From Stefan Rahmstorf and the Potsdam Institute for Climate Impact Research (PIK)
Expert assessment: Sea-level rise could exceed 1 meter in this century
In contrast, for a scenario with strong emissions reductions, experts expect a sea-level rise of 40-60 centimeters by 2100 and 60-100 centimeters by 2300. The survey was conducted by a team of scientists from the USA and Germany.
“While the results for the scenario with climate mitigation suggest a good chance of limiting future sea-level rise to one meter, the high emissions scenario would threaten the survival of some coastal cities and low-lying islands,” says Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research. “From a risk management perspective, projections of future sea-level rise are of major importance for coastal planning, and for weighing options of different levels of ambition in reducing greenhouse-gas emissions.”
Projecting sea-level rise, however, comes with large uncertainties, since the physical processes causing the rise are complex. They include the expansion of ocean water as it warms, the melting of mountain glaciers and ice caps and of the two large ice sheets in Greenland and Antarctica, and the pumping of ground water for irrigation purposes. Different modeling approaches yield widely differing answers. The recently published IPCC report had to revise its projections upwards by about 60 percent compared to the previous report published in 2007, and other assessments of sea-level rise compiled by groups of scientists resulted in even higher projections. The observed sea-level rise as measured by satellites over the past two decades has exceeded earlier expectations.
Largest elicitation on sea-level rise ever: 90 key experts from 18 countries
“It this therefore useful to know what the larger community of sea-level experts thinks, and we make this transparent to the public,” says lead author Benjamin Horton from the Institute of Marine and Coastal Sciences at Rutgers University in New Jersey. “We report the largest elicitation on future sea-level rise conducted from ninety objectively selected experts from 18 countries.” The experts were identified from peer-reviewed literature published since 2007 using the publication database ‘Web of Science’ of Thomson Reuters, an online scientific indexing service, to make sure they are all active researchers in this area. 90 international experts, all of whom published at least six peer-reviewed papers on the topic of sea-level during the past 5 years, provided their probabilistic assessment.
The survey finds most experts expecting a higher rise than the latest IPCC projections of 28-98 centimeters by the year 2100. Two thirds (65%) of the respondents gave a higher value than the IPCC for the upper end of this range, confirming that IPCC reports tend to be conservative in their assessment.
The experts were also asked for a “high-end” estimate below which they expect sea-level to stay with 95 percent certainty until the year 2100. This high-end value is relevant for coastal planning. For unmitigated emissions, half of the experts (51%) gave 1.5 meters or more and a quarter (27%) 2 meters or more. The high-end value in the year 2300 was given as 4.0 meters or higher by the majority of experts (58%).
While we tend to look at projections with a focus on the relatively short period until 2100, sea-level rise will obviously not stop at that date. “Overall, the results for 2300 by the expert survey as well as the IPCC illustrate the risk that temperature increases from unmitigated emissions could commit coastal populations to a long-term, multi-meter sea-level rise,” says Rahmstorf. “They do, however, illustrate also the potential for escaping such large sea-level rise through substantial reductions of emissions.”
Article: B. P. Horton, S. Rahmstorf, S. E. Engelhart, A.C.Kemp: Expert assessment of sea-level rise by AD 2100 and AD 2300. Quaternary Science Reviews (2013). [doi: 10.1016/j.quascirev.2013.11.002]
Link to the article when it goes online: http://dx.doi.org/10.1016/j.quascirev.2013.11.002
============================================================
The basic premise of Stefan Rahmstorf’s claim is that sea level rise will accelerate before the end of the century. So far there has been no evidence of acceleration, it appears entirely linear no matter whether we look at tide gauges or satellite measurements.
The image below (From Holgate 2007 On the decadal rates of sea level change during the twentieth century in GRL) shows Holgate’s reconstruction of the sea level rise rate for the 20th century from the highest quality tide gauge data.
![holgate-9-station-with-std-dev-digitized[1]](http://wattsupwiththat.files.wordpress.com/2013/11/holgate-9-station-with-std-dev-digitized1.jpg?quality=83)
As you can see, the sea level rise rate widely varied during the 20th century. It reached about 4 mm/year around 1911, and again in the 1930s, 1950s and around 1980. It was much lower in the 1920s, 1940s, 1960s and mid-1980s.
Holgate concludes:
Based on a selection of nine long, high quality tide gauge records, the mean rate of sea level rise over the period 1904–2003wasfoundtobe1.74±0.16mm/yr after correction for GIA using the ICE-4G model [Peltier, 2001] and for inverse barometer effects using HadSLP2 [Allan and Ansell, 2006]. The mean rate of rise was greater in the first half of this period than the latter half, though the difference in rates was not found to be significant. The useof a reduced number of high quality sea level records was found to be as suitable in this type of analysis as using a larger number of regionally averaged gauges.
For satellite measurements there also doesn’t seem to be any acceleration.
German veteran meteorologist Klaus-Eckart Puls has done an analysis of sea level rise. Contrary to many claims, we see that sea level rise has decelerated markedly since 2003.
![Puls_2[1]](http://wattsupwiththat.files.wordpress.com/2013/11/puls_21.jpg?quality=83)
– See more at: http://notrickszone.com/2012/12/06/meteorologist-klaus-eckart-puls-sea-level-rise-has-slowed-34-over-the-last-decade/#sthash.h1npSYgJ.dpuf
So, neither tide gauges nor satellite measurements suggest acceleration is occurring. Even if we use the worst case value, 3.2 mm/year cited by CU in a linear calculation…
…we get this:
years left 2100-2013= 87 years
3.2 mm/year * 87 years = 278.4mm or 0.2784meter…about a quarter of the 1 meter (or more) claim made by Rahmstorf.
Rahmstorf isn’t working in reality.
Related articles
- IPCC’s New Estimates for Increased Sea-Level Rise (yaleclimatemediaforum.org)
- Scientists Find That Sea Level Rise Is Much Slower Than Expected…No Human Fingerprint (notrickszone.com)
- IPCC sea level exaggeration (wattsupwiththat.com)
In a cross examination ask the experts for an estimate of sea level change which they expect to be exceeded along one in every twenty future history timelines until the year 2100. Then ask them how they intend to verify that proposition. That is, what state of affairs would make them accept it was false after all.
Experts agree:
Consequence for a far out projection of excessive sea level rise by 2100 for these experts:
Nonexistent.
Consequence for failing to make an alarmist projection:
Career catastrophe.
Number of experts opting for career catastrophe?
None left on the payroll.
Few if any of the buildings currently in existence will still be in existence in 200 to 300 years.
Long before the seas take these buildings, they will have fallen down on their own from old age.
The simple solution is to let these buildings age away, and then not replace them when they do.
A no cost solution to rising tides and cities.
What I fail to understand is what causes the rather large oscillation in the rate of sea level change. I mean it is a huge lump of water ( 1.3 billion cubic kilometers ) but its rate of change changes quite rapidly. Why?
If these people could accurately predict the measurement of recession along with the degree of recession at different ages for the average climate scientists’ hairline then I just might accept their predictions for sea level rise and receding shorelines. Until then could they at least try to show a little consideration and stop bothering us with their schemes of self grandiosity.
It all preys on the fact that people are too lazy to delve in to details-they just believe the headline propaganda flashed in front of their eyes. The upper limit is what was asked for and this is the headline propaganda they read, in spite of ALL the predictions thus far being wrong. Once people believe the incorrect fundamental assumptions, all that follows is predicated on very shaky foundations. When it all collapses in a massive heap, everything is crushed irreparably.
The whole Fabian “Utopia” which is the excuse for all the BS is a model which will fail horrendously.
Given that reality has been thus far at the very BOTTOM edge of the 95% curve, perhaps this is the one that should be on the headlines-it seems to be the closest.
“The American Geophysical Union, representing more than 62,000 Earth, atmospheric, and space scientists worldwide”
There are 62,000 of them? Why do we keep hearing only from the same few dozen of them? Don’t the other 61,900 have anything to say?
Keitho says: November 22, 2013 at 12:09 pm
The short term changes of sea level rise are closely correlated to ENSO, see
http://sealevel.colorado.edu/files/2013_rel6/sl_mei.png
ENSO changes the fraction of total precipitation falling on land, which takes time to return to the oceans.
The global sea level rise according to satellite data as interpreted by the University of Colorado Sea Level Research Group has declined from 3.23 mm/yr during 1993 – Dec 2003, to 2.46 mm/yr during Jan 2004 – Aug 2013, without GIA adjustment, as shown:
http://www.friendsofscience.org/assets/documents/FOS%20Essay/GlobalSeaLevel.jpg
The Pacific Ocean sea level rise has decelerated from 3.23 mm/yr to 1.72 mm/yr over the same time periods.
http://www.friendsofscience.org/assets/documents/FOS%20Essay/PacificSeaLevel.jpg
However, the average of the 10 long tide gauge records on the Pacific coast of Canada shows that the sea level has DECLINED at 0.50 mm/yr from 1973 – 2011. These graphs are at:
http://www.friendsofscience.org/index.php?id=712
Note that sea level rise means the average sea level change with respect to the land. The GIA (glacial isostatic adjustment) is the effect of increasing ocean basin size. The graph of sea level rise by the University of Colorado in the lead post is sea level rise plus 0.3 mm/y GIA, which is NOT sea level rise. It is what the sea level rise might have been IF the ocean basin size had not changed.
The satellite SLR is greater than the global tide gauge SLR because the University of Colorado adds a dubious 0.9 mm/yr adjustment to the raw satellite measurements, which they claim is due to sensor drift.
Thanks very much Ken. I am now off to look for a matching pattern between rainfall on land and the wobbles in the sea level record. With my newly learned statistical prowess and the diversity of data I may be gone for some time. 🙂
Steve Case @ur momisugly 11:29 am
Thank god for WUWT and Mr. Watts, eh? It’s my “go to” source for information.
Many moons ago I volunteered my diving services to archaeological teams working on the West Florida Coast. They were cataloging numerous ancient and inundated Indian villages. Florida was shaped over 6 to 7 millions years as is evidenced today by the geologic formations. Sea levels rise and sea levels fall but I’m having problems doing the maths when it comes to: primitive man x camp fires (+ planned and accidental brush burning) = CO2 output – ergo local flooding.
http://ufdc.ufl.edu/UF00027829/00016/9j
ace says: “… according to the first paragraph, Rahmstorf is suggesting 40 – 60 cm. by 2100, not a meter, as alluded to in your final paragraph.”
Keep coming back, ace. Next time, please read the post and understand it before commenting. Or comment near the end of the thread, where you won’t attract as much embarrassing attention.
Ok Willis, what does the wiggly line from Holgate 2007 correspond to? Sun spot cycles, the AMO, the PDO, the rate of CO2 release (oops, can’t be that one). Get to work!
Still think this 1841 sea level benchmark on the `Isle of the Dead’, Tasmania by Antarctic explorer, Capt. Sir James Clark Ross is one of the greatest questions when it comes to a discussion of sea level. Why is this not showing the ½+ meter rise in the last 175 years? The mark should be underwater at low tide, and it is not. These charts are just more adjustements by dishonest “climatologists” to me, I know they are fudging it upward every year.
(to see the scribed sea level mark clearly, thanks to the late John Daly)
Every time I read one of these things I have to chuckle and shake my head. Apologies if I sound like a broken-record again, but what sort of climate should one expect, especially at a half-precession old, and at best 50:50 chance of being the most recent end interglacial?
How is it, precisely, does anyone suggest we detect a one-meter sea level rise (anthropogenic signal) by 2300 if the lowest estimate of sea level rise during the second thermal pulse right at the end of the last interglacial was +6M amsl
http://business.uow.edu.au/sydney-bschool/content/groups/public/@web/@sci/@eesc/documents/doc/uow045009.pdf
and might have run up to +52M amsl http://lin.irk.ru/pdf/6696.pdf ?
These are not unreasonable questions if you are familiar with the concept of signal to noise ratio (SNR) http://wattsupwiththat.com/2011/01/05/on-%E2%80%9Ctrap-speed-acc-and-the-snr/#more-30992
So what are we to expect in terms of climate at an end extreme interglacial?
Boettger, et al (Quaternary International 207 [2009] 137–144) abstract it (http://eg.igras.ru/files/f.2010.04.14.12.53.54..5.pdf):
“In terrestrial records from Central and Eastern Europe the end of the Last Interglacial seems to be characterized by evident climatic and environmental instabilities recorded by geochemical and vegetation indicators. The transition (MIS 5e/5d) from the Last Interglacial (Eemian, Mikulino) to the Early Last Glacial (Early Weichselian, Early Valdai) is marked by at least two warming events as observed in geochemical data on the lake sediment profiles of Central (Gro¨bern, Neumark–Nord, Klinge) and of Eastern Europe (Ples). Results of palynological studies of all these sequences indicate simultaneously a strong increase of environmental oscillations during the very end of the Last Interglacial and the beginning of the Last Glaciation. This paper discusses possible correlations of these events between regions in Central and Eastern Europe. The pronounced climate and environment instability during the interglacial/glacial transition could be consistent with the assumption that it is about a natural phenomenon, characteristic for transitional stages. Taking into consideration that currently observed ‘‘human-induced’’ global warming coincides with the natural trend to cooling, the study of such transitional stages is important for understanding the underlying processes of the climate changes.”
and:
“In this respect, the Holocene shows a stable SST trend similar to those in previous interstadial stages, tending toward progressively cooler climate conditions in accordance with the slow decrease in summer insolation in the Northern Hemisphere and the minimal eccentricity of the Earth’s orbit. Within the framework of ODP-977A data, this orbital configuration suggests that the present warm period could be more prone to abrupt oscillations than MISs 5 and 7. In turn, the next bifurcation of the climate system may appear as an extremely intense cooling if the future natural climate is going to develop as an analog
of some of the preceding warm periods.” http://home.sandiego.edu/~sgray/MARS350/pleist2.pdf
As Anthony details in this article, we aren’t even close to experiencing “evident climatic and environmental instabilities”, not yet anyway. But given that “the present warm period could be more prone to abrupt oscillations than MISs 5 and 7” then sea level excursions might even exceed those quoted above.
Really folks. One meter? Is that all you got at the possible end-Holocene?
http://www.globalwarmingheartland.org/?gclid=CMH64fTro0C
Here Nils-Axell Morner states that 1M/ Century is impossible. It didn’t rise that fast after the ice age when ice sheets were receding by 300 meters /century.
Because the thermosteric component was chief in 20th century the 0.2784meter are only in case of continuing 20th century temperature trend. If not there will be even much less change and if cooling occurs due to solar activity multicycle slump, the sea level could be already lower in 2100 than now.
so sea levels continue to rise….even when temps don’t
..and temps affect the weather…even when it’s hiding in the bottom of the ocean
65% of tide gauges show no sea level rise at all…
…that makes the rest of them null and void
John says:
November 22, 2013 at 8:29 am
_________________
An “Expert” is a drip under pressure
&
If he has a brief case under his arm he is a “consultant”.
Alternatively ;
An expert is a man who is more than forty miles from home.
ie; everybody at home knows he doesn’t have a bloody clue.
In one of the well known SciFi stories of future times one of the Galaxy’s leading scientists has built his reputation on the reading and analysis of long past science research.
No on ground science or observations was necessary anymore in that world of the future for science to be practiced
That “future” science is apparently already here as it appears it wasn’t neccessary for Horton, Rahmsdorf or others to do the basic on ground research for themselves.
They just read up on what past researchers have published, selected those papers that supported their proposition and Lo!, the case is proven.!
Hey, I have a great idea! We have many scientists, engineers, and other experts posting here. Let’s take a poll of people’s estimates of sea level rise and get it published. It would be at least as valid as Rahmstorf et al’s paper, and most likely, more so.
Interestingly, I note comments about the recent Super Typhoon, warmed seas, higher sea levels etc.
The reason for the storm surge – funneling perchance!
Reality: less than a foot. Truly “much ado about nothing”. Wake me when it’s over.
Why not stay with Chao, Yu & Li (Science April 11th 2008) and forget the rest of the speculation about sea level change? They studied the sea level data of the twentieth century and corrected it for all water held in storage by dams built since the year 1900. When so corrected, global sea level rise became linear for the past 80 years. Something that has been linear that long is not about to change anytime soon. The slope of their 80 year sea level curve was 2.46 millimeters per year.That works out to 24.6 centimeters per century or just a little under ten inches. Certainly nothing like 20 feet as per Al Gore or several meters that these other guys are dreaming up.
So how “ambitiuos” should we be to “prevent” a 50 cm differential (50 cm versus 100cm, stated in the article) in sea level? I’m pretty sure even the peeps that believe this forcast have more pressing issues to deal with in the next eighty years, and better uses for their money than carbon taxes and cost ineffective green technologies.. Brady V Manning is more compelling, and 25 cm is much more likely. Yawn. Broncos 27, Patriots 24 in OT.
Re: Ken Gregory @ur momisugly 12:09 pm wrote:
“The global sea level rise according to satellite data as interpreted by the University of Colorado Sea Level Research Group has declined from 3.23 mm/yr during 1993 – Dec 2003, to 2.46 mm/yr during Jan 2004 – Aug 2013, without GIA adjustment, as shown:
http://www.friendsofscience.org/assets/documents/FOS%20Essay/GlobalSeaLevel.jpg”
________________
Yes it did, but at the time, the University of Colorado Sea Level Research Group put up this graphic:
http://web.archive.org/web/20040216212753im_/http://sealevel.colorado.edu/combine_ib_sm.jpg
Which said not 3.23 mm/yr but only 2.8 mm/yr. Over time, the history of satellite sea level data has been rewritten.
Remove those changes and that 2.46 mm/yr will be further reduced to 2 mm/yr or less.
Cheers!
In Climate science, reality has a well known upside-down bias.