From high and dry University of Arizona, home of the world famous parking lot USHCN weather station, we have word via Eurekalert that a simulation says it will be bad as “sea levels are expected to rise by up to three feet by the end of this century”.
They say we can now ignore thermal expansion of seawater due to rising temperatures because it “contributed only slightly to rising sea levels”. It may be too late already, gosh. At the present 3 mm per year rate measured by satellite, and with 89.5 years left, that works out to 89.5yrs x 3.1mm/yr = 277.5 mm which works out to 0.91 feet or 10.9 inches. UofA, and especially Jonathan Overpeck are going to have to kick it into high gear if they are going to make three feet by 2100.
Rising oceans — too late to turn the tide?
Melting ice sheets contributed much more to rising sea levels than thermal expansion of warming ocean waters during the Last Interglacial Period, a UA-led team of researchers has found.
Simulation of Rising Sea Levels
Thermal expansion of seawater contributed only slightly to rising sea levels compared to melting ice sheets during the Last Interglacial Period, a University of Arizona-led team of researchers has found.
The study combined paleoclimate records with computer simulations of atmosphere-ocean interactions and the team’s co-authored paper is accepted for publication in Geophysical Research Letters.
As the world’s climate becomes warmer due to increased greenhouse gases in the atmosphere, sea levels are expected to rise by up to three feet by the end of this century.
But the question remains: How much of that will be due to ice sheets melting as opposed to the oceans’ 332 million cubic miles of water increasing in volume as they warm up?
For the study, UA team members analyzed paleoceanic records of global distribution of sea surface temperatures of the warmest 5,000-year period during the Last Interglacial, a warm period that lasted from 130,000 to 120,000 years ago.
The researchers then compared the data to results of computer-based climate models simulating ocean temperatures during a 200-year snapshot as if taken 125,000 years ago and calculating the contributions from thermal expansion of sea water.
The team found that thermal expansion could have contributed no more than 40 centimeters – less than 1.5 feet – to the rising sea levels during that time, which exceeded today’s level up to eight meters or 26 feet.
At the same time, the paleoclimate data revealed average ocean temperatures that were only about 0.7 degrees Celsius, or 1.3 degrees Fahrenheit, above those of today.
“This means that even small amounts of warming may have committed us to more ice sheet melting than we previously thought. The temperature during that time of high sea levels wasn’t that much warmer than it is today,” said Nicholas McKay, a doctoral student at the UA’s department of geosciences and the paper’s lead author.
McKay pointed out that even if ocean levels rose to similar heights as during the Last Interglacial, they would do so at a rate of up to three feet per century.
“Even though the oceans are absorbing a good deal of the total global warming, the atmosphere is warming faster than the oceans,” McKay added. “Moreover, ocean warming is lagging behind the warming of the atmosphere. The melting of large polar ice sheets lags even farther behind.”
“As a result, even if we stopped greenhouse gas emissions right now, the Earth would keep warming, the oceans would keep warming, the ice sheets would keep shrinking, and sea levels would keep rising for a long time,” he explained.
They are absorbing most of that heat, but they lag behind. Especially the large ice sheets are not in equilibrium with global climate,” McKay added. ”
Jonathan Overpeck, co-director of the UA’s Institute of the Environment and a professor with joint appointments in the department of geosciences and atmospheric sciences, said: “This study marks the strongest case yet made that humans – by warming the atmosphere and oceans – are pushing the Earth’s climate toward the threshold where we will likely be committed to four to six or even more meters of sea level rise in coming centuries.”
Overpeck, who is McKay’s doctoral advisor and a co-author of the study, added: “Unless we dramatically curb global warming, we are in for centuries of sea level rise at a rate of up to three feet per century, with the bulk of the water coming from the melting of the great polar ice sheets – both the Greenland and Antarctic Ice Sheets.”
According to the authors, the new results imply that 4.1 to 5.8 meters, or 13.5 to 19 feet, of sea level rise during the Last Interglacial period was derived from the Antarctic Ice Sheet, “reemphasizing the concern that both the Antarctic and Greenland Ice Sheets may be more sensitive to warming temperatures than widely thought.”
“The central question we asked was, ‘What are the warmest 5,000 years we can find for all these records, and what was the corresponding sea level rise during that time?'” McKay said.
Evidence for elevated sea levels is scattered all around the globe, he added. On Barbados and the Bahamas, for example, notches cut by waves into the rock six or more meters above the present shoreline have been dated to being 125,000 years old.
“Based on previous studies, we know that the sea level during the Last Interglacial was up to 8.5 meters higher than today,” McKay explained.
“We already knew that the vast majority came from the melting of the large ice sheets in Greenland and Antarctica, but how much could the expansion of seawater have added to that?”
Given that sea surface temperatures were about 0.7 degrees warmer than today, the team calculated that even if the warmer temperatures reached all the way down to 2,000 meters depth – more than 6,500 feet, which is highly unlikely – expansion would have accounted for no more than 40 centimeters, less than a foot and a half.
“That means almost all of the substantial sea level rise in the Last Interglacial must have come from the large ice sheets, with only a small contribution from melted mountain glaciers and small ice caps,” McKay said.
According to co-author Bette Otto-Bliesner, senior scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., getting the same estimate of the role ocean expansion played on sea level rise increases confidence in the data and the climate models.
“The models allow us to attribute changes we observe in the paleoclimate record to the physical mechanisms that caused those changes,” Otto-Bliesner said. “This helps tremendously in being able to distinguish mere correlations from cause-and-effect relationships.”
The authors cautioned that past evidence is not a prediction of the future, mostly because global temperatures during the Last Interglacial were driven by changes in the Earth’s orbit around the sun. However, current global warming is driven by increasing greenhouse gas concentrations.
The seasonal differences between the northern and the southern hemispheres were more pronounced during the Last Interglacial than they will be in the future.
“We expect something quite different for the future because we’re not changing things seasonally, we’re warming the globe in all seasons,” McKay said.
“The question is, when we think about warming on a global scale and contemplate letting the climate system change to a new warmer state, what would we expect for the ice sheets and sea levels based on the paleoclimate record? The Last Interglacial is the most recent time when sea levels were much higher and it’s a time for which we have lots of data,” McKay added.
“The message is that the last time glaciers and ice sheets melted, sea levels rose by more than eight meters. Much of the world’s population lives relatively close to sea level. This is going to have huge impacts, especially on poor countries,” he added.
“If you live a meter above sea level, it’s irrelevant what causes the rise. Whether sea levels are rising for natural reasons or for anthropogenic reasons, you’re still going to be under water sooner or later.”
Reference:
McKay, N., J. T. Overpeck, and B. Otto-Bliesner (2011). The role of ocean thermal expansion in Last Interglacial sea level rise. Geophys. Res. Lett., doi:10.1029/2011GL048280, in press. A version of the accepted paper is available online at the Geophysical Research Letters site: http://www.agu.org/journals/gl/papersinpress.shtml
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Update: Leif Svalgaard has the full paper here. Thanks Leif.
Well, climate scientists give each other airs. Do earth scientists throw dirt at their critics?
😉
I was going to point out that Overpeck’s opinion has to be taken at a discount because he has a financial interest in hype, via climateappraisal.com to which he is/was a consultant. In going back to check facts, it turns out Climate Appraisal’s web presence is currently dead, and its absence from Google’s cache suggests it may have been that way for some time. The main thing available currently is an advertorial on wikipedia (http://en.wikipedia.org/wiki/Climate_Appraisal). It would be interesting news if the outfit had ceased to function.
The new U of Arizona postdoc anthem:
We’re going on the grant hunt,
The global-warming grant hunt.
We’re going on the grant hunt,
And bag some major bucks!
8.0 metres in 5000 years. That’s 1.6mm a year. Hmm to an idiot like me that would suggest that the ice age ice melts at this rate without AGW.
Well good golly and aren’t we the lucky sods today that we “narrowly” missed that 200 year window of that 5000 year window of that “Last Interglacial” window of 120 000 to 130 000 years ago, otherwise we might have had a future rise of three feet, but we might have felt a tad bit relieved with the thinning ice and the renewed flow of fresh water.
Eric Anderson says:
July 18, 2011 at 10:55 pm
How many people actually live a meter above sea level. I know, I know, I’ve seen the estimates: 100M, 146M, etc. Where are these folks
I live about 1m above sea level but much of the Fens where I live are lower than sea level and are kept dry by pumping stations. Then there is Holland. etc etc.
But notice a lot of these people actually live below sea level.
“As a result, even if we stopped greenhouse gas emissions right now, the Earth would keep warming, the oceans would keep warming, the ice sheets would keep shrinking, and sea levels would keep rising for a long time,” he explained.
They really ought to check the safety catch on that AGW gun of theirs & get a bullet proof cap to the bottom of the holster, that way they won’t quite so easily shoot themselves in the foot! So what’s the point of worrying?
I seem to recall reading a paper stating that the ice sheet in both Greenland & Antarctica was in a hollow,due to the weight of the ice build up over thousands & millions of years,& that if is all melted,all that would happen would be the creation of inland seas on both land masses! Is this correct? Not that I’m bothered.
Forgot the obvious, the clue was in the sub-title,”Simulation”. Pocket OED 1925, Simulate, simulant, simulacrum:- Feign, pretend to have or feel (oh no it’s back to feelings again), wear the guise of, act the part, counterfeit, having the appearance of, shadowy likeness or mere pretence of, unreal thing.
J. Felton says (July 18, 2011 at 7:02 pm)
“I have my own simulation on my home computer. …”
Me too! Mine’s called the “Microsoft Pinball Arcade” and does a pretty good job of simulating a range of Gottlieb tables from the 1930s to the 1990s. On the 1960s table, though, in moments of high excitement, I’ve noticed that the simulated ball sometimes passes clean through the simulated flipper.
From this I conclude that
EITHER (a) it is possible for a simulation to be slightly less than perfect;
OR (b) In the 1960s, Gottlieb had developed a way of implementing quantum effects on the scale of an inch diameter bearing ball.
I wonder which it could be …
One problem with paleo sea levels is that the ground won’t stand still. Yes, there are a few marine features some number of meters above current sea level in North America. But those in New England, Ontario, and Quebec appear to be due to glacial isostacy. And everything on the West Coast is moving up, down, and/or sideways. Can’t really trust those areas to stand still for 100,000 years
That leaves the Gulf Coast, and Eastern Seaboard North to perhaps Delaware Bay. New Jersey was presumably pulled down some by the weight of the glaciers to the North that extended as far South as Staten Island. So, are there wave benches and fossil deposits from the last interglacial all along the coastal plain from Galveston to Cape May?
No, there do not seem to be. Some, of course might have been removed or covered by recent erosion/sedimentation, and some of the coastline is consists of recent sediments that are consolidated and sinking. But a lot of the coastline is Cretaceous through Pliocene “bedrock” that probably isn’t going to compress much more. If sea levels were generally significantly higher in the last interglacial than today, a lot of evidence should have survived. Way more than has survived I think.
The script below the map gives the game away, because there were no SUVs in the last interglacial pereod and they are trying to scare the public with this sea level rise! this is schoolyrd game level scamming!
Just for the math of it, how much is the theoretical maximum sea level rise if all ice on earth would melt? and combining that with the maximum sea water expansion ?
Why does it matter if the cause of past warming is different from the present warming? Are there studies that show different causes have different effects on the thermal expansion of the oceans?
And please, don’t say the current warming is ‘unprecedented.’
Another case of getting the right answer for the wrong reasons:
As a result, even if we stopped greenhouse gas emissions right now, the Earth would keep warming
The reason is that ‘greenhouse gasses’ do not contribute in any significant way to global warming. The Earth will warm, the Earth will cool and CO2 is an order of magnitude smaller than a contributing factor.
AdderW – if all the world’s ice melted, sea level would be about 80 meters (260 feet) above where it is now. Almost all of that comes from the Antarctic, with about 6.5m from Greenland and 0.5m from other glaciers.
The caption to the picture: “If sea levels rose to where they were during the Last Interglacial Period, large parts of the Gulf of Mexico would be under water (red areas), including half of Florida and several Caribbean islands. Credit: Jeremy Weiss, Department of Geosciences, The University of Arizona”. My 9th grade English teacher would not approve of the first sentence at all, nor would my geography teacher.
Well, I’m sure McKay and Overpeck can explain the recent sea level changes as well then.
For example, the latest number says the sea level has fallen by 6.9 mms in the last year (late Feb, 2011 data) and it is clearly decelerating.
-6.9 mms is a big number.
I guess they would have to conclude that glacier mass balance increased in the past year (since thermostatic change is so small – water vapour in the atmosphere increased but only about 1.0 mm worth).
Change in sea level – year over year – since 1994 from the satellites including all the adjustments they like to make.
http://img20.imageshack.us/img20/9914/sealevelfeb11.png
“Just for the math of it, how much is the theoretical maximum sea level rise if all ice on earth would melt?”
Who cares? It would need to be about 50Celsius hotter than it is now to melt ALL the ice and if that happened sea level would be the least of our worries.
These guys are idiots……..
“Evidence for elevated sea levels is scattered all around the globe, he added. On Barbados and the Bahamas, for example, notches cut by waves into the rock six or more meters above the present shoreline have been dated to being 125,000 years old.”
======================================================================
Earthquakes and rising land; two tectonic processes in phase with
equinoctial precession (and ice ages).
For proof, look at Barbados, the easternmost island in the Lesser
Antilles in the Caribbean. Barbados is terraced. From the air, the
terraces look like a huge flight of stairs.
Two theories exist as to what formed the terraces. Each theory
begins with the same premise, that the island periodically rose from
the sea during a major earthquake. Each time it rose, the first theory
goes, one reef died and a new one grew at a lower point on the island.
The second theory holds that each terrace was carved from a single
large fossil reef. Each time the island rose, wave action sculpted a
new terrace.
In 1965, Professor Robley K. Matthews of Brown University had the
terraces dated. The lowest one dated at 82,000 years old, the second
one dated at 103,000, and the top one dated at 122,000. The steps
had been sculpted in sync with precession of the equinoxes. (Broecker
et al., 1968)
===============================================================
Barbados is one of the most famous of the tectonically rising sites…………………
By now that student has his Ph.D. This means that doctoral students heading for a career in a climate related field no longer are required to step away from the computer and do field grunt work. Or actually pour a chemical from a flask into a test tube. All they have to do is hit “enter” and abracadabra, they are awarded a Doctorate. And their work will be the basis for increased energy regulations and taxes on you and me.
They measure the ocean temperature 120,000 years ago to .7C warmer than today? I don’t think anyone today can accurately measure the average ocean temp with all the currents thermoclines etc. Just go diving 1 time and you will usually swim through several different temp profiles. For them to state accuracy to tenths of a degree is unbelievable to say the least. And since we did not have direct measurement 120,000 years ago I find it very hard to believe that proxies could give you tenth of a degree accuracy.
I’ve always believed in synchronicity and that whichever creator you might happen to believe in has a very well refined and playful sense of humor. I was reading the comments on this thread and was about half way down at Duster’s concerning Holocene highstands when my doorbell rings and the dog goes crazy. We probably get about one door-to-door visitor a month here – Girl Scouts selling cookies. A very neatly dressed pretty young girl slips a flyer through the screen door (dog is not too keen on her), thanks me and leaves. The feature text is as follows:
Violence, immorality, and global warming, along with oil spills and other environmental disasters—all these problems have led concerned people to ask,
WILL HUMANS RUIN THIS EARTH? YOU ARE WARMLY INVITED TO COME AND LISTEN TO THE ANSWER
And, I’m warmly invited yet. Too rich. Apart from the whimsical aspects of the experience, I’m struck with the thought that the ecos, greens and grantistas are not the only pro AGW groups to have a dog in this fight. I’ve scanned the flyer and put it on my Picasa web album as follows:
https://picasaweb.google.com/kjsorenson/WillHumansRuinThisEarth?authuser=0&feat=directlink
Don’t tell anyone but the satellite orbit is declining by 300 mm/year!
Roy Weiler says:
July 18, 2011 at 5:44 pm
We might as well just give up now. The tipping points have been reached, our only hope is adaptation!!
/sarc
And adaptation requires huge amount of taxes…
AGW fanatics love to couch their deep ecological game plan as a “moral imperative.”
So be it. Here is a moral imperative to contemplate. Let us consider, for a moment, the possibility that we are on the cusp of a Little Ice Age or even, are nearing the end of the interglacial. Oh, the humanity. Is it not a moral imperative to at least model this as a what if? Does it not behoove all jurisdictions to develop contingency plans to cover this “alternate future?”
At present, the relative effort going toward modeling cold futures must be a single digit percentage of efforts going toward modeling warm futures. That is a moral outrage. This is especially true when one honestly faces the likely consequences of cold futures.