Gavin Schmidt and Michael Mann
Today we witnessed a rather curious event in the US Senate. Possibly for the first time ever, a chair of a Senate committee, one Senator James Inhofe (R-Oklahoma), invited a science fiction writer to advise the committee (Environment and Public Works), on science facts–in this case, the facts behind climate change. The author in question? None other than our old friend, Michael Crichton whom we’ve had reason to mention before (see here and here). The committee’s ranking member, Senator James Jeffords (I) of Vermont, was clearly not impressed. Joining Crichton on climate change issues was William Gray of hurricane forecasting fame, Richard Benedick (a negotiator on the Montreal Protocol on ozone-depleting chemicals), and David Sandalow (Brookings Institution). As might be expected, we paid a fair bit of attention to the scientific (and not-so-scientific) points made.
Many of the ‘usual suspects’ of half-truths and red herrings were put forth variously by Crichton, Gray, and Inhofe over the course of the hearing:
- the claim that scientists were proclaiming an imminent ice age in the 1970s (no, they weren’t),
- the claim that the 1940s to 1970s cooling in the northern hemisphere disproves global warming (no, it doesn’t),
- the claim that important pieces of the science have not been independently reproduced (yes, they have),
- the claim that global climate models can’t reproduce past climate change (yes, they can)
- the claim that climate can’t be predicted because weather is chaotic (wrong…)
and so on.
We won’t dwell on the testimony that involved us personally since the underlying issues have been discussed and dealt with here before, though we will note that comments from both of us pointing out errors in the testimony were entered into the Senate record by Sen. Barbara Boxer (D-California). Instead, we will focus on the bigger picture.
First, let’s be clear where there is agreement. Climate science doesn’t deal in certainties – it deals in probablities and the balance of evidence. We agree with Crichton’s statement that ‘Prediction is not fact’. That certainly doesn’t mean, however, that projections of possible future climate changes are not meaningful or useful, as Crichton claims.
Crichton seemed to imply that “prediction” (such as that provided by weather or climate models) is useless in the decision making process. (As an aside, we wonder how Gray, who is largely known for prediction of hurricane behavior based on (statistical) modeling, felt about this?). We fundamentally disagree. All science is about observation, understanding and prediction. When those predictions work, you make new predictions. When they don’t, you revisit the observations, attempt to improve your understanding of the underlying processes, and make a new prediction. And so on. In the case of climate models, this is complicated by the fact that the time scales involved need to be long enough to average out the short-term noise, i.e. the chaotic sequences of ‘weather’ events. Luckily, we have past climate changes to test the models against. Even more to the point, successful climate predictions have actually been made in past Senate hearings. The figure at the end of this comment by Jim Hansen demonstrates that projections of global mean climate presented in a 1988 senate hearing (17 years ago) have actually been right on the money
Others panelists attempted to combat the onslaught of disinformation. Sandalow sensibly suggested that the National Academy of Sciences be used to inform the Senate on where the consensus of the science is, and Benedick made some excellent points about how legislation can be successful in the face of scientific controversy and uncertain predictions. However, none of that provided as good theater as the other witnesses.
A highlight of the session was Gray making one particular statement that he may be asked to defend (at least financially): “I’ll take on any scientist in this field …. I predict that in 5 to 8 years the globe will begin to cool” (1:10:00 on the video). This would appear to be a direct call to those “global warmers” (see also here, here and here) who are trying to get contrarians to put their money where their mouths are (with very limited success). We eagerly await developments!
Inhofe ended the hearing by declaring his desire to ‘sit back and look at [this] in a non-scientific way’. We think he already has.
Re: 145
Increased cloud cover would result in more reflectivity, but would also result in a greater percentage of heat trapped in the atmosphere. It is unknown, to me at least, how much of each would be the result
I didn’t say anything to the contrary. What I said was that the discussion of feedbacks doesn’t end with “Clapyron”.
Well, to turn the tables on you, Sashka, which peer-reviewed publications have you read? “Energy and Environment” and “World Climate Report” are not peer-reviewed, for your information, so discard those from your list.
Thanks again for your enlightening reading advice. For the record, I’ve never seen a single issue of “Energy and Environment” or “World Climate Report”. The journals that I read include JC, JAS, JPO and JMR. (I wonder if you know what these mean.) May I ask what what are the sources of your wisdom, apart from Sierra Club?
Also, being on the Sierra Club web site does not discredit my arguments
Yes indeed. My arguments would be discredited if I read “industry” journals (which I don’t). But yours cannot be. Brilliant.
which have been made by several highly-touted climatologists in the past (some of whom post on this site from time to time). I was attracted to the Schneider interview because it was of Dr. Stephen Schneider, a climatologist with an impressive publication list.
Unfortunately Gavin doesn’t permit me to reply to this. Tell you what: I also blog on willmott.com. Post a “hello” on this thread: http://www.wilmott.com/messageview.cfm?catid=15&threadid=29176 and I’ll give you an earfull of my unmoderated views.
[Response:See response to #152 -gavin]
Re: #149, “Here: Kyoto is estimated to cost 5 trillion dollars.
http://www.aei-brookings.org/admin/authorpdfs/page.php?id=236
You agree that 5 trillion dollars is draconian, don’t you?”
Not if it saves 10 trillion dollars in property damage, 100,000 lives a year due to drought-induced famine, increased frequency and intensity of severe weather events, or other related incidents.
Also, the leader which you likely support most (Bush) has racked up a 3 trillion dollar debt in his time in office. Do you call that draconian as well?
Re: #151, “Thanks again for your enlightening reading advice. For the record, I’ve never seen a single issue of “Energy and Environment” or “World Climate Report”. The journals that I read include JC, JAS, JPO and JMR. (I wonder if you know what these mean.) May I ask what what are the sources of your wisdom, apart from Sierra Club?”
Yes, I know what those mean. I read some of them (not too familiar with JMR), as well as Int. J. of Clim, Mon. Wea. Rev., Science, Nature, etc.
As for the Sierra Club bit, the ONLY article I have posted on RC is the Schneider interview. I have read seriously only one or two articles from the Sierra Club website, though I support their stands on most issues.
Your sentiments of the Sierra Club smacks of McCarthyism, however. They are a force for good and for the betterment of the planet and bring the public’s eyes and ears to environmental issues.
“Unfortunately Gavin doesn’t permit me to reply to this. Tell you what: I also blog on willmott.com. Post a “hello” on this thread: http://www.wilmott.com/messageview.cfm?catid=15&threadid=29176 and I’ll give you an earfull of my unmoderated views.”
Why should I? If these views are slanderous, I do not want to be exposed to them. Also, the Wilmott site certainly does not have the scientific background that RC has. I will stick with those who can publish their studies in peer-reviewed journals, rather than those who think Michael Crichton is one of the greatest climatological minds on the planet.
As for your constant demands for references, I’ll direct you to this site that has dozens of reports/studies which show conclusively that CLIMATE CHANGE IS HAPPENING!!!
http://www.ncdc.noaa.gov/paleo/recons.html
Get your head out of the sand, Sashka. Read some of these!
[Response: To Steve, Sashka, Dan et al. – The noise level on this thread is mounting rapidly. Please confine future statements to scientific issues (and not each other’s presumed reading or voting habits) and deal with them seriously. There are plenty of places on the web where you can indulge in un-moderated flame throwing – this is not one of them. Be warned, comments that we feel advance the discussion will be allowed, others will not. Play nice now! -gavin]
re #138
You seem reasonably sound and sophisticated, but inexperienced in understanding climate.
I think you raise a lot of points worth discussing. We should address them carefully; it may be a useful exercise for all concerned. However, in short, you underestimate the maturity of the present understanding of climate, and you overestimate the importance of unforced variability. Both of these errors are much promulgated in the so-called “conservative” political literature, so I imagine you are coming at this from an atypical direction. I think throwing pop science at you is a mistake. It will be necessary to formulate arguments carefully. As the ground you propose to examine is not as fertile as you may think, there isn’t a lot of published discussion to draw upon.
In short, though, I think that the interest in unforced variability and in instabilities both in the field and in the general public masks the well-known fact that the time constant for radiative equilibrium of the atmosphere alone is on the order of weeks. The time constant of the upper ocean is perhaps ten years. While the characteristic time scales of the deep oceans, the cryosphere, and the carbon cycle are much longer, the fact remains that these problems are to all appearances separable. This means that whatever the phenomena of climate dynamics may be, the statistics of weather can be understood (roughly and qualitiatively) from a specification of the instantaneous state of the long time scale phenomena.
Now, bringing it back to the particular phenomenology that relates to policy, we really don’t have much time to exercise the long time scale phenomena. There’s a very important caveat. We need CGCMs (coupled ocean-atmosphere models) rather than GCMs (ocean only and atmosphere only models run asynchronously) specifically because of a decadal time scale heat transfer into the oceans. The details of this are work in progress, and there’s (fortunately for me) considerable room for improvement. In practice, there is no sign that this is happening fast enough to hit dynamic predictability limits in the next century. Farther out in time, the complaints that we don’t capture century-scale dynamics may be more relevant, but that’s typically outside the realm of policy debate anyway (although perhaps it shouldn’t be).
We have no a priori reason to expect any given system of the complexity of the climate system to be dynamically predictable on a century time scale, it is true, but we have no a priori reason to expect it to be unpredictable either. In fact, the question is not even well-posed, since the system is a very complex physical one, without a known mathematical representation! The question, however, must have a qualitative answer, and this answer can only come from experience thinking about the system itself.
The answer appears to be that the climate, as meaningfully understood for human impacts, is predictable over a century or two for a given trajectory of primary forcings. It’s not provable, (perhaps it’s not even a formal conclusion), but there don’t seem to be any candidate phenomena that would indicate otherwise. Furthermore, the empirical evidence is reassuring, both in replicating paleoclimates, and in replicating the observational trend over the twentieth century.
All of this is my own opinion of how to describe the situation to a mathematical dynamicist or someone influenced by that school of thought. It’s an informal argument, not published anywhere by me or anyone else as far as I know, and probably not passing muster of peer review. I do think it describes what’s going on (and would welcome informed critiques).
However, let’s consider the implications if that’s all nonsense, and climate is not meaningfully predictable for a century. The conclusion that you appear to take is that therefore no expensive policies should be undertaken to minimize human forcing of climate. This seems to me completely irrational.
It is certainly known that human activity is changing the radiative properties of the atmosphere, and in precisely what degree. Chaos doesn’t enter into the forcing term – it’s classical radiative physics. We also know that this forcing is large compared to natural variability in the forcings. There are various ways to estimate how the system will respond to such forcing. Suppose we grant the possibility that our knowledge of this is weak.
Now, a rational response to a risk is to weigh the probable outcomes with a suitable cost function, and to expend preventively comparably to the risk. If we know a lot about the situation, the risks are well-constrained. If we know relatively less about the situation, it is at least possibly true that the outcome “nothing of any serious consequence happens” may be relatively more plausible. It is also the case that “enormous and cataclysmic changes occur” also become relatively more plausible. In a rational risk-weighting, the outcomes with greater cost dominate the total risk, increasingly as their likelihood is less well-constrained. Therefore, the less reliable the models, the greater the risk-weighted cost of allowing the perturbation to continue to increase. If you don’t believe the models, you ought to be more alarmed, not less.
That we are substantially changing the radiative properties of the atmosphere is not open to sensible dispute. Given that, the argument that “in the absence of further information we should do nothing”, taken to mean “do nothing to the economy” rather than “do nothing to the radiative properties of the atmosphere”, is clearly irrational.
Gavin – please put us all out of our misery and close this thread.
We all need to get a life. Most of all me.
Sashka – since I don’t yet have a life, please await my replies to your many important posts and piquant observations.
– Dan
[Response:See response to #152 -gavin]
Michael,
I question one point in your last post:
“If we know relatively less about the situation, it is at least possibly true that the outcome “nothing of any serious consequence happens” may be relatively more plausible. It is also the case that “enormous and cataclysmic changes occur” also become relatively more plausible. In a rational risk-weighting, the outcomes with greater cost dominate the total risk, increasingly as their likelihood is less well-constrained. Therefore, the less reliable the models, the greater the risk-weighted cost of allowing the perturbation to continue to increase.”
If we take this to a logical extreme, don’t we wind up with the paradoxical proposition that, “if we know nothing at all that is predictive, we should be most willing to invest to thwart the possible catastrophic outcome”?
I think the question of what to do from a policy point of view, to mitigate risk in a situation of uncertain degree of uncertainty, is extremely problematic and far too subtle to expect any government to handle it well. And from that point of view, to be cynical, the whole issue is academic (though still interesting), since however ideally we pose and model the question, the decisions will be sure to be made in the spirit of acrimony, ignorance and irrationality on all sides.
Re: 152
Michael, that was a lot better!
I mostly agree with what you wrote in the first half of your essay (the agrreable part ends with In fact, the question is not even well-posed, since the system is a very complex physical one, without a known mathematical representation!). Again, it is my strong opinion that the post of this nature should have come from the founders but I appreciate your taking time to write it.
The answer appears to be that the climate, as meaningfully understood for human impacts, is predictable over a century or two for a given trajectory of primary forcings. It’s not provable, (perhaps it’s not even a formal conclusion), but there don’t seem to be any candidate phenomena that would indicate otherwise.
It’s not provable indeed but candidate phenomena do exist. There are “known knowns and known unknowns”. The former are represented by the COnveyor belt that can stop any day, for all we know. The example of the latter is whatever cause Medieval Warming and Little Ice Age. Why can’t it happen again beginning tomorrow?
[Response:Economics removed – William]
Well, here are a few thoughts, in the spirit of bipartisanship, regarding costs.
When people the right say, “why should we spend to avert a possible bad outcome, when we dont know very well yet the probability of that outcome.”
The left invariably replies, “isn’t that what we did when we went into Iraq, on the theory of pre-emption of a possible bad outcome, and didn’t we want up spending hundreds of billions, thus far with little to show for it?”
My own feeling is, yes, that is what we did, so I’m not sure why the right thinks preemption was a good idea then but is a bad idea now.
On the other hand, if you are on the left (as I am), and therefore likely think it (preemption when the risk is unknown) was a bad idea then, why is it suddenly a good idea now?
Of course this an oversimplification. One could say (a) Iraq was, at least in intent, about more than just averting a potential bad WMD outcome, and in any case, the probabilities and degree of catastrophe between Iraq WMD and Global warming cannot be compared.
My own view is, (a)if we wind up at the lower end of the IPCC expected warming, maybe we shouldn’t be spending large sums to avert it, whereas if we are likely to land at the high end, the costs miht start to get fairly grave (b) nobody has a very good idea how much it would really cost to avert, or slow, global warming (hope this doesn’t contradict (a)).
If there is acrimony and bias is the GW science debate, I think it is multiplied several-fold in the discussion of costs of averting it versus costs of living with it.
On the other hand, arguably there are policy changes we could make that have no cost. For instance, we could have a revenue neutral increase in tax on burning of fossil fuels – whereby all revenue gains would be offset by tax cuts in other areas. This would serve multiple purposes, of (a) weaning us from dependence on foreign oil and simultaneously depleting terror-exporting countries of their revenue stream, (b) reducing other pollutants besides CO2, (c) encouraging a more gradual and less economically disastrous transition from an economony based on a finite resource, (d) slow global warming, (e) move us in the direction of a VAT tax rather than an income tax (actually, personally I don’t think e is such a great thing, but as many conversative groups favor it, I don’t see why they would oppose a revenue-neutral tax on fossil fuels.
Re: 152
You agree that 5 trillion dollars is draconian, don’t you?”
Not if it saves 10 trillion dollars in property damage, 100,000 lives a year due to drought-induced famine, increased frequency and intensity of severe weather events, or other related incidents.
IF. It’s a huge if. While 5 trillion dollars is a certainty.
Your sentiments of the Sierra Club smacks of McCarthyism, however.
Really? To imply that Sierra Club is not an objective source is McCarthyism? OK, I’m not going to get to this level.
the Wilmott site certainly does not have the scientific background that RC has.
FYI: Willmott is mainly populated by Ph.D.’s in hard sciences.
As for your constant demands for references, I’ll direct you to this site that has dozens of reports/studies which show conclusively that CLIMATE CHANGE IS HAPPENING!!!
I didn’t ask for the references for this. Nor did I ever dispute that climate change is happening? Why are you screaming? Upset that you had to eat your words about lies spun by many climate skeptics?
Re # 147 – Dr. Gray gets paid to forecast and research, not bet. However, will you make your forecast on the temperatures and donate to charity even if he does not respond and if he is correct?
[Response: I don’t get paid to bet either. If I’m risking my money I expect the chance of a corresponding gain – William]
[Response: And Gray made the offer in public… asking how serious that was is a valid inquiry. -gavin]
Re: response to #152, I agree. I was getting too charged up. I should take a less emotional response to this issue, since increased emotion leads to poorly-made arguments. Sorry, guys.
re #156:
I am gratified that you find my posting agreeable until just before what I consider to be my thesis statement. Let me restate it:
“The question [of whether climate is predictable on a century time scale], however, must have a qualitative answer, and this answer can only come from experience thinking about the system itself.”
The climate research community on the whole believes in the predictability of the large features of climate on the century time scale, though possibly not on the millenial time scale or longer.
re #137:
In response to:
>>Climate does not have the attributes that one associates with highly chaotic systems – though there are some feedback loops, so it would be a mistake to claim that it is 100% non-chaotic.
Sashka writes:
But of course it does. Lorenz derived his equations from the same Navier-Stokes equations that any GCM is based upon.
This shows a lack of clarity of thinking about the subject.
The state of the Lorenz system is unpredictable over a sufficiently long time interval; it has chaotic weather. However, the *statistics* of the Lorenz system are not only predictable but static. The shape of the trajectory space does not change. The shape of the trajectory space is the system’s climate.
Its climate is entirely predictable even though its weather is not. Indeed, its climate is changeless.
re #150:
Pat:
>>> Do the latest model simuations by The Max Planck Institute for Meteorology in Hamburg include the carbon cycle?
me:
>> Not to my knowledge. The quoted text gives me no reason to think otherwise.
Sashka:
> Look for references to Archer and Maier-Reimer.
Indeed, since my name is on one of those papers, I am aware of this work. I certainly wasn’t claiming that there are no models of the carbon cycle!
I was trying to state that there are not yet, to my knowledge, 21st century scenario model runs of CGCMs coupled with complete terrestrial carbon cycle models.
CGCM 21st century scenario runs is what the public usually means by “climate models”. The idea that runs of that sort predict carbon as well as climate is a common misperception in public discussions of the science.
[Response: Cox et al (2000)? -gavin]
Re: 161
“The question [of whether climate is predictable on a century time scale], however, must have a qualitative answer, and this answer can only come from experience thinking about the system itself.”
As you correctly pointed out, the problem is not even well-posed. Why must it have an answer? There may be no answer at all. What is “qualitative answer” in this context anyway?
The climate research community on the whole believes in the predictability of the large features of climate on the century time scale, though possibly not on the millenial time scale or longer.
Correct. I only note that the belief is at least partly based on wishful thinking.
The state of the Lorenz system is unpredictable over a sufficiently long time interval; it has chaotic weather. However, the *statistics* of the Lorenz system are not only predictable but static. The shape of the trajectory space does not change. The shape of the trajectory space is the system’s climate.
Its climate is entirely predictable even though its weather is not. Indeed, its climate is changeless.
On the sufficiently long time scale – yes. On a shorter time scale – no. If you define the “climate” time scale in Lorenz model being shorter than typical time between jumps you’ll have a variable climate with 2 states with non-periodic unpredictable time of change.
As you probably noticed, William cut off the part of my post where I challenge your policy/risk analysis. If you like we can take it elsewhere.
I am surprised by the folks who are surprised that congress is calling a science fiction writer to testify and those who think that this sort of thing is peculiarly republican. Both of the major parties now use hollywood types to pitch policies for them. Michael Crichton, whatever his faults, is well above, say, Sean Penn, in terms of both raw smarts and policy relevant knowledge. I seem to recall that Sally Field was once called to testify about farm policy because she had played a farm woman in a movie. I have no idea which party was in charge at the time; both are awful on farm policy so it could well have been either.
The point of hearings of this sort is not knowledge creation, it is entertainment.
Jeff
Thanks, Gavin.
Cox 2000 does indeed report some experiments that fit (albeit a bit uncomfortably) into the category I defined, so I accept the correction, and I appreciate the interesting link.
That said, the CGCM 21st century projections (IPCC scenario runs) typically used in policy discussions do not include a coupled carbon cycle model, though many people seem to think that they do.
“I seem to recall that Sally Field was once called to testify about farm policy because she had played a farm woman in a movie.”
I read that in the 1980s, Sally Field, Jessica Lange, and Sissy Spacek were all invited to testify on farm policy.
And being an environmental engineer (and regular viewer of “60 Minutes”), I definitely remember Meryl Streep being invited to testify on Alar!
http://www.yale.edu/opa/v31.n17/story3.html
P.S. I’ll give everyone two guesses which party invited Ms. Streep to testify on Alar, based on her education and experience in chemistry and toxicology. :-/
Re #158 (Sashka): I read the document you linked to at http://www.aei-brookings.org/admin/authorpdfs/page.php?id=236 and found out that the $5T number you claimed as the cost of Kyoto compliance is not that at all, but is actually Bjorn Lomborg’s quote of Nordhaus’ figure for how much it would cost to pay for global warming-caused damage in the developing world over the course of the current century if nothing were done to impede the warming. Lomborg’s talk was a little incoherent, so I somewhat understand your confusion, but probably it would be best to stick with primary sources for this sort of information. BTW, the point Lomborg was trying to make in quoting the (probably spurious anyway) $5T figure was that it is chump change for the global economy over the course of a century.
RE: #151 Sashka:
Your comments on the Quantitative Finance site Wilmott.com addressing Climate Change do not seem to be any more well received there than those on RealClimate.
Those in the Wilmott Brainteaser Forum, however, seem acceptable to the Wilmott members.
Is your area of expertise in Finance, Climate or Mathematics?
165:
Mark,
Just one point of clarification. Streep did not pretend to be an expert on the science and/or safety of alar. What she said was, to paraphrase, Americans have a right to know what additives are in their food. Silly, yes. I personally don’t care about Ms. Streep’s opinions and they don’t influence mine. But it is far different from Crichton appearing as someone capable of passing judgment on AGW.
Another general point regarding cost – because I think, again, both sides have been guilty of the same oversimplification. Some (not all) lefties have analyzed cost of AGW by simply looking, for example, at harm to existing farms if their climate changed, without regard to the fact that farmers would adapt, choose different crops to grow, etc. Not a very sensible analysis.
But I have also seen quotes of the cost of averting AGW that fall victim to the same oversimplification: that look at what it would cost if we all switched to hybrids, or changed our home heating to an alternative source, without regard to the fact that new tehnologies will be developed to fill demand, cost of hybrids will come down as production scales up, etc. Nobody can really say what averting AGW will cost, because it is not possible to incorporate rate of improvement of technology into an economic model. If fusion reactors become available in fifty years, the ultimate cost will be far less, for example, than if they become available in 200 years, and no model can forecast which is these outcomes is more likely.
Re: 188, responding to belatedly noticed comments by William.
The weather next January is… weather. Not climate.
Sure. However: (1) I was merely addressing Steven’s claim that models correctly reproduce weather statistics; (2) I can rephrase this question. Will the average winter in NY over the next 10 years be mild or cold? This is a climate question to which you have no means to provide a confident answer.
Teleconnections are taken into account in the models. Teleconnections are just atmospheric dynamics.
My point was that those are present in both weather and climate models.
Re: 166
I have to confess that I read the document a while ago and could have mixed up. In this case I apologize. Could anyone post a link to another estimate?
Re: 167
Good points, especially in the 2-nd and 3-rd paragraphs.
re #162:
Sashka,
I would like there to be a moderated venue to discuss economic and policy aspects of this matter. The policy and economic aspects of the problem are, I believe, considerably less well-understood than the physics and chemistry, and dominate the difficulties ahead. However, even if I had the time it is less than clear to me that further discussion with you would be fruitful.
I think your idea that the “climate” of the Lorenz system *may* be (in my opinion peculiarly) defined such that it is changing is not exemplary of reasoned discourse. That interpretation is quite irrelevant.
You appear to understand the definition of climate that I was applying. The usual definition of climate is “the statistical properties of weather”. In this sense, the climate of the Lorenz system is stationary and hence perfectly predictable. Therefore, for entirely reasonable and germane definitions of weather and climate, that system demonstrates that weather may be unpredictable while climate remains predictable, which directly refutes your stated position that the statistical properties of an unpredictable system must necessarily be unpredictable.
I believe that you have the intellectual capacity to understand this. I would appreciate if you were not so stubborn as to refuse to concede the point.
Re #159: I’d be happy to donate to a charity of your choice should temperatures fall or increase at a slow rate, IF you’re willing to donate to a charity of my choice, should temperatures increase above a slow rate. Details here:
http://www.longbets.org/196
Thanks for bringing up this suggestion – I hope you’re interested.
Well, regarding the question of whether climate is / might be chaotic, I would like to lay one last kick into this dead horse.
As most readers of my posts have now discerned, I don’t have a rigorous math background, or even an non-rigorous math background or, for that matter, any math background, or any science background beyond seventh grade frog dissection. Still, I am compelled, as an educated layman, to share a few thoughts, even if they are “not well formed”.
Someone correct me if I’m wrong, but to me the difference between climate and weather can be reduced (with some oversimplification) to different aspects of heat transfer. Weather is all about convection, which, it seems to me, is almost always chaotic. Climate is about radiation and conduction. Shine a heat lamp at an object with an atmosphere (enclosed, for example in a glass case), and the temperature inside the glass will reach an equilibrium based on the amount of heat entering, from the lamp, and leaving, through conduction, into the room (assuming of course the room is kept at a lower temperature). At least, that is how basic thermodynamics have been described in that I’ve read.
The point of equilibrium will of course depend on all of those forcings that are studied in climate – what is in our man-made atmosphere, what is the albedo of the surface of our “planet”, but I have no doubt that an equilibrium will be achieved.
Since these processes, radiation and conduction, are not chaotic, where would chaos come from in climate? The logical candidates are the feedbacks – the ways in which change in climate will influence future change in climate. But I have difficulty seeing how these feedbacks would become chaotic. Is there a point in global warming where albedo would suddenly increase instead of decreasing? Doesn’t seem likely. Would natural CO2 sinks pop up in some unpredictable way, sufficient enough to start reducing the CO2 content of the atmosphere? I just don’t see from what the chaos would arise.
Does this prove that climate is non-chaotic? Certainly not. But if we set up an expectation that one should be able to prove formally that climate is non-chaotic, maybe we are setting up a rather unrealistic, and somewhat unfair expectation. It seems to me that there a many fully accepted tenets of science that have not, and cannot, be formally proven.
Please feel free to correct if I am off-base.
– Dan
[Response: Climate is the statistics of weather (the average, if you want to think of it in simple terms). There is no distinction in terms of processes. Large parts of the world have weather without having convection – William]
Re #170 (Sashka): I’m not aware of much out there besides Nordhaus. But, here’s his web page with recent work: http://nordhaus.econ.yale.edu/recent_stuff.html . There a number of links to pdfs that look like they might fill the bill. It appears he hasn’t done much new work on global warming for several years. For potential other stuff, use Google Scholar; if you’re not familiar with it, once you find a particular study (easy with the author and title) it will give you a list of subsequent published research citing to the study. This allows one to get a pretty good sense of the current thinking in a given area of research. The articles themselves are frequently subscriber-blocked, but normally the abstracts can be viewed. As with the page noted above, Nordhaus and some others I’ve seen have posted their past publications on their own web sites even though many may remain blocked at the publication site.
BTW, I should mention that I don’t find the whole subject of Kyoto costs very interesting since I think that while there will be a global mechanism for reducing GHG emissions in the not very distant future, it won’t have much resemblance to Kyoto. Nonetheless, Kyoto is valuable in terms of establishing international cooperation on solving the problem. From what I can see, and I hadn’t been aware of this, that seems to be Nordhaus’ general view as well.
Further to #171 etc,
Not only is the climate of the Lorenz model easy to understand, it is also simple to predict how it will respond to a variety of “external forcings”, in the form of either a parameter perturbation or direct forcing term in the dynamical equations. Eg see here and here. However the detailed trajectory is unpredictable except in the very short term.
This of course gives the lie to the septic standby “we can’t predict the weather, therefore we can’t predict the climate”. I should emphasise that demonstrating the falsity of that claim was not the specific purpose of the linked papers, indeed I doubt that this particular issue has ever been considered scientifically interesting. That some septics actually try to use this argument only demonstrates the vacuity of their position.
My concerns about human activity causing rapid climate change has led me to have a goal to inform others about this who may not know. However, my ways of communicating this have resulted in much dislike or hatred toward me by those who have chosen to remain indifferent or skeptical. I don’t know if I’ve helped or hurt the goal, and I don’t know if speaking out is worth any effort on my part anymore. Comments?
Re #172 – An interesting question- How will the temperature change be determined? How many years will be used in the calculation? i.e. What is the starting point temperature?
Re #176 (Pat Neuman): It sounds like you may have been free-lancing this stuff, which is tough under the best of circumstances. Resources are available to help. This is way OT so I’ll leave it at that other than to say to look for an email from me.
Re #173 (Dan Allan): Large-scale reasons for the chaos include planetary tilt (= seasons), a high rate of rotation (= major Coriolis effect), much more solar heat applied at the equator than at the poles, unevenly distributed land, air and water, a molten core resulting in tectonic activity including continental drift and volcanos, the occasional hammer from space, a really large satellite creating major tides in addition to minor ones from the sun, plus some stuff I’m probably forgetting. Add all of them together and this planet *sloshes*. Is it sounding like enough of a mess yet? Climate, which is a function of all of these things (and more) is plenty chaotic even without a bunch of monkeys pumping crap into the air and water. Did someone suggest otherwise?
Regarding climate vs. weather, consider a pot of boiling water: It’s chaotic all right, but similar to climate its behaviour can be predicted within certain parameters. Predicting the weather is perhaps analogous to trying to predict the path of a specific steam bubble as it rise from the bottom of the pot. Given some good observations and a suitable model one could hope to do so for a brief distance, but inevitably chaos would take over and we would fail to predict the exact point where the bubble would surface. At the same time, we could observe the boiling and come up with pretty good measures of the overall rate of boiling, the range of the size of steam bubbles, the number that are at the surface at any given point in time, etc., in other words everything that really matters about the pot of water as distinct from the individual bubbles.
Re 178 (Steve Bloom)
I think my situation is similar to what others have to deal with, in part a result of what skeptics Inhofe, Crichton, Christy and Pielke Sr. have said, and in larger part due to what’s not been said, or allowed to be said, by managers of federal and state offices having responsibilities in public safety throughout the U.S. I think it criminal.
[Response:FWIW RP Sr explicitly denies being a skeptic and has said things (can’t find them just now) to make this plausible. That said, I find his insistence on land use and small scale stuff doesn’t help. Christy whilst a sort-of skeptic helpded author the ?AGU? position statement. But C and Rp are both definitely scientists. Neither deserves bracketing with Inhofe or Crichton – William]
Re 180
I forgot to include, Patrick Michaels, a meteorologist of some sort.
William,
I think you may have misinterpreted what I said.
In what I described (176, 180, 181) as “my situation” (as in what I’ve had to deal with in part as a result of what skeptics Inhofe, Crichton, Christy and Pielke Sr. and Michaels have said), … I think Christy and Pielke Sr. do fit with the others (skeptics of GHG driven rapid global warming).
The fact that Christy and Pielke Sr. are scientists allows their skeptical positions on rapid GHG driven global warming to be even harder to deal with when I attempt to inform people that rapid GHG driven global warming is happening and that humans need to act quickly to reduce GHG emissions in order to delay and to reduce the catastrophe that lies ahead due to global warming.
The positions of Christy and Pielke Sr., and other scientists with weak positions on reducing GHG emissions, have been most detrimental in advancing the need to act strongly to reduce GHG emissions from ground and air and power plants.
[Response: I think your position with regard to RP and JC is unreasonable. See [[Roger A. Pielke]] and [[John Christy]]. That said, I don’t much care for JC’s senate testimony… but we’re getting off topic so I shall stop – William]
Re: 171, 175
Once again: I never that statistical properties of an unpredictable system must necessarily be unpredictable. In particular, I never said that climate is unpredictable. What I said was (and Mr. Tobis grudgingly agreed to that above) that there is not and (IMO) there may not be a proof that climate is predictable.
Lorenz was only mentioned to demonstrate the potential for chaos in climate, so a deep discussion is off-topic.
Re 182 correction, should read as …
… need to act strongly to reduce GHG emissions from ground and air travel, and power plants.
Re: 182, 184
The positions of Christy and Pielke Sr., and other scientists with weak positions on reducing GHG emissions, have been most detrimental in advancing the need to act strongly to reduce GHG emissions from ground and air travel and power plants.
You sound as if you want everyone who disagree with your position to shut up.
GHG driven global warming is happening. It doesn’t follow, however, that we need to act either quickly or strongly. I agree with Michael Tobis that the policy and economic aspects of the problem are considerably less well-understood than the physics and chemistry, and dominate the difficulties ahead. My opinion is that we should better focus on adaptation to the inevitable rather than wasting resources trying to stop what cannot be stopped.
The talk about catastrophe that lies ahead due to global warming is no more than fear-mongering. For all we know, the climate change will be gradual. An abrupt change is possible but not very probable. We don’t have any means to credibly assess the probability of abrupt change. Much less can we assess our ability to delay or avoid the catastrophe should the danger be real. The catastrophic scenarios are so far away in the left field that they shouldn’t be even mentioned in a reasonable policy discussion.
Re # 183;
I am responding to the exchange in # 132 and #137, notably
Dan Allan:
>> Climate does not have the attributes that one associates with highly chaotic systems – though there are some feedback loops, so it would be a mistake to claim that it is 100% non-chaotic.
Sashka:
> But of course it does. Lorenz derived his equations from the same Navier-Stokes equations that any GCM is based upon. (caveats apply)
Aside from the caveat at the end, which presumably is not “caveat emptor, the previous claim may be totally invalid” this reply remains fundamentally incorrect.
There’s nothing morally wrong with saying something incorrect, but refusing to be corrected on it is disturbing. It makes me suspect that like so many others who doubt climate science, you are pushing an agenda rather than searching for truth. You may reassure me by withdrawing your claim in #137 quoted above. That will incline me to take discussions with you more seriously.
I will concede, in any case, that there is not a proof that climate is predictable, in most reasonable senses of the words “proof”.
You can only prove statements about a model, not about the world, because the world is not a mathematical abstraction. Even the most robust laws of physics are empirical observations before they are mathematical assertions. There’s a lot more I could say about that, but it’s seriously outside the RC bounds. Let me just sneak in the observation that however great the impact of this problem may be on the value of climatology, it seems to me drastically more severe when applied to economics. Yet a modern society expects its government to make economic decisions all the time, without demanding “proof”.
Re: 185
You are right: it wasn’t a caveat emptor. The caveats applied to the large set of factors that distances a CGCM from Navier-Stokes equations and even further away from Lorenz equations. There is no way to directly map Lorenz’s results onto the climate system. I agree that I made a gross simplification but I disagree that the statement is fundamentally incorrect. If you elaborate on your fundamental disagreement I might reconsider my views under the weight of arguments.
Let me just sneak in the observation that however great the impact of this problem may be on the value of climatology, it seems to me drastically more severe when applied to economics.
I agree.
Yet a modern society expects its government to make economic decisions all the time, without demanding “proof”.
That’s an interesting thought. IMHO, the reason why it is so is that people didn’t enjoy the boom-bust cycles all that much. But I’m not sure how many people expect the government to be right all the time. I guess, not too many.
Whatever the case may be, what is the implication? Had the lack of proof of predictability been the only problem with the proposed mitigation of climate change, I would agree that your argument is pretty strong. But it isn’t. The only reason I brought up the issue of predictability was that Gavin and Michael pretended that there is no issue.
[Response: I don’t recall having made any such statement, but regardless, the proof of the pudding is in the hindcasting. Simulations of the last century and on-the-money forecasts made in 1987 as well as innumerable model evaluation studies of the response to volcanic or solar forcing demonstrate empirically that some quantities in climate are indeed predictable (given a reasonable knowledge or estimate of the forcings). The clearest quantity with some apparent predictability is the global mean temperature anomaly, where the chaotic (unpredictable) component appears to be much smaller than the forced (predictable) one. -gavin]
Re: #185, “You sound as if you want everyone who disagree with your position to shut up.”
This is untrue, except that, by adding the element of confusion to the mix (which most skeptics do well), progress to find environmentally-friendly alternatives to high-polluting infrastructure and industries (such as coal-fired power plants and Hummers) is slowed due to political inertia.
“For all we know, the climate change will be gradual.”
This has been true in the past, but at the present, it is not. The IPCC’s estimates of temperature increase over the course of the 21st Century (1.4 C to 5.8 C as of the 2001 report) are at least more than double (and almost 10 times at the upper end) the rate of increase over the 20th Century.
This would result in an exponential rate of increase, which cannot be called “gradual” in the least.
“It doesn’t follow, however, that we need to act either quickly or strongly.”
Why do you say this? If the bulk of the evidence is present that says a business-as-usual scenario will result in this exponential rate of temperature increase, then we must find ways to reduce this increase.
The possible biological effects of this temperature increase are staggering, such as the loss of millions of species and desertification of land (which will reduce the ability of this planet to feed the species, including other humans, which call it home). If we fail to do anything (not even including something drastic) to combat this possible calamity, we as a species should essentially be charged with a sort of negligence causing genocide.
Also, since when is proof mandatory to change one’s way of life? If there is a chance that you could develop cancer by eating too many hamburgers (for example), you may decide to reduce the number you eat to minimize the risk. If there is a chance you may become diabetic from drinking large quantities of soft drinks, you may reduce (even eliminate) the amount of soft drinks you consume to minimize the risk. Waiting until you get cancer or become diabetic from maintaining a high-risk lifestyle before you make changes is a foolish way of living.
This scenario is similar to the climate change issue. If there is a chance that whole ecosystems will die, and since we as (supposedly) intelligent beings (apparently) have the ability to effect ecosystem-friendly changes to our lifestyles, it is almost suicidal not to change anything and let these vital regions die before we actually do anything.
“The catastrophic scenarios are so far away in the left field that they shouldn’t be even mentioned in a reasonable policy discussion.”
Ummm. Remember the Pentagon report? That was far from being in “left field.” Even some Neo-Conservatives and some members of the Christian Right (both of whom I normally do not agree with) are saying we must invest in renewables to allow for a healthy environment and to reduce America’s dependence on Middle-Eastern oil (reducing the monies available to Islamic Fundamentalists).
Re: 187
Gavin, I was referring to the last bullet point in your and Michael original article. You countered Crichton’s claim regarding unpredictability with a joke.
I don’t find the simulations of last century convincing until the success of the simulation is quantified. To my eye, the simulated interannual variability [define it as Sum(delta_T^2) in the detrended time series] is way below observed. I’m not sure therefore how you can say that unpredictable component is much smaller than forced.
Again and again: I don’t deny that the climate is predictable on the decadal time scale and possibly even longer. I objected to trivializing a non-trivial issue.
[Response: The tired claim that ‘weather isn’t predictable therefore climate can’t be’ is quite well countered by satire as in the link we gave. How predicitable climate actual is and on what timescale is a much more serious issue and one that we certainly don’t trivialize. Possibly you assumed that we implied that ‘weather isn’t predictable, therefore climate must be’? – this clearly does not follow and does not represent our thinking. Since we are all now agreed, maybe we can move on? -gavin]
Re #185 (Sashka): You wrote:
“The talk about catastrophe that lies ahead due to global warming is no more than fear-mongering. For all we know, the climate change will be gradual. An abrupt change is possible but not very probable. We don’t have any means to credibly assess the probability of abrupt change. Much less can we assess our ability to delay or avoid the catastrophe should the danger be real. The catastrophic scenarios are so far away in the left field that they shouldn’t be even mentioned in a reasonable policy discussion.”
I have to disagree. There’s already a body of work on many aspects of this, with some pretty considerable additional research going on. Part of the problem is semantic: “Abrupt” and “catastrophic” are inavoidably subjective terms, although the former is a bit more prone to definition (e.g., any change of climate state involving a rapid transition from one state to another, although of course we then have to further define “rapid” and “climate state”). Some conflate them entirely (as you seem to have done above), which is understandable but not very helpful to advancing the discussion. As well, a catastrophic change could easily be gradual (in human terms, anyway).
Just to throw out a few examples:
Artic sea ice summer disappearance: Abrupt (human scale), perhaps not catastrophic unless you’re an Inuit or a polar bear (and yet antother definitional problem appears). (Oh, and the models predicted this one as part of the package of overall Arctic warming.)
Greenland melting: Abrupt (geologic scale, but short), arguably catastrophic.
West Antarctic Ice Sheet melt: Like Greenland, only bigger.
East Antarctic ice sheet: Abrupt (geologic, but still shortish), absolutely catastrophic (even over centuries; 70 meters covers an awful lot of arable land and infrastructure, and there’s no guarantee that the remaining dry land will be an Eden).
Permafrost melt: Abrupt (human scale), locally catastrophic for sure and maybe globally depending on the consequences of the methane pulse. Already happening (although the extent is still unclear).
Clathrate melting: Potentially abrupt (scale less certain here, and would depend greatly on depth of melt), potentially very catastrophic. This may be our best way of melting East Antarctica.
Tibetan plateau melt: Abrupt (human scale), catastrophic if you’re one the 50% of the human race living in that watershed, or live someplace they may wish to migrate to. Already happening, probably to the point of complete melting.
Sierra snow pack reduction or elimination: Abrupt (human scale), not especially catastrophic if you’ve got $50 billion or so in loose change laying around to completely rebuild the CA water infrastructure. This is of course a minor impact compared to most of the others. Enjoy your vegetables while they’re cheap!
Notice that these all involve melting, which raises the issue of synergies between them. Up north, things seem to be melting rather quickly at the moment: http://paos.colorado.edu/~dcn/reprints/Overpeck_etal_EOS2005.pdf , plus some up-to-the-minute info at http://nsidc.org/news/press/20050928_trendscontinue.html and http://cires.colorado.edu/science/groups/steffen/greenland/melt2005/ .
And last but not least:
Ocean acidification: Abrupt (human scale), catastrophic if you’re a fish, a plankton, a coral, or anything that eats them or depends in any way on ocean ecosystems. Otherwise, no problem. :)
Not all of these are already committed to, but as noted some are. Others will happen to a degree, some maybe not at all, or maybe all of them will. How much of the future are we willing to bet on the assumption that there’s no problem at all?
Re: 188
By gradual I meant non-catastropic. Gradual is not the same as small.
If the bulk of the evidence is present that says a business-as-usual scenario will result in this exponential rate of temperature increase, then we must find ways to reduce this increase.
That’s fine as long as this reduction can be shown to be meaningful (beyond uncertainty) and at reasonable cost compared to the expected results.
Also, since when is proof mandatory to change one’s way of life?
We are talking about policies that will be in effect for decades at huge expense to the taxpayer. It’s not one’s way of life. A lot more is at stake.
Remember the Pentagon report?
I don’t care about Pentagon’s views on climate change. And I wholeheartedly support investing in renewables.
This may seem like a minor point, so I explain my purposes in its dogged pursuit below.
Dan Allan:
>> Climate does not have the attributes that one associates with highly chaotic systems – though there are some feedback loops, so it would be a mistake to claim that it is 100% non-chaotic.
Sashka:
> But of course it does. Lorenz derived his equations from the same Navier-Stokes equations that any GCM is based upon. (caveats apply)
and:
> There is no way to directly map Lorenz’s results onto the climate system. I agree that I made a gross simplification but I disagree that the statement is fundamentally incorrect.
Your “but of course it does” is simply incorrect. “A gross simplification” is backpedaling, which to me is not good enough. I want a simple, straightforward admission of error.
A reasonable reply would be “I’m sorry, I was confused. It’s certainly the case that the Lorenz system has a predictable climate. Therefore it offers no support for the assertion that the realistic climate system ‘of course’ is chaotic, and I withdraw any implication that it does.”
It really isn’t much to ask in scientific circles. Scientists don’t much like to say things in print, though it’s not unheard of. In conversation, though, it comes up regularly. “You’re right, I was confused, thanks.” It’s becoming a lost art in the rest of society.
Politicians just try to change the subject, usually, and rarely admit to an error. (One’s predatory opposition can be expected to indulge the horrifying predatory habit of mindlessly siezing on this sort of thing as “flip-flopping”, after all.)
Certainly the naysayers are almost entirely political these days. One so misses the days when an actual conversation with someone open-mindedly skeptical of the climate change problem was possible that one tries to engage anyone who seems articulate. In the end they, almost without exception, turn out to be much more like lawyers marshalling points to support their argument than like scientists testing their argument by focusing on its weaknesses. This would be awfully tedious and enervating if it weren’t, given the circumstances, so terrifying.
So, Sashka, are you interested in deciding what an optimum policy would be in the light of climate science, or are you here to defend your idea of the optimum policy, whatever the science might say? That you won’t fully admit to even a minor, unambiguous error gives me the impression that you have no intention of admitting anything. If so, this means you and I are playing different games, and we can each win the argument by our own lights.
Unfortunately, it seems that any decision makers are so interested in the political game that they seem to have forgotten that the more civilized and interesting one even exists.
Re #177: I’m happy to use the methodology in the bet James Annan made with the Russian climatologists. Details here:
http://julesandjames.blogspot.com/2005/08/bet.html
If you’re serious about this, contact me by clicking on my name or through the longbets.org link, and we can start arranging details off-line.
Re 185
Comment by Sashka … > My opinion is that we should better focus on adaptation to the inevitable rather than wasting resources trying to stop what cannot be stopped.< Sashka, Adding more rain to a river basin where rivers are already rising will cause the rivers to go over their banks sooner than if the rain had stopped or was reduced. Adding more GHGs to a global climate that is already heating up will make the very hot come sooner. By reducing GHGs, millions of people would suffer less during their lifetimes. Reducing GHG emissions as much as possible is the right thing to do.
Re: #191, “By gradual I meant non-catastropic. Gradual is not the same as small.”
Gradual: 1. taking place or progressing by degrees; 2. not rapid or steep.
How can you use a word for which your meaning has no relevance? That makes absolutely no sense whatsoever!
“We are talking about policies that will be in effect for decades at huge expense to the taxpayer. It’s not one’s way of life. A lot more is at stake.”
How could it be a “huge expense to the taxpayer” if the taxpayer would not have to shell out $4 (US) per gallon and up for gasoline? I’d think of it as a huge savings to the taxpayer if they wouldn’t have to shell out a high price for gasoline for their gas-guzzlers and for heating oil for their houses. Sure, buying a hybrid that goes 70 mpg costs a bit of an arm and a leg right now, but over the long run, the savings on gasoline will more than make up for this initial cost.
“I don’t care about Pentagon’s views on climate change.”
My point was that not only people on the left of the political spectrum are conservationists in nature. Some segments of the right are, as well.
Re 185 Should read…
Adding more rain to a river basin where rivers are already rising will cause the rivers to go over their banks sooner than if the rain had stopped or was reduced. Adding more GHGs to a global climate that is already heating up will make the very hot come sooner. By reducing GHGs, millions of people would suffer less during their lifetimes. Reducing GHG emissions as much as possible is the right thing to do.
Re: 190, 195
I acknowledge that sematics need to be clarified. Indeed, when I said catastrophic I meant abrupt. I don’t think this is an uncceptable usage and it was my impression that Pat Neuman meant it that way.
However, I’m willing to use your definition. I’ll accept, for the purposes of this discussion, that at some – highly uncertain – time in the future some of the “catastrophic” melting events will indeed take place due to the GW. Questions:
1. How do we know that we can substantially delay or stop them?
[Response: Economics deleted – William]
Re: 192
Michael, I made no error at all. Atmospheric dynamics are governed by Navier-Stokes equations (plus thermodynamics + atmospheric chemistry + Coriolis force etc. – those were the caveats). Lorenz derived a simplified system from Navier-Stokes equations and showed it to be chaotic. Therefore climate does have attributes of chaotic system, contrary to what Dan Allan claimed. Q.E.D.
Now, your claim about stationarity of the “climate” in the Lorenz system is not without a merit but hinges on the selection of the time scale. Either way, your point has no bearing on the Earth climate because clearly the system has multiple time scales some which are a lot longer than any time scale that can be reasonably associated with climate.
Certainly the naysayers are almost entirely political these days.
And so are the yeah-sayers. I didn’t really utter much of “nay” before I was accused of being a McCarthyst, no less.
Sashka, are you interested in deciding what an optimum policy would be in the light of climate science, or are you here to defend your idea of the optimum policy, whatever the science might say?
If you found me in denial of something that climate science proved beyond reasonable doubt please point me in that direction. For lack of such pointer, consider your question answered.
I took liberty of sending you a personal e-mail because the relevant post of mine didn’t appear on this page.
Re #197 (Sashka): Thus we get to the crux of the problem: How much are we willing to pay now to avoid these future problems? The response implicit in your answer seems to be “not much” absent a degree of certainty that science probably can’t provide for the simple reason that we haven’t been able to observe such events before; i.e., we’re running the experiment now. Some of these changes are a bit more prone to prediction than others, but there will still be some uncertainty about the exact amount of GHGs over what period of time will be needed to make them happen and about the implications of each change. The problem is that by the time uncertainty is eliminated we will have very few options. But just out of curiosity, how much certainty would it take to convince you?
I should add that the semi-destruction of New Orleans by Katrina (at a cost of how many billions?), despite the fact that it was known for decades that a relatively small investment in the levees could have forestalled most of the damage from at least this storm, is a good example of our society’s ability to deal with this sort of problem. This example raises an interesting point, which is that the uncertainty regarding a major hurricane hitting New Orleans was only in the timing and our society still decided it had other priorities for the money. An even worse example of this is the Chinese deciding to rely more and more on coal despite the probably-horrific consequences of losing the Tibetan plateau glaciers, although in that case they can probably be confident that it will be at least a generation before things start getting bad (and of course the Chinese plants are only part of the problem).
(BTW, I just saw a paper in GRL [abstract below] indicating that in addition to the problem of water supply disruption from the lack of a Tibetan glaciers cap, climate change makes the Indian subcontinent vulnerable to flipping into a stable dry state. Other research indicates that the loss of the ice should make the monsoon wetter, though. More uncertainty, I guess.)
GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L15707, doi:10.1029/2005GL022771, 2005
Is the Indian summer monsoon stable against global change?
K. Zickfeld
Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany
B. Knopf
Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany
V. Petoukhov
Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany
Oboukhov Institute for Atmospheric Physics, Moscow, Russia
H. J. Schellnhuber
Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany
Tyndall Centre for Climate Change Research, Norwich, UK
Abstract
The stability of the Indian summer monsoon is investigated by means of a box model of the tropical atmosphere. At the heart of this model is the moisture-advection feedback which allows for the existence of two stable regimes: besides the â??wetâ?? summer monsoon, a stable state exists which is characterized by low precipitation. The model is employed for the identification of changes in the qualitative systems behavior in response to changes in boundary conditions. The most notable result is the occurrence of saddle-node bifurcations against changes in those quantities which govern the heat balance of the system, i.e., the planetary albedo, the insolation, and the CO2 concentration. These findings are remarkable insofar as they indicate that anthropogenic perturbations of the planetary albedo, such as sulphur emissions and/or land-use changes, or natural variations in insolation and CO2 concentration could trigger abrupt transitions between different monsoon regimes.
Received 23 February 2005; accepted 8 July 2005; published 9 August 2005.
re 198:
Shash,
A couple of points: I never made a categorical claim that all climate was nonchaotic. My statements were qualified. For example: “Climate does not have the attributes that one associates with highly chaotic systems – though there are some feedback loops, so it would be a mistake to claim that it is 100% non-chaotic”.
I think the question is the magnitude of the chaotic effect: if it so small as to be far below the signal level, that isn’t really very consequential, is it? Indeed if weather is chaotic – which we all agree on – than it seems certain that, just by virtue of the two ends of a thirty-year time slice being effected by one day’s worth of “weather” climate in some tiny way is also chaotic. But I don’t see how this effect is of the slightest consequence, ultimately.
An additional point is the one Gavin made: the models, as is shown in graph c in the article, are able to reproduce past climate pretty darn well via direct (non-chaotic) reactions to forcings. This is evidence to me of what already seemed to make sense logically: that chaotic effects in climate generally are quite small. I know that you will dispute my interpretation of this graph, and claim that the models were built by a sort of trial-and-error to fit the historical forcings / temperatures. But we will have to disagree on that point.
One other point: I thought you agreed with Michael, earlier, when he said that the question of whether climate is chaotic is, technically speaking, not well-formed mathematically, and therefore cannot be answered one way or the other precisely. Yet now you have, apparently, *proven* that it is chaotic in spite of this.
William – sorry if I’m being dense – where on the planet is there no convection? (your reply to 173). If temperature were uniform and there was no therefore convection, would there be wind? precipitation?