Brett, the IPCC AR4 WG1 report explicitly states that it had to exclude possible sea level rise due to these effects since there wasn't (and still isn't) a scientific basis for estimating how fast the melt could proceed. Coming up with such an estimate is a complex exercise that involves modeling both ice sheets in detail, and while the glaciologists are working hard on the problem it may be another five years or so before we start seeing the results of that work.

The key point is that it is now uncontroversial among glacologists that the effects of this "dynamical" melting will be substantial. See this paper for a discussion of the situation (I think from about a year ago, but there's nothing more recent with this kind of detail). Note that just a few years ago there was more or less a consensus that the 2001 IPCC assessment that the ice sheets would accumulate mass as warming progressed during the 21st century was still correct, so the field has been a little whipsawed.

Jim Hansen observes (start with this recent note, but see this linked paper for the specific discussion of this point) that under natural conditions this type of rapid ice sheet melting (of the sort seen at the end of glacial periods) is paced by high-latitude insolation increases due to orbital (Milankovitch) changes. These changes are quick in geological terms but slow on a human scale. While on the one hand there is less ice to be melted now than during a natural deglaciation, on the other hand there is no natural "speed limit" of the sort mentioned above.

Old news. From a 2002 article, Further, they suggest that the observed process may also have contributed to the extensive melting of the Greenland Ice Sheet during the last Interglacial period, some 125,000 years ago. According to the U.S. Geological Survey, previous studies have shown that during the last Interglacial period, carbon dioxide (CO2) concentrations in the atmosphere were relatively high, temperatures may have been higher than the present, and sea level may have been approximately 6 meters (19.5 feet) higher. "During this time when the climate was warmer, the ice sheet was less extensive.

What the heck is going on here? This can't be. The present warming is unprecedented, yet this article expects us to believe that CO2 concentrations were high, temperatures higher than present, and sea level 6 meters higher than today.

Was this natural or due to AGW? Everyone knows that any warming can only be attributed to AGW, but what I want to know is how our ancestors managed to pull this off. Alien help?

Obviously, the moulins hate our coastlines for their freedom.

As a non expert in this field but with a very keen interest, i am worried about where all of this fresh water from melting ice in the Arctic is going! Will these large quantities of meltwater effect the thermohaline as has been theorised and mentioned on earlier entries on this site. Whether your a sceptic or not,this must be worrying, wasn't it large amounts of fresh water pouring into the North Atlantic that caused the Younger Dryas at the end of the last glacial?

um, why is it so difficult to grasp the credibility of the connection between extracting and releasing massive amounts of carbon based energy into the atmosphere and rising global temperatures? CO2 concentrations are accelerating NOW, and it's largely due to human influence...there is hardly any lack of consensus on this process.

what's with this argumentative stance that there needs to be absolute certainly on the source of global temperature rise, melting glaciers, etc. before we take proactive measures to protect our future viability?

is it so the "progressives", "liberals", and "Al Gore" types can be proven wrong?

what position or interests are you defending by arguing and suggesting that we do nothing?

Brett,

The article written by Paul Brown of AlterNet is written with all the fervor of a true believer, complete with the looming apocalypse and the seemingly mandatory belittling of all who dare to disagree. For you to say that AlterNet is a "progressive" newsite is exceedingly kind on your part. It is a blatantly in-your-face leftwing rag. You should try to make your postings at least somewhat science-oriented, and from somewhat more neutral sources.

Steve

Reply: Steve, I try, but there are times when it cannot be avoided either way (right or left) in order to get the story.

Paul,

The key word in the link is relatively high.

Over the last 650,000 years, CO2 levels have been found to vary naturally between 180 to 280 ppm.

180 ppm during ice ages.

280 ppm during warm periods.

Current CO2 levels are elevated at about 385ppm.

This provides a warming of the atmopshere and allows it to hold more water vapor (another greenhouse gas).

So, the net result is much greater warming now than before.

Is this amount of melting likely to slow the gulf stream further?

Yep, people started noticing this effect about five years ago. In the intervening period it's gotten a lot more noticable.

Paul, nobody thinks you're that stupid, nor is your rhetorical flopping around going to convince anyone. All you're doing is embarassing yourself.

But just in case you really are confused:

Wait for a warm day and put an ice cube outside in a sunny location. Observe that the ice cube melted due to natural influences.

Take another ice cube and put it in the same location. Let it begin to melt, but then take a good-sized magnifying glass and focus it on the ice cube. Observe that the ice cube melted faster due to the combination of natural and anthropogenic influences.

There you go.

My underwater suspension Tunnel idea prevents this also.

Greenland ice cap melting faster than expected

COPENHAGEN, Oct 11 (AFP) Oct 11, 2007
The ice cap in the northern hemisphere is melting a lot more rapidly that scientists thought, according to new research published Thursday by the Danish National Space Center.

http://www.terradaily.com/2007/071011171235.27npmcyt.html

More Global Warming craziness! How about the arctic, indian (maldives), pacific (tavalu)sea levels are falling! The interior Antarctic Ice sheets are reaching records thicknesses, Scottish mountains just recieved snow a month earlier than normal, there's been significant snow fall in the Alps, we've had record lows in 7 states since the beginning of October, we've had very low hurrican activity, Alaskan glaciers have advanced 1/3 of a mile in less than a year, the glaciers in France and Switzerland are growing, Mount St. Helen's glacier is growing rapidly, ok, I quit...this must be all attributable to global warming...

Brett,

I know that you are an expert on Canadian weather. I've been noticing that it's been quite warm in mainland nunavut over the past couple of days. Is there a simple explanation for their current warm pattern. I plan on watching winter temps in northern Canada/Greenland closely this year, to see if the low ice coverage causes an even greater warm anomaly than has been present over the last few years.

Thanks

Reply: There has been a blocking ridge of high pressure recently in that region keeping things fairly mild.

To be intellectually rigorous, I should say that I will be watching to see if there is a particularly large warm anomaly, which, if it did occur, would support those predictions which state that low arctic ice levels will lead to a significant increase in warming rate up there.

I'll be a bit liberal here in terms of expectations. Show me, at a 65% confidence level:
- Frequency and distribution of moulins in Greenland for the past 150 years
- Average moulin dimensions, same period
- Proxies of moulins for MWP

If these showed something abnormal now, I would get excited. Otherwise, ho hum .....

Charles,

ok, I quit...this must be all attributable to global warming...

Your sarcasm aside, I'm interested to see your information sources. If you have links, will you please post them?

Glaciers on Mount Saint Helens have, of course been growing since the eruption a couple decades ago simply due to the fact that all existing glaciers at the time were either reduced in size or were completely obliterated by the eruption. Water from those glaciers and from snow contributed the moisture to the lahars that swept down the mountain.

I think most people are aware of the amount of precipitation that the Pacific Northwest receives every year (I certainly am). Mount Saint Helens gets roughly 145 inches of precipitation annually, including about 16 feet of snow. Although the region is warming in general, it is still cold enough at higher elevations to support glacier formation. If it wasn't, all the glaciers in the Northwest would have disappeared long ago. On the other hand, the elevation that supports glacial development continues to rise with the temperature; glaciers on nearby Mount Rainier, Mount Hood, and Glacier Peak have been receding for the past few decades.

Changing gears, here is an explanation I found for the decline in Indian Ocean sea level:

http://stephenschneider.stanford.edu/Publications/PDF_Papers/MornerEtAl2004.pdf

And also one for Arctic sea level:

http://www.whoi.edu/science/PO/arcticsealevel/conclusions.html

To sum up, the decline in sea level in the Indian Ocean is possibly attributable to increased evaporation in the region:

In the central Indian Ocean, eustatic sea level lies well below the geoid surface because of an exceptionally high rate of evaporation (Morner, 2000). Therefore, if this evaporation increases further, sea level will fall significantly.

Changes in Arctic sea level are varied depending on the region. The Woods Hole study concludes that Arctic sea levels are rising near the coastlines and falling in the central Arctic Basin.

Also, it might be worth asking how many record highs have been set since the first of the month here in the U.S.A. I don't have the specific data, but looking at the HPRCC graph (linked below), I'd say it's highly likely that more record highs have been set across the country this month than record lows.

http://www.hprcc.unl.edu/maps/index.php?action=update_daterange&daterange=Month

In any case, none of this short term data you and I have discussed is significant unless it is shown to be part of a larger and longer trend. That said, I would still like to see your sources. If you could provide links, that would be much appreciated.

Does anyone know how to pronounce "moulin?" I need to know, for it may become a talking-point at certain parties I attend. And it doesn't matter how valid my points are at such parties; everyone sticks their noses up at me if I pronounce a word incorrectly.

Also Elliot Abrams will need to know, in order to create puns.

I tend to be distrustful of such articals, simply because they are so sensational. I used to get like Chicken Little and run around shouting, "The sky is falling," but I'm getting too old for that. The sky hasn't fallen yet, and the first end-of-the-world theory I subscribed to was back in the 1970's, and stated the end would be in 1980. When Mount Saint Helens blew in 1979 I started stock-piling toilet paper and peanut butter. The only good that came out of it was that I didn't need to buy toilet paper for a long, long time.

Notice how the piece by Paul Brown in Alternet discusses the discovery of the lake under the ice. One gets the impression recent melt-water has created the lake, and the entire icecap is being lifted and floating. In actual fact the radar which discovered the lake was only recently invented, and the lake may have been there for thousands of years.

I recall reading of a huge lake under the ice in Antarctica. I think it was discovered by setting off charges at the surface and listening to the echoes. The Russians were drilling down to investigate it, but were stopped because their drill likely would pollute the water. As I recall that huge lake was something like 100,000 years old.

Anyway, you can call me a bitter, old skeptic if you want, but articals such as this one always get my hackles up. It might be interesting to photograph my face as I read.

With all the things that happen within and below a glacier, how can we still believe in the reliability of ice-core data to estimate past climatic conditions

Jeez, if you're trolling for 'news' on AlterNet, you may as well also post links to more credible sites like Junk Science. Reply: I am not trolling for news on Alternet. That just hapened to be the site in which this story was on. Actuially one of my co-workers meteorologist Jim Andrews heard about the story and told me. Brett

This is a propaganda piece, featuring the usual suspects. If they have new data and new conclusions to advance, let them do so through the sacred "peer-review" process.

That being said, it's nice that ice-penetrating radar has been invented. Hopefully we'll now be able to acquire some reliable data. It's also nice to have these people admit the science is not settled.

Glaciers go through periods where they gallop, and periods when they slow down. Small differences in temperature drive large changes in velocity. It is normal cyclical behavior and a view over 10-20 years is meaningless.

Greenland receives about 2,000 trillion liters of snowfall every year (average snowfall 1m x 2 million km2.) It all either melts, sublimates or accumulates. All studies show that the bulk of Greenland never has any melt, and is thus accumulating snow. How many thousands of Niagara Falls would that quantity of snow fill up, without any impact on sea level?

Hysterics has no place in science.

Patrick Henry

Hysterics has no place in science!

Good point and science has found that there is a net loss from Greenland.

http://www.agu.org/pubs/crossref/2005/2005GL023955.shtml

Likewise, the IPCC has found that both conclusive proof is net loss of snow from both the Greenland and Antarctic ice sheets.

http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch04.pdf

Andrew,

Over the last 650,000 years, CO2 levels have been found to vary naturally between 180 to 280 ppm. 180 ppm during ice ages. 280 ppm during warm periods. Current CO2 levels are elevated at about 385ppm. This provides a warming of the atmopshere and allows it to hold more water vapor (another greenhouse gas). So, the net result is much greater warming now than before.

So, 125,000 years ago CO2 concentrations were 280 PPM, temperatures higher than today, and sea level was 6 meters higher than sea levels today with 385 PPM CO2. Explain that one to me one more time. I fail to see the logic there. Seems to me that Greenland's ice cap should have melted about 100 years ago when CO2 concentrations were at 280 PPM.

Unless, something other than CO2 was causing the melting and/or freezing.

Mr. Bloom,

What say ye?

The bulk of Greenland has no melt, eh PH? have you been living in a cave with no communication with the outside world? See here for a nice graphic showing the progression of the melt.

Oh, and pasted below is more on the study the other Patrick linked above. Note that this is just one part of Greenland.

"Greenland is melting at record speed

"The inland ice on Greenland is vanishing much faster than scientists previously believed. This can be seen from new research results from the Danish National Space Center.

"Each year, in the south eastern part of Greenland alone, the glaciers produce a mass of icebergs which is equivalent to a gigantic ice cube measuring 6?km on all sides. And the reduction of the inland ice is accelerating. At the moment, four times as much inland ice is disappearing compared to the beginning of the decade.

"'If this development continues, the melt water from the inland ice will make the world?s seas rise by more than 60 cm this century', says senior researcher Abbas Khan of the Danish National Research Center, who was responsible for the research project. The results were obtained in co-operation with the University of Colorado and have just been published in the international research magazine Geophysical Research Letters.

"The researchers have measured the rate of melting with special, highly sensitive GPS stations placed on the mountains along the inland ice. When a quantity of inland ice disappears, the pressure on the surrounding mountains eases and they therefore rise slightly. This can be measured by the GPS stations. The measurements show that the mountains along the fast glaciers in south east Greenland are rising by 4-5 cm a year. Meanwhile, the rim of this inland ice will be 100 m thinner a year."

This is the bio of the author of the AlterNet story:

Paul Brown was the environment correspondent for The Guardian newspaper for 16 years and has worked in newspaper journalism for more than 40 years. He has written extensively about climate change, population, biodiversity, pollution, energy, desertification, and ocean management. Brown has appeared in and written television documentaries on environmental issues, contributed to books on green politics, and is the author of several books on the environment. www.globalwarningbook.com

Brett, OTOH, has used material from Steve Milloy, who is no scientist and certainly no journalist. Reply: I think I used info. from him one time, and I honestly do not remember what it was. Brett. I'm still waiting for balance.