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
America’s foremost experts on sea level, at least perceived as such, would need to drive a day and a half without stopping to see the ocean. Just sayin’.
Boy, they are sure amping up the alarm since Frankenstorm.
1 meter = 1000mm = 10mm a year
In 10 years satellite sea level is up 32mm = 3.2mm per year
Tide Gauge data shows a lower rise.
What a bunch of con artists.
The more open water there is, the more heat is trapped in the Arctic waters
omg – what can one say? This is beyond stupid.
So can someone reconcile this forecast with the NOAA global mean sea level trend of 2.8mm per year in this link?
…http://ibis.grdl.noaa.gov/SAT/SeaLevelRise/LSA_SLR_timeseries_global.php
“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.”
Great line from a ‘climate scientist’! So much for the models.
Where in the hell did they get that as an actual rate. As others mentioned, the measured rate is less than a third of a meter. They must be taking a ridiculously short time span to fudge a rate of a meter by the end of the century.
Making Hay out of nothing?
Gasping at straws?
Correction:
grasping at straws?
Check that, I read the abstract and he’s talking about all the effects he thinks are going to affect the rate such as the Antarctic is going to melt.
Not Dr Hay mouthing off again?
What a load of horse manure! He needs to take a basic electronics course and see what an electronic circuit does with even a small amount of positive feedback.
HINT – it instantly latches to the high output state and stays here as long as there is an input!
What he describes is physically impossible and if he had a clue about feed back in circuits he would know it! If what he said was true than temperatures would never have dropped following the big melt at the start of the current interglacial.
The error is obvious, they are not aware of negative feed backs because they are so wedded to the theory of positive feedbacks that they are not even looking for them. Since they are not aware of them and have such a poor understanding of feedback in systems the don’t understand that they MUST find the negative feedbacks that have kept the climate more or less the same for about 10,000 years. Their own data show global temperatures are range bound within a relatively narrow range. The only way that can happen is that some negative feed back is overwhelming all positive feed backs as the system approaches the upper limit of the range.
None so blind as those who will not see.
Larry
How do they get away with this nonsense? 0.5 metres by the year 2100 is 5 millimetres per year. I have never seen an actual global measurement based estimate of the sea level rise, either satellite or tide gauge, that is anywhere near 5 mm per year. Right now, the tide gauges say maybe 2 mm per year, and the satellites say maybe 3 mm per year. Nobody “exceed[s] the high end” of 5 mm per year.
w.
I have lived worked and played on or near the ocean all my life (61 years) and any sea level rise is so small it has no relevance just like half a degree of agwnonsense.cheers
Wouldn’t headlines such as these be problematic for Obama, who said last time that upon his election the seas would start to recede?
Unproven wild-ass theory alert!!!:
“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.”
There are so many factual errors in this piece, I find it hard to believe anyone s taking it seriously…
what are they smoking?
“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.
Isn’t sea level rise being corrected downwards, similarly ice cap melting and that is why they are sending up a new satellite “GRASP” or something like it to correct the over estimates? You know professors, you got to love em, but in my experience they are laregly isolated from reality and generally out of date as one would be, teaching from their old notes and working on lifelong pet projects. I don’t want to offend. I owe a great deal to my professors but when I went out into the practical world where you had to turn a profit, I found I had to become a student again, learning the stuff in a 20 year gap or so in my knowledge. This is okay. But only if they don’t start activist rants, say, against the steam engine, long after it has already been replaced. Naturally having an activist bent, they do this a lot. They certainly don’t waste time reading sceptical stuff and they miss a lot. Trust me Dr Hay, you have come to the subject 20 years too late.
I am surprised to see this post here. It is worth noting that the models tend to be conservative, so it is not that surprising that sea level is rising faster than predicted. I think that maybe the level of complexity is beyond modelling, so while the models will get the broad brush stuff right, the fine detail will not be predicted until after it happens.
And this is the first time something did not meet your expectations? Try questioning your faith (often called models) before you make a fool of yourself and any one else who uses the title scientist.
Here’s America’s longest tide gauge record (San Francisco):
http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?stnid=9414290
The linear trend shown on that graph is 2.01 mm/year, but that’s calculated from data through 2006. There’s been no sea-level rise at all at San Francisco over the last 30 years, so the calculated long-term average rate of sea-level rise keeps decreasing. It’s now down to 1.92 mm/year:
http://tidesandcurrents.noaa.gov/sltrends/sltrends_update.shtml?stnid=9414290
But even if sea-level rise resumes at its old rate at San Francisco (which I do expect, BTW), 1.92 mm/year will add up to just 6.7 inches (0.17 meters) by 2100.
Not so scary, eh?
There’s an even better tide gauge record of sea-level in Germany; here’s the graph:
http://tidesandcurrents.noaa.gov/sltrends/sltrends_global_station.shtml?stnid=120-022
There does appear to have been some acceleration in rate of sea-level rise there… circa 1860. There’s been none since then.
Average over the last 160 years: 1.4 mm/year, which adds up to 4.6 inches (1.2 meters) by 2100.
When I saw that this GSA conclave will be meeting here in NC this weekend, I considered dropping in. But they want $315 for a one-day admission, so I’ll pass. Is anyone else planning to go?
Dave Burton
webmaster, http://www.sealevel.info/
I wonder if in the year 2095 when there has been maybe a quarter of a meter of sea level rise he will be claiming that the next 750mm is there trapped in the system and it will spring up at any time…Of course I would be very impressed, since he would be about 140 years old at the time 😉 (and I’d be pushing the neighborhood myself which would likewise impress me) I am more concerned we are going to have a downturn in temperature and sea level will fall significantly. Of course it isn’t the sea level part that concerns me, it’s those confounded glaciers burying mountain villages that are the worry.
Did they recently legalize recreational pharmaceuticals in Colorado? I’d hate to accuse the good doctor of something illegal.
I guess he didn’t notice sea level rise was decelerating:
http://naturalclimate.wordpress.com/2012/01/30/sea-level-deconstruction/
Well, that should make all of those positive feedbacks so much easier to identify, you know, once we can walk across the Bering Strait again.