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.
Jim Sorenson says:
July 19, 2011 at 8:03 am
I received one of these. It is from the Jehovah’s Witnesses. Bizarre. They have a long history of adamantly opposing world government. My guess is that they hired a marketing person to broaden their appeal.
Anthony,
Just check this out – The BBC – Climate change sceptics should get less BBC coverage and be challenged ‘more vigorously’, says report on science output
Broadcasters to give less airtime to critics of majority view
By Daily Mail Reporter
Last updated at 12:44 PM on 19th July 2011
Apparently the BBC says the science is settled and used a far left wing zealot under a so called independent review of BBC coverage of science authored by Steve Jones, a professor of genetics at University College London. He’s a well known left wing anti conservative who has spent most of the last 40 years studying snails actually making a decision on AGW for the BBC on their AGW coverage. One BBC executive, who has seen the report, told the Telegraph: ‘It is about recognising when the debate has moved on beyond whether a theory is true or not, and on to what we do about it.’
Senior executives at the corporation say climate change is considered a special case because of the weight of political argument it causes.
But they acknowledge that the majority view supports the idea of man-made global warming.
Anthony this is really crazy by the BBC.
Read more: http://www.dailymail.co.uk/news/article-2016299/Climate-change-sceptics-BBC-coverage-challenged-vigorously-corporation-body-rule.html#ixzz1SZHFkWLg
On sea level rise: Most of the calculations I have seen assume a uniform temperature change and temperature for the entire water column. Most seem to forget that water expansion/contraction with temperature is not linear. As water cools it contracts until about 4 degrees centigrade then it begins to expand. Not only that but it is not necessarily linear in its temperature response (ever wonder why water isn’t used in thermometers?). The change in temperature with depth has been pretty well documented with most of the water at depth being uniformly of the less than 4 degrees centigrade variety. The majority of water temperature change occurs in the first ~700 meters with most of that in the first 100m. Very little mixing occurs below that (neglecting the overturning circulations). If one really wanted to predict the effect of heating the surface temperature by some amount, one would have to model the diffusion of that temperature through the depths and then integrate the density changes over the variable functions of temperature and depth. It would not be a pretty calculation. A good first order approximation would probably be to assume the change only occurred in the first one hundred meters equally and calculate the expansion of that mass. That would probably give a number that correlates to 90-95% of the actual rise (not sure which would be larger though).
Kelvin Vaughan: “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.”
Fair point. I did think about The Netherlands and similar places, as well as those below sea level who are kept dry by levees and pumps, and probably should have mentioned that in my comment. No question there would be some impact, but I am highly skeptical of the huge estimates of people who would be negatively impacted by a 1 meter rise. Also, these “studies” which simply look at contour elevations and don’t take into account things like levees, pumps, etc., are interesting as an initial due diligence exercise to find out how many people live in areas that could potentially be impacted, but don’t do much practical good in looking at specific areas to see whether people will actually be negatively impacted in practice. If I live right next to the shore but at 10M, then a 1M rise probably won’t mean much to me; if I live at or below sea level, but have good levees in place that could handle a 1M rise, then I also probably won’t be negatively impacted much.
I wrote an article on this very subject of sea levels
http://judithcurry.com/2011/07/12/historic-variations-in-sea-levels-part-1-from-the-holocene-to-romans/
The long versiion is available through a link early in the summary carried above. Sea levels are currently well below where they were in Roman times.
tonyb
It’s typical that they use sea-level estimates for the last interglacial from Barbados, which is known to be very tectonically unstable (it is basically a piece of ocean bottom that has temporarily been pushed up above sea level) and the Bahamas which are known to be isostatically affected by the Laurentide icecap.
Measurements from the highly stable West Australian and Gawler cratons indicate sea-levels 2-3 meters above the present during the last interglacial.
And as for the SST being only 0.7 degrees warmer than at present and being familiar with literature on the subject, it is obvious to me that some real vigorous “adjusting” must have been applied. As a matter of fact it would not be easy to find any major area where the warming wasn’t more than that
Kelvin Vaughan , the Fens as you know it are creations of man pumping the water out of the area ,indeed some of the same Dutch engineers that helped drain the low laying land of Holland worked on the Fens to make them look like they do . If it was to flood that would actual be a return to their natural state .
Owen says
“Most seem to forget that water expansion/contraction with temperature is not linear. As water cools it contracts until about 4 degrees centigrade then it begins to expand.”
That is fresh water. Salt water does expand in a nearly linear manner.
Is it possible that ice thickness in Greenland and Antarctica gets thicker and thicker with each glacial cycle. So sea level gets lower and lower at the same temperature with each new inter-glacial.
They are right, sea level will rise by up to 3ft. The key is that “up to”. It is like stores when they say “save up to 90%”, when in fact you will be luck to find anything even 20% off.
That a total sea-level rise is impossible – see http://www.sciencemag.org/content/321/5894/1340.abstract
tty says:
July 19, 2011 at 9:52 am
It’s typical that they use sea-level estimates for the last interglacial from Barbados, which is known to be very tectonically unstable
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tty, they are flat out lying………..
Why did they do all the way out there to measure sea level rise?
Because they knew that Barbados is rising…..
It would be impossible for them to have studied sea level rise in Barbados without knowing about the Barbados Ridge………….
They had to have known…..so the only other choice is that they are flat out lying……………
Wil says:
July 19, 2011 at 9:11 am
Anthony,
Just check this out – The BBC – Climate change sceptics should get less BBC coverage and be challenged ‘more vigorously’, says report on science output
Broadcasters to give less airtime to critics of majority view
The BBC are funded by the UK Government. The UK government are raking in stealth taxes from global warming and their business associates are making money out of it as well.
The problem with this study is that rather than looking at times when it was warmer and checking the sea levels, they looked at times when sea levels were higher and checked the temperatures. If they had done it the other way around they would have found that not all warming results in similar sea level rises. For some five thousand years in the early to mid-Holocene, (about 8000 to 3000 years ago) the Eurasia Arctic Ocean Coastline July temperatures were two to seven degrees warmer than now, and Greenland did not slide into the ocean, despite that it must also have been warmer than the present by quite a lot for thousands of years. Contrary to statements in the article, also, that we are “warming all seasons” (the implication being that previous changes were not uniform throughout the year, but these are) current warming is concentrated primarily in the coldest months and days of the year, summer warming is much weaker. (interestingly, in the last about forty years, January temperatures warmed a lot in the US, more so than any other month, which warmed relatively little, including the other winter months. January is generally the coldest month in the US. I know other places around the world have more winter than summer warming, but I don’t know if the are concentrated primarily in one month or all winter months) As such comparing the global mean sea surface temperature difference and relating it to sea level can be misleading, as we are not seeing the strong summer warming that would melt large amounts of ice (small amounts are a different story 😉 ) But even when warming of summer months occurs this does NOT imply by necessity higher sea levels.
MacDonald, G.M., et al., 2000. Holocene treeline history and climate change across northern Eurasia. Quaternary Research, 53, 302-311.
“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.”
Odd how no one is interested in what causes interglacials.
Forgive me if this has been posted somewhere else but NASA’s research into Ceres and Vesta have shown that earths orbit changes are because of these two bodies and could explain Climate changes in the past.
http://hotair.com/archives/2011/07/18/video-nasa-dawn-reaches-vesta/
The time to study interglacial-related sea level rise is at the beginning of an interglacial, not at the end of one as we are now.
It might be an idea to start studying the reverse process – rather more relevant to our future.
gator;
Or, more to the point, what sustains interglacials. And what tends to terminate them. I betcha CO2 doesn’t appear on either list.
More about the terraces on Barbados:
http://esp.cr.usgs.gov/info/eolian/Muhs2001QRBarbados.pdf
This is actually a pretty cool document. Note at the beginning, the authors clearly state:
Uplifted.
As I recall when the data were showing rising OHC, the “consensus” position was that steric changes from ocean warming were the main driver of SLR with mass increases from melting ice sheets a minority contributer. It is amazingly fortuitous that, just as data suggesting runaway ocean warming are becoming much harder to come by, they should discover that really the situation is exactly the reverse. No, really.
Garbage in… Garbage out…
Satellite altimetry GMSL is garbage. The models that are used…. Garbage.
The trending down of GMSL by use of Jason-2 does favor a deceleration of rising sea levels,
but I don’t support it.
There are possibly over 50 papers written on the prediction of rising sea levels but rarely use the same method, nor do they resemble each other.
Currently, there are only 2 published papers on historical and predictive GMSL, and they both use different modeling methods. They somewhat arrive to the same conclusion, yet fall short of empirical evidence available.
The models used in the 2 papers mentioned, both use Co2 as function of rise.
I assume this paper does as well.
This paper chooses to not use glacial melt and/or GIA as a predictor. I agree.
I would like it if the University of Colorado at Boulder would do the same.
But the end result of all these models is the same.
Garbage.
Trends are exaggerated garbage.
Satellite altimetry is faux global garbage.
The data provided comes with a use-at-your-own-risk-no-guarantee clause from the provider.
Just plain and simple garbage..
The only purpose of this paper and the other papers like it, is to convey, that while none of these
institutions can agree with each other on modelling or predictions practices, they will all agree that Co2 is a function of that rise.
G.A.R.B.A.G.E..
Globally Assumed Research By Alarmists Gone Ecocentric
Good Day !
Finally, let’s say that things do rise by a meter. 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 relatively close to the coast, have seen numerous beaches all up and down the pacific, have seen thousands of structure, and offhand I’d have a hard time finding a single home that is within 1 meter of sealevel. 10 meters? Yeah. 5 meters? Probably a few. 1 meter? You’d have to be crazy to live near the coast and only one meter above sea level. Forget global warming and sea level rise — a decent storm would wipe you out.
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While I agree with your main point, I must add that you underestimate the amount living below five meters. I live on Hilton Head Island at 14.12 feet elevation. I was told by the insurance company that I could not get flood insurance below 14 feet, so was saved by some few millimeters. So, me and many others are below five meters and barely insurable, as I am not alone where I live at that elevation.
Dr. Overpeck has been invited to New Mexico by some of our neighbors in Santa Fe to help us solve our problems with global warming. There is at least a small group of us in Las Cruces who really do not really appreciate that help.
http://www.nmenv.state.nm.us/Oots/documents/PR-Overpeck-9-28-10.pdf
Bernie
From Tucker on July 19, 2011 at 2:42 pm:
Offhand I’ve never heard of National Flood Insurance being denied. After light searching, I can’t find anything on the official US government site that indicates it’s not available to you. From the relevant official Hilton Head Island government site all I can find is a “Flood Elevation Certificate” may be required for new construction or with qualifying renovations and additions. If yours is an existing house without such changes, I can’t see what the problem would be.
You can input your address at the local site (“Flood Zone Search” page) and get rate info. It also has a map of the different rate zones.
Or are you referring to flooding insurance, as found with regular homeowners-type insurance?
Kadaka,
I misspoke. You are correct. Below 14 feet, you fall into another category, which I was told was not pleasant. However, the point I was attempting to make is that many live below five meters elevation near the coast. I am certainly not an AGW hugger, but facts are facts, as you so eloquently pointed out in my post earlier.