Bishop Hill The Royal Society and sea level
Jan 19, 2011 Climate: WG2 Royal Society WUWT has a guest post looking at sea level rises...and possibly falls:
Based on the most current data it appears that 2010 is going to show the largest drop in global sea level ever recorded in the modern era. Since many followers of global warming believe that the rate of sea level rise is increasing, a significant drop in the global sea level highlights serious flaws in the IPCC projections. The oceans are truly the best indicator of climate.
Hat tip then to John Shade (of Climate Lessons fame) who notes the views on sea level rise put forward in the Royal Society's recent paper on climate change:
Because of the thermal expansion of the ocean, it is very likely that for many centuries the rate of global sea-level rise will be at least as large as the rate of 20cm per century that has been observed over the past century. Paragraph 49 discusses the additional, but more uncertain, contribution to sea-level rise from the melting of land ice.'
Oops. As John Shade notes, it woud be instructive to have an annual review of the Royal Society's paper in the light of new data.
Reader Comments (90)
I see there is an orchestrated, well-funded campaign underway here to discredit Sea Change. Is Soros backing it? Or Big Salt? Or maybe Big Rail - they have a lot to gain from dry ocean beds. The fact is our seas are disappearing fast and if we don't act now future generations will turn to us and say 'what was all that about, eh? - that lack of action'.
Those who think we do not control the level of our seas are no better than Canuters. I think the Bishop may need to redefine the meaning of post-control if we are to keep them at bay. They want to delay action on our sinking seas. But when we get our computer models, with their multicolour outputs, and our PR-machine in place, they will be immersed in a flood of press releases that would sink a ship (remember them?). Eat your heart out, Big Rail.
I see oracles in coracles, comely mermaids to the fore, blocking shipping lanes etc until our views are heard and our demands are met. Is this sceptred isle to be an isle no more? Perish the thought. We can turn back the tide of waterlessness that is engulfing us. We can and we must. We may just need, how is that put, a little exaggeration of the actualities, a little bit of offering up scary scenarios, making simplified, dramatic statements, and making little mention of any doubts we might have... That sure worked for the climate folks, so why not for we sea people?
Anyone care to start RealSea.com? We'll need a wealthy financier or two.
@BBD,
Newlyn is indeed rising, but from 1915 that rise is not significant. My point was, using actual measurements recorded at the time, there is no correlation between sea-level changes and consumption of fossil fuel. You can make it more complicated if you wish. In fact, if anyone can show a correlation between directly measured MSL and recorded fossil fuel use from the turn of the last century, I would be very interested to hear of it. My only proviso is that rapidly rising consumption from 1950ish is reflected in the MSL info.
Zed
I will say right at the outset that I cannot take your position (used to).
I will, however, say that you do have a certain strength of character in voluntarily coming into a forum such as this and attempting to educate the rest to see the error of their ways as you see them. The manner/technique is simply the one you use, it may not be the most efficacious way forward but I will give you credit for trying (you will at this very moment be thinking I am taking the piss or trying to lead you up some garden path, I am not but accept that from your point of view it's amost impossible for me to prove that in any case).
As a former pro-AGW ''believer myself (and it was most uncomfortable making the shift but it was necessary in light of contrary evidence) I would respectfully ask you, please, to consider whether there is ANY aspect of AGW theory that is now in question?. I have no qualifications in the field, I'm just an interested bystander that's all, how you?
I've heard it said that if the world began to cool again that would be sufficient evidence to contradict AGW, I find this reasonable from a pro-AGW point of view.
What, please, is your own view? Would this be morphed into climate 'change' and therefore continue to confirm the hypothesis?.
Very respectfully
BM
SSAT
Your point was well made and well taken.
What's been annoying me about Ordnance Datum Newlyn is that nowhere can I find a study telling me by how much it has subsided over any fixed timescale.
When you consider the glacial isostatic rebound for the UK mainland gives uplift in Scotland and subsidence in much of England and Wales (more ice sheet over Scotland 12kya), you can see that this matters.
Part of me 'knows' that GI rebound means that Newlyn is subsiding and that this is going to show up in the apparent rise in MSL measured by the tide gauge. But how much?
It's just general curiosity plus a general caution about individual tide gauges. Is the land moving, or is it sea level? Or both?
I have some experience with float sensors for indicating liquid level. We find it dificult to indicate to within +/- 2 mm in still water. I am also a sailor and I don't believe it is possible to measure sea level level better than +/- many inches.
@ John Shade
Clearly, we need to act now, or face our grandchildren having to stay in beach hotels which are 5km from the sea. As a starter, we can recycle all the emptyings from vacuum cleaners and cover the ice sheets with them to decrease the albedo. Duvets may also help.
Folks, Are you discussing this?
http://sealevel.colorado.edu/current/sl_noib_global_sm.jpg
Sorry to sink your lifebot, but sea levels are most definately rising.
@ BBD
Geography class in the 60's taught me that NW Scotland was rising and SE England was sinking. Logically there must be a neutral axis and if my memory serves me, I took it to be explained as the Tees-Exe line. 50 years later & the subject comes up again! All I need now is to come across a problem solvable only by a quadratic equation and my old headmaster will be proved right:(
bluecloud above:
Yes, but by how much exactly and what is the rate of change? Does the trend support the estimates of increased OHC? Does it support the estimates of ice melt?
How reliable are the estimates in the first place, and how much weight should we give them?
Please see my comments at 1:47pm and 4:04pm above.
SSAT
Heh!
Bluecloud, a clear Canutist. I wonder who is paying you to make such posts?
George Steiner
I have to say I broadly agree. Claiming to measure global mean sea level (itself a rather elastic if not meaningless concept) to millimetric precision with uncertainties in the +/-0.4mm range stretches credulity to breaking point.
Especially when you recall that the measurement is an order of magnitude smaller than the uncertainty range of the instrument used to make it.
ICE suspends trading in emissions
https://www.theice.com/publicdocs/circulars/11007.pdf
Here's a measurement of sea level change at North Shields UK, which shows coverage for 108 years.
I am no expert so am unable to asess the quality of the source!!
"The mean sea level trend is 1.88 millimeters/year with a 95% confidence
interval of +/- 0.16 mm/yr based on monthly mean sea level data from
1895 to 2003 which is equivalent to a change of 0.62 feet in 100 years"
http://tidesandcurrents.noaa.gov/sltrends/sltrends_global_station.shtml?stnid=170-053
John Shade...nice blog over at Climate Lessons. Sorry I am only just learning of it.
JS
Oh I'm sure bluecloud is sincere and working for free. Doesn't make him correct though. Let's see if he has the intellectual honesty to admit that satellite altimetry is incapable of the level of accuracy being claimed for it.
The signal processing and modelling necessary to 'refine' the raw data to millimetric scale exceed the actual uncertainty range of the instrument by an order of magnitude.
This is the crucial distinction between precision and accuracy.
Ronaldo
As I said above, the problem with a single tide gauge is that it only measures local conditions. These include any subsidence of the foundation of the gauge itself, and any more widespread subsidence, eg that caused by glacial isostatic rebound.
You need lots of tide gauges before you can really get started, and even then, there are significant complicating factors including tides and tidal interactions (harmonics) and the distortions imposed on the seas themselves by the geoid.
What about Lunar effects on tides globally? Is that a factor in all of this? And what about some comet that shows up every 10,000 years. Will that effect tides and the perception of lower sea levels here and rising sea levels there?
@ bluecloud
"Folks, Are you discussing this?"
Only when referenced to anthropomorphic CO2. There is a big difference between the claim that AGW will cause sea-level rises and the measurements of such from the little ice age. Where is the acceleration of S-L rise coincident with the last 50 years of fossil fuel consumption? Why does data for 2010 show reducing S-L?
Kevin
Both lunar and solar tidal effects and the constant interaction between them are significant. Cometary bodies are too low in density and too small to have measurable tidal effects.
@ Ronaldo,
Thank you for that: another tide gauge that shows no influence from increased consumption of fossil fuels from the 1950's onwards.
How about considering mean sea level as cyclic or quasi-cyclic? Data from Jason/Topex possibly with GeoSat included suggest it maybe the case and that levels are starting to level or potentially drop. However, this does not necessarily imply that what is being observed is not an artefact of the measurement process such as signal aliasing.
http://tiny.cc/2sthe
Bias errors between platforms are huge, 14cm, with drift of +/-0.4mm/yr and a mean sea level trend of about 3mm/yr.
BBD
Thanks.
Am I alone in finding the WUWT guest post less than convincing? Having reread it, I'm finding it very hard to understand how a couple of years falling sea levels significantly change the overall trend. OK, you can debate the scale of rise, but it's pretty hard at this stage to see them as much more than a blip.
Haven't we moved on from habitually seeing "hottest year", "coldest December", "biggest drop", etc. as such a big deal?
I'd like to see a more analytical evaluation of the data if anyone can point me in the right direction. Thanks.
Pedro asks:
No. Please see my comment at 1:47pm:
And he goes on to say:
Debating the scale of the rise seems to be the key issue. Again, please see 1:47pm but especially 4:04pm above (I don’t want to clutter the thread up with lots of cut’n’paste).
Considerable influence on sea level caused by changes in barometric pressure. We see it here in Fiji quite dramatically with the passage of a cyclone.
"This depression of the water surface under high
atmospheric pressure, and its elevation under low
atmospheric pressure, is often described as the inverted
barometer effect (Crowder 1995). The water level does
not adjust itself immediately to a change of pressure and it
responds to the average change in pressure over a
considerable area. Changes in sea level due to barometric
pressure seldom exceed 30 cm (Aung et al. 1998). It is
also to be noted that a decrease of barometric pressure by 1
hPa may cause a ~1 cm rise in sea level and vice versa."
http://www.publish.csiro.au/?act=view_file&file_id=SP05002.pdf
BBD:
Thanks for your reply. I agree with your comment about being careful not to over-interpret the cause. Surely the same is also true in terms of single years of data, especially when, as in the WUWT post, such a short time period was considered. I defer to your self-evidently superior knowledge regarding the scale of the rise. Sounds like we need to be careful getting to grips with size and direction.
Pedro (and others)
The sea level data clearly shows that the level is dropping..., and rising slowly, .... and rising more quickly. This is all evident from looking at the data :)
The difference between each statement is the time over which you average the data, Just on an eyeball assesment of the front page graph of the Colorado data, 2010 has seen a drop, but as others note this drop is pretty much within the bounds of noise. If you take the last five years, the rate has been slower than in the previous two five year periods. Averaged over 30yrs or so its around the oft quoted 2-3mm/yr. What's pretty unequivocal is that the rate of rise is not increasing, it's falling. This is consistent with a lull in the rise, with a levelling out, and indeed with having reached the top of a curve and preparing to fall again. All those scenarios are possible. Calamitous and fast rise is about the only possibility that is not shown by the data.
Pick your cherries here!
@ Pedro,
The post at WUWT was about anthropomorphic sea-level rise. The fact that sea-level does not slavishly obey the AGW hypothesis, either absolute or trend, was the point of the post. Not sea-level rise per se which has been rising since the LIA.
Pedro asks:
Yes. I'm sorry if I am not making myself clear. The current fall in MSL is caused by La Nina, and is a transient. As were similar falls in 2008 and 1998.
We must be careful not to over-interpret. Agreed.
@ Cumbrian Lad,
"Calamitous and fast rise...."
AKA AGW.
SSAT
I should have said earlier that I agree with your point that SLR has been monotonic for at least a century and it is generally acknowledged that the signal of AGW is only supposed to show up post-1950.
The argued recent acceleration in SLR remains (at least for me) controversial.
It's a bit like glacer melt. This seems to pick up from 1800 - certainly 1850 - and trend up somewhat post-1950. But if it wasn't CO2 forcing pre-1950, then presumably it was recovery from the LIA.
So at least some of the increase in GAT since ~1850 is, to coin a phrase, very likely attributable to natural variation.
Potentially a silly question but....
If you take sufficient water out of the oceans to flood a parched area of Australia, equivalent to the size of France and Germany, is this sufficient to register a 1mm drop in sea levels?
We keep hearing about the impact of melting of Greenland ice etc
John Shade
I fear I must disagree, within a year I expect to see that climate change causes devastating decline in sea levels, reducing mans capacity to harvest food from the oceans and causing deprovation in former coastal villages that will become further away from their source of income. The lower global level will inhibit trade routes from growing economies and there will have to be funds allocated to research what would happen if the trend continues into the next millenium.
/sarc
Heh, it won't reducing mans capacity to harvest food from the oceans (or at least from the ocean floor) because when sea levels drop, more farmland will be exposed. And just think, as sea levels drop it will provide opportunities for the construction of new cities and towns and new roads between the towns, thus increasing job opportunities (of course, the people moving to the new cities will be the ones being displaced by the advancing glaciers).
I tend to agree with BBD on this, i.e. that there's no way we can have much confidence in the claimed accuracy of the satellite measurements. And it is not just the complexities of calculating the MSL through the noise of waves/swell and tides that is the problem. The Sun and Moon exert gravitational forces on the Earth's crust such that our mountains and coastlines also rise and fall with the tides - though the tidal range is in the inches rather than feet. Also, I am not an advocate of Hapgood's theory, but I think the earth's crust is a lot more elastic and occasionally volatile than we currently think, and moves up and down due to changes in pressure from below, not just glacial rebound/ isostacy. For example, there's good evidence that sea levels in northern Greenland were about 5-10m higher 7000-8000 years ago (driftwood on raised beaches) - yet at roughly the same time, the sea levels in south-west England were 5-10m lower than present (Mesolithic footprints and tree stumps visible only at low tides on either side of the Severn Estuary). Now unless there has been a considerable and sudden seismic shift we don't know about in these last 8000 years, that means an average rise/fall or tilting in the Earth's crust in the 2500 miles between Greenland and Albion of about 2mm pa. - significant enough to vary global sea levels or cast doubt on satellite accuracy? Just because glacial rebound can explain the raised beaches on Jura and on the north-east coast of Scotland, it doesn't necessarily explain all the others, especially when the weight of the ice over Greenland wont have reduced by much in the Holocene, and the weight of sea ice is obviously carried by the ocean. I am not a geologist but there does appear to be a lot that doesn't add up, and the Sunken Continent theory does have some merit to me - http://davidpratt.info/sunken.htm . Could the consensus view on Plate Tectonic theory be as mistaken as it is on AGW ? Anyone got any better explanation for the discrepancy in sea levels between Greenland and England in mesolithic times?
p.s. For anyone interested in historical sea level data see David Middleton's comments and links on http://wattsupwiththat.com/2010/04/13/ipcc-sea-level-prediction-not-scary-enough/ e.g.
http://i90.photobucket.com/albums/k247/dhm1353/Climate%20Change/4000BC.png
http://i90.photobucket.com/albums/k247/dhm1353/Climate%20Change/18150BC.png
http://i90.photobucket.com/albums/k247/dhm1353/Climate%20Change/300000BC.png
Just as with the GISP/Vostok ice-core temperature proxy graphs, it looks like the sea level rises we are experiencing now are nothing exceptional or worthy of any concern. [And as the Holocene has gone on much longer than previous inter-glacials, surely there's more statistical chance of us experiencing higher sea levels than before].
Sam the Skeptic Jan 19, 2011 at 11:08 AM
your long post was very well put and expressed my views on the subject very well.
Congratulations - repeat as necessary until they grow up.
Golf Charley
I think the 'area size of France and Germany' was the area affected, not the area flooded. The parts flooded were in the river valleys and flood plains, not the whole of the area 'affected'. So one might say that 'Cumbria was affected by floods' when all the rivers are high and overflowing, but the portion of the county actually flooded is much smaller.
"Because of the thermal expansion of the ocean"
Is that so great? I thought it was just the top layer that warmed much and that all the deep water stayed at about the same temperature.
James P says:
More detail here:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch5s5-5-3.html
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch5s5-5-4-1.html
A real life Tatooine could possibly happen. Then what with the sea?