John Droz writes in with this:
A few months ago a widely-publicized article by Houston and Dean was published in the Journal of Coastal Research (and on your site), noting that although sea-level is rising; the tide gauge data does not show any increased rate of rise (acceleration) for the 20th and early 21st centuries. This was augmented by a recent paper authored by an Australian scientist as well (<<http://www.jcronline.org/doi/full/10.2112/JCOASTRES-D-10-00141.1>>).
In the most recent volume of the Journal of Coastal Research, there is a point/counterpoint on this study. It was started by an attack on this paper by Rahmstorf & Vermeer and followed by a response to this by Houston & Dean (below).
Discussion of: Houston, J.R. and Dean, R.G., 2011. Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses. Journal of Coastal Research, 27(3), 409–417
Stefan Rahmstorf† and Martin Vermeer‡ <<http://www.jcronline.org/doi/full/10.2112/JCOASTRES-D-11-00082.1>>
Here’s the rebuttal:
Reply to: Rahmstorf, S. and Vermeer, M., 2011. Discussion of: Houston, J.R. and Dean, R.G., 2011. Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses. Journal of Coastal Research, 27(3), 409–417
J. R. Houston† and R. G. Dean‡ <<http://www.jcronline.org/doi/full/10.2112/JCOASTRES-D-11A-00008.1>>
Rahmstorf and Vermeer (RV) argue that modeling sea level as a function of temperature using their semi-empirical approach as presented by Rahmstorf (2007) and Vermeer and Rahmstorf (2009) is superior to the standard approach of analyzing sea-level rise as a function of time used by Houston and Dean (2011). Their criticism applies not only to this paper, but also to the work of eminent sea-level experts such as Douglas, Holgate, Woodworth, and others who have used the same standard approach we use. In making this claim, RV present their Figure 1 as the key evidence supporting the efficacy of their model. Figure 1 purports to show good agreement between accelerations based on their modeling and accelerations based on the data of Church and White (2006). However, it is easily seen that the portion of Figure 1 where the agreement is “good” compares their modeling versus increasingly meaningless data, and they have been selective in showing only data that appear to match their modeling and not the data that strongly disagree.
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Houston and Dean (2011) considered only tide-gauge records with lengths greater than 60 years, noting that shorter record lengths are “corrupted” by decadal fluctuations. Douglas (1992) shows that as a result of decadal fluctuations, as record lengths become increasingly shorter than approximately 50–60 years, about half of tide-gauge records display increasingly large positive accelerations, while the other half displays increasingly large negative accelerations. These positive and negative accelerations are uncorrelated to accelerations based on record lengths greater than approximately 50–60 years. Note in Figure 1 that as the record length becomes shorter, the 2-sigma range becomes increasingly large so that for most of the right-hand side of Figure 1 it is not possible to know whether the accelerations are positive or negative, making comparisons increasingly meaningless.
In Figure 1, RV show only the data that agree with their model. On the x axis of Figure 1, record lengths are shorter than 60 years for starting years after around 1940. It happens that at around 1940 the acceleration shown is approximately zero. Thus, as seen in Figure 2, the record from 1940 to 2001 has a strong linear trend with decadal fluctuations but approximately no acceleration. If the record from 1940 to 2001 has zero acceleration, how is it then possible that all shorter records (starting years after 1940) shown in Figure 1 have positive accelerations that increase as record lengths shorten? It is not possible. Again, RV only plot the data as long as they agree with their model. If the plot is extended, e.g., to the starting year of 1985, the acceleration is −0.044 mm/y2, more than twice the range shown for negative accelerations in Figure 1. If the plot is extended further, the folly of analyzing records shorter than approximately 60 years becomes increasingly obvious. The acceleration for a starting year of 1995 is −0.51 mm/y2, about 25 times the range shown for negative accelerations in Figure 1. RV compare their model to data as long as there are positive accelerations and do not continue the plot when accelerations become negative, which must happen for the overall record from 1940 to 2001 to have an acceleration of approximately zero. Their rationale for stopping at a starting time of 1970 is that after 1970 “… short-term noise dominates the calculations and results oscillate strongly” (p. 789). But Douglas (1992) shows, e.g., that 30–40-year record lengths (starting times 1960 and 1970 in Figure 1) show positive and negative accelerations 10–20 times larger than accelerations determined from 80-year records. Yet RV criticize our analysis of 80-year records from 1930 to 2010 as being too short. The fact is that decadal fluctuations begin to dominate records shorter than about 60 years, and accelerations become increasingly meaningless for starting years in Figure 1 greater than about 1940. Moreover, positive accelerations peak some time after the starting time of 1970 and eventually plunge to very large negative values. In summary, RV compare their model results to meaningless data after the starting year of about 1940 and are selective in only showing data with positive accelerations after 1940.
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Church et al. (2004) correctly analyze the same data set (their own) that RV incorrectly analyze and conclude that “Decadal variability in sea level is observed but to date there is no detectable secular increase in the rate of sea level rise over the period 1950–2000” (p. 2624). This conclusion is evident from Figure 2 and in stark contrast to the claims of RV and the acceleration they show in Figure 1 for a starting year of 1950.
RV link sea-level rise with temperature using a simple linear relationship with two free variables of opposite signs that allow them to “fit” any smooth data set. However, they are curve fitting, not modeling physics, so the approach cannot be used to predict future sea level. Holgate et al. (2007) criticized RV’s assumption of a linear relationship between global mean surface temperature and the rate of global mean sea-level change and concluded, “We find no such linear relationship” (p. 1866b). Further they concluded, “… at the 50- to 100-year time scale, the linear relationship has little skill in predicting the observations not included in the original model formulation” (p. 1866b). A recent workshop of the Intergovernmental Panel on Climate Change (IPCC, 2010) considered the semi-empirical approaches of Rahmstorf (2007), Vermeer and Rahmstorf (2009), and others and concluded, “No physically-based information is contained in such models …” (p. 2) and “The physical basis for the large estimates from these semi-empirical models is therefore currently lacking” (p. 2).
RV also present less fundamental criticisms of Houston and Dean (2010). For example, they note that data considered by Houston and Dean are biased to the northern hemisphere. This criticism would apply to any study of sea-level rise and is attributable to the lack of historical tide-gauge data in the southern hemisphere. In fact, it applies to the historical temperature that RV use in their analysis. However, we note that Watson (2011) published an analysis of sea level in Australia and obtained small decelerations very similar to those of our study.
RV argue that impoundment by dams decreased the rate of sea-level rise after around 1960. They say that our paper claims that groundwater mining would offset this impoundment, and they then argue that this mining is relatively small. They neglect to mention that groundwater mining is only one of the offsetting factors given in Houston and Dean. Houston and Dean (2011) state, “However, in the IPCC, Bindoff et al. (2007) note that the reservoir impoundment is largely offset by other anthropogenic activities that accelerated since 1930, such as groundwater extraction, shrinkage of large lakes, wetland loss, and deforestation” (p. 415). Houston and Dean further state that “Huntington (2008) showed ranges of the contribution of each term of the land–water interchange determined in several studies and concluded that the net effect of all the contributions was to increase the sea-level trend” (p. 415). This conclusion is in direct opposition to the claim of RV that impoundment by dams significantly decreased the rate of sea-level rise.
The important conclusion of our study is not that the data sets we analyze display small sea-level decelerations, but that accelerations, whether negative or positive (we reference studies that found small positive accelerations), are quite small. To reach the multimeter levels projected for 2100 by RV requires large positive accelerations that are one to two orders of magnitude greater than those yet observed in sea-level data.
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izen says:
“The problem with Dean and Houston however is not the source of funding for this research so much as their long-term involvement with beach-front development and the confirmation bias they have that engineering solutions will be sufficient to defend beach-front property because Sea Level Rise is not accelerating at an increasing rate.”
No mention, of course, of Gore’s beach front mansion, or of the many $millions that Michael Mann alone has collected for his climate alarmist confirmation bias — based on proxies that Mann knew beforehand were composed of bad data.
As I’ve noted repeatedly, if it were not for their psychological projection, the alarmist crowd wouldn’t have much to say.
Camburn says:
July 21, 2011 at 9:56 pm
“So, you agree that folks funded by grants etc have a confirmation bias because of their funding source?”
You have it backwards – as izen pointed out, people with a confirmation bias search out agreeable funding sources. And agreeable editors/publications, too…
Any advocacy group presenting ‘science’ has to be taken with a grain of salt, whether it’s GreenPeace, the George Marshall Institute, SEPP, Cato Institute, various wind power groups, or Florida beach property associations. They will only, in general, present the side of the data that supports their purposes, another side of the coin in terms of confirmation bias.
You yourself, Camburn, have shown a bit of confirmation bias wrt Envisat (http://www.skepticalscience.com/argument.php?p=3&t=171&&a=68#58323). A bit ‘o pot calling the kettle black, eh?
Claims that the IPCC is an advocacy group, however, are pretty ridiculous. Their mandate was to assemble the best info on climate change and impacts available, and present it. If you disagree with their conclusions, you have to go to the many papers they used as inputs, and point out why the mass of them are incorrect, or conversely show that the IPCC did poor selection of works, or misinterpreted them. I haven’t seen a good case made for any of those arguments, though I’ve seen a lot of logical fallacies from various advocacy groups.
izen says:
July 22, 2011 at 10:30 am
@- Dave Wendt says:
July 22, 2011 at 12:04 am
“Empirical observation already confirm warming, the majority of the science and scientists expect this to continue because of the rise in CO2.
How much of a ‘problem’ this may be can be seen historically.
I can think of very few civilizations that did NOT find climate change a problem, sometimes a catastrophic one.
Usually it is changes in rainfall disrupting the agricultural infrastructure that feeds those urban civilizations that has caused the collapse.
History indicates that past societies did not respond well to climate change, in ANY direction. Does anything give you optimism for our present societies when faced with significant change ?”
.
“Empirical observation already confirm warming,” I would never argue that that the planet is not warmer today than in the 18th and 19th centuries, but I haven’t found anyone else willing to argue that a return to those temperature levels would be a positive development.
“the majority of the science and scientists expect this to continue because of the rise in CO2”.
My personal scientific idol is Richard Feynman, You might want to peruse the last book he published before his death. The title is “What Do You Care What Other People Think?”
“How much of a ‘problem’ this may be can be seen historically.
I can think of very few civilizations that did NOT find climate change a problem, sometimes a catastrophic one.”
I have to beg to differ on this one. I would suggest that the record is almost completely clear that climate change that made the climate colder has indeed been catastrophic, but subsequent warming periods from those low points were generally seen as positive developments. I would point out that prior to the IPCC the “Medieval Climate Anomaly” was called the “Medieval Climate Optimum” for most of my life and similarly for the other high points on the curve.
The history of the planet since the turn of the 20th century has been one of the greatest increase in overall human well being that has ever been seen. Over a year ago the world past the point where the majority of the people on the planet could be classified as “middle class”(middle class being defined as those who have sufficient income beyond subsistence needs to allow significant discretionary spending). The prime driver of that trend has been the expanding availability of economical and reliable energy, particularly in China and India.
Recent history has established another notion that is most pertinent to this whole climate kerfuffle. That is, that any society’s ability to adapt to the vagaries of weather and climate is directly proportional to its level of wealth. Since virtually every one of steps we are being prodded(cattle-prodded) to take to address this “possible” problem seem custom designed to destroy the world’s capacity to create wealth and prosperity and to continue the most dramatic improvement in human conditions ever experienced, until I see some suggested remedies which aren’t entirely worse than the disease they propose to treat I will do all in my power to resist.
@- Smokey says:
July 22, 2011 at 10:42 am
“No mention, of course, of Gore’s beach front mansion, or of the many $millions that Michael Mann alone has collected for his climate alarmist confirmation bias — based on proxies that Mann knew beforehand were composed of bad data.”
The relevance of Gore’s beach front property escapes me. perhaps its a ‘dog whistle’ thing?
I think I agree with Dean and Houston’s implied conclusion from this research; that SLR will be within the bounds of engineering adaption.
I suspect that extravagant amounts of that capability may be expended on Gore’s and others’ beach front property. I am not convinced all the cost will be carried by the owners.
@- Dave Wendt says:
July 22, 2011 at 12:16 pm
“I would suggest that the record is almost completely clear that climate change that made the climate colder has indeed been catastrophic, but subsequent warming periods from those low points were generally seen as positive developments. I would point out that prior to the IPCC the “Medieval Climate Anomaly” was called the “Medieval Climate Optimum” for most of my life and similarly for the other high points on the curve.”
The term ‘Medieval climate Optimum’ was a Eurocentric term for a period that was not synchronous with other warm peaks over the last thousand years – try finding matching peaks in opposite hemispheres –
http://pages.science-skeptical.de/MWP/MedievalWarmPeriod.html
Its clear that the Medieval warm climate peak is ambiguous in its timing, magnitude and duration. In some regions it may have triggered drought and problems for large societies.
But by all means detail the start and duration of the Medieval optimum and why the climate was a benefit rather than political/technical changes- and for whom. I suspect not all gained the same benefit.
For instance in the Roman warm period it might be claimed Rome benefited from greater agricultural productivity, although I am not sure the dates support that. However Rome’s gain was at the expense of Etruscan, Celtic and ME cultures.
And any warmth during the Minoan warm period would not be a factor for the success of the Minoans.
“Recent history has established another notion that is most pertinent to this whole climate kerfuffle. That is, that any society’s ability to adapt to the vagaries of weather and climate is directly proportional to its level of wealth.”
I would be interested to see how that is established.
Nomadic hunter-gatherers adapt extremely well to climate change.
Large societies that emerged on river flood plains because of the agricultural fertility tended to have problems with the vagaries of weather and climate.
I think I prefer the ideas of J A Tainter that it is the problem of marginal gains/returns that threaten societies. If cheap changes make a big difference then poor societies can adapt. If small changes are very expensive to make then even rich societies will face problems adapting.
“Since virtually every one of steps we are being prodded(cattle-prodded) to take to address this “possible” problem seem custom designed to destroy the world’s capacity to create wealth and prosperity and to continue the most dramatic improvement in human conditions ever experienced, until I see some suggested remedies which aren’t entirely worse than the disease they propose to treat I will do all in my power to resist.”
I have no problem with arguments that the advocated response to AGW are wrong, expensive or counterproductive. Cheap mitigations or adaptions would not be a problem of course, it is that despite the wealth of our societies the policies advocated by some are considered expensive.
The problem is when dislike of possible political responses spills over into dismissing thermodynamic realities.
To a degree I have to agree with izen. All previous societies found climate shifts in either direction to be a problem. However it was the regional effects that caused the problems.
For example a change in global climate (in either direction) will result in some areas getting more rain and some getting less. In previous societies this was a disaster because they couldn’t import in volume from another region.
However this doesn’t hold true today. An area that suffers crop reductions resulting from CC is linked to and is able to import from other regions where the change has been beneficial. The result will simply be a change in the internal figures concerning global trade, rather than the collapse of the societies involved.
Those old societies wouldn’t have fallen if they had been able to import train loads of food from elsewhere.
izen says:
July 22, 2011 at 4:19 pm
@- Dave Wendt says:
July 22, 2011 at 12:16 pm
The term ‘Medieval climate Optimum’ was a Eurocentric term for a period that was not synchronous with other warm peaks over the last thousand years – try finding matching peaks in opposite hemispheres –
Try here
http://www.co2science.org/data/mwp/mwpp.php
“But by all means detail the start and duration of the Medieval optimum and why the climate was a benefit rather than political/technical changes- and for whom. I suspect not all gained the same benefit.”
Both human and climate history are sufficiently uncertain and speculative that trying to argue the specifics and interactions of either or both is not likely to be productive. I am generally comfortable, although not entirely certain(<97%), with the notion that in terms of human well being warmer is better. If you can recommend some works, by historians or others, that you think support the opposite view I am certainly willing to consider them.
Along those lines I like to recommend this site to people
http://web.me.com/uriarte/Earths_Climate/Earths_Climate_History.html
I don't know anything about the author, other than his name, and I can't say I find much of what he says entirely flawless or convincing, but he does provide a nice overview all in one place. I suspect you would find him even less convincing than I do, but if you did take the time to read his entire work, which is admittedly of a daunting length, you would have to admit that he appears to be a person of well above average intellect, who seems to have invested a great deal of time and effort into this work. The fact that neither you nor I may find what he writes entirely convincing doesn't make him wrong, it just illuminates the point I've tried to make for a long time i.e. that the state of climate science is currently so abysmal that the phrase "I'm convinced by" doesn't merit inclusion with much of any of it.
"“Recent history has established another notion that is most pertinent to this whole climate kerfuffle. That is, that any society’s ability to adapt to the vagaries of weather and climate is directly proportional to its level of wealth.”
I would be interested to see how that is established."
I have actually seen studies that support this proposition, although I don't have the links available at the moment, but in terms of easily understood examples consider the two big tsunamis in the past decade. You might also consider Hurricane Katrina's assault on the Gulf Coast of the US versus the earthquake that devastated Haiti.
KR:
After reading the problems with Envistat, I believed it was not a reliable reading of sea level rise. Then, I read a paper published in 2009 using Envistat and Jason-1 as the base of the paper.
Now I am not quit as sure that Envistat data as presented has not been corrected before it was presented.
At this point and time tho, until I can find more postive confirmation, Envistat, in my opinion, is not a reliable measure of current sea level trends.
@- JohnB says:
July 22, 2011 at 6:43 pm
“….. a change in global climate (in either direction) will result in some areas getting more rain and some getting less. In previous societies this was a disaster because they couldn’t import in volume from another region.
However this doesn’t hold true today. An area that suffers crop reductions resulting from CC is linked to and is able to import from other regions where the change has been beneficial. The result will simply be a change in the internal figures concerning global trade, rather than the collapse of the societies involved.”
That presupposes that an area with famine will be offset by an area of comparable surplus. Even if this condition is met both provider and receiver have to be willing and able to carry out the transfer of resources. Recent events in NE Africa do not indicate this is always the case.
@- Dave Wendt says:
July 22, 2011 at 7:02 pm
“I am generally comfortable, although not entirely certain(<97%), with the notion that in terms of human well being warmer is better. If you can recommend some works, by historians or others, that you think support the opposite view I am certainly willing to consider them."
I am reluctant to disturb your comfort, and would agree that warmth is correlated with human well-being at least in those ecologies where warmth improves agricultural yield. But rainfall is more often the limiting factor in agriculture. Water management the key civilizational skill.
The industrial revolution that has added a whole new qualitative level to human well-being emerged from the LIA – but correlation is not causation!
"Recent history has established another notion that … any society’s ability to adapt to the vagaries of weather and climate is directly proportional to its level of wealth….. but in terms of easily understood examples consider the two big tsunamis in the past decade. You might also consider Hurricane Katrina's assault on the Gulf Coast of the US versus the earthquake that devastated Haiti."
I am not sure those example make the point as unambiguously as you think. Subsistence farming on a remote island coast may be easier to re-establish than the urban infrastructure of a city/port. Japan will need its wealth to adapt to the flooded nuclear power stations.
In the context of Sea level rise from a warming climate melting land-based ice, the rate, and rate of acceleration, are probably within relatively cheap adaption responses. Catastrophe is avoidable with engineering solutions given the maximum probable rate.
But the necessity for adaption seems inevitable.
I see no convincing arguments that Sea level will fall over the next century, or even stabilize. Observations of the major ice-caps do not favor expansion, or even stasis. Exhibiting unpredictable instability might be a better description.
John: Both approaches to determining acceleration in the rate of sea level rise appear to have serious flaws. Houston and Dean fit sea level rise data the following equation, which appropriate only when acceleration is constant: h(t) = 0.5*at^2 + vt + h0. Unfortunately, there is no theoretical basis for assuming that the acceleration in sea level rise should have remained constant over the historic record. As the authors point out, noise in data makes it impossible to determine the “average effective” acceleration over time periods shorter than about 60 years – periods much to long to assume acceleration is constant. Using equations that assume acceleration is constant with time, they calculation the acceleration over varying segments and get different results. IMO, such results are meaningless. In particular, they tell us nothing about the acceleration of sea level rise since the major shift in climate in the late 1970’s, which began a period rapid warming. Without a means to detect acceleration of sea level rise since 1975, it is completely senseless to speculate about what past “acceleration” means for the future.
RV’s approach appears equally flawed. They fit data to the equation: dH/dt = a*(T-T0) + b*(dT/dt). The a*(T-T0) term could be called the “term that keeps on giving”. If sea level and temperature were in equilibrium with neither rising and the temperature suddenly and permanently rose 1.0 degC above T0 (approximately where we are today), this term predicts that sea level will rise at a constant rate of almost 1 mm/yr (a = 0.8 mm/yr-deg) until all of the ice caps on earth have melted and still continue to rise afterwards. Extrapolations involving this term are obviously risky and unphysical. The b*(dT/dt) term represents the immediate rise in sea level as heat diffuses into and thermally expands the top mixed layer of the ocean – a process which must take less than a decade to fit the large decade-to-decade variation in the rate of sea level rise. The value of b is consistent with the top 100 m of the ocean fully responding to rapidly to changes in surface temperature or the top 200 m of the ocean responding to half of the average surface temperature change. This mixed mixed layer is significantly deeper than the mixed larger associated with seasonal changes in ocean temperature or modeled from Mt. Pinatubo’s eruption. Slower warming of the deeper ocean during the last century (which observations apparently show has occurred) and the associated expansion are handled by the “term that keeps on giving”. That’s also physically absurd: The RATE of thermal expansion of water after warming depends on the RATE the water is warmed, not the magnitude of the warming.
What fraction of 20th century sea level rise can be attributed to each of these terms? If one modeled 20th century warming as a linear 1 degC/century increase in temperature (from T0 to T0+1), the a*(T-T0) term would average 0.4 mm/yr and total 4 cm for the century and the b*(dT/dt) term would be constant at 0.25 mm/yr (b = 2.5 ± 0.5 cm/degC; dT/dt = 0.01 degC/yr) and total 2.5 cm for the century. The total of rise sea level for this model would be 6.5 cm, in excellent agreement with the results (ca 7 cm) shown in Figure 1 for the 20th century. However, the IPCC and Figure 3 of RV indicate a rise of 17 cm for the 20th century! How can the same equation give two different answers? Looking more closely, it turns out that RV calculated parameters a, b and T0 by fitting to the sea level rise from a climate model, not to actual sea level rise data. Climate models predict less than 50% of actual 20th century sea level rise. Then, somehow the same eqn can be used to predict actual 20th century sea level rise (which is more than twice as big) from actual 20th-century temperature data!
The purpose of the RV paper was to find an eqn capable of predicting sea level rise because climate models underestimate sea level rise. So RV starts by using data from a climate model to find parameters for their eqn????
Frank:
Pretty amazing isn’t it?
Tidal guages measure sea level per location. The rate of rise, whatever it is, has been so small over a long period of time that no infrastructure changes have been required.
I think that sums it up in a nutshell.
The failure of sea level rise pick-up is a BIG PROBLEM. Maybe it’s in the pipeline after over 30 years of global warming, melting glaciers, melting Greenland ice cap, melting Antarctica and so on…………..
What a pile of lies!!!
I forgot about thermal expansion in the pipeline. ;O)