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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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.
This is kinda where I am. Even if “average global temps” are meaningful — which I’m not sure about — and eve if they’re rising — which I’m not sure about — I’m not in any way convinced the sea levels are prone to catastrophic rise. Antarctic ice 2 miles thick and at temperatures of 40 below isn’t going to melt at 30 below. Glaciers melting over the next three centuries aren’t the same as 40 days and 40 nights of world wide rain.
And in the absence of oceans overwhelming the current coast line — exactly what is bad about warming?
Jerejeva et al., 2008 includes an excellent ESL reconstruction back to 1700 AD.
Modern ESL rise is not anomalous, just like the late 20th century warming was not anomalous.
If sea level rose to dangerous levels the simply low cost solution would be to channel it inland to deserts or other places where water is desperately needed. Problem solved, jobs created, lifestyle quality raised, poverty alleviated.
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…
Ecotretas
Asymptoting SLR better hurry up then. At my place on the east coast of Aust SLs are 16 inches [40 cms] lower than they were 47 years ago and falling.
As a Louisiana boy I worry about sea level rise. Chalmette Battlefield, a low lying land area where the battle of New Orleans was fought in 1815, is still dry ground.
The French Quarter, site of the founding of New Orleans in 1718, was built on a bit of dry ground beside the Mississippi River, and only a couple of feet above sea level, can be seen as dry ground in satellite photos of the city the day after Katrina.
No sea level rise from the land of the DIX (ten dollar french note originating in New Orleans, and source of “Dixie”)
What’s the difference in Volume of 1 Litre of Water at 5 degrees celsius and 1 litre of water at 15 degrees celsius?
Gee! Look at how warming oceans rose in the past. What a novel idea… for climate researchers.
Good for them and interesting results.
When the elites of the Alarmist movement stop buying expensive sea-front properties, then I shall take notice of the risks and hazards of sea-level rise.
When they stop flying to conferences, I shall take note of the danger of CO2.
When they stop lecturing and start doing, then I will listen, until then their own actions betray their real thoughts. They do not believe in CAGW either!
Since there isn’t much sea level rise, what does that indicate about ocean heat storage (heat in the “pipeline”)? The more “Greenland melts” and raises sea levels, the less that rise can come from ocean heat storage, they are mutually exclusive.
Anthony, please put a warning at the top that this article contains graphic glacial violence that might be not be suitable for younger ice huggers.
‘Rapid at first’ doesn’t sound very reassuring to me. The article says that the evidence from two independent studies:
It also says:
And also:
I don’t think any of this is cause for complacency, especially as the article says:
Geez, I think I must’ve gotten up on the wrong side of the bed.
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.
Well, without doing the search myself, it was 1) almost certainly web pages, not web sites. And 2) the 3.5 million is almost certainly a grossly inflated count. I can’t imagine why search engine estimates are so grossly inflated. They’re so bad I never use them to compare the database size of different search engines.
with worst-case scenarios varying between 0.59m and 1.4m.
Doesn’t good science look at all possibilities? Why are these
cretinsJQS scientists only looking at the best and worst case of the worst case? Can’t they bring themselves to consider that maybe, just maybe there are best and worst cases of the best case to consider. (If I were a reviewer or editor, what would be the response if I asked if the best case of the worst case made any sense? Actually, I’d probably ask if the worst case of the best case was worse than the best case of the worst case. I’d have to do it over the phone – no, on YouTube – with cigar and a Groucho Marx impersonation.)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).
Ever after learning a little bit about Esperanto, I’ve become a lot more tolerant with people who verbize nouns. However, they seem to have crossed my vertical asymptote. Why are these
idiotsWC reporters using aysmptoting but not exponentiating? Besides, if you look backward in time, that exponential has an asymptote itself. Grr.If we assume we’re only looking forward, they could say exponentially, linearly, or asymptotically. Or refer to an exponential, linear, or asymptotic rise.
Whew. I think I feel better. Here’s to hoping that the comments below are useful.
You know what you call the last 20 feet? Measurement error.
How could anybody not know.
World Climate Report might be listening but will the warmists?
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.
I’ve been posting for years that sea level is currently rising at about 1/2 the average for the last 22,000 years. If you look at the first chart you will see that about 22,000 years ago sea level was about 130 meters below the current level. 130/22,000 equals 0.0059 meters per year (0.59 meters per century). The current rate of sea level rise is 3.2 +/- 0.4 mm/yr. That works out to 0.32 meters per century or 54% of the 22,000 year average.
In response, I’ve been told that looking at a 22,000 average is “deceiving”! Huh? Looking at 22,000 years is deceptive compared to a prediction?
I’ve also been told that 22,000 years ago we didn’t have cities on the coast so the comparrison doesn’t matter. Huh? Suddenly because we build cities sea level isn’t supposed to change?
Darren Parker says:
August 10, 2010 at 4:40 am
What’s the difference in Volume of 1 Litre of Water at 5 degrees celsius and 1 litre of water at 15 degrees celsius?
Since a liter is a fixed volume (1 liter), the question is meaningless. The answer is, of course, 1 liter.
I think what you meant is:
If you take one liter of water at 5C and warm it to 15C what is its volume?
The expansion coefficient of water is 2.1, so 1 liter of water warmed by 10 degrees C becomes 1.0021 liters.
If you want to see the historic change in sea level look to Florida near Miami. Off shore about 2 miles and 120 feet down is an old coral reef. Now go inland about 3 miles and you find an old quarry used to build walls and building in the early years of settlements. That is made of old coral reef. So we have known boundries available to us for what can be not what will be.
Or the old fort at Saint Augustine. Made of coral quarried from inland above ground.
Darren Parker: August 10, 2010 at 4:40 am
What’s the difference in Volume of 1 Litre of Water at 5 degrees celsius and 1 litre of water at 15 degrees celsius?
Nothing, of course.
The consensus among geologists is that climate scientists have no historical perspective, and idea what they are talking about.
A 9,000 year old city is 36 metres underwater. They were warned to stop driving their Humvees, but failed to listen.
http://news.bbc.co.uk/2/hi/south_asia/1768109.stm
Step number one is create fear. Use pictures and graphs. Then find a cause and blame the culprit. Next step is promise a solution and force people to put money on the problem.
We have many people to put on this because we saved 500 million people recently from swine flu.
The first graph sure puts things into perspective. No wonder many geologists are so sceptical of CAGW.
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“No significant acceleration in the rate of sea level rise during the 20th century has been detected”
IPCC Working Group I – Executive summary
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Here is a little something for warmists worried about coral atolls sinking.
“Atolls are created by sea level rise, not destroyed by sea level rise.”
Willis Eschenbach
“The atoll falls along with the sea level. When the sea level rises, wind erosion decreases. The coral grows up along with the sea level rise. ”
Solomon Star