From the University of Southampton
What the past tells us about modern sea-level rise
Researchers from the University of Southampton and the Australian National University report that sea-level rise since the industrial revolution has been fast by natural standards and – at current rates – may reach 80cm above the modern level by 2100 and 2.5 metres by 2200.
The team used geological evidence of the past few million years to derive a background pattern of natural sea-level rise. This was compared with historical tide-gauge and satellite observations of sea-level change for the ‘global warming’ period, since the industrial revolution. The study, which was funded by the Natural Environment Research Council (iGlass consortium) and Australian Research Council (Laureate Fellowship), is published in the journal Scientific Reports.
Lead author Professor Eelco Rohling, from the Australian National University and formerly of the University of Southampton, says: “Our natural background pattern from geological evidence should not be confused with a model-based prediction. It instead uses data to illustrate how fast sea level might change if only normal, natural processes were at work. There is no speculation about any new mechanisms that might develop due to man-made global warming. Put simply, we consider purely what nature has done before, and therefore could do again.”
Co-author Dr Gavin Foster, a Reader in Ocean and Earth Science at the University of Southampton, who is based at the National Oceanography Centre, Southampton (NOCS), explains: “Geological data showed that sea level would likely rise by nine metres or more as the climate system adjusts to today’s greenhouse effect. But the timescale for this was unclear. So we studied past rates and timescales of sea-level rise, and used these to determine the natural background pattern.”
Co-author Dr Ivan Haigh, lecturer in coastal oceanography at the University of Southampton and also based at NOCS, adds: “Historical observations show a rising sea level from about 1800 as sea water warmed up and melt water from glaciers and ice fields flowed into the oceans. Around 2000, sea level was rising by about three mm per year. That may sound slow, but it produces a significant change over time.”
The natural background pattern allowed the team to see whether recent sea-level changes are exceptional or within the normal range, and whether they are faster, equal, or slower than natural changes.
Professor Rohling concludes: “For the first time, we can see that the modern sea-level rise is quite fast by natural standards. Based on our natural background pattern, only about half the observed sea-level rise would be expected.
“Although fast, the observed rise still is (just) within the ‘natural range’. While we are within this range, our current understanding of ice-mass loss is adequate. Continued monitoring of future sea-level rise will show if and when it goes outside the natural range. If that happens, then this means that our current understanding falls short, potentially with severe consequences.”
The use of the phrase “since the industrial revolution”, presumably another term for the neologism ‘Anthropocene’, exposes the circular reasoning that inevitably bedevils climate change™ research.
Given the dramatic changes in sea level moment to moment (waves), hour to hour tides, and month to month (seasons, currents, winds, eg ENSO) measurement thought to be accurate to the mm seem dubious at best. I would think every statement on this subject should include error bars referring to the uncertainties of measurement and of the arithmetic chosen to average out the ongoing changing position of any point of the sea surface.
And reference also must be made to the reference point, given that the land rises and falls as well.
Perhaps satellites can be as accurate as claimed, but maybe there are problems with their measuring systems that limit mm-level resolution as well.
Any experts out there on this?
Opps. The last sentence was my comment and not meant to be indented. Here is the link:
http://onlinelibrary.wiley.com/doi/10.1002/grl.50559/abstract;jsessionid=5529DEBFBF5E41AC06765B65861C8492.f04t04
I believe the explanation for not seeing it now but seeing it later in other skeers was that it was inappropriate to assume a linear SLR because the rise would be exponential. Therefore you wouldn’t notice it now but you would be treading water by 2100 if you live on the coast. I don’t recall how they handled melting a kilometer or so depth of ice in places where the sun shine is limited and temperatures are usually below freezing other than handwaving at black soot and increasing global temperatures.
This seems to be one in a continuing series SLR scare stories.
This is a suggestion/appeal to Anthony that I think fits with (some of) the subject of this post.
I met with a group of old colleagues for a few beers last night. All are retired scientists from industry and some I hadn’t seen for 20 years. When I mentioned I was sceptical about climate change, they regarded me with incredulity and amusement. I obviously didn’t realise that the Arctic ice was melting, sea temperatures were rising, sea levels were rising. The gulf stream had changed course – one of the others corrected this to the jet stream. Global warming was happening…
Reducing fossil fuel usage was obviously good, so was reducing the carbon footprint, … They had an understandable and sensible view of climate change as portrayed by the media.
I had lots to say, about the Antarctic and the pause, and though I tried to explain all the sceptical points, the conversation had moved on. I felt that I had missed an opportunity to communicate the sceptical case.
Realising that setting the record straight is at the heart of this site, I wonder if this could be the subject of a future post. A sort of question and answer format that addresses commonly contested issues would be good. I realise that this is not new, but it always needs updating and I’m sure even regulars at this site will benefit from some up to date advice.
I must admit that I have been living in a sceptical bubble involving the best sceptical sites and was a bit shocked when I realised that all my old friends were totally convinced by popular propaganda from the BBC and MSM. WUWT would be doing a great service if it provides a “service pack for sceptics to convince believers in a window of opportunity of 15 minutes”.
Now there is a challenge.
(I wouldn’t put this to a sceptical site that wasn’t scrupulously fair with the data.)
[Reply: this request should be posted in Tips & Notes. ~mod]
Even IF they showed that sea level rise is accelerating (which they have so far failed to do) who says it has anything to do with global warming? More people in the world means a greater demand for fresh water. And how do some people get at that water? Do farmers irrigate their fields? Do bears sh###$$ in the woods?
Groundwater abstraction is about “one fourth of the current rate of sea level rise of 3.3 mm per year.”
Here is the paper’s abstract
Just to back up the SLR problems for the alarmists here are the ALL MODELS graphs AGAIN as used by the IPCC. This is from the Royal Society.
This accounts for about 99% of the planet’s ice, 89% in Antarctica and 10% in Greenland. Antarctica is negative until 2300 and Greenland is positive.
So where is all this future SLR to come from? Yes perhaps some thermal expansion and the 1% from melting mountain glaciers.
But the problem is the much bigger Antarctica ( 89%) will be storing more ice for centuries to come and act as a decelerator for future SLR.
Sorry here’s that link to the RS all models graphs.
http://rsta.royalsocietypublishing.org/content/364/1844/1709/F4.large.jpg
When the water gets over my dock on the Chesapeake, I’ll start to worry.
The full paper is now available at Nature. (I believe it costs quite a bit to make these open access).
http://www.nature.com/srep/2013/131212/srep03461/full/srep03461.html
I have to learn to keep my coffee cup out of reach when reading your comments. The cost in coffee and ruined key boards is starting to mount. In this case, I had just done cleaning up from that quip when I encountered the flying pigs quip and had to start all over again.
Your keyboard has my apologies. I have to ask, though, why you are drinking coffee while working at a keyboard. It is well known that beer cleans off of keyboards much better, and is less likely to cause permanent damage to its internal circuitry. It also makes it a lot easier to read badly written science fiction, which is an essential skill if one is following WUWT (in both directions;-).
Just more of the “sea level rise is accelerating” nonsense. If you look at the the record, sea level rise has a long term average of 3-4mm per year. So for the level to increase another 80cm by 2100 the average rate of increase would have to double or triple over the next 84 years. Then it would have to triple again to hit their 2.5 meter increase by 2200.
Sorry, could you give any sort of backing to this statement? I mean, I sort-of-agree (and said much the same thing) but when I visit my favorite readily-available SLR link:
http://en.wikipedia.org/wiki/Current_sea_level_rise
and
http://en.wikipedia.org/wiki/File:Trends_in_global_average_absolute_sea_level,_1870-2008_%28US_EPA%29.png
To be specific, total SLR from 1870 to the present is just under 9 inches (inches, Jeeze, why not use barleycorns instead?) Following a tedious conversion to metric and division, that is an average of 1.6 mm/year. The peak rate in this entire graph (unsurprisingly) came in the late 1930s following the dust bowl — the 1930’s by strange chance was the decade when almost exactly 1/2 of the state high temperature records were set and, I suspect, the actual Global Average Surface Temperature (if we were ever able to accurately and retroactively measure it) was actually higher than it is at the present, regardless of what the heavily adjusted “anomaly” from the unknown absolute average temperature might be.
There is at least some evidence to support this, BTW. Arctic ice reportedly disappeared over roughly this same time frame, much as it did over the last decade. The clustering of state high temperature records. The great dust bowl itself, which was indeed a catastrophic climate event although not one that anyone can tie to CO_2. This is all the more surprising since high temperature records don’t correct for the UHI effect which alone should cause more high temperature records in the present and since we sample so many more locations at the present (making it even likelier still that the 30’s temperature records should have been broken long ago if the current temperature was in fact higher).
But either way, you’re off by over a factor of 2 in your assertions of SLR rates. They are 1-3 mm/year over most of the tide-gauge record, average of 1.6, and they show a strong correlation to the 50-60 year cycle visible in GASTA as well (possibly linked to the PDO). You can’t quite fit a linear trend and single sine wave to it though, probably because the SLR rate lagged the initial temperature rise at the end of the LIA by 30-40 years.
rgb
rgb
rgbatduke said @ur momisugly December 12, 2013 at 12:08 pm
Not to mention also a waste of money that could have been used for some useful purpose!
Went up the Maine coast last week end. We walked down to the Atlantic & marvelled at the ocean (& stepped in, & boy was it cold!). The next day we walked down & there was a good 40ft (12192mm) of shingle beach exposed that hadn’t been the day before. The water was obviously 5 or 6ft (1524 to 1828.8mm) lower than it had been the day before. According to my calculations you should be able to drive a 1968 Holden from Providence, RI to Scunthorpe, N. Lincolnshire (though you’re going to have to jog way north to Greenland to stay out of the water, I’d guess) by sometime mid-June 2014, if the current sea-level fall continues, right?
Bloke down the pub,
City of Troy, when it was actually a thriving city the sea was pretty much at the city walls, now the sea is a couple of kilometres away.
Though to be fair to alarmism the Thames barrier was built to stop the increase flooding.
While at the Guardian some time back I was astonished at the number of people who said that co2 was the most important greenhouse gas. I referenced them to the IPCC which said water vapour. Many keep saying that sea levels are rising, I suspect they think sea level has been stable during the Holocene and only started rising in the last 30 odd years. Many believe in runaway warming even though the IPCC says this is not supported in the literature and so on. I second your suggestion: it’s time for the LOW DOWN PAGE.
80 cm by 2100 is ~9.3mm a year. last few decades is 3.3 mm a year or is it 3.1mm a year? No matter. The rate would have to be about 3X what is observed to meet that forecast. Perhaps they used a model. Heidi Klum would be my choice. For now.
rgb:
Indeed, the most credible empirical estimates of the long-term rate of SLR are below 2mm/yr and what we have here is physics-free projections inexplicably predicated upon future rates several times higher. Your suspicion that GAST in the 1930s was actually higher than today, however, is likewise lacking in solid observational basis. As best as can be determined from available non-urban station records world-wide (which I’ve been gathering, vetting and updating scrupulously since the 1970s) GAST actually peaked somewhat earlier in the 20th century at a level ~0.2K below that experienced during the 1997-98 El Nino. It’s In the contiguous USA that the average peaked in 1934 at a level effectively indistinguishable from that seen in 2012.
rgbatduke says (December 12, 2013 at 12:08 pm): [snip]
RGB, the Babe Ruth of WUWT!
This was compared with historical tide-gauge and satellite observations of sea-level change for the ‘global warming’ period, since the industrial revolution.”
Last time I checked, the Industrial Revolution began in the late 1700s to early 1800s; ie. early Little Ice Age. Talk about moving goal posts.
Indeed, the most credible empirical estimates of the long-term rate of SLR are below 2mm/yr and what we have here is physics-free projections inexplicably predicated upon future rates several times higher. Your suspicion that GAST in the 1930s was actually higher than today, however, is likewise lacking in solid observational basis. As best as can be determined from available non-urban station records world-wide (which I’ve been gathering, vetting and updating scrupulously since the 1970s) GAST actually peaked somewhat earlier in the 20th century at a level ~0.2K below that experienced during the 1997-98 El Nino. It’s In the contiguous USA that the average peaked in 1934 at a level effectively indistinguishable from that seen in 2012.
That is very interesting. Do you have this published?
rgb
It seems the satellite guys might have a different view on the rate of sea level rise compared to the sea level experts;
From NASA’s GRASP mission conference 2011 [ Geodetic Reference Antenna in Space ]
http://www.gps.gov/governance/advisory/meetings/2011-06/bar-sever.pdf
From Frame 4 of this presentation;
[quote]
Impact of TRF on GMSL Record from Tide Gauges: competing approaches for TRF
realization yield estimates for sea-level rise ranging from 1.2 to 1.6 mm/yr.
[ TRF= Terrestrial Frame of Reference ]
[ GMSL = Global Mean Sea Level ]
Also a paper win which a table of sea level data points are included;
Global sea-level rise and its relation to the terrestrial reference frame
http://sas2.elte.hu/tg/msc_gravi/collilieux_sealeverise.pdf
For those who would like to have a look at the global tide gauge data for locations around the Earth;
PMSL / Permanent Service for Mean Sea Level
http://www.psmsl.org/data/obtaining/
To find the sea level tide gauge data for a location in the tables just click through the “ID” numbers.
The locations of the tide gauges are grouped into their national groupings which then run meridionally from a start in Iceland and Europe, eastward into the Pacific and America’s.
Last time I checked, the Industrial Revolution began in the late 1700s to early 1800s; ie. early Little Ice Age. Talk about moving goal posts.
Especially when there was no significant CO_2 increase until the middle of the 20th century, especially not on a log scale. Of course there still hasn’t been a significant increase on a scale of decibels, which is likely the relevant one — around 1 dB over the entire industrial era.
rgb
Is land reclamation factored into sea level rises?
There are many projects around the world reclaiming land/forming new land
Seems odd to be fussing about an ill-understood event or trend which started in the late 1700s and seemed to slow after the 1860s. Here in Australia you can get for free any amount of alarm over sea level rise, but you couldn’t buy an actual, discernible sea level rise. I’m sure somebody can find a shack on a sand spit between swamps which has sunk, but otherwise…
Maybe it’s cheaper to blame erosion on CO2 than to pay more attention to tedious coastal maintenance and regulation. No doubt the clever New Yorkers who dumped all that rubble into the Hudson mouth to make more low lying real estate in a notorious hurricane belt would love to change the subject from local responsibilities to coal mines in Queensland or factories in Poland.