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New Analysis Concludes Global Sea-Rise By 2100 Kinematically Limited to 2 Meters or Less
5 September 2008
Despite projections by some scientists of global seas rising by 6 meters (20 feet) or more by the end of this century as a result of warming, a new study by researchers from the University of Colorado at Boulder; the University of Montana; and Scripps Institution of Oceanography, University of California San Diego, concludes that global sea rise of more than 2 meters (6.6 feet) is a near physical impossibility in that timeframe. A more plausible, but still accelerated level, is about 0.8 meter (2.6 feet). The paper is published in the 5 September edition of the journal Science.
The researchers made calculations using conservative, medium and extreme glaciological assumptions for sea rise expected from Greenland, Antarctica and the world’s smaller glaciers and ice caps—the three primary contributors to sea rise.
We consider glaciological conditions required for large sea-level rise to occur by 2100 and conclude that increases in excess of 2 meters are physically untenable. We find that a total sea-level rise of about 2 meters by 2100 could occur under physically possible glaciological conditions but only if all variables are quickly accelerated to extremely high limits. More plausible but still accelerated conditions lead to total sea-level rise by 2100 of about 0.8 meter. These roughly constrained scenarios provide a “most likely” starting point for refinements in sea-level forecasts that include ice flow dynamics.
—Pfeffer et al. (2008)
The gist of the study is that very simple, physical considerations show that some of the very large predictions of sea level rise are unlikely, because there is simply no way to move the ice or the water into the ocean that fast.
—Tad Pfeffer, fellow of CU-Boulder’s Institute of Arctic and Alpine Research
The team began the study by postulating future sea level rise at about 2 meters by 2100 produced only by Greenland, said Pfeffer. Since rapid, unstable ice discharge into the ocean is restricted to Greenland glacier beds based below sea level, they identified and mapped all of the so-called outlet glacier gates on Greenland’s perimeter: bedrock bottlenecks most tightly constraining ice and water discharge.
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, and they would have to start moving that fast today, not 10 years from now. It is a simple argument with no fancy physics.
—Tad Pfeffer
In Antarctica, the majority of ice entering the ocean comes from the Antarctic Peninsula and the Pine Island and Thwaites glaciers, said Pfeffer. Most of the marine-based ice in West Antarctica is held behind the Ross and Filcher-Ronne ice shelves, which Pfeffer’s team believes are unlikely to be removed by climate or oceanographic processes during the next century. The researchers used varying glacier velocities to calculate sea-rise contribution estimates from the Antarctic Peninsula, Pine Island and Thwaites glaciers.
The team also used assessments of the world’s small glacier and ice cap contributions to sea level rise calculated by a CU-Boulder team and published in Science in July 2007 (Meier 2007). That study indicated small glaciers and ice caps contribute about 60% of the world’s ice to oceans at present, a percentage that is accelerating.
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.
—Tad Pfeffer
Considering all major sources of sea level rise, including Greenland, Antarctica, smaller glaciers and ice caps and the thermal expansion of water, the team’s most estimate of 0.8 to 2 meter rise by 2100 is still potentially devastating to huge areas of the world in low-lying coastal areas, said Pfeffer.
The study was funded by the National Science Foundation and a University of Colorado Faculty Fellowship.
Resources
W. T. Pfeffer, J. T. Harper, S. O’Neel (2008) Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise. Science Vol. 321. no. 5894, pp. 1340 - 1343 doi: 10.1126/science.1159099
Mark F. Meier, Mark B. Dyurgerov, Ursula K. Rick, Shad O’Neel, W. Tad Pfeffer, Robert S. Anderson, Suzanne P. Anderson, Andrey F. Glazovsky (2007) Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century. Science Vol. 317. no. 5841, pp. 1064 - 1067 doi: 10.1126/science.1143906
September 5, 2008 in Climate Change | Permalink | Comments (35) | TrackBack (0)
Comments
Posted by: ai_vin | September 06, 2008 at 09:34 PM
BTW The latest La Nina pattern began in the third quarter of 2007 so any slowing in GW you see now is explainable.
Posted by: ai_vin | September 06, 2008 at 09:41 PM
Thanx ai_vin, I was starting to get tired. :( Should try to remember that it isn't so much as trying to convince others but to dispute information being spread around so that the less informed get a fuller picture.
Anyway, the myth of the 1970S global cooling scientifc consensus.
http://ams.confex.com/ams/pdfpapers/131047.pdf
which is a peer reviewed paper on the subject printed in the Bulletin of the American Meteorological Society.
There might be more ice than last year but from a perspective like ai_vin's post of temperature, that would be an overly simplistic view of the ice readings. It is a steady decreasing of ice levels in the arctic. Using a base line of the lowest year would be a statistical error which would give erroneous perceptions.
And of course a new update from NSIDC.
http://www.greencarcongress.com/2008/09/arctic-experien.html#more
Posted by: aym | September 07, 2008 at 11:46 AM
Back on topic:
IPCC's James Hanson testified April 26, 2007 before US House of Representatives that: "...sea level rise this century may be measured in meters if we follow business-as-usual fossil fuel emissions," concurring with this study.
However according to peer-reviewed paper in May 2008, Nature (Dominguez et al) updated estimates for sea level rise are 1.6 ± 0.2 mm/year.
1) Centre for Australian Weather and Climate Research
2) Antarctic Climate and Ecosystems Cooperative Research Centre
3) Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory
http://www.nature.com/nature/journal/v453/n7198/abs/nature07080.html
No environmentally concerned person wants to follow fossil fuel business as usual. The are a multitude of good reasons not to do so. The point is we do not need Mr. Hanson's/IPCC's exaggerated claims to know which way the wind blows.
Posted by: Sulleny | September 08, 2008 at 02:39 PM
The problem with convincing people to believe in all of the hype is that they've been lied to and can't realistically decide who/what is correct. Lying to prove a point just doesn't work. If the goal is the eradication of all internal combustion engines (and I'm not saying it is), just say so. Lies stink, but the truth has a ring to it.
Personally, all the BS started with Kyoto. When the "experts" decided man-made CO2 has a greater effect on warming than natural CO2, I had to laugh. You can't seriously tell me this makes sense. CO2 is CO2, period. Apparently the experts picked CO2 as man's greatest scourge to the environment because we can't control water vapor, the real #1 influence of warming.
I'm sure there is a set of statistics somewhere that can prove any side of an argument. But it's a well known fact that 57% of all statistics are made up on the spot. (I just made that up):)
Having said all this, I'm still doing my part to save the planet. Not because I buy the fact that man can control the earth, (arrogant thinking at it's finest), but because there are huge piles of cash to be made! I say "Hurray for Al Gore!" I'm sitting in my 14,000 sq. ft. house with the AC on full blast. I'm just trying to keep up with Al! Next, I'll have to form a company in England to take advantage of all the hysteria Al has stirred up. Woohoo! More money! Way to go Al baby! Where should I send your finders fee?
Come on folks. You don't think Al and T. Boone Pickens are in this for their stewardship of the planet, do you?
Posted by: BC | September 10, 2008 at 11:55 AM
Al's a bonafide scientist and he's got a Nobel Prize to prove it.
Posted by: Always wrong | September 10, 2008 at 03:04 PM
The article linked to said this
We add our observational estimate of upper-ocean thermal expansion to other contributions to sea-level rise and find that the sum of contributions from 1961 to 2003 is about 1.5+-0.4 mm yr-1, in good agreement with our updated estimate of near-global mean sea-level rise (using techniques established in earlier studies of 1.6+-0.2 mm yr-1.
It doesn't say that the present levels are 1.6 or the future ones. You do realize that. I mean is it that hard to read? It's an enhanced computational model that more closely matches things in the time period of the past.
TOPEX/Poseidon and Jason-1 satellite data show an increase of sea levels. An increase of ocean level of 3.2 +- 0.4 mm/year is the present level of increase. Whether it stabilizes or even goes down is something else.
http://sealevel.colorado.edu/
As for Kyoto. No it didn't say that man-made carbon contributed more. It was that it tipped the balance that was there so that more heat gets trapped.
Just because some people are trying or are making money doesn't invalidate the science though it does inflame people.
Posted by: aym | September 11, 2008 at 09:01 AM
"When the "experts" decided man-made CO2 has a greater effect on warming than natural CO2, I had to laugh."
You might have heard '150 billion tonnes of carbon go into the atmosphere from natural processes every year.' This is almost 30 times the amount of carbon humans emit. But in the natural process, for roughly the last 10K years until the industrial revolution, every gigatonne of carbon going into the atmosphere was balanced by one coming out. What we have done is to alter only one side of this cycle. We put approximately 6 gigatonnes of carbon into the air but, unlike nature, we are not taking any out.
Thankfully, nature is actually compensating in part for our emissions, because only about half of the CO2 we are emitting is staying in the air. Nevertheless, since we began burning fossil fuels in earnest over 150 years ago, the atmospheric concentration that was relatively stable for the previous several thousand years has now risen by over 35%. So whatever the total amounts going in and out on their own, humans have clearly upset the pre-existing balance and altered significantly an important part of the climate system.
"Apparently the experts picked CO2 as man's greatest scourge to the environment because we can't control water vapor, the real #1 influence of warming."
There is no climate model or climate textbook that does not discuss the role water vapor plays in the Greenhouse Effect. It IS the strongest Greenhouse gas, contributing 36% - 66% to the overall effect for vapor alone, 66% to 85% when you include clouds. It is however, not considered as a climate "forcing" because the amount of H2O in the air basically varies as a function of temperature. If you artificially increase the level of H2O in the air, it rains out immediately (in terms of climate response times). CO2 put into the air by burning fossil fuels, on the other hand, has an atmospheric lifetime of centuries before natural sinks will finish absorbing any excess from the air. This is plenty of time to have substantial and long lasting effects on the climate system. And the experts picked CO2 as man's greatest scourge because as the climate warms in response to the CO2, the humidity rises and the increased H2O concentration acts as a significant amplifier of CO2 driven warming, basically doubling or tripling its effect.
Posted by: ai_vin | September 12, 2008 at 10:46 AM
One more thing, and I'll try to make this simple for you; The difference between between "natural CO2" and "man-made CO2" is time. Natural CO2, the CO2 that goes in and out of the air because of natural processes, does so on the short term. Plants take it out of the air to grow, but most of it only stays in the plant while its alive. Once it dies it either rots or gets eaten. Even for the oldest trees this is only 4,000 years.
Man-made CO2 comes from fossil fuels; key word here is - FOSSIL. We're talking about carbon that could have been taken out of the air 300,000,000 years ago or more!
Posted by: ai_vin | September 12, 2008 at 01:14 PM
no body talks about that the oceans with current chemistry have an equilibrium point of less than 550 ppm, meaning that no matter how much CO2 is put in the air the oceans will absorb it turn it to CaCO3 and it will precipitate as calcarouse ooze on the seafloor
Posted by: | September 18, 2008 at 06:21 PM
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One more thing; I knew your "World wide temperatures have been static or decling for almost ten years" statement didn't sound true. This comes from the "warming stopped in 1998" falsehood.
1998 was a record high year in both the CRU and the NASA GISS analysis. In fact, it was not just a record year, it blew away the previous record, it was elevated far above the trend line because 1998 was the year of the strongest El Nino of the century. But El Ninos are often followed by La Ninas which cause mostly the opposite effects of El Niño. And sure enough 1999 and 2000 saw a drop far below the trend line. However 2001 saw temperatures climb back up, in fact in was the second hottest year on record up to that point. I say 'up to that point' because 2002, 2003, 2004 and 2005 all saw even higher temperatures. [I don't have data for 06 or 07 and 08 isn't over yet.]