From World Climate Report: Sea Level History Lesson
We are sure you’ve heard that sea level is rising? We conducted a web search on “Global Warming and Sea Level” and nearly 3.5 million websites are immediately located. And before you conduct the search yourself, you already know what you will find. The earth is getting warmer due to the buildup of greenhouse gases, the warmer sea water expands causing sea level to rise, and most of all, you will read all about the ice melting throughout the world pouring fresh water into ocean basins causing sea level to rise far more. Alarmists insist that the worst is just around the corner, and the sea level rise will accelerate or even quickly jump to a new level given some catastrophic collapse of large sheets of ice near the fringes of the polar areas. Coastlines will be inundated, the human misery will be on a Biblical scale, ecosystems will be destroyed … this goes on for millions of websites!
But things aren’t really so simple.
The United Nations’ IPCC group presents the graph below (Figure 1) regarding eustatic (or global) sea level over the past 125 years, and as noted by the IPCC and by many others, the rate of rise is definitely higher in the most recent 50 years than the first 50 years of the record. So, it becomes quite possible to suggest that sea level rise is accelerating, and may continue to accelerate in the future. Alarmists can certainly find material in the IPCC document to bolster their claim that sea level is not only rising, but the rate of the rise is increasing.
Figure 1. Annual averages of the global mean sea level based on reconstructed sea level fields since 1870 (red), tide gauge measurements since 1950 (blue) and satellite altimetry since 1992 (black). Units are in mm relative to the average for 1961 to 1990. Error bars are 90% confidence intervals. (figure source IPCC)
Back in August of 2008, scientists from all over the world attended a workshop entitled “Empirical Constraints on Future Sea-Level Rise” and they just published a summary of their findings in the Journal of Quaternary Science. Somewhere along the way, they decided to refer to the group as “PALSEA” for PALeo SEA level working group.
The PALSEA group begins their article noting:
The eustatic sea-level (ESL) rise predicted for the 21st century represents one of the greatest potential threats from climate change, yet its magnitude remains a subject of considerable debate, with worst-case scenarios varying between 0.59m and 1.4m. In general, the basis for this debate revolves around the uncertainties in the dynamical behaviour of ice sheets (such as loss of buttressing through ice shelf break-up or enhanced ice flow through water lubrication of the ice sheet base), which may lead to a nonlinear sea-level response to climate change.
Note that the authors are talking about worst-case scenarios leading to “0.59m and 1.4m”; if the trend of the past 50 years continues (from Figure 1), sea level will rise around 0.20 meters (around 8 inches) by 2100. The PALSEA team notes that measuring sea level can be tricky “Because changes in ice mass will also cause changes in regional (due to gravitational and rotational feedbacks) and global (due to volume) sea level, the changes in sea level at a particular coastline record the difference between vertical motions of the land and sea, commonly referred to as relative sea-level (RSL) changes. Such isostatic effects are a function of the distance from the large ice sheets.”
Now for the good stuff! The PALSEA team states that
Given a broad range of emission scenarios the IPCC AR4 predicted global warming of between 1.18C and 6.48C during the 21st century. The last time that a global warming of comparable magnitude occurred was during the termination of the last glacial period (TI).
Furthermore, they write
Given this evidence for periods of rapid warming during TI, at least some of this warming occurred on decadal to centennial timescales. Because of the general similarity between the magnitude and rate of warming predicted for the 21st century and the warming that occurred during certain periods of TI, it is interesting to consider rates of sea-level rise during TI as a case study of the response of sea level to climate change.
The PALSEA group presents the graphic below (Figure 2) showing three different rates of sea level rise following an increase in temperature. As seen there, sea level could rise exponentially (as suggested by many climate change alarmists), it could rise linearly, or it could rise and then level off (the “asymptoting” curve).
Figure 2. An illustrative sketch of three models (black) for the time-dependent response of sea level to a perturbation in temperature (red) (from PALSEA, 2010).
Here’s what they conclude:
Therefore, we suggest that option 1 (exponential sea-level rise) is extremely unlikely. …An exponential increase in rates of sea-level rise with respect to temperature would result in 21st-century sea-level rise an order of magnitude larger than estimates using alternative patterns of response – it is an important result that the palaeo-sea-level data rule out such a response.
Finally, they write “the palaeo sea-level data suggests that sea-level rise related to current warming may be rapid at first and slow over time.”
Basically, their analysis of what happened in the past favors the “asymptoting” curve that is quite different from the exponential curve favored by those proclaiming the worst is yet to come! Mother Nature showed us in the past how sea level responds to warming – we at World Climate Report are listening!
Reference:
PALSEA (the PALeo SEA level working group: Abe-Ouchi, A., Andersen, M., Antonioli, F., Bamber, J., Bard, E., Clark, J., Clark, P., Deschamps, P., Dutton, A., Elliot, M., Gallup, C., Gomez, N., Gregory, J., Huybers, P., Kawamura, K., Kelly, M., Lambeck, K., Lowell, T., Mitrovica, J., Otto-Bleisner, B., Richards, D., Siddall, M., Stanford, J., Stirling, C., Stocker, T., Thomas, A., Thompson, W., Torbjorn, T., Vazquez Riveiros, N., Waelbroeck, C., Yokoyama, Y. and Yu, S.) 2009. The sea-level conundrum: case studies from palaeo-archives. Journal of Quaternary Science, 25, 19-25.
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So what they are saying is that if you tied someone to the beach, in hopes of drowning them, they would die of old age before they ever got wet.
Do people realize that even their worst case is so slow and so little, that people won’t even notice? 8 inches is one cement block. Better get started, we’ve got 100 years to build that wall, and so far no one has noticed any sea level rise at all.
Would I be right in thinking that any of the water in the oceans below about 3 degC would shrink in volume as it warms rather than swell?
[Reply:] Yes, until it got above about 4 degC. RT-mod
Icarus says:
August 10, 2010 at 5:39 am
“”John Marshall says:
August 10, 2010 at 3:19 am
All these predictions are based on interpolation beyond the last known data point. Mathematically this is not the correct methodology because all climate/ice cover/sea level graphs are representations of a chaotic system with many variable inputs, any interpolation like this will produce the wrong answer! We only know what the sea level is today but not tomorrow.”
[Icarus’ response] Read the article cited in this post – it’s not about ‘interpolation’ at all, but about the study of palaeoclimate data in an effort to draw analogies with current climatic conditions and come to some conclusions about possible and likely sea level rise.””
That’s what I was seeing in the article. And based on data over the past several hundred years (I’ll take it as “good enough” actual sea level data) and the fact we know we’re currently observing the sea levels coming out of a glaciation, and given the steady small rise in sea levels (not acceleration) data gatherers are reporting now; it looks to me like we’re currently riding along the top level of the asymptote. It looks like they’ve laid out a decent case of how sea levels have behaved coming out of a glaciation.
My only quibble is any speculation that temperatures are going increase dramatically, which is a whole ‘nother topic. If temperatures rise 5-6C over some reasonably short period (if my granny had wheels, she’d be a wagon – h/t to ? in a recent post), I’m with them – the sea levels will probably rise rapidly and then begin to level off as shown in the first figure.
But right now, my granny doesn’t have wheels.
What they actually say in their conclusion is that sea level rise is likely to be constrained to a of up to1 m. They are no more assertive than ‘loose limits’ which places their constraints in the same range as current estimates e.g. Rahmstorf (2007a) 0.5–1.4m.
“Using palaeo-data and direct observations, it is possible to put loose limits on just how rapidly we might expect sea-level rise to occur over the next century. For example, one may expect sea-level rise over the next century to fall between the lower limit of 20th-century sea-level rise (0.12m per century; Meehl et al., 2007) and the sea-level rise at the conclusion of TI (1m per century; Carlson et al., 2008).”
It is also clear that if their upper loose estimate of 1 m/century is to be realized then rates of rise must accelerate above today’s rate. In other words we cannot have yet reached the the rate they consider to be “rapid at first”.
It is also clear that historically an initial rise at a high rate of 1m/century is sustained for centuries before reducing asymptotically.
In short they are
Just because an area that clearly used to be above water is now submerged doesn’t automatically imply that the sea level rose. It also could be the case that the land fell. For example, Alexandria, Egypt sunk into the sea around the 4th century BC and now lies under about 8 meters of water.
Darren Parker says
What’s the difference in Volume of 1 Litre of Water at 5 degrees celsius and 1 litre of water at 15 degrees celsius?
I am not sure if you meant this as a joke or a mistakenly framed real question.
Of course 1 litre is 1 litre at any temperature.
If you are asking how much a litre of water would expand if raised from 5C to 15C I think the answer is 2ml. The coefficient of volume expansion is 207 x 10 power-6.
For 1000 ml and a 10C rise this is 1000 x207 x10 divided by 1000000 which is 2.
This is a great graph. If only people would use a little more critical thought, they might realise that sealevel measurements are nontrivial; just like air sampling from ice cores and global temperature measurements. Australias baseline sea level measurement project has always seemed to me to be a sensible way to assess the risk of rising sealevels. If cagw were real, that project would give a great early warning of the first signs of an increased rate. No sign yet.
As changes in sea levels are dictated by processes driven by deterministic chaos, it is impossible to make accurate predictions of future behaviour based on historic events. In addition, because of the inherent non-linearity, historic trends have no meaning.
Sea levels will continue to oscillate up and down, and as ever, life will have to adapt to the changes. It’s a pity the authors of this paper did not take account of this when producing their paper, perhaps they will realise this in the future and withdraw it.
This has happened before:-
“Climate scientists withdraw journal claims of rising sea levels.” – Guardian, Feb 2010.
http://www.guardian.co.uk/environment/2010/feb/21/sea-level-geoscience-retract-siddall
[Reply:] Yes, until it got above about 4 degC. RT-mod
This is true for fresh water, but not for the ocean. Salt ocean water has a freezing point below zero and gets denser close to the freezing point.
pouncer asked on August 10, 2010 at 3:30 am:
“I’m not in any way convinced the sea levels are prone to catastrophic rise… And in the absence of oceans overwhelming the current coast line — exactly what is bad about warming?”
In the hysterical science of solipsism known as catastrophic AGW, any possible aggregate rise in temperatures or sea levels – or really, any change in anything at all – conjures the frightening images of a Roland Emmerich film (The Day After Tomorrow, 2012) happening in the believer’s kitchen, back yard, or college campus.
Honestly I think the hysterical CAGW solipsist is mentally very much like the sun worshipping Mayan savage of Mel Gibson’s Apocalypto.
DaveF says:
August 10, 2010 at 6:33 am
Would I be right in thinking that any of the water in the oceans below about 3 degC would shrink in volume as it warms rather than swell?
[Reply:] Yes, until it got above about 4 degC. RT-mod
——————————–
Only if it’s freshwater!
[Reply] Oops, correct. Sea water densest at around 0 degC. Mea Culpa. RT-mod
There is proof all around us that we can and HAVE survived far worse global warming and coastal flooding. The result is the world we live in today. I’m also not aware of any reason why sea levels won’t continue to rise if that is the direction natural processes take us. Surely everyone is aware it has happened before, and if not then the following example should provide clarity.
http://www.culture.gouv.fr/culture/archeosm/en/fr-cosqu1.htm
The Proceedings of the National Academy of Sciences (PNAS) published a paper by Vermeer and Rahmstorf (2009), “Global Sea-level Linked to Global Temperature.” In this paper they devised a preposterous model for sea level rise that fits all the needs of a dedicated alarmist.
It stunned me to see this nonsense published by the NAS. The consequences of their model are simply bizarre. You can see links to the logical consequences of their model here. There is some math, but you can get the gist of it by skipping the math and reading the text and observing the plots.
ClimateSanity
latitude says:
August 10, 2010 at 6:28 am
> So what they are saying is that if you tied someone to the beach, in hopes of drowning them, they would die of old age before they ever got wet.
Only if he’s (they’re?) really old. I’d expect dehydration or hypothermia would happen first.
1) What is the volume of current ice?
2) Can all that ice melt?
3) How much ice will end up in the atmosphere?
4) What is the average slope of all shore lines?
5) Will the increase in ocean expansion rise linearly with the ia linear increase in melting ice?
6) Does increase in global temperature increase snow fall in areas of current glaciers/ice packs?
Makes some sense, a good amount of sense> Any geologist can tell you that “the present is the key to understanding the past” and any historian will tell you failure to understand the past will impede your understand of the present. Makes sense to me.
Steve Goddard “The consensus among geologists is that climate scientists have no historical perspective, and idea what they are talking about.”
Really?
The European Federation of Geologists:
“The EFG recognizes the work of the IPCC and other organizations, and subscribes to the major findings that climate change is happening, is predominantly caused by anthropogenic emissions of CO2, and poses a significant threat to human civilization.
It is clear that major efforts are necessary to quickly and strongly reduce CO2 emissions. The EFG strongly advocates renewable and sustainable energy production, including geothermal energy, as well as the need for increasing energy efficiency.”
http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change
“The Geological Society of America (GSA) supports the scientific conclusions that Earth’s climate is changing; the climate changes are due in part to human activities; and the probable consequences of the climate changes will be significant and blind to geopolitical boundaries. Furthermore, the potential implications of global climate change and the time scale over which such changes will likely occur require active, effective, long-term planning.”
I guess they must have come to those conclusions without the help of climate scientists then?
Reply] Oops, correct. Sea water densest at around 0 degC. Mea Culpa. RT-mod
Still not quite correct. At typical ocean salinity levels, salt water gets denser all the way down to the freezing point, which is (for typical ocean water) at -1.8 C.
(See e.g. http://www.arctic.noaa.gov/essay_wadhams.html )
Ecotretas says: August 10, 2010 at 4:13 am
“When I tell people that 18000 years ago the sea was 120 meters below the actual level, people just smile. I believe 95% of people that defend AGW, have never looked at, or have been told, about the first image in this post…”
Especially as this can be put into a human history context. 10,000 years ago, with sea level over 50 metres lower we start to see evidence of agriculture and civilisation and facts like the UK and France were connected by land. Even things like the Pyramids were built not long after a significant recent rise in sea level.
Steve,
Finding an ancient city under the water may not have anything to do with the average change in the sea level, of course.
Everyone who visited the ancient Troy ruins could see that Trojans’ landing stage ramp for hauling cargo from ships to town is about a mile from the shore now.
It doesn’t mean that the sea level at Troy somehow got so much lower in 3000 years, of course. But it means that some geological processes, such as river drift accumulation or seismic collapses (remember Lisbon disaster?), can dramatically change any shoreline in relatively short time, possible changes in sea level being far less important.
http://en.wikipedia.org/wiki/Asymptote
In analytic geometry, an asymptote of a curve is a line such that the distance between the curve and the line approaches zero as they tend to infinity.
So what is infinity in regards to sea level? Infinite height? Impossible. Infinite time? The Solar System won’t last that long.
So what do they mean by asymptote?
The best work on Holocene sea levels was done by Rhodes Fairbridge 40 years ago. I’ve’ seen nothing better since. Based on that work, the worst cast scenario postulated by the IPCC would put the ESL in 100 years at the average level for the entire Late Holocene (+1.25m).
Further, I read no mention of the Laurentide. A couple of the largest pulses in Early Holocene sea level rise occurred when the bounding moraine of the Laurentide Glacier gave way and caused most of the water volume of Lake Laurentide to dump into the ocean. It was not a rapid sea level rise due to a rapid warming event, but rather an event caused by the build up of melt water behind a dam that gave way.
Notice also the way the presenters of the data choose the measuring stick. A 150 unit rise in 100 years seems really big until one realizes how much a millimeter is. That’s less than six inches. The ignorant dolts that buy into these arguments are impressed by big numbers with no sense of what they really mean. The IPCC realized this when they converted the projections in the first report from meters to centimeters. A prediction of 0.64m sea level rise in 100 years became 64cm because Americans knew 64 was a bigger number than 0.64. It is interesting to note also that in the public presentation of the graph, the x-axis was narrowed considerably and the y-axis raised so the apparent slope of the curve steepened. It’s propaganda behind a political ideology, that’s all.
Good article. Gradual sea level rise will be a problem, but not an insurmountable one.
The predictions seem roughly around the IPCC ones.
The longer term graph of sea levels shows just how stable sea levels have been over most of human civilisation. Kind of lucky, as it meant you didn’t have to keep moving your port cities all the time.
The idea that climate scientists don’t know about events on geological time scales is a bit silly.
stevengoddard says:
August 10, 2010 at 6:22 am
[b]A 9,000 year old city is 36 metres underwater. They were warned to stop driving their Humvees, but failed to listen.[/b]
Well, at least we now know what happened to Atlantis, and where to look for it.
Well the sea level in North Wales has not risen back to levels which it was at over 700 years ago. See below.
“The castle’s other remarkable feature is the defended “Way from the sea,” a gated and fortified stairway plunging almost 200 ft down to the foot of the castle rock. Once, this gave access to supplies from the sea, but the tide level has since receded, leaving Harlech somewhat isolated upon its rock. During Madog ap Llywelyn’s uprising of 1294-95, this maritime lifeline proved the savior of the garrison, which was supplied and victualled by ships from Ireland.”
http://www.castlewales.com/harlech.html