If present trends continue, scientists predict that the Arctic could become ice-free within 23 years. To put that into context, it took the last 30 years for it to lose almost a third of its ice. "It's amazing. It's simply fallen off a cliff and we're still losing ice. If you asked me a couple of years ago when the Arctic could lose all of its ice, then I would have said 2100, or 2070 maybe," said Mark Serreze, an Arctic expert at the University of Denver's National Snow and Ice Data Center (NSIDC).
Experts say they are "stunned" by the loss of ice, with an area almost twice as big as the UK disappearing in the last week alone.
So much ice has melted this summer that the Northwest passage across the top of Canada is fully navigable, and observers say the Northeast passage along Russia's Arctic coast could open later this month.
If the increased rate of melting continues, the summertime Arctic could be totally free of ice by 2030.
Mark Serreze, an Arctic specialist at the US National Snow and Ice Data Centre at Colorado University in Denver, said: "It's amazing. It's simply fallen off a cliff and we're still losing ice."
On June 23, 2008, James Hansen (I offered this $1,000 bet with Dr. Hansen in April) said…."We see a tipping point occurring right before our eyes," Hansen told the AP before a luncheon at the National Press Club. "The Arctic is the first tipping point and it's occurring exactly the way we said it would." Hansen, echoing work by other scientists, said that in five to 10 years, the Arctic will be free of sea ice in the summer.
As usual, trying to distort the misinformation you spread. This is what scientists are talking about, SEA ice in the Arctic Ocean, not, as Greenpeace was trying to claim and the subject of that news clip, the Greenland ice sheet (i.e., ice on LAND). As usual, mixing apples and oranges to make dubious claims.Hansen, echoing work by other scientists, said that in five to 10 years, the Arctic will be free of sea ice in the summer.
shamrock5585 said:hmmm... i knew it was less dense and i knew water expands when frozen but i never looked at it in depth... i guess this makes sense because the amount of water the ice displaces is equal to the force holding up the ice due to buoyancy... so when the ice melts it will weigh the same as the water it displaced... hence it will make the same amount of water it displaced in the first place... interesting
Yes that is true, and will cause a local lowering in the apparent sea level. But the rising of land in one location is compensated for the sinking of land elsewhere. An example: the sea level in SE England appears to be rising faster than it should be, this is because the land is sinking in the SE - the mantle beneath is creeping back towards the N from where it was displaced by the last ice sheet.Evo said:Don't forget that as ice melts, the land beneath it rises. It's a *very* slow process, but one that is happening right now from the retreat of the last ice age.
Ivan Seeking said:http://news.nationalgeographic.com/news/2008/06/080620-north-pole.htmlArctic warming has become so dramatic that the North Pole may melt this summer, report scientists studying the effects of climate change in the field.
"We're actually projecting this year that the North Pole may be free of ice for the first time [in history]," David Barber, of the University of Manitoba, told National Geographic News aboard the C.C.G.S. Amundsen, a Canadian research icebreaker. [continued]
Recent models suggest that the Arctic won't see its first completely ice-free summer until somewhere between 2013 and 2030.
An already relentless melting of the Arctic greatly accelerated this summer—a sign that some scientists worry could mean global warming has passed an ominous tipping point.
One scientist even speculated that summer sea ice could be gone in five years.
Greenland's ice sheet melted nearly 19 billion tons more than the previous high mark, and the volume of Arctic sea ice at summer's end was half what it was just four years ago, according to new NASA satellite data obtained by the Associated Press (AP).
Sea ice has dramatically thinned between 2004 and 2008. Old ice (over 2 years old) takes longer to melt, and is also much harder to replace. As permanent ice decreases, we are looking at ice-free summers in the Arctic as early as 2030.
http://nsidc.org/arcticseaicenews/During the first half of August, Arctic ice extent declined more slowly than during the same period in 2007 and 2008. The slower decline is primarily due to a recent atmospheric circulation pattern, which transported ice toward the Siberian coast and discouraged export of ice out of the Arctic Ocean. It is now unlikely that 2009 will see a record low extent, but the minimum summer ice extent will still be much lower than the 1979 to 2000 average.
Evo said:Arctic Ice has only been measured since 1979. Years 2008 and 2009 have both seen an increase in Arctic ice coverage since the unusual conditions that caused a decrease in 2007.
http://nsidc.org/arcticseaicenews/
Antarctic Ice ice has been increasing for 30 years.
http://www.nasa.gov/centers/goddard/news/topstory/2005/sea_ice.html
Too bad we've only had records from 1979, and those older records, not so good. Not long enough to get a real picture of cycles there. But data is getting better. It will be interesting to see more data as years go by.sylas said:The summer extent in 2008 increased with respect to the exceptional low point of 2007; but not with respect to anything else. 2008 was easily the second lowest summer minimum in sea ice extent since we've had records.
Just so as to not confuse members, the FAQ is about the Arctic, not the Antarctic.That's a great site, Evo; with lots of good information.
I really recommend their FAQ page.
Fortunately the expansion of water near it's maximum density is very small 0.01%/cbilliards said:Water also expands when heated. In fact, thermal expansion of the oceans is, according to the IPCC, the largest single contributor to sea level rise.
Evo said:Too bad we've only had records from 1979, and those older records, not so good. Not long enough to get a real picture of cycles there. But data is getting better. It will be interesting to see more data as years go by.
I guess my greatest concern is what is happening in the oceans. I am not concerned about humans being inconvenienced by having to abandon waterfront property, or the fact that we will see some species go and new species flourish.
Just so as to not confuse members, the FAQ is about the Arctic, not the Antarctic.
jimmysnyder said:Last Sunday my wife and I staked out a nice place on the beach in Seaside Heights, NJ. We planted the umbrella in the sand, unfolded the folding chairs, spread the tarp and placed books on the corners to keep the flapping down. Then we went wading in the ocean, took a promenade on the boardwalk, and rode the ski lift to nowhere. What a blast. But while we weren't paying attention, there must have been some global warming. Whether man-made or woman-made is yet to be determined. Then one of the ice caps melted and the waterline came and wetted the tarp. Poor books. We picked up and drove inland just ahead of the melting of the other cap. This helped but little as one of the polar ice caps on Mars melted next. We went home exhausted, but happy.
It's really quite frightening.sylas said:I'm mostly interested in the science aspects. Impacts and so on is not really my baliwick.
[/URL]kldickson said:There's not a lot of Antarctic rock above sea level.http://www.physorg.com/newman/gfx/news/hires/RonneFichner.jpg
That sounds dubious to me. If the land is already above sea level and then rises, it would have no effect whatever on sea level. Would the land really rise? Last year some workers drove a truck on my lawn to cut down a tree and the ruts are still there.ideasrule said:Keep in mind that much of Antarctica has a few kilometers of ice pressing down on it. Once some of that ice is gone, the land would rise, displacing sea water and forcing sea level to rise.
jimmysnyder said:That sounds dubious to me. If the land is already above sea level and then rises, it would have no effect whatever on sea level. Would the land really rise? Last year some workers drove a truck on my lawn to cut down a tree and the ruts are still there.
‘It will, without doubt, have come to your Lordship's knowledge that a considerable change of climate, inexplicable at present to us, must have taken place in the Circumpolar Regions, by which the severity of the cold that has for centuries past enclosed the seas in the high northern latitudes in an impenetrable barrier of ice, has been during the last two years greatly abated. This affords ample proof that new sources of warmth have been opened, and give us leave to hope that the Arctic Seas may at this time be more accessible than they have been for centuries past, and that discoveries may now be made in them, not only interesting to the advancement of science, but also to the future intercourse of mankind and the commerce of distant nations.’
sylas said:It doesn't need to be. All you need is for the ice to be resting on rock. If so, then melting ice will raise sea level, because the ice surface is above sea level, and it isn't floating.
Andre said:I have been wondering about available long term data of arctic temperatures comparing the warmer spell in the 1940s with those of nowadays. So I went to GISS
http://data.giss.nasa.gov/gistemp/station_data/
and clicked on Northernmost Siberia, Greenland and the NWT in Canada, then I selected the first series of stations that were providing data as of at least 1930 until now. Now what would be the difference between the 1930-40s warming and the current warming?