End of Century Sea Level Rise Forecasts are Overdone
The opening of a moulin on the Greenland Ice Sheet. Image courtesy of NASA.
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An increase in global sea level of more than 2 meters (6.6 feet) by the year 2100 is implausible, according to scientists from the University of Colorado at Boulder.
The team, led by Professor Tad Pfeffer, estimated the volume of ice that all glaciers and ice sheets across the globe could lose through ice melt and the release of icebergs into the ocean, according to the short Nature Reports article.
In order for a greater than 2 meter (6.6 feet) by 2100 the discharge of icebergs into the ocean would need to increase more rapidly than ever observed at rates that are probably not feasible.
The below exerpts are from the more in depth ScienceDaily article................
"For Greenland alone to raise sea level by two meters by 2100, all of the outlet glaciers involved would need to move more than three times faster than the fastest outlet glaciers ever observed, or more than 70 times faster than they presently move," said Pfeffer. "And they would have to start moving that fast today, not 10 years from now. It is a simple argument with no fancy physics."
"In my opinion, some of the research out there calling for 20 or 30 feet of sea rise by the end of the century is not backed up by solid glaciological evidence," said Pfeffer.



Comments (33)
“The new study factors in the dynamic effects of glaciers and ice sheets on sea level, aspects that have been excluded from earlier model estimates owing to poor understanding of the processes.”
WHAT?
Somebody in a field of study that they actually have a degree in casts doubt on the veracity of a Dr. Hansen prognostication?
Somebody in these young fields of study admits that their models are wrong?
Why?
Maybe we haven’t done enough basic research to understand basic climate?
Could it be that we just don’t know enough of what forces actually makes weather and climate?
Have our current “Super Computers” failed us because we are not as smart as we think and thus they regurgitate nothing but nonsense instead of science fact?
I find that hard to believe that anybody would be so bold as to actually write an article saying that we are not the omnipotent all knowing beings as the AGW side portrays itself. Is that heresy in a field of overwhelming consensus? I shutter to think that. Alas I fear that the minions of the mindless bow their heads to no one but those espousing guilt from our success as a species. This article will undoubtedly be maligned and vilified as it is not a consensus pleaser.
In any case it is an interesting article, giving one pause to think (A rare commodity in a world of overwhelming AGW consensus)
On the bright side, Diogenes can now rest in peace as we may have found an honest man.
Posted by ted | September 16, 2008 8:50 AM
I attended a presentation last week by IPCC lead author David Randall at Colorado State University, where he used the "two meters this century" number and alarmed an audience of over a thousand students and teachers. Perhaps he doesn't communicate with his colleagues in Boulder?
The CU graph shows that sea level has been declining for three years.
http://sealevel.colorado.edu/
100% proof that the IPCC and Hansen are dead wrong.
Posted by Patrick Henry | September 16, 2008 9:52 AM
The last three years we have been told that The Arctic is melting at a rate faster than any time in the last million years, yet sea level is declining. Obviously the Arctic claims are incorrect, and the people making them should be honest enough to acknowledge.
http://sealevel.colorado.edu/
Reply: How do see that sea level is dropping PH? I guess you are just totally ignoring the longer term trend line on the graph and just picking out the leveling off of the past 12 months. Very convenient.
Posted by Patrick Henry | September 16, 2008 11:45 AM
"In my opinion, some of the research out there calling for 20 or 30 feet of sea rise by the end of the century is not backed up by solid glaciological evidence," said Pfeffer...well i be darned, an egghead with some common sense...and in boulder colorado no less...quick somebody call a doctor, this dude must be ill...is there a doctor in the house...paging doctor hansen...paging pontificating, doom and gloom doctor hansen...emergency, please report to the al-gore-memorial-ward-for-lying-hysterics...there is skeptic in the emergency ward that is suffering from a co2 induced heat stroke, and gasp, he is on the verge of a catastrophic tipping point of realization that AGW is a farce...have a nice day, bros!!!
Posted by sammy k | September 16, 2008 12:04 PM
Something of a straw man argument to point out the Greenland alone can not produce enough sea level rise.
Most everybody knows that west Antarctica has much more ice than Greenland.
Posted by Andrew | September 16, 2008 12:09 PM
Nice to read something with a measure of restraint and a little common sense for a change instead of all the hysteria.
This article definitely won't make the cut in the main stream media newsrooms.
Posted by D Caldwell | September 16, 2008 1:15 PM
Note that their least estimate of 80 cm is also the most likely, according to the paper.
Even that will be quite bad enough.
Posted by David B. Benson | September 16, 2008 7:07 PM
Oh, goody, more red meat for the site denialists to have their way with.
FYI, Brett, it has been pointed out that there is no "research out there calling for 20 or 30 feet of sea rise by the end of the century." Concern about a likely worst-case scenario for this century has been focused on the 2 to 3 meter range, to which these results add no new constraint.
This RealClimate post has the details.
Posted by Steve Bloom | September 16, 2008 8:01 PM
The 'most plausible' sea rise is between 3 and 6 foot. Yet it is 'implausible' that sea level will rise more than 2 metres (6.6 feet).
Seems odd to me that the 'implausible' level is so close to the top of the 'most plausible' level.
Posted by Michael | September 16, 2008 8:07 PM
Brett,
Here is the "longer term trend"
http://www.globalwarmingart.com/images/thumb/0/0f/Recent_Sea_Level_Rise.png/700px-Recent_Sea_Level_Rise.png
and here
http://www.globalwarmingart.com/wiki/Image:Holocene_Sea_Level_png
Sea level has been going up continuously for the last 20,000 years. There is no indication that it has accelerated - quite the opposite. If the oceans were warming and the ice sheets melting, we would have to see an increase in the rate of sea level rise, but we don't.
Supposedly the last few years has brought unprecedented melting to Greenland and the West Antarctic Ice Sheets, yet sea level is declining. Obviously something is wrong, and I doubt it is the sea level measurements.
Posted by Patrick Henry | September 16, 2008 9:32 PM
Steve Bloom,
Read between the lines to understand what the author is saying.
glaciers involved would need to move more than three times faster than the fastest outlet glaciers ever observed, or more than 70 times faster than they presently move," said Pfeffer. "And they would have to start moving that fast today, not 10 years from now.
Do you think a 70X speedup overnight is going to happen?
Posted by Patrick Henry | September 16, 2008 9:38 PM
What makes them think once the North Arctic Ice melts out during the summer it will return the following winter?
Posted by Patrick Cyclonebuster | September 16, 2008 10:40 PM
This article is interesting.
http://www.jamaica-gleaner.com/gleaner/20080330/focus/focus6.html
We are definitely going to get around a 2m rise at some point in the near future!
Basically the coastal cliffs in Jamaica record the various levels at which the sea level stabilized for an extended period.
The waves were able to cut notches in to the cliffs during that time.
It gives us a good indication of where levels will stabilize as different ice sheet melt. This is probably due to the climate settling in a particular state with respect to temperature.
There is lots of evidence out there which suggests that rapid mluti-meter SLR does occur:
High rates of sea-level rise during the last interglacial period
http://www.nature.com/ngeo/journal/v1/n1/full/ngeo.2007.28.html
This is the scary one from down under....
Coral reef clue to fast sea rise
http://www.guardian.co.uk/world/2005/feb/24/australia.environment
Remember these scientist were saying that the arctic sea ice was suppose to be melting in 80+yrs time. Now it looks like its going to melt in the next 5yrs!
Thats almost as good (bad) as the weather forecasts we get on TV :)
Posted by paulm | September 17, 2008 1:40 AM
Patrick Henry said:
Do you think a 70X speedup overnight is going to happen?
What will probably occur is something not clearly foreseen, like the a submerged ice shelf which is pined to the bedrock coming loose and floating up displacing many cm each time as the shelf disintegrates.
We need to accept that there are events which we don't understand how they happen, but we know that they have happened before! And will probably happen again under similar circumstances.
Posted by paulm | September 17, 2008 1:49 AM
Here are some ideas for future post titles, that perhaps could be run on a once-per-week basis:
End of Century Temperature increase forecasts are Overdone
End of Century ocean pH decrease forecasts are Overdone
40,000 species extinctions per year forecasts are Overdone
End of Century increased drought Forecasts are Overdone
End of Century increased flood Forecasts are Overdone
End of Century increased intensity/frequency of Hurricanes Forecasts are Overdone
End of Century increased Tornado intensity/frequency Forecasts are Overdone
End of Century enhanced weed growth Forecasts are Overdone
End of Century Global ice loss Forecasts are Overdone
News of Death of the MWP has been greatly exaggerated
Posted by paminator | September 17, 2008 2:25 AM
Patrick, it's better to read the actual lines and be familiar with the other research in the field. Among other things, you're ignoring the melt contributions of all the other ice, in particular the West Antarctic Ice Sheet. For a 2 meter rise we would expect a contribution on the order of half a meter from Greenland.
Re the sea level graphs you linked, note that they don't support your argument at all.
Posted by Steve Bloom | September 17, 2008 6:35 AM
That's a cool picture of a moulin. Wouldn't want to fall in that hole. Even with the spikes on his boots, the guy in the picture is awfully brave getting that close without a safety rope.
Hey, I thought Greenland wasn't melting? Judging from the picture and other pictures of melting ice on Greenland, I have to ask, is this evidence enough that the ice is melting? Or are my eyes deceiving me?
According to Patrick Henry's flyover report, Greenland is fine. But wait, if it's -64 on top of the Greenland ice sheet, how can there be melting?
Posted by Gary B | September 17, 2008 1:46 PM
Almost forgot. That ice looks fairly dirty too. Based on the ash on snow experiment posted here on this blog many months ago, I have to wonder if soot is contributing to more melting. If it is, then wouldn't or couldn't more ice melting be attributed to man?
Man creates soot - soot lands on ice - ice melts. Granted soot comes from wildfires and volcanoes too, but man does emit soot into the air ala diesel trucks, buses, trains, ships, coal fired power plants, oil refineries and many other sources.
Just curious, if man can contribute soot to the atmosphere and add to the increase in melting ice, can't the same be said of global warming via greenhouse gas emissions? It is proven that man can change the planet's environment on large scales. Soot is an example. Why not greenouse gases?
Posted by Gary B | September 17, 2008 1:53 PM
Hi Steve Bloom,
So if sea level continues to decrease as it has done for the last 30 months, how long before it rises 2 meters?
http://sealevel.colorado.edu/current/sl_noib_global_sm.jpg
OK, have it your way - don't read between the lines.
"We consider glaciological conditions required for large sea level rise to occur by 2100 and conclude increases of 2 meters are physically untenable"
http://www.sciencedaily.com/releases/2008/09/080904145113.htm
Posted by Patrick Henry | September 17, 2008 2:07 PM
paulm: The scenario you proposed doesn't work. If an ice shelf was submerged, and if it broke free to rise to the surface, it would not displace any more water since it was already displacing the maximum it could. An ice shelf by definition is floating, so it's already displacing water. There is a minor rise in sea level, however, as the resulting ice island melts, but the only added rise in sea level comes from the differences in density between fresh water (from the glacier fed ice shelf) and sea water. Nothing to get all worried about, though. There might also be a minor increase in displacement if the glacier was "lifting" some portion of the mass of the ice sheet prior to the calving event.
Posted by Bob Tisdale | September 17, 2008 3:39 PM
Gary B: There are places on Greenland other than the Summit. Temperatures at lower altitudes do rise above freezing.
Also, I believe there was a recent paper that reported black soot on snow was at higher concentrations 100+ years ago than it is today, contradicting climate models of the effect. You should be able to find it in Google news.
Posted by Bob Tisdale | September 17, 2008 8:09 PM
paulm: Research it a little more and you might find that sea levels have been 20 meters higher than they are today in different parts of the world. I believe those sea levels were reached during the prior two interglacials. Research it a little more and you might find that sea levels were 100+ meters lower than today during the peak of the last ice age. At that time, England and Japan were connected to their respective mainland. The Sea of Japan and Long Island Sound were lakes. Florida was three or four times wider.
What you've reported is old alarmist hype. That and $5 will buy you a cup of coffee.
Posted by Bob Tisdale | September 17, 2008 8:24 PM
Brett Howdy: Working this week but can,t believe the abuse of Science to further the personal agenda.
Have you seen the latest picture of the backside of Mt. Everest. No snow? Well it was cold on the plane but when I got to LA,rain,rain,and rain. Just as has been predicted, by the IPCC. Since no one will answer any questions about global warming, why not rename this blog, Global Warming and Energy Crisis. More Fudge. Wow?
KIPP
Posted by Kipp alpert | September 17, 2008 9:56 PM
paulm,
In order for wave-cut cliffs to exist in Jamaica, and not other places like Cuba, one needs to imagine either Jamaica rose or Cuba sank.
There are also wave-cut terraces along the coast of California, due to the uplift of the continental plate. Some are quite a ways above sea level.
In places like Norway and Scotland there are wave-cut terraces caused by the fact those plates rose when the burden of ice from the Ice Age melted away. Meanwhile southern England sank, as if the plate was tilted by the burden of ice. Apparently the south lifted as the north was pushed down. (Sort of like the bow of rowboat lifting from the water as a fat person sits in the stern.) When the ice melted this process was reversed.
Beyond a few spots where uplift occurred faster than the sea rose, most of the shorelines of the world show signs that the sea has risen several hundred feet since the last ice age, and that this rise has been, for the most part, gradual.
However, for those who like the idea of calamity and "Noah's Flood," there are some signs there may have been a few drastic events, where the sea rose abruptly.
In order for these events to occur you need a truly vast reservoir of water to be abruptly released into the seas. One such reservoir, of a size which makes the Great Lakes look small, may have been dammed up in the Hudson Bay region by plugs of ice, and another in the Baltic. If "unprecedented" warming occurred ten thousand years ago, and the plugs of ice gave way abruptly, then these vast reservoirs of held-back melt-water could hsve rushed into the sea all at once, causing an abrupt sea-level rise.
If you look at the modern map you can see NO such vast reservoirs of melt-water. It is therefore difficult to see how the sea levels could abruptly rise, for the mechanics don't exist. Even if you add "unprecedented" warming into the equation, the best you can do is collapse a few ice shelves, which already are displacing water and wouldn't displace more by melting.
In order to write a good science-fiction tale about a modern "Noah's Flood," we need to do a better job of inventing the mechanics which would make such a flood possible.
Posted by Caleb | September 18, 2008 5:07 AM
paulm,
Hi again. I thought I ought describe the mechanics which might explain a past "Noah's Flood," (which seems to be referred to in the lore of many cultures, world wide.)
I explained how northern Scotland was pressed down as southern England was uplifted, by the weight of ice to the north. As the ice melted, the north would rise and the south sink.
Assume a huge ice-melt lake exi