GSA Annual Meeting Presentation: Could Estimates of the Rate of Future Sea-Level Rise Be Too Low?
Boulder, Colorado, USA – Sea levels are rising faster than expected from global warming, and University of Colorado geologist Bill Hay has a good idea why. The last official IPCC report in 2007 projected a global sea level rise between 0.2 and 0.5 meters by the year 2100. But current sea-level rise measurements meet or exceed the high end of that range and suggest a rise of one meter or more by the end of the century.
“What’s missing from the models used to forecast sea-level rise are critical feedbacks that speed everything up,” says Hay. He will be presenting some of these feedbacks in a talk on Sunday, 4 Nov., at the meeting of The Geological Society of America in Charlotte, North Carolina, USA.
One of those feedbacks involves Arctic sea ice, another the Greenland ice cap, and another soil moisture and groundwater mining.
“There is an Arctic sea ice connection,” says Hay, despite the fact that melting sea ice — which is already in the ocean — does not itself raise sea level. Instead, it plays a role in the overall warming of the Arctic, which leads to ice losses in nearby Greenland and northern Canada. When sea ice melts, Hay explains, there is an oceanographic effect of releasing more fresh water from the Arctic, which is then replaced by inflows of brinier, warmer water from the south.
“So it’s a big heat pump that brings heat to the Arctic,” says Hay. “That’s not in any of the models.” That warmer water pushes the Arctic toward more ice-free waters, which absorb sunlight rather than reflect it back into space like sea ice does. The more open water there is, the more heat is trapped in the Arctic waters, and the warmer things can get.
Then there are those gigantic stores of ice in Greenland and Antarctica. During the last interglacial period, sea level rose 10 meters due to the melting of all that ice — without any help from humans. New data suggests that the sea-level rise in the oceans took place over a few centuries, according to Hay.
“You can lose most of the Greenland ice cap in a few hundred years, not thousands, just under natural conditions,” says Hay. “There’s no telling how fast it can go with this spike of carbon dioxide we are adding to the atmosphere.”
This possibility was brought home this last summer as Greenland underwent a stunning, record-setting melt. The ice streams, lubricated by water at their base, are speeding up.
Hay notes, “Ten years ago we didn’t know much about water under the Antarctic ice cap.” But it is there, and it allows the ice to move — in some places even uphill due to the weight of the ice above it.
“It’s being squeezed like toothpaste out of a tube,” explains Hay. The one thing that’s holding all that ice back from emptying into the sea is the grounded ice shelves acting like plugs on bottles at the ends of the coastal glaciers. “Nobody has any idea how fast that ice will flow into the oceans once the ice shelves are gone.”
Another missing feedback is the groundwater being mined all over the world to mitigate droughts. That water is ultimately added to the oceans (a recent visualization of this effect in the U.S. was posted by NASA’s Earth Observatory: http://earthobservatory.nasa.gov/IOTD/view.php?id=79228).
All of these are positive feedbacks speeding up the changes in climate and sea-level rise.
“You would expect negative feedbacks to creep in at some point,” says Hay. “But in climate change, every feedback seems to go positive.” The reason is that Earth’s climate seems to have certain stable states. Between those states things are unstable and can change quickly. “Under human prodding, the system wants to go into a new climate state.”
WHAT: Could Estimates of the Rate of Future Sea-Level Rise Be Too Low?
WHEN: Sunday, 4-November, 9:15–9:30 a.m.
WHERE: Charlotte Convention Center, Room 219AB
ABSTRACT: https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_209198.htm
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Dr. Hay may find this upcoming NASA JPL project problematic with his claims:
Finally: JPL intends to get a GRASP on accurate sea level and ice measurements
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NOW, STOP LYING AND MISLEADING EVERYONE AND FIX YOUR CALCULATIONS.[It is appreciated that sometimes emphasis is required in a statement but many of your colleagues here find shouting quite offensive . . mod]
>>
This level of stupidity goes beyond the pale. That is why I used capitals for emphasis. (Something I hardly ever do beyond one word, again where emphasis is needed). This is not “shouting”, it is emphasis.
If you or anyone else reading this erroneously interpreted written words as being shouting that is really not my fault but just to be politically correct I will issue a politician’s apology:
“If anyone was offended by my use of capital letter in writing that phrase, I offer my full apology for any offence that may have been caused. That was not my intention. My thoughts and prayers are with the friends and family of those concerned at this difficult time.”
Reality check :
Here is a plot from a recent Jevrejava paper drawn from tide gauge data. (red dots are mine)
http://i40.tinypic.com/nx3q1.png
Sea level rise (as defined by the level of the sea !!) stopped accelerating around 1995 and , while still showing a positive rate of change it is decelerating.
If satellite estimations of sea level are showing something different from the physical reality they need to be fixed. That does not involve redefining what “sea level” means nor adding more positive feedback to already broken climate models.
These guys are not stupid, so this kind of public announcement can only be seen as yet more of the “in order to be effective we need to be deceitful” school of climate anti-science activism.
” One of those feedbacks involves Arctic sea ice, another the Greenland ice cap, and another soil moisture and groundwater mining.”
The idea of such a positive feedback is simply not backed up by the data. Looking at the rate of change of Arctc sea ice shows the accelerating decline STOPPED in 2007.
http://i46.tinypic.com/r7uets.png
That is not at all compatible with the idea that the increased exposed area is causing any measurable positive feedback. This is yet another hypothesis without any physical evidence of it happening.
That graph shows a strong correlation between AMO and rate of change ice extent. The fact that ice extent has stopped decreasing despite AMO being warmer is strong evidence of a NEGATIVE feedback, not a positive one.
typo correction…
daveburton wrote:
> “… 4.6 inches (1.2 meters) by 2100.”
of course that should be:
> “… 4.6 inches (.12 meters) by 2100.”
Ted Carmichael wrote on November 2, 2012 at 12:24 am:
“(And then I noticed: Cool! It’s actually in Charlotte, where I live. I wonder if I can sneak in…)”
I’m in Cary, less than 3 hours away. Unfortunately, unless you’re a student, list price for one-day admission is $315. But, Ted, please drop me an email. You can find my email address on my web site:
http://www.sealevel.info
“Whatever sea level rise has taken during the course of my own life would be unlikely to cause the demise of a single person. Dozens and dozens of tide gauges bear this out. Measuring at Midway Atoll in the Central Pacific, the National Oceanic and Atmospheric Administration found that sea level rose .7 millimeters a year from 1947 to 2006. At this rate, in a hundred years, the oceans would rise a little less than three inches. Again, such modest, unthreatening rises have taken place dozens of times in the past, and will again.” — Don’t Sell Your Coat, yours truly
Ok, but what does Dr. Nils Axil Morner say?
University of Colorado at Boulder is Roger Pielke Jr’s place isn’t it?
“Lose most of the Greenland ice cap in a few hundred years”?????????? With boreal forests growing along the arctic coast between 130,000 and 125,000 years ago there was no loss of “most” of the Greenland ice cap. That was a 5000 year period with temp. 4 – 5 C up to 8 C warmer than present. If that was the case it would certainly make the present collecting of continuous ice cores problematic.Certainly the melting over a couple of centuries would produce massive layers of completely melted snow/ice that refroze as massive, `reset’ layers in the ice sheet. These would be very obvious in the present day cores.
OK, so lets just forget that the ice in Antartica is getting thicker by much the same amount shall we?
And they tell me over here Americans don’t do irony, sarcasm, & cruelty! You naughty people you ;-)!
Deja vu. Now, let me see, UNIPCC AR4 Table SPM 1 (Revised & corrected), Rate of Sea-Level Rise, overall rate of sea level rise between 1961-1993, 1.8mm/yr ± 0.5mm/yr error bar. Rate of sea-level rise 1993-2003, 3.2mm/yr ± 0.7mm/yr error bar. Engineer’s hat on, 1.8mm + 0.5mm = 2.3mm/yr, 3.2mm – 0.7mm = 2.4mm/yr = same bloody number! Nils Axel Morner reckons average rate of sea-level rise over the last century has been 2.3mm/yr!!!! Then again, 1.8mm – 0.7mm = 1.1mm/yr, 3.2 + 0.7 = 3.9mm/yr, (1.1 + 3.9)/2 = 2.5mm/yr (I would never worry about 2/10ths of anything much)! Most peculiar & strange that these numbers all appear to be about the same, if I was a synical grumpy old man of dubious parentage I would have said somebody somewhere has been playing games with the numbers, but then that’s just me, isn’t it? Then of course there was UNIPCC AR4 initial publication in 2007, in which the original Table SPM 0, (as published) Rate of Sea-Level Rise, you know the one which, according to the UNIPCC WORLD’s LEADING EXPERTS ON CLIMATE CHANGE (their words not mine), 450 lead authors, 800 co-authors, 2,500 scientists, 140 Guvments around the world all reviewed it LINE BY LINE (their words not mine) couldn’t add up a simple column on figures nor get the frigging decimal points in the right place to start with, & they want us to spend trillions of Dollars we don’t have on something they can’t even get right first time with all that EXPERTISE on tap? No way José!!! Can anyone tell me how the latest tree-hugging Polar Bear cuddling Gaia worshipping jamboree fest is going, did they have enough Champagne, Caviar, Claret (let’s hope it was the ’87 cos the ’88 was ghastly!), & Chablis to go round in whatever 5-Star luxury resort they were forced by we taxpayers to inhabit, I would feel absolutely awful if those thousands of EXPERT SCIENTISTS & THOUSANDS of BUREAUCRATS had to huddle round a miserly camp fire with a tin of beans sharing a can of 7-Up! I expect if they did they would at least be able to reflect upon their humble circumstances & offer up a few prayers to whichever Myan Idol they saw fit in thanks for what they received! 🙂
The bathtub isn’t a fixed size.
The tectonic plates are still moving. Together and apart. Mountains are rising.
Harold Pierce Jr asks about sedimentation. The Amazon dumps 1,600,000,000,000 pounds of sediment onto the continental shelf every year.
A tidal gauge at San Francisco. Hmmm . . . how stable is San Francisco ?!?!
And, suppose the ocean has risen 3 feet by 2100. It’s the end of the world as we know it? Why should anyone care? If you are going to scare everyone, come up with something scary.
You folks are just trying to confuse this issue with facts. Seems that these folks believe that the climate should be static. If the sea levels rise, I’m sure our descendents will be fully capable of adjusting.
The use of GPS satellite systems and continuously operating reference stations (CORS) will ultimately tell the true story of sea level rise. However, this requires the CORS network to be expanded to include more coastal stations in other countries, and a commitment from NOAA to not “adjust” the data.
http://www.ngs.noaa.gov/CORS/
Well they learnt one thing , by 2100 given he will be long dead so there is no chance of people reminding him of his BS claims . Make your ‘predictions ‘ nice and far in the future and you can always claim its ‘going ‘ to happen and never have to worry about answering the question why it did not .
or just maybe it all came out of the shrinking and cooling atmosphere… durr
tty says:
November 2, 2012 at 12:34 am
Almost the whole East Coast of the US is sinking. It is in fact a classic example of a “ria” coast where the river mouths are at the end of long inlets that are really drowned river valleys (e. g. Chesapeake bay) and where sediment from the rivers form barrier islands off-shore. On stable coastlines rivers build deltas out into the sea instead.
Given this it is actually rather odd that it took almost 200 years to beat the 1821 high-water mark in New Yoork.
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That’s correct except that Manhattan happens to be the first major exception as you move North from Florida. NYC is built on quite old and quite uncompressable Ordovician schists capped with a variably thick layer of sediment and some fill along it’s river fronts in some places. You’d have to know the exact geology of the Battery (which I don’t) to know how much compressable dirt is under the tidal gauge at the Battery.
They are going to fix the satellite records now because they have improved ocean mass (glacial melt) numbers and improved ocean heat steric rise numbers.
Eric Leuliette (of NOAA) and Josh Willis (managing the ARGO program) are arguing the rise should be reduced to 1.6 mm/year.
Basically, the previous models of glacial isostatic adjustment were not correct (shown by recent measurements using GPS of Antarctica and by redoing the assumptions used for GRACE) and the steric ocean heat rise was over-estimated (shown by the ARGO floats).
The old models allowed the researchers to adjust the Raw satellite data to get the results the models said should be there or something close to 3.0 mm/year. But the old models were flawed and we are back to 1.6 mm/year, the same number as most of the 20th Century.
http://ibis.grdl.noaa.gov/SAT/SeaLevelRise/documents/NOAA_NESDIS_Sea_Level_Rise_Budget_Report_2012.pdf
http://www.tos.org/oceanography/archive/24-2_leuliette.pdf
Louis Hooffstetter says:
November 2, 2012 at 4:40 am
The use of GPS satellite systems and continuously operating reference stations (CORS) will ultimately tell the true story of sea level rise.
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It’ll help quite a lot. Unfortunately, it won’t do anything about the secondary problem that all existing or proposed tidal gauges are on coast lines and thus are not optimally distributed to detect overall sea level changes. They simply can’t see any changes in large portions of the oceans. Ultimately, I expect that we will get genuinely high confidence measurements from satellites. But that’ll be a few decades I think.
Gosh, it’s such fun trying to make a technical post in a 19-character wide, 4-line deep box!
“The last official IPCC report in 2007 projected a global sea level rise between 0.2 and 0.5 meters by the year 2100.”
That’s not true.
AR4 WG1 Summary for Policymakers, Table SPM.3 shows projected sea-level rises of 0.18 – 0.59 metres to occur between 2090 and 2099 (relative to the 1980-1999 average sea level).
falsus in uno, falsus in omnibus.
Michael D Smith says:
November 1, 2012 at 7:25 pm
“But in climate change, every feedback seems to go positive.”
Possibly the dumbest thing I’ve heard all year. Positive feedbacks of any duration are almost impossible in nature, they are always resource limited and always end up being overtaken by negative feedbacks after the initial runaway condition initiates. Anyone have an example where this is not the case?
Is there really anyone who believes such a statement could be remotely possible, even for an instant? Baffling.
You obviously shouldn’t have asked, because it makes perfectly good sense to people who know science.
To start off with, climate change just means the climate has changed and doesn’t show the direction of that change. Here is an example of climate change based on a cooling climate when our planet is getting reduced solar irradiance during Milankovitch Cycles. The positive feedbacks are the same positive feedbacks for warming, it’s just the direction of the change is different.
When the Earth cools, the albedo effect changes to reflect more sunlight, which makes the Earth cool faster. Snow accumulation eventually doesn’t even melt in summer, so glaciers are formed. The glaciers trap carbon beneath them, so the greenhouse gases, methane and CO2, are reduced from the atmosphere. The cooler climate reduces water vapor, so another important greenhouse gas is reduced. Reduced water vapor also reduces clouds which reflect sunlight. Fewer clouds means fewer chances of them returning heat to the surface of the Earth.
Now, that’s just some of the main feedbacks involved, but it’s easy to imagine them all in reverse. They are mechanisms for positive feedback in climate change, whether it’s warming or cooling and they amplify the trend.
There is an extra concern beyond the above ice age cycle example and it has to do with the carbon cycle. The ice age cycle started once our present world was designed by the connection of North and South America and our modern thermohaline circulation. Oceans are vast and can store tremendous amounts of heat. Sediment cores in the arctic show it was still sea ice covered during the Holocene Climatic Optimum. There is obvious evidence of changes in high latitude areas, like the treeline being further south. The return of permafrost would have had to sequester some carbon, but is all that methane being released only the product of recent sequestering or could prolonged warming release carbon that never had the chance to be released during the brief interglacials. There could be 25 ice age cycles worth of methane locked away in that permafrost. A large methane release in a short period of time could create a domino effect with warming releasing more methane.
Similar problems can exist with methane hydrates in and near the ocean. That land area in the north has experienced most of it’s glacial rebound, so the permafrost could be trapping methane hydrates on land. An open ocean can release methane by erosion. The warming ocean or changes in currents can also release methane hydrates from the sea floor. There is evidence now of the Gulf Stream destabilizing methane hydrate and there has been evidence of methane hydrate outgasing from areas covered with sea ice. So far methane hasn’t been much of a problem, but there is the potential of it contributing more to global warming than CO2.
The year 2100 is a long way off and there is the potential for the sea level to rise enough that cities like NYC and DC will have to be abandoned. The Earth does have the potential to create runaway warming and glacier melt. I don’t think it’s likely, but we haven’t tried warming the Earth near the end of it’s interglacial before. The fact is you can’t accurately estimate the time period of the climate change when positive feedbacks are involved.
Gamecock says:
November 2, 2012 at 4:21 am
And, suppose the ocean has risen 3 feet by 2100. It’s the end of the world as we know it?
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Not the end of the world, but a one meter/three foot rise would be getting into the pretty damn inconvenient range. There is a LOT of infrastructure built very close to sea level even in/near what we think of as inland areas like Albany, NY or Sacramento.
Great post Dave! Crystal clear clarity. You should do a guest post here like that one.
Alan the Brit wrote on November 2, 2012 at 4:19 am:
“UNIPCC AR4 Table SPM 1 (Revised & corrected), Rate of Sea-Level Rise, overall rate of sea level rise between 1961-1993, 1.8mm/yr ± 0.5mm/yr error bar. Rate of sea-level rise 1993-2003, 3.2mm/yr ± 0.7mm/yr error bar. Engineer’s hat on, 1.8mm + 0.5mm = 2.3mm/yr, 3.2mm – 0.7mm = 2.4mm/yr = same bloody number!”
Moreover, that “1.8mm/yr” figure is from GIA-adjusted & averaged coastal tide-gauges, and that “3.2 mm/yr” figure is from averaged & adjusted mid-ocean satellite altimetry. They are different quantities, measured in different places, by different methods.
Just about the only thing the two kinds of measurements have in common is that they’re both inflated by model-derived GIA adjustments. But even those are different: the satellite figures are inflated by 0.3 mm/year, and the coastal tide-gauge average is inflated by about twice that.
Even if you trust* the satellite figures, if you measure sea-level rise in different places, you’ll generally get different numbers, so if you conflate measurements from two different locations you can easily create the illusion of either acceleration or deceleration. That’s what the IPCC did in AR4.
Tide-gauge measurements, by themselves, show no acceleration (actually, a slight deceleration).
Satellite measurements also show no acceleration (actually, deceleration).
But by conflating the two, alarmists create the illusion of acceleration in rate of sea-level rise.
* (I don’t trust the satellite figures. Here’s why. ENVISAT’s retroactive data “corrections” tripled the rate of sea-level rise that it had measured over the preceding decade; compare the before and after versions. Even if the correction was correct, it stands to reason that if it took a decade to discover an error that big, there’s a good chance that other major errors remain uncorrected.)
Oops. Upon rereading, I think tty was talking about tectonic depression of NYC, not sediment compaction. The Hudson South of (roughly) Fort Edward is in fact a drowned river valley that continues off shore as the Hudson Canyon. Is NYC sinking? How the hell can one tell? It’s not like there is a stable reference nearby whose altitude is fixed or is changing in a known fashion. For what it’s worth, one GIA for NYC seems to have it sinking at, as I recall, about one inch per century, but I have no idea how GIAs in general are computed or if the numbers have any credibility. Dakar, Sengal (Latitude 14N) has a GIA for heaven’s sake. Exactly where were the glaciers that depressed the West African coast?
I suppose one could measure the actual rate using GPS, but that’s not something one can currently do on a few Sunday afternoons with Inexpensive tools. Thanks to geometry, GPS’s are much better at horizontal measurements than vertical and getting sub mm accuracy is, I believe, non-trivial.