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Science Story: the Making of a Sea Level Study

Filed under: — group @ 6 April 2010

Guest commentary by Martin Vermeer

On December 7, 2009 the embargo expired, and my and Stefan’s joint paper ‘Global sea level linked to global temperature’ appeared in the Proceedings of the U.S. National Academy of Sciences. It had been a long time coming! But this post is not so much about the science as about the process, and about how a geodesist from Helsinki and an oceanographer from Potsdam, who to this day have never even met, came to write, to the surprise of both of us, a joint paper on sea level rise.

My own entry into climatology happened only a few years ago. A significant trigger was RealClimate, which I had learned to appreciate as one of the rare reliable Internet sources amidst the junk. Contributing to the oft-slandered science is my small ‘thank you’ and revenge as a scientist.

As I remember, it was the commenter calling himself Rod B. who enquired, sometime August 2008, what the story really was with Rahmstorf (2007). Trying to answer, I ended up reading the paper and getting interested. What seduced me was the simplicity of this, so-called semi-empirical approach: linear regression of sea level rise dH/dt against temperature T, yielding two unknown parameters: a regression coefficient a, and an intercept, or ‘equilibrium temperature’, T0. See our Ups and downs of sea level projections for a more detailed explanation.

The curve of temperature as a function of time over the 20th century has three parts: a steep rise in the beginning, a flat middle part commonly attributed to aerosols, and a very steep upswing at the end. Physically one would expect for the curve of the sea level rise rate dH/dt as a function of time to look rather similar, as indeed it does: this justifies the Rahmstorf (2007) approach of regressing the one against the other. Looking more carefully however one sees that the dH/dt curve has slightly more of an S-like shape, turning downward in the middle, before swinging up again at the end.

This suggested to me that, in addition to a proportionality to temperature T, sea level rise would also contain a term proportional to the time derivative of temperature, dT/dt. In other words, global sea level would be a good global thermometer, but with a ‘quirk’. I could even think of a physical mechanism for such behaviour.

I contacted Dr. Rahmstorf, proposing the idea: one would expect the ocean surface to warm up rapidly to completion, contrary to the deep ocean and the continental ice sheets. This would argue for a term, in addition to the secular a (TT0) term, of form b dT/dt. Stefan’s response was cautious; not surprising, as being something of a media figure in Germany surely means that he has to contend with his share of cranks. But he suggested I look myself into the idea, which I subsequently did: in for a penny, in for a pound.

I downloaded Stefan’s script, modified it, did the first computations with the same real tide gauge and temperature data Stefan had used — surprise: negative b. Hmmm, strange. That was for real data from the real Earth; what would happen if I applied the extended relationship to simulated data from the same general circulation model (actually, an Earth system model) for the period 1900-2100 that Stefan had used in his paper for testing his relationship? This model was in one essential way very much simpler than reality: it completely lacked the contribution of land ice melting to sea level.

Stefan helpfully sent me Matlab snippets and model output, and indeed I got it all working. What was more, the disagreement found by Stefan for the late 21st Century — between sea level rise as predicted directly by the model, and indirectly through the semi-empirical relationship between temperature and sea level rise — went almost completely away when using the new, extended relationship. With a positive value for b, just as expected from theory for an ocean surface water response.

Global sea level against time. Top, sea level rise, bottom, sea level itself. Red, sea level from observations; blue, with uncertainty band, the fit from global temperatures using our new relationship; black, the fit using Stefan’s original relationship. The thin red wiggly curve shows annual sea level values.

That was encouraging, but what again about the real data? Remember that this is real observational data from tide gauges, altimetric satellites and meteorological stations, warts and all, with a very imperfect spatial sampling both for the tide gauge data and for the surface temperature data. Nothing like the clean, formally perfect model output of truly global mean surface temperature and sea level.

At that point I was about to give up.

I remembered however Stefan mentioning a ‘reservoir correction’ and decided to see if that made a difference. It was not hard to find Chao et al. (2008), who had painstakingly compiled a list of all man-made reservoirs the world over, and the amount of water stored in them. I fitted a simple arctan function through their water storage curve and added that to Stefan’s already extended script. All that water, up to 30 mm sea level equivalent, that should have been in the ocean was progressively kept bottled up on land as dams were being built: a known correction that should be applied.

Wow. Introducing the b term had already improved the Pearson correlation r of fit from 90% for Stefan’s original relationship to 97%; nice, but hardly on its own compelling. Bringing in the Chao et al. man-made reservoir correction brought it up to 99.2%!

Slowly it dawned upon me that, hey, maybe I’m on to something real here, something based in physics: it seems the world ocean can be a remarkably good global thermometer, once you get to know its quirks.

The world ocean, a pretty good global thermometer (drawn using
GMT).

Stefan relates the moment when he realized that I had something worth publishing: January 16, when he saw the results of the ‘millennium run’ that I had done on the data he had sent me. All of the volcanic explosions over the last thousand years, which were translated first into top-of-atmosphere radiative forcing and then turned into sea water thermal contraction and a drop in modeled sea level, were faithfully reproduced in the sea levels obtained from the model temperatures by my new relationship! A beautiful performance on what are large, rapid and erratically occurring excursions in both global temperature and sea level. And that’s how Stefan came on board.

With the small number of independent data points we needed to make sure we were not ‘fitting an elephant‘, so I read up on statistics during winter 2008/2009, and in particular, information theoretical methods like the Akaike Information Criterion. The model intercomparison was useful for just that. I’m not the only one studying these ideas, and I learnt a lot from tamino and James Annan’s Empty Blog. Jaynes (2003) was also on my 2009 Christmas reading list; Hypothesis testing, null and alternative hypotheses, confidence bounds and all that, is a traditional approach to statistics that is easily misunderstood and often misused. Statistical refutations of “silly null” hypotheses abound — like the silly null of no relationship between temperature and sea level rise. If this sounds all cryptic to you, I don’t blame you. Pick up Jaynes (2003), it’s an eye-opener.

As part of his contribution, Stefan tightened up the draft paper to be suitable for submission to Nature. Nature gave us some very helpful reviews which we used to further improve our manuscript. The most useful reviewer remark had to do with the extraction of water from underground aquifers, a process potentially almost as important as the artificial reservoir storage that we did take into account — only, nowhere in the literature was there an equally painstaking accounting exercise to be found as what Ben Chao and colleagues did for the reservoirs. So, we settled for a sensitivity analysis, skillfully whipped up by Stefan.

Nature turned us down, like they do over 90% of manuscripts; had they accepted, the paper would have been out already in summer. We resubmitted to PNAS who obtained three further helpful reviews, the paper was improved yet again and finally published in December. As it happens, this landed it right on top of the Copenhagen meeting.

Stefan tells me that we have exchanged over a thousand emails in the run-up to this paper. I see some poetry in that number being close to that of the East Anglia stolen email selection. Easy, informal email plays a vital role in the work of climatologists, and the loss of trust in its confidentiality could be very disruptive for the science: if the internal discussions of an authoring team would have to be expressed with the same care as the finished product, not a lot of authoring would get done.

Would I have dared, or managed successfully, to submit to a top journal all on my own? Hardly. It is an illusion to think that you can just enter a field that’s not your own and become a productive researcher, whatever you might read or what denialists-of-service may pretend. There is a lot of domain knowledge involved, and precious little of it is simple. In this case, I did learn a lot (and I continue to do so), but this takes both a willingness to learn, and great teachers. RealClimate, and the community it represents, are an indispensable resource for that.

Still waiting for Al Gore’s cheque…

P.s. Over at Nature Stefan has a commentary on sea level today.

References

Martin Vermeer and Stefan Rahmstorf (2009): Global sea level linked to global temperature, Proceedings Nat. Acad. Sci. 2009 vol 106 no. 51 pp. 21527-21532, DOI: 10.1073/pnas.0907765106, open access link

Jonathan Overpeck and Jeremy L. Weiss (2009): Projections of future sea level becoming more dire, Proceedings Nat. Acad. Sci. 2009 vol. 106 no. 51, pp. 21461-21462, DOI: 10.1073/pnas.0912878107 link.

Stefan Rahmstorf (2007): A Semi-Empirical Approach to Projecting Future Sea-Level Rise, Science 315, 368-370, DOI: 10.1126/science.1135456 link

B.F. Chao, Y.H. Wu and Y.S. Li (2008): Impact of Artificial Reservoir Water Impoundment on Global Sea Level, Science, 320, 212-214 link

Edwin Jaynes (2003): Probability theory: the logic of science. Cambridge University Press, ISBN 0-521-59271-2.


237 Responses to “Science Story: the Making of a Sea Level Study”

  1. 201
    Completely Fed Up says:

    “I elaborate (again) : the fact that NO industrial country has developed without FF means that, at least for some applications, FF aren’t easily replaceable.”

    Well NO industrial country has had the level of technology.

    Therefore the past is no indication of future performance.

  2. 202
    Completely Fed Up says:

    “I elaborate (again) : the fact that NO industrial country has developed without FF means that, at least for some applications, FF aren’t easily replaceable.”

    What applications?

    “b) they have never been replaced for other specific needs ”

    What needs?

    Magnus Pike never waved his hands in an argument half as much as you do.

  3. 203
    Completely Fed Up says:

    “I elaborate (again) : the fact that NO industrial country has developed without FF means that, at least for some applications, FF aren’t easily replaceable.

    b) they have never been replaced for other specific needs ”

    What other specific needs? You specifically mention nothing, so therefore there are no such needs.

  4. 204
    Amy says:

    Frank Giger:

    It might help if you actually followed a thread and understood what people are talking about before you start threatening to call politicians and ask them to vote based entirely on your own ignorance. Your complaint at 745 about people discussing “[m]ass extinctions” and possibly “95% of the human population [being] destroyed” is entirely predicated on your own failure to find out why that conversation had begun in the first place.

    Whatever your reason for not doing so, I do hope that you will perhaps take away from this that your own bias can cause you to react hastily and to therefore reach incorrect conclusions — not to mention that it makes you look intellectually lazy.

    So, here is where I believe the discussion started:

    473 Barton Paul Levenson says:

    PKthinks (461): the mainstream media and policy makers have exaggerated the threat to such a degree that people then lose faith in the science itself.

    BPL: What part of “human civilization could be completely destroyed if business as usual continues” do you not understand?

    I could be wrong, but I would have thought it fairly obvious that if we do absolutely nothing and continue to burn fossil fuels at the current rate, a point will likely come in the future where the earth is too warm for humans to inhabit in large numbers?

    You may have had a point if your complaint had been about the fact that other people reading this thread might not have known why the conversation had originally started, and so, probably would have gone away the wrong impression. Sadly, that wasn’t your point.

    Do remember to get in touch with your “Congressman and Senator” again and tell them that you were a little hasty in your original reaction, and that they should now “vote [for] AGW legislation”, won’t you? It’s a little sad that it only took a few people saying something that you didn’t like for you to react in that way, given that you have previously said that the science is sound.

  5. 205
    Gilles says:

    “What other specific needs? You specifically mention nothing, so therefore there are no such needs.”

    Oh, sorry, CFU, I thought you knew them : transportation, heating, metallurgy, cement, glass, paper,plastics, glues, paintings, medicines, detergents, fertilizers, and many more…

    Of course there are substitutes for everything – but as a general rule, more expensive , since otherwise they would already have been use instead. Now if you’re claiming that you don’t see why replacing everything with more expensive techniques would impact in any way the global economy, I wonder what “expensive” really means for you. Note that all alternatives use a lot of the above mentioned commodities, and that their current price is calculated with everything produced by cheap fossil fuels

  6. 206
    C. Streif says:

    #189, @ AC
    Well, AC, if you say now that the aim should be an emissions reduction to 5% or less of current emissions for something approaching climate stabilization , then we have no quarrel except over words on this particular issue. I also agree that coal is the most important factor .
    But I must admit I am a bit bemused by your attitude. You tell me I’m harbouring fantasies because I said to stabilize climate it would be necessary to switch to 100 % non-fossil energy in the end – not that outlandish a claim surely in climate change circles–, yet for your own presumably more realistic mitigation scenario you assume that cutting global emissions by two thirds and finally to 5% is no big deal, as we won’t have rising living standard, so India and China, according to your assumption, will not develop significantly, but mysteriously the Chinese and the Indians nevertheless will agree to “phase out coal” as Hanses so coyly phrases it (“by 2030″, he adds), meaning in your scenario that they will get their plants converted to CCS, thereby doubling their energy costs despite the fact that the majority of the population is still poor (while the Americans still drive around in big cars because all of the oil can be used up anyway). Uhm, is this any less fantastic than what I said?
    You also told me I was careless in the way I cited literature (“citing abstracts out of context” or “not having understood the argument”), which I find a bit puzzling when all the articles I cited and even the one you cited did in fact support my assertion (and the main point of our whole discussion) that within the time scales we’re talking about total emissions are what counts for climate outcome because of the longevity of CO2, among other things, so that to stabilize emissions have to go down to essentially zero, while you didn’t cite a single source that supported your original assertion that we will never have to cut radically because we will be able to emit more cumulatively if we cut some now. (The one you cited, Hansen, flatly contradited you according to my standards. Yes, I know, in your last comment it becomes clear that your interpretation of what does and doesn’t constitute a radical cut is somewhat idiosyncratic, but even then… )
    Thanks for telling me that your judge the merit of a scientific paper by author’s politics ;). I do hope you weren’t serious about that one. I still think calling Matthews a “contrarian” because you didn’t like his conclusions (he doesn’t look like one, by the way, I googled his picture) wasn’t a good idea.
    Also by the way, like you, I used to think that Germany had met its Kyoto target through the crumbling GDR economy. However, I researched this last year and it’s not true. (You’ll find a lot of the data on this page:http://www.umweltbundesamt.de/energie/index.htm) Primary energy use has shrunk very little, emissions went down a lot. Most poignantly, electricity use has gone up, yet emissions from electricity have fallen steeply. Most of what would have been needed to reach Kyoto is from clean energy, some reduction in growth is from energy efficiency and if you ask me the switch from oil to gas as the main heating fuel also helped. Yes, I know the French emit less thanks to nuclear power (so are you a supporter of nuclear energy?). They also have warmer winters (less heating) and travel less than the Germans do. Fact is Germany had more ambitious Kyoto targtets than other countries and met them.

  7. 207
    Completely Fed Up says:

    “and finally to 5% is no big deal, as we won’t have rising living standard, ”

    And what about your living requires the burning of fossil fuels?

    Why not define living standard as the Swedes do: how well you live your life, and NOT how the US does: how much more money do you have than someone else.

  8. 208
    Completely Fed Up says:

    “What other specific needs? You specifically mention nothing, so therefore there are no such needs.”

    Oh, sorry, CFU, I thought you knew them : transportation,

    Electric cars.

    heating,

    Passive heating solar.

    metallurgy,

    Are not made from fossil fuels.

    cement,

    Curing causes emission of previously held Carbon.

    glass,

    Isn’t made from fossil fuels

    paper

    aren’t made from fossil fuels

    ,plastics,

    are made instead of burning fossil fuels, retain the carbon

    glues,

    Horses hooves

    paintings,

    Yeah, big industrial. you know I think you mistake “oil painting”

    medicines,

    aren’t made from fossil fuels

    detergents,

    aren’t made from fossil fuels

    fertilizers,

    Shit from horses. Not made from fossil fuels

    and many more…

    given you’ve managed to miss 90% with the ones you stated, many LESS would be closer to the truth.

  9. 209
    Completely Fed Up says:

    “with everything produced by cheap fossil fuels”

    Only if you don’t pay the externalised costs.

    How much will it cost in energy and money to pull back all the carbon emitted? then store them.

    Fossil fuels are EXPENSIVE.

    Wind is cheapest.

  10. 210
    Completely Fed Up says:

    “Oh, sorry, CFU, I thought you knew them : transportation,”

    Electric cars.

    “heating,”
    Electric fires. Insulation. Solar passive heating.

    ” metallurgy”

    These use metals not hydrocarbons.

    “, cement”

    Still doesn’t use fossil fuels.

    “, glass”

    Uh, made of silicon not carbon.

    “, paper”

    Wood, not petrol.

    “,plastics”

    If you burn the fossil FUEL you can’t make plastic out of it.

    “, glues”

    Horse hooves

    “, paintings”

    Yeah, big industry.

    Still doesn’t use fossil fuels.

    “, medicines”

    Hmmm. So instead of my cancer cure, all I need is a gallon of five-star…?

    “, detergents”

    Fat, caustic soda and lye.

    “, fertilizers,”

    Cowshit.

    ” and many more…”

    ..that have nothing to do with fossil fuels…

  11. 211

    Gilles (199): so obviously something is different with fossil fuels. What is different is obvious : all other energies produce only electrical power (for which FF can also be used). But hydrocarbons have uses that cannot be entirely fulfilled by electricity

    BPL: Ever heard of “biodiesel?” How about “ethanol?” “Methanol?”

  12. 212
    Anonymous Coward says:

    C. Streif,

    You have a fertile imagination. You made up most of the statements and positions you attribute to me. Have fun arguing with strawmen.

    As to the part of your post that’s not laden with strawmen…
    Germany burns more than France but also more than Swizterland and Sweden which are hardly warmer coutries.
    Yes, Germany is making progress but the fundamental problem is that electricity usage is out of control for a country which is phasing out nuclear and I have not seen any indication that people have come to terms with that. Travel may be excessive as well as you say. Frivolous air travel certainly needs to be curbed and rail fees are too expensive compared to the price of gas.
    You say that “emissions from electricity have fallen steeply” but once again your claim supported by spin rather than figures. Your link has emissions for elecricity generation roughly stable after the first years of reunification. 2000-4 emissions are higher than 1995-9 and the only reason 2005-2009 are lower is that the preliminary figures for 2009 are very low, due to the economic crisis I presume. For all the “clean” and “green” stuff, 2005-2009 emissions are still going to be higher than 1995-9 in spite of the crisis. The amount of electricity produced has no effect on the climate. Only emissions matter, and they stopped falling in 1993.

  13. 213
    Hank Roberts says:

    > there are substitutes for everything – but
    > as a general rule, more expensive

    You ignore the externalized costs, which for CO2 include climate change.
    These get handled eventually by governments — lead in pipes and gasoline; sulfur in fuel oil; asbestos in everything; PCBs in everything, and so on.
    http://www.ginandtacos.com/2008/08/31/atheistsfoxholes-libertariansairplanes/

  14. 214
    Gilles says:

    “Oh, sorry, CFU, I thought you knew them : transportation,”

    ….
    ..that have nothing to do with fossil fuels…

    CFU, you really don’t understand the point. Of course there are substitutes for all that. The only thing is that they are generally much more expensive, less convenient and/or can be produced at a smaller scale. The point is NOT whether we can live without FF or not. We obviously can, for the very simple reason that we already did in the past and that many people still do currently. The point is if that we cannot produce as much as we do without FF, because everything would be much more expensive (including substitutes energy) and we wouldn’t have enough money to buy so much. If everything is more expensive, you’re simply poorer, and the inflation-corrected GDP is lower.

    The only question is : how much lower? well look at the correlation between and GDP and FF and you will have a gross answer.
    BTW, you don’t seem to know that metals needs reduction of their oxides by carbon – I know, we could use charcoal or hydrogen, but read again above.

  15. 215
    Steve Fish says:

    RE- The many comments by Gilles.

    Please explain why you think that working toward long term climate and economic stability by a near term transfer to renewable energies, even at the expense of a short term reduction in standard of living and GDP, is preferable to a complete crash of civilization from environmental problems and increasing scarcity of fossil fuels (your admitted prophesy). Don’t tell me that this is impossible because it hasn’t already been done. A crash is a crash. Don’t tell me that developing nations will be hurt because, ultimately, a crash is a crash.

    If we can’t make it on renewable energy resources, we crash. If we don’t try, we crash. Can you not think of any way out of this mess? If you don’t think it is even worth trying to solve this problem, then why are you posting at all? Do you just enjoy telling others that the future of their progeny is worthless?

    Steve

  16. 216

    Gilles (214): The point is if that we cannot produce as much as we do without FF, because everything would be much more expensive (including substitutes energy) and we wouldn’t have enough money to buy so much.

    BPL: Yeah, but “the point” you list happens to be egregiously wrong.

  17. 217
    Hank Roberts says:

    > we wouldn’t have enough money

    Nonsense. It’s almost a trivial amount of money compared to the natural variation in the amount of money in the financial system.

    Look at just the last five years. The amount of money in existence varied enormously.

    How can this happen? Because it’s a bookkeeping term.

    The real wealth isn’t money. There’s your problem right there.

    This is a bookkeeping problem.

  18. 218
    Gilles says:

    Steve :” If you don’t think it is even worth trying to solve this problem, then why are you posting at all?”

    But I didn’t say it wasn’t worth trying ! I said that it was very unlikely that we’ll succeed in mitigating the effects of fossil depletion enough to keep our standard of living, and that I wasn’t sure at all that there are enough fossil fuels to make climate change that dangerous. If you have bad harvest and you fear starving for death, you’re not much interested in doing a diet , are you ?

    Of course it would be fine to be able to power a society like ours only with renewables ! again, why should I be against that ? this wouldn’t make any sense. My position is
    1) that I doubt very much that renewables will be enough to avoid problems linked with fossil depletion (the most probable being economic and financial crashes)
    2) that the close coming of fossil peak and the associated economic problems will make climate change rather immaterial for most people – compared with these issues. SRES scenarios simply ignore totally the problems arising from depletion of natural resources.
    3) much likely, if renewables were enough to continue the growth, for instance, they wouldn’t change at all the total amount of burnt fossil fuels – mankind greed , or more simply basic needs for the poorest people , would simply make it use fossil fuels PLUS renewables to produce the maximum amount of wealth it can.

    so I’m posting for the very same reason as anybody posting here : to alert on what I think is the most critical issue for the next future. We just differ on its nature.

    BPL: Yeah, but “the point” you list happens to be egregiously wrong

    BPL, I’ll wait to see a society without fossil fuels, and having a standard of living comparable to ours, before believing you. But I don’t think we’ll have to wait much before seeing the effects of oil depletion – actually I think we are just seeing the beginning.

  19. 219
    Gilles says:

    HR :”Look at just the last five years. The amount of money in existence varied enormously.
    How can this happen? Because it’s a bookkeeping term.
    The real wealth isn’t money. There’s your problem right there.”

    I couldn’t agree more to that. The real wealth is NOT money. It’s the amount of goods you can produce per work hour. Money is just a symbolic transcription of that (actually money is just a RELATIVE allocation of the fraction of goods you are allowed to consume. Increasing or decreasing the global amount of money produces only inflation/deflation. But actually the amount of money didn’t vary that much these last years in regard to the recession).
    When I said “we won’t have enough money”, i just mean that with the diminishing energy input, we’ll be simply poorer – because everything will get more expensive compared to our income.

    Aren’t we slightly OT with respect to the original title of the thread ? ;)

  20. 220
    Completely Fed Up says:

    “BPL, I’ll wait to see a society without fossil fuels, and having a standard of living comparable to ours, before believing you”

    If you’re going to wait, then do so.

    Stop posting twaddle about things you don’t know and STFU.

    WAIT for a fossil fuel free future, stop complaining that it’s impossible.

  21. 221

    Gilles III 218: I’ll wait to see a society without fossil fuels, and having a standard of living comparable to ours, before believing you.

    Gilles, Jr., 1910: I’ll wait to see a society without horse-drawn transportation, and having a standard of living comparable to ours, before believing you.

    Gilles Sr., 1860: I’ll wait to see a society without slavery, and having a standard of living comparable to ours, before believing you.

  22. 222
    Gilles says:

    221 : BPL : so you seem to belong to the cornucopian church believers, who think that “if everything has grown in the past, then it cannot do anything else than grow in the future ?” interesting ..

    interesting also to remark that your period of comparison is strictly coincident with the development of fossil fuels in general, and oil in particular. Do you have another historical example ?

  23. 223

    “[Wealth is] the amount of goods you can produce per work hour.”

    What about services?

    And ignoring that issue for the moment, surely “value of goods” would be more apposite than “amount of goods?” One Stradivarius is worth any number of factory-made Skylark violins. (Actually, it’s worth far more than all the Skylarks ever made.)

    It may seem nit-picky, but a degraded environment is a negative “good,” and the economic system needs to account for that. Doing so means going beyond simplistic “amounts”–as discussions of the definition of wealth say, the question ends up invoking “values” of all sorts.

  24. 224

    Gilles (222): 21 : BPL : so you seem to belong to the cornucopian church believers, who think that “if everything has grown in the past, then it cannot do anything else than grow in the future ?” interesting ..

    BPL: Not even remotely. That’s why I care about stopping global warming.

    Gilles: interesting also to remark that your period of comparison is strictly coincident with the development of fossil fuels in general, and oil in particular. Do you have another historical example ?

    Seigneur Gilles de Point du Lac (1789): I’ll wait to see a society without serfs, and having a standard of living comparable to ours, before believing you.

    Gilles le Seigneur (1183): I’ll wait to see a society without two-field rotation, and having a standard of living comparable to ours, before believing you.

    Guillius Gallensis (353): I’ll wait to see a society that doesn’t sacrifice goats to Ceres, and having a standard of living comparable to ours, before believing you.

    Gil (512 BC): I’ll wait to see a society that doesn’t sacrifice at least one child to the harvest gods every spring, and having a standard of living comparable to ours, before believing you.

    Gl (11,000 BC): I’ll wait to see a society without mammoth hunts, and having a standard of living comparable to ours, before believing you.

  25. 225
    Steve Fish says:

    RE- Comment by Gilles — 25 April 2010 @ 11:14 AM:

    You have missed my point. Degradation of the biosphere and depletion of fossil fuels will both by themselves, or in any probable combination, ultimately result in conflict, starvation, a very large die off, and a major crash of civilized society.

    You say- “so I’m posting for the very same reason as anybody posting here : to alert on what I think is the most critical issue for the next future. We just differ on its nature.” This is not quite correct. Most people posting here about critical issues are also offering potential solutions, while you are not. Just saying that won’t work, and that won’t work, and that won’t work is just argumentative and pointless. There is no one “critical issue” if the outcomes of all of them are the same without some intelligent action.

    Steve

  26. 226
    Gilles says:

    BPL : actually all examples between the apparition of agriculture and the industrial civilization didn’t have very different standard of living – and they all disappeared sooner or later. Not particularly a good example to argue we are immune against a decline.

    ““[Wealth is] the amount of goods you can produce per work hour.”

    What about services?

    To develop services, you have to increase the part of population that is not busy with the production of food or commodities – that’s exactly increasing productivity.

    “It may seem nit-picky, but a degraded environment is a negative “good,” and the economic system needs to account for that.”

    Well, maybe, but it’s always the same question : at which point do you estimate that it becomes more costly that the benefit you draw from the civilization ? that’s far from being obvious …

    Steve : ” Most people posting here about critical issues are also offering potential solutions, while you are not. Just saying that won’t work,”

    more exactly , they claim that they believe there is a solution. That is not exactly “offering a solution”. I could also claim that I believe that we’ll find a solution to climate change and that we don’t need to reduce FF consumption : why is it more unreasonable than claiming that we could replace fossil fuels without any problem?

    if you bet on unknown solutions, you can bet on anything you want, after all.

  27. 227
    Completely Fed Up says:

    “if you bet on unknown solutions, you can bet on anything you want, after all.”

    They aren’t unknown solutions.

    Solar passive heating. Known.
    Solar PV. Known.
    Wind power. Known.
    Tidal power. Known.
    Hydroelectric. Known.

    The solutions are only unknown to gullible here who sticks his fingers in his ears and goes “lalalalala! You’re not looking!”.

  28. 228
    Gilles says:

    ““if you bet on unknown solutions, you can bet on anything you want, after all.”

    They aren’t unknown solutions.”

    please show me evidence that it is enough to avoid the use of fossil fuels, and apart from hydropower (which is of limited application), that it is even enough to avoid the use of thermal plants at all. Look at the figures, and stop denying the mere reality (and worse accusing the others of doing it).

  29. 229
    Completely Fed Up says:

    “please show me evidence that it is enough to avoid the use of fossil fuels”

    Yet again Mr Amnesia strikes again:

    http://www.realclimate.org/index.php/archives/2009/10/an-open-letter-to-steve-levitt/

  30. 230
    Steve Fish says:

    RE- Comment by Gilles — 26 April 2010 @ 6:02 PM:

    Because you say- “more exactly , they claim that they believe there is a solution” – you apparently don’t believe that there is a solution. So, why bother to post? What is gained by telling others that all is lost and there is nothing to do about it? Please explain your motivation.

    Steve

  31. 231
    Gilles says:

    230 Steve : i thought this was a scientific site, and I don’t think that the first goal of science is “proposing a solution”, but rather telling the truth.

    Proposing a solution requires first a clear identification of the “problem”. Well thinking more about it, I’m not sure to be quite certain about what is the problem. It seems that the problem is to keep as much as possible our standard of living without any of its inconvenience – no pollution, no CO2, no finite reserves. Actually very close to the dream of immortality. Well I shall admit that it is a very ancient dream of mankind – kind of Faust archetype. But it is also basically a very childish idea. Things never last eternally. yes , climate may change, sea level can change, energy resources can be exhausted. And even our civilization can die (actually EVERY civilization has died isnt’it?) I don’t think mankind as a whole is threatened. We are a very robust species. The only one that can survive from the torrid desert to the icy poles (even without fossil fuels ! ). More, we seem to like living in difficult and hostile environments – we even climb very high mountains and dive under deep water for leisure, although it is very far from our biotope. So I don’t worry very much about mankind. The only real problem is that we don’t want to give up our comfortable houses, cars, travel for holydays. Sorry again, “ours” means only “the 10 % richest people in the world during the richest period of its whole history”. Maybe two billion lives on a total of 80 billions – the other 78 billions and probably a big number of coming dozens of billions have or will never know that kind of life , anyway. But I don’t think either that these things will disappear very rapidly. Even fossil fuel exhaustion will be very gradual , may be – 2 or 3 % a year, even less. That’s enough for them to disappear totally after some centuries, but individually, things will just become more difficult or expensive during our lifetime, but not vanish totally. Only our grand children or grand-grand children may not know things like airplanes or cars – but if they never met them, they won’t suffer much from their non-existence.

    So again, which “solution” to which problem ?

  32. 232
    Hank Roberts says:

    > I’m not sure to be quite certain about what is the problem.
    http://www.nature.com/nature/journal/v425/n6956/full/425365a.html

    Everything else will happen, but that’s the fastest and most immediately disastrous.

  33. 233
    Completely Fed Up says:

    “So again, which “solution” to which problem ?”

    The problem of your inability to listen to an argument and make intelligble points.

    Oh, and the problem of CO2 production causing climate change that will at best destabilise and at worst (and likely under BAU) the collapse of our civilisation and our reversion to a rude existence living from hand to mouth.

    The solution is simple to everyone else on the planet: stop producing CO2 from fossil fuels by burning them.

  34. 234
    Gilles says:

    CFU :” the collapse of our civilisation and our reversion to a rude existence living from hand to mouth.

    The solution is simple to everyone else on the planet: stop producing CO2 from fossil fuels by burning them.”

    I don’t think you really listen to what I’m saying. If stopping producing CO2 causes ALSO a collapse of the civilization, how can it be considered as a “solution” to avoid the collapse of civilisation ?
    and where is the scientific assessment that the risk of collapsing through stopping FF is much much lower than the risk of climate change ? where do they have been compared in an objective way, with the same , objective, unbiased tools ? I saw here only wishful thinkings !

  35. 235
    Gilles says:

    “Everything else will happen, but that’s the fastest and most immediately disastrous.”
    The effects of fossil (first oil) depletion are just starting now, and I really think that most people in the world consider them as fastest and most disastrous that the change of the pH of oceans. But I can be wrong, try to check around you ?

  36. 236
    Completely Fed Up says:

    Coastal fishermen in the third world would disagree.

    They don’t use much oil anyway. But they DO fish.

  37. 237
    Hmmm says:

    I was wondering, when you used the reservoir correction, did you take into account the man made lost lakes?

    Lake aral for example will dwarf the biggest man made lakes.

    And when counting the volume of manmade lakes did you use max volume? Or the mean volume in lake?


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