if the topics were conflated.
Addendum #2: Quite an interesting puzzle....
According to The University Corporation for Atmospheric Research UCAR the causal link for the ozone hole and the relatively stable continental temperatures over time, appears to be formally presented as
Antarctica ozone hole ---> changes in Southern Annular Mode (SAM) ---> current Antarctic (at least continental) weather patterns
OTOH,
Over at the Westher Channel they show nice graphs of the prevailing wind patterns over Antarctica, with the general flow pattern starting at the pole and moving outward, appearing to be formally presented as
Normal Antarctica wind patterns + warmer air along the western antarctic ----> current ice shelf loss.
Because the research in question does not indicate which wind causal pattern they use for their research, it could very well be the case that the first causal path,
Antarctica ozone hole ---> changes in Southern Annular Mode (SAM) ---> Southern Ocean currents ---> Antarctic (at least continental) weather patterns
Sometimes, the scientific research can be a bit difficult to read. The article, [link:http://www.aos.princeton.edu/WWWPUBLIC/sara/statistics_course/papers/lovenduski_grl_05.pdf|Impact of the Southern Annular Mode on Southern Ocean circulation
and biology]
again, at least at first glance, appears to be supporting this causal change, however it does not introduce the concept of the ozone hole as a primary factor driving variability in the SAM. It does, however, appear to be testing the hypothesis that
changes in Southern Annular Mode (SAM) ---> Southern Ocean currents ---> Antarctic (at least continental) weather patterns
figure 1 appears to show a strong correlation with SAM and winds, and ocean currents
there appears to be a less strong correlation with SAM, winds and sea surface temperatures (SST) , with the only increased temperature correlations found around the area in question, western Antarctica and the Antarctic peninsula.
from this reading, it remains possible that the ozone hole, does account for changing ice shelves (at least in a statistically significant way), thus falsifying (in the Popperian mode) my original hypothesis
researchers may adopt the second causal chain,
Normal Antarctica wind patterns + warmer air along the western antarctic ----> current ice shelf loss
as appears to be done by a researcher at Lamont-Doherty Earth Observatory
with a more sophisticated model
changing ocean currents (implicitly caused by a changing climate?) ---> warmer air along the western antarctic ----> current ice shelf loss
then my first statement,
"At first glance, the way I read the graph and the story about loss of ice shelves, my hypothesis is no, ice shelf loss is not a function (at least a statistically significant function) of changes in the size of the Antarctic ozone hole."
would be, in the Lakatos verification rather than falsification tradition, remain sound, because the global current conveyor belt serves as the impetus of change.
Not knowing how researchers hypothesize the relationship between changing wind patterns and ocean currents, naturally adds an element of uncertainty into any analysis. Either way, the researcher from Lamont-Doherty Earth Observatory explains how climatologists continue to work on both their modeling and data collection, just as they have done over the past forty years.
All things being equal, their partial explanations (or partial models) continue to remain robust in their ability to explain and describe the phenomena in questions, as well as provide above average predictive power.
It also sounds reasonable to assume that changing ocean temperatures around the continent are a function of both traditional Antarctica wind patterns and new Antarctica (and Southern Ocean) wind patterns introduced by the presence of the Antarctica ozone hole. The NASA researchers appear to be building this type of argument or theory in their Antarctic Sea Ice presentation.
kickysnana
(3,908 posts)Odin2005
(53,521 posts)Nihil
(13,508 posts)(For so many different reasons but the net outcome is good.)