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Climate Hustle

Has sea level rise accelerated since 1880?

Posted on 7 April 2011 by Tamino

Many thanks to Tamino from Open Mind for allowing SkS to republish his post So What? as the rebuttal to "sea level rise is decelerating".

A paper by Houston & Dean studies 57 tide gauge records from the U.S. (including Hawaii and oceanic territories) and concludes that sea level rise has not accelerated. In fact the authors seem to go out of their way to state that the average result shows deceleration at every opportunity. But there are some big questions about their analysis. Why do they use tide gauge records from just U.S. stations? Why not a global sample? Why use individual tide gauge records when we have perfectly good combinations, from much larger samples, which give a global picture of sea level change and show vastly less noise? Why do they restrict their analysis to either the time span of the individual tide gauge records, or to the period from 1930 to 2009? Why do they repeatedly drone on about “deceleration” when the average of the acceleration rates they measure, even for their extremely limited and restricted sample, isn’t statistically significant?

But the biggest question of all is: what’s the big deal?

Here’s some sea level data, in fact two data sets. One is a global combination of tide gauge records by Domingues et al. (2008, Nature, 453, 1090-1094, doi:10.1038/nature07080). Using around 500 tide gauge records globally, it’s the latest version of the “Church & White” dataset. The other is satellite data:

I averaged the two data sources during their period of overlap, and computed a smoothed version:

This is a global data set, and it’s a worldwide average so its shows vastly less noise than individual tide gauge records. We could even use it to look for acceleration or deceleration in sea level rise. But one thing we should not do is restrict consideration to the quadratic term of a quadratic polynomial fit from 1930 onward. That would be pretty ignorant — maybe even misleading.

As so often happens, one thing to be cautious of is that the noise shows autocorrelation. As Houston & Dean point out, the Church & White data since 1930 are approximately linear, so to get a conservative estimate of the autocorrelation I used the residuals from a linear fit to just the post-1930 data and fit an ARMA(1,1) model.

If we compute the linear trend rate for all possible starting years from 1880 to 1990, up to the present, we get this:

According to this, the recent rate of sea level rise is greater than its average value since 1930. Significantly so (in the statistical sense), even using a conservative estimate of autocorrelation. But the increase itself hasn’t been steady, so the sea level curve hasn’t followed a parabola, most of the increase has been since about 1980. How could Houston & Dean have missed this?

Here’s how: first, they determined the presence or absence of acceleration or deceleration based only on the quadratic term of a quadratic fit. That utterly misses the point. Changes in the rate of sea level rise don’t have to follow a parabola, since 1930 or any time point you care to name. In fact, by all observations and predictions, they have not done so and will not do so.

Second, by using individual tide gauge records, the noise level is so high that you can’t really hope to find acceleration or deceleration of any kind, with any consistency. Not using quadratic fits, and certainly the non-parabolic trend which is present can’t be found in such noisy data sets.

Even so, we can also fit a quadratic (as Houston & Dean did), and estimate the acceleration (which is twice the quadratic coefficient):

Well well … it looks like starting at 1930 is the way to get the minimum “acceleration” by this analysis method. Could that be why Houston & Dean chose 1930 as their starting point?

If we restrict to only the data since 1930, as Houston & Dean did, and fit a quadratic trend, we get this:

Can you tell, just by looking, whether it curves upward or downward? Clearly, the parabolic fit doesn’t show much acceleration or deceleration, if any. We can get a better picture by first subtracting a linear fit, then fitting a parabola to the residuals?

That answers the question: the quadratic fit shows acceleration in the Church & White data. But, when autocorrelation is taken into account, the “acceleration” is not statistically signficant.

But — just because the data don’t follow a parabola, doesn’t mean that sea level hasn’t accelerated. Let’s take those residuals from a linear model, and fit a cubic polynomial instead:

Well well … there seems to be change after all, with both acceleration and deceleration but most recently, acceleration. And by the way, this fit is significant.

And now to the really important part, which is not the math but the physics. Whether sea level showed 20th-century acceleration or not, it’s the century coming up which is of concern. And during this century, we expect acceleration of sea level rise because of physics. Not only will there likely be nonlinear response to thermal expansion of the oceans, when the ice sheets become major contributors to sea level rise, they will dominate the equation. Their impact could be tremendous, it could be sudden, and it could be horrible.

The relatively modest acceleration in sea level so far is not a cause for great concern, but neither is it cause for comfort. The fact is that statistics simply doesn’t enable us to foresee the future beyond a very brief window of time. Even given the observed acceleration, the forecasts we should attend to are not from statistics but from physics.

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Comments 51 to 100 out of 106:

  1. New York set to be big loser as sea levels rise

    I haven't been able to find the original report, from the European Geosciences Union (EGU) meeting in Vienna, so this BBC item should do for now.

    I suppose some would argue that there is nothing to worry about because America can afford to move everything important from New York to some other area nearby...probably.
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  2. JMurphy -

    They don't have to move anything. All they have to do is a build a 110 cm sea wall. We have much bigger sea walls than that in the UK.

    It's all modelling. Modelling is not reality.

    I'll believe it when the port of New York reports some serious problems down at the docks (long shore??).
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  3. Here's the latest from Church & White 2011 (h/t to Peter Hogarth for the linkey):

    Needless to say, definitely not linear. We've seen the like before (that makes it a natural cycle, doth it not?), so nuttin' to worry 'bout (unless ye be a unicorn).

    The Yooper
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  4. Logicman -

    I really think you are underestimating humanity's ability to adapt. China created cities of millions out of nothing in the space of 10 years. The idea they would find it difficult to move their cities say 50 metres away from their current coastline, or build metre high sea walls is ridiculous.
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  5. dm#52: "All they have to do is a build a 110 cm sea wall. "

    As it only would need to extend from Alexandria to Port Said, a mere 300 km, that should be no problem. Of course, one has to excavate some depth to build a sea wall of any height, especially in a delta. Ballpark it at $1 mill per km if they start right now. But they'll probably wait a decade or two to start, because so many people keep saying not to worry about it.
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  6. @ muoncounter

    They can always fund the building seawalls/citizen relocation program by taking just half of the funding climate science research gets every year. You know, those uncounted trillions, uh...billions, er...millions, um...thousands...never mind.

    Half of not enough is indeed not enough by far.

    The Yooper
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  7. Yooper,
    What's an easy way to build a seawall 300 km long? Sandbags. And one thing Egypt has, it's plenty of sand. I'm thinking this is an investment opportunity: Print up millions of bags with slogans like 'Don't worry, it only has to be a 110 cm high.'
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  8. Heh. I hear they've been stockpiling stone blocks in piles for millennia for just such an occasion...
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  9. DB and muoncounter,

    You guys are too funny. Now all they have to is arrange some cheap slave labour and the are set to go ;) Seriously though, thanks for posting the Chruch and White graphic Daniel.
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  10. " The idea they would find it difficult to move their cities say 50 metres away from their current coastline, or build metre high sea walls is ridiculous."

    And do you suppose that 50m away is just wilderness now? What about what's already there?

    We can do these things but they are extremely expensive. According to the economic studies done (eg Stern), way more expensive than not letting it happen in the first place. No one proposes that species is going to go extinct because of sealevel rise; what is stated is that sealevel rise will cost us in money and lives, more than cost of curbing emissions.

    You also seem to think that deltas, plains simply move. Not so. Fundamental to formation of those structures is that sediment budget is such that incoming exceeds erosion. If rate of sealevel rise increase, this equation changes and with it the nature of the coast line. Easily verified by looking at tectonically active coastlines.

    What you seem to be stating is that sealevel rise isnt a problem for you, but are ignoring those us for whom sealevel rise is already a problem. If you have a cheap solution for our city that ratepayers can afford, then we are all ears.
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  11. Scaddenp -

    The Stern report! No one takes any of that very seriously in the UK. Even climatists tend to gloss over it, because really it was just "think of a number and double it". Stern is always happy to include figures on the negative side, but not on the positive. Extra CO2 and global warming means of course a huge increase in plant growth. I doubt you'll find he put any plus signs in for that.

    Muoncounter -

    The idea that having to deal with sea level makes a country poor is ridiculous. If it was true, then the Netherlands would be the poorest country on the planet, rather than one of the richest. I am sure there are lots of young unemployed men in Egypt who would be only too happy to be given jobs building a sea wall. Having to build a sea wall would just mean there was less money for the corrupt ruling elite to spend on trinkets in European capitals.
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  12. #61 - daniel
    "Extra CO2 and global warming means of course a huge increase in plant growth."
    The widely reported decline in tree growth is due to the heat stress, which has overwhelmed the trees' ability to take advantage of excess CO2 to promote growth."

    Silva LCR, Anand M, Leithead MD (2010) Recent Widespread Tree Growth Decline Despite Increasing Atmospheric CO2. PLoS ONE 5(7): e11543. doi:10.1371/journal.pone.0011543

    "The idea that having to deal with sea level makes a country poor is ridiculous. If it was true, then the Netherlands would be the poorest country on the planet, rather than one of the richest."

    The history of the Netherlands shows that land reclamation was performed in stages as the wealth became available to pay for it.

    A basic principle of economics states that if one thing is purchased then the buyer must forgo the purchase of other things. This is called opportunity cost. Sea wall construction diverts funds from other uses. In the poorest countries the protection of land is bought at the price of less money spent on health and education, etc.

    That gets you an F in biology, an F in economics and an F in history. Because your use of straw men is too transparent, you get an F in rhetoric as well.
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  13. daniel maris @61

    The Stern report! No one takes any of that very seriously in the UK. Even climatists tend to gloss over it, because really it was just "think of a number and double it".

    Hmm, kindly do not speak for me, or other UK citizens (like Phil Scadden)

    Stern is always happy to include figures on the negative side, but not on the positive. Extra CO2 and global warming means of course a huge increase in plant growth. I doubt you'll find he put any plus signs in for that.

    Stern discusses the positive, and negative, effects on crop yields here
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  14. daniel maris wrote : "The Stern report! No one takes any of that very seriously in the UK. Even climatists tend to gloss over it, because really it was just "think of a number and double it""

    I find it amazing (and the height of arrogance) how some people can project their own political beliefs and opinions onto not just some others but everyone else - in this case, in the UK. Those statements I have quoted, have no basis in reality whatsoever, and it is now apparent that most of this poster's comments so far have been a litany of unsubstantiated, inaccurate and self-denying wishful thinking.
    Is there any chance of having some facts, backed up by references ? Until you start showing some, your comments can be taken as evidence-light, misinformed opinion.
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  15. JMurphy @64,

    I agree completely with your stance on this. The person is question may not realise it, but they are trolling. I have asked them twice now on this thread to speak to the topic at hand (Tamino's expose of the fatally flawed analysis of the Houston and Dean paper) and they have avoided doing so. So it is likely that the trolling is an effort to detract by the failure of yet another 'skeptic' paper.

    Those trying to argue it is not bad et cetera should please take the argument to the "It is not bad" thread.
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  16. Extra CO2 and global warming means of course a huge increase in plant growth.

    Statements like this always demonstrate such an extreme ignorance of both climate and plant biology that I usually need to go buy a new computer (having smashed, in a fit of impotent, annoyed rage, the one I was using to read the offending sentence).
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  17. scaddenp, where was that photo you posted taken? (the aerial view of a coastline)
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  18. Daniel, the Stern report is but one example from WG2. Show me a study that that doesnt underestimate warming that comes out with a different result. Lomberg is the only attempt I know of and he grossly underestimated warming and has since changed his tune.

    For discussion of "plant food" (not true), go to is not that bad.
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  19. GFW - its the Marlborough Sounds area on the northern part of NZ's South Island. (I live much further south).
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  20. dm#61: "having to deal with sea level makes a country poor is ridiculous."

    Hardly what was said from #55 on. However, it is clear that countries under economic stress will not be able to deal with such problems.

    What is ridiculous is this tendency to prescribe for other countries -- let the Chinese move their cities, put Egyptians to work filling sandbags -- rather than find global solutions to what is undeniably a global problem.
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  21. Muoncounter,

    You are making an assumption there. I have already made clear I support a rapid move to renewable energy production supported by carbon capture gas. So if CO2 is the cause of global warming then I am on your side of the argument.

    For me renewable energy is attractive for a wide variety of reasons but the precautionary approach to carbon addition is one.

    However, I am simply not impressed by a lot of the climatist arguments and the idea that a slow sea level rise will be a catastrophic I find unconvincing. I mean, we've already had a slow sea level rise according to you with absolutely no discernible effects. (Not to say there haven't been effects, just that they have not impinged on our national life.)
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  22. Albatross,

    AS for Tamino's analysis, well it could be correct, but of course Tamino is arguing against a paper by "Houston and Dean" published in the Journal of Coastal Research I think. Presumably Houston and Dean are reputable scientists and would in turn come up with lots of counter-objections to Tamino's analysis.

    I know enough about statistics and surveys to know that by asking the right sort of questions in the right series and by tweaking confidence levels you can come up with the answers you want.

    I think there are just so many variables involved in this debate that it is impossible to say at the moment whether major AGW is taking place. I tend to focus on personal experience. There's no doubt that the British climate is a lot warmer than 50 years ago. But that might be explained by the removal of smog through air quality legislation. I am also aware through personal experiecne that London is much, much warmer than surrounding parts and also that weather stations taht were once in the countryside or in fairly isolated airports are now in built up areas.

    My main issue though with the sea level rise discussion was the assumption that it would have a catastrophic impact. I don't see that the rises most scientists are talking about would have such an impact. I think it is perfectly reasonable for me to point to the Netherlands - a fact in itself - as a country that suffers no discernible negative effects from being located in large part below sea level. What can be done in the Netherlands can be done elsewhere, if the worse comes to the worse.

    Of course a 9 metre rise over a short period would be a different matter. But most scientists don't seem to think the ice sheets will melt. So if we are sticking with majority scientific opinion, that has to be set to one side.
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  23. Logicman,

    I think we have to move away from big hydro schemes. However, are you saying that agricultural production is LOWER now in Egypt following the Aswan Dam opening compared with before? I very much doubt that is the case, and that really is what I am saying - humanity is v. adaptable and will adapt if the rate of change is slow enough.

    You're making a prediction about what will happen over the next 90 years, which is fair enough, and we or our heirs will see whether and to what extent it comes true. As it is (I live in a tidal area) I have seen no evidence of the effects of sea level rise at all and have not read of any specific effects in the media (although you get erroneous connections made with such phenomena as coastal erosion which is always with us).
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  24. Muoncounter -

    Referring to past times, I was meaning that climate modelling is pretty dodgy if you have no way of estimating say methane generation from dinosaurs (that's just one example). Climate modelling can only be valid I think on the basis of current data.

    My position on sea level rise is clear: that if it is in the order of less than say 5 mms per annum, then humanity can adapt to it without too much trouble. There may be some casualities of such a rate of change (just as there will be casualties from not letting sea level rise, given that land everywhere is either going up or down relative to the sea), but not many.
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    Moderator Response: See, and comment on, the post "It's Not Bad." Enter that in the Search field at the top left of this page, or find it by browsing the Arguments you can see by clicking the "Arguments" link in the blue horizontal bar at the top of this page. Further off topic comments will be deleted, even if parts of them are on topic. You've already been politely warned, so now you're just getting on my nerves. [Dikran Marsupial] You also ought to read Are surface temperature records reliable?.
  25. daniel maris@72 smog is an urban phenomenon, I can't see how its removal can account for the warming of the U.K., which is also evident in rural locations.

    As for sea level rises, the Netherlands are wealthy and can afford to take measures to guard against sea level rises, Bangladesh is another matter entirely.

    The comment about dinosaur methane was about 10 days late, but it did make me laugh! ;o)
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  26. Daniel, the issue is cost of adaptation versus cost of emission reduction. Checked out how much a Holland solution cost and project that? You also seem to ignore that it is not theoretical - its a problem right now for some of us. How a small city is going to find money for dutch solution is no small task. And is there any point if sealevel will just keep on rising. A dyke for 1m is one thing. A dyke for 6m?

    And by the way, I also think sealevel rise is not the main problem. I am guessing hydrological cycle disruption is/will be main issue. Just a lot harder to predict an quantify.
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  27. dm#72: "I tend to focus on personal experience."

    Perhaps that is not the best way to approach a global scientific problem.

    #74: "There may be some casualities of such a rate of change (just as there will be casualties from not letting sea level rise, given that land everywhere is either going up or down relative to the sea), but not many. "

    That's a rather astonishing statement. Sounds like 'it's OK with me as long as it happens to the other guy.' If that is the outcome of focusing on personal experience, it's time to start doing some actual research.
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  28. scaddenp @76, on average around 250 million Euro's a year are spent by the Dutch on sea defences. See table 21.2 (page 12). The estimated net loss to national income of an emissions trading scheme in the Netherlands with a carbon price of 95 Euro per tonne and a 12 million tonne reduction in emissions is 0.3%, or 1.65 billion Euro*. Therefore, for the Netherlands, sea level rise alone is insufficient reason to restrict the carbon price. It is, however, just one cost amongst many, and probably the lowest of the significant costs.

    *I needed an exhange rate conversion to calculate this, and the exchange rate may have not matched that at the time the figures were published.
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  29. A dyke for 1m is one thing. A dyke for 6m?

    I hear tell that was tried, once. It may be that they're finally locating where it used to be, once upon a time...

    The Yooper
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  30. Thanks Tom. What about the cost of building them in the first place though? My city (Dunedin NZ) needs about 7 kms of dyke to prevent losing a major portion of city that is at sealevel, currently protected by an eroding dune barrier. The airport (25km from city) is on only flat land for miles and miles, but its only 1m about sealevel. The farmland around already has salt incursion. These are tough problems for a city of only 128,000. Government help? Well the major cities here have same or worse. So thats one tiny, wealthy part of planet. Scaling that to nile, Ganges, Mekong?

    Daniel's opinions seem to be based an fact-free assessment so I was hoping that he could support his stance with the some actual studies, and hard numbers.
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  31. scaddenp @80, James Koch estimates a cost of around ten million US dollars per mile (7 million Euro) to construct levees, and 35 million for sea wall (24 million Euro). A proposed project to protect Houston would cost around 50 million US dollars (34 million Euro) per mile including the necessary sea gates for a 5 meter wall.

    Of course, such capital works can be defrayed over time. The Dutch program, for example, includes 63 million Euro (90 million US dollars) in maintenance costs with the rest (270 million US dollars) being for new capital works.

    These costs are well within the capacity of any modern industrial society to pay, and are probably cheaper than relocation of cities in most cases. (Parts of cities, on the other hand, may be better abandoned to the sea.) They are certainly affordable for a nation like Egypt (GDP = 216 billion US dollars) although the low per capita income means such an expenditure will certainly have a social cost in that the expenditure will have to substitute for other services. For Bangladesh with a GDP of 105 billion, and a per capita income of 641 US dollars per annum, the costs would be exhorbitant. Again, however, it would be cheaper for the West to build sea walls for Bangladesh than to curtail carbon emissions, at least in this century. That is assuming sea level rise were the only imposed cost, which it is not.

    To put that in context, with a temperature increase of 4 degrees (expected by the end of the century with BAU), Bangladesh can expect to experience local temperatures which exceed the level at which the human body can get rid of heat. The consequence is sustained a few days without preventative measures is 100% mortality of both humans and livestock. Preventative measures can be as simple as cooling of in the delta waters, but such events will lead to national mortality rates in the tens of thousands.

    If climate sensitivity is currently underestimated, or CO2 increases follow the current trends (pre-recession) rather than the lower IPCC predictions, large areas of the tropics may become uninhabitable to humans, livestock or wildlife several times per decade. I do not know how you would cost this potential, but compared to it, the cost of sea defenses is inconsequential. (This may be the greatest potential human cost from BAU, but is probably not the greatest cost as measured by economists).
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  32. Tom Curtis,

    I think you'll probably find that Dutch estimate is misleading as it probably relates to just sea wall defence. But to inhabit a below sea level area requires a lot more effort: pumps, canals all over the place. I think if you factor that in, the Dutch probably spend several billion Euros each year, but of course the benefits they obtain justify it.
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  33. Scaddenp,

    I am not disputing sea level rise as a likely scenario, so there is no need for me to offer alternative scientific analyses. I am denying that sea level rises of 6 or 9 M in the next 100 years have a scientific consensus behind them - are you claiming they do have a scientific consensus behind them? If so, where's your evidence?
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  34. Muoncounter,

    Assuming your policy prescriptions were followed and sea level rise was stopped then some parts of the globe where land is rising will gradually find their port facilities are further and further away from land. They will be a casuality of your policy proposals. Whatever you do will have some negative effects. If you divert 3% of your GDP to tackle global warming, that's 3% less to spend on hospitals and so on. Someone somewhere will probably die prematurely. But you're prepared to take that risk.
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  35. dm#84: "Assuming your policy prescriptions were followed and sea level rise was stopped"

    My prescriptions? You're the one suggesting that the Chinese can move their cities and the Egyptians would be whistling while they worked on a 300 km seawall.

    And nothing said here is stopping sea level rise.

    As for your 3% solution, more nonsense. The bad effects of AGW will cost way more. You really need to do some reading; these unsubstantiated opinions based on your 'personal experiences' are just sad.
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  36. daniel maris @82, from the same source, Dutch expenditure on flood protection (excluding sea defense) is about 550 million Euro (790 million US dollars) a year. That is expected to rise over the immediate future to 1.2 to 1.6 billion Euro (1.7 to 2.3 billion US) a year as part of a particular project, which includes additional sea defenses.
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  37. Daniel, I am working on 0.75-1.9m possibility as per Vermeer and Rahmstorf 2009 . This does obviously imply accelerating sealevel rise and is quite dangerous enough. However, if globe doesnt stop warming then, then 6m in next 100 years is easily foreseeable.

    Your idea that it isnt that bad is still unsubstantiated by any citations from anyone who has studied the problem.
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  38. daniel maris@84

    If it is possible for cities to build massive sea walls to protect against rising waters, or move inland (as you have suggested) then certainly it should be no problem to build or extend their docks on the new unclaimed land created by rising continents. New land created over a much longer time than what we are discussing WRT sea level rise.
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  39. Well, the costs of seawalls and the like are one thing. What about modern industrialised cities placing important infrastructure at or near sea level for convenience. Power plants for cooling water, ports for shipping, sewage plants for effluent disposal, airports for the nice flat land.

    And you can't just shift a city one or ten kms from its current location the way you shift a sofa to a better position. You either have to knock down a whole heap of businesses and dwellings if proximity to the sea is important - ports being the obvious example - or leapfrog existing areas to find the next big piece of available, suitable land. And if there's none 'available', then suitable areas will have to be taken over and adapted to the essential use.

    The costs of seawalls pale into nothing compared to the costs for governments compulsorily acquiring land for essential infrastructure.

    (As it happens, I live in a city where the airport is a bare 2m above sealevel and less than 2km from the beach. So we're going to be in trouble by the middle of the century if things go the way I expect.)
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  40. We can adapt modern cities and build seawalls to protect densely populated deltas - given enough time and money. Time is uncertain but the money should be compared to cost of curtailing emissions. So far daniel has completely failed to address this other than ill-informed criticism of Stern.
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  41. Scaddenp -

    You have failed to show that Stern has accounted for the value of additional crop yields in his report. I suspect he hasn't but - quite frankly - the whole report is a mass of supposition, assumption and presumption topped off with vague projection.

    I have already said that I take the precautionary approach and want to move rapidly to 100% renewables generation of electricity. So from your point of view I am not part of the problem.

    You are of course assuming that carbon addition is the cause of global warming and suspected sea level rise. If it proves not to be, then you will ahve been pursuing a very dangerous, risk happy policy. Again, using the precautionary approach, I would say if you can protect against sea level rise with sea walls you should because climate is too complex to be able to be sure of what is causing the sea level rise.
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  42. Scaddenp -

    I'm not claiming to be a climate scientist or oceanic specialist (I wonder how many of you are). Looking at Wikipedia -

    it seems that you can take your pick of anything from a reduction since 2005 in sea level to plus 8 metres or more over the next 100 years - all estimates produced by reputable scientits.

    It ends up with a reference to a "more plausible" rise of 0.8M over the next 100 years, which if I had to choose would probably be my choice, purely because it reflects more the reality of my personal experience over a few decades. Of course the rise - if rise it be - might accelerate, but on the other hand perhaps the scientists who say it is going down are right.
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    Moderator Response: [DB] Climate scientist/oceanic specialist or not, quoting Wiki on science blogs to substantiate a position is no way to gain credibility; links to peer-reviewed published articles supporting your position are best. Baseless and unattributed claims about "scientists", without naming names, similarly detracts from your credibility and amount to hand-waving.
  43. DB - I suggest you re-read my post. I wasn't seeking to substantiate a position - I was merely pointing to the variety of scientific interpretations of the data. All the references for the papers were set out in the Wiki link.

    I registered a personal preference for 0.8M but really that is no different from people who state a preference for 8M, despite that not being backed by the majority of scientists. I could have stated a preference for the study showing a reduction in sea level.
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    Moderator Response: [DB] I re-read it. Again, you are lacking in properly substantiating your position: Upon what basis - other than guesswork and arrangement of internal organs - do you opt for 0.8 vs the latest best estimates of 1.2-2.0 meters SLR (the highest scientific estimate I've seen is from Hansen 2011, about 5 meters, so I have no idea where you get your 8 meter estimate)? The Hansen paper is in press, so it has not yet entered into mainstream consensus.
  44. DB -

    Influenced by discussion here I misread 880 mm as 8800mm. :)

    I have indicated why I opt for the lower end estimates - because the reported increases to date over the last century seem to have had no discernible effect whatsoever on life around the UK, which makes me wonder whether the data is correct or possibly overestimated.

    But as far as I am concerned 0.8M over 100 years is not a catastrophe for reasons I have already been through.
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  45. My idea of a precautionary approach is to work with the information and science available and do risk assessment both ways. As far as I can see your position is largely uninformed and I have no faith in arguments from personal experience, including my own. Someone else pointed you to relevant section on Stern, but my point was that it was one of many in WG2. By contrast, you have not produced any report that suggests cost of climate change is less the cost of restricting emissions.

    However, I am glad that you are that do support actions that will reduce CO2 emissions which is the point of being interested in such debates.
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  46. daniel maris @94 - sea level rises over the last century have averaged around 2 to 2.5 mm a year, which over a century is about 200 to 250 mm, or only 10 to 12.5% of typical tidal variations and less than variations in high tide levels due to the relative position of the sun and the moon. For most peoples life time, the differences is about a third of that. Just how observant are you claiming to be that you expect that to have a discernible effect? Particularly in Britain, most of whose coastline is rising as a result of isostatic rebound, so would have experienced a smaller rise, and potentially a local fall in sea level?

    In contrast to the slow rises of the 20th century, however, those of the coming 100 years will be significantly faster - 4 times faster by your preferred estimate - and potentially twenty times faster (if Hansen is correct).
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  47. Scaddenp,

    I make my own judgements, just as you and others do - because you can't believe ALL of the contradictory scientfic analyses. If I was to dig out a report that said the benefits of global warming would outweigh the costs, woudl you believe it, even if produced by an eminent economist? Of course not. You'd argue every point, just as I have argued points Stern makes. But I wasn't really arguing that the cost benefit analysis of global warming was positive, it was that Stern was sloppy in his approach.

    I think you and others here just underestimate the complexity of the problem here. This is not say something like the link between air pollution and lung diseases or between CFCs and the ozone layer.
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  48. Well - since you guys love papers, here's one from a Yale University person who shares my concerns about the Stern report and who specifically states that he lists only harmful effects, exactly what I was complaining about.
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  49. Daniel, kind of the reason why we have the IPCC. So experts evaluate the evidence. Actually debate about a contradictory economic report would be a very good thing. I'm prepared to be convinced. Its just that I havent seen any so I make my judgement on the basis what studies have been done on the subject rather than just guessing.

    Now where is the contradictory scientific analysis by the way? (But please tell me about it in a appropriate thread). So far I see peer-reviewed published science in one corner and blog disinformation in the other.
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  50. Daniel, how are you supposed to be credible when you insist that Stern report only lists harmful effects when someone has pointed you to chapter and verse showing that this is not true?

    And by the way, I agree with the conclusions of your paper - but I am unqualified to comment on the critique. Still waiting for that better analysis.
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