RealClimate logo


Technical Note: Sorry for any recent performance issues. We are working on it.

What do climate scientists think?

Filed under: — gavin @ 24 June 2010 - (Español) (English)

by Gavin and Eric.

… and why does it matter?

There is a lot of discussion this week about a new paper in PNAS (Anderegg et al, 2010) that tries to assess the credibility of scientists who have made public declarations about policy directions. This come from a long tradition of papers (and drafts) where people have tried to assess the state of the ‘scientific consensus’ (Oreskes, Brown et al, Bray and von Storch, Doran and Zimmerman etc.). What has bedevilled all these attempts is that since it is very difficult to get scientists to respond to direct questions (response rates for surveys are pitiful), proxy data of some sort or another are often used that may or may not be useful for the specifics of the ‘consensus’ being tested (which itself is often not clearly defined). Is the test based on agreeing with every word in the IPCC report? Or just the basic science elements? Does it mean adhering to a specific policy option? Or merely stating that ‘something’ should be done about emissions? Related issues arise from mis-specified or ambiguous survey questions, and from the obvious fact that opinions about climate in general are quite varied and sometimes can’t easily be placed in neatly labelled boxes.

Given these methodological issues (and there are others), why do people bother?

The answer lies squarely in the nature of the public ‘debate’ on climate. For decades, one of the main tools in the arsenal of those seeking to prevent actions to reduce emissions has been to declare the that the science is too uncertain to justify anything. To that end, folks like Fred Singer, Art Robinson, the Cato Institute and the ‘Friends’ of Science have periodically organised letters and petitions to indicate (or imply) that ‘very important scientists’ disagree with Kyoto, or the Earth Summit or Copenhagen or the IPCC etc. These are clearly attempts at ‘arguments from authority’, and like most such attempts, are fallacious and, indeed, misleading.

They are misleading because as anyone with any familiarity with the field knows, the basic consensus is almost universally accepted. That is, the planet is warming, that human activities are contributing to the greenhouse gases in the atmosphere (chiefly, but not exclusively CO2), that these changes are playing a big role in the current warming, and thus, further increases in the levels of GHGs in the atmosphere are very likely to cause further warming which could have serious impacts. You can go to any standard meeting or workshop, browse the abstracts, look at any assessment, ask any of the National Academies etc. and receive the same answer. There are certainly disputes about more detailed or specific issues (as there is in any scientific field), and lots of research continues to improve our quantitative understanding of the system, but the basic issues (as outlined above) are very widely (though not universally) accepted.

It is in response to these attempts to portray the scientific community as fractured and in disagreement, that many people have tried to find quantitative ways to assess the degree of consensus among scientists on the science and, as with this new paper, the degree of credibility and expertise among the signers of various letters advocating policies.

It is completely legitimate to examine the credentials of people making public statements (on any side of any issue) – especially if they make a claim to scientific expertise. It does make a difference if medical advice is being given by a quack or the Surgeon General. The database that Jim Prall has assembled allows anyone to look this expertise up – and since any new source of information is useful, we think this can be generally supported. Prall’s database has a number of issues of course, most of them minor but some which might be considered more problematic: it relies on citation statistics, which have well-known problems (though mostly across fields rather than within them), it uses Google Scholar rather than the standard (ISI) citation index, and there are almost certainly some confusions between people with similar names. Different methodologies could be tried – ranking via h-index perhaps – but the as long as small differences are not blown out of proportion, the rankings he comes up with appear reasonable.

So it is now possible to estimate an expertise level associated with any of the various lists and letters that are out there. Note that it is worth distinguishing between letters that have been voluntarily signed and lists that have been gathered with nothing but political point scoring in mind (the Inhofe/Morano list was egregious in its cherry picking of quotes in order to build up its numbers and can’t be relied on as an accurate reflection of peoples opinions in any way, and similarly contributing to RealClimate is not a statement about policy preferences!). Additionally, it isn’t always clear that every signatory of each letter really believes every point in the statement. For instance, does Lindzen really believe that attribution is impossible unless current changes exceed all known natural variations (implying that nothing could be said unless we got colder than Snowball Earth or warmer than the Cretaceous or sea level rose more than 120 meters….)? We doubt it. But as tests of political preferences, these letters are probably valid indicators.

So, do the climate scientists who have publicly declared that they are ‘convinced of the evidence’ that emission policies are required have more credentials and expertise than the signers of statements declaring the opposite? Yes. That doesn’t demonstrate who’s policy prescription is correct of course, and it remains a viable (if somewhat uncommon) position to acknowledge that despite most climate scientists agreeing that there is a problem, one still might not want to do anything about emissions. Does making a list of signers of public statements, or authors of the IPCC reports, constitute a ‘delegitimization’ of their views? Not in the slightest. If someone’s views are widely discounted, it is most likely because of what they have said, not who they sign letters with.

However, any attempt to use political opinions (as opposed to scientific merit) to affect funding, influence academic hiring, launch investigations, or personally harass scientists has no place in a free society – from whichever direction that comes. In this context, we note that once the categorization goes beyond a self-declared policy position, one is on very thin ice because the danger of ‘guilt by association’. For instance, one of us (Eric) feels more strongly that some of Prall’s classifications in his dataset cross a line (for more on Eric’s view, see his comments at Dotearth).

But will this paper add much to the ‘there [is/is not] a consensus’ argument? Doubtful. People are just too fond of it.

But there really is.


427 Responses to “What do climate scientists think?”

  1. 351
    Gilles says:

    “Great, Gilles, now go publish a paper based on this 5 sigma signal.”

    well ..like this one for instance ???

    http://arxiv.org/abs/1006.5289

    (actually it is 5.6 sigmas…)

    let me be clear again : my point was NOT that you require 5 sigmas or more with respect to some background variation. It is that you require 5 sigmas or more (if you want to be “sure” ) with respect to some uncertainty. IF you know precisely enough the background (which is no more a background “noise” but rather a background “signal”) , and that you can confidently substract it, it’s ok. BUT you must at least justify that you are confident in the value of your background.

    Of course Fig 9.5 doesn’t tell anything else. The blue curves “without anthropogenic influences” are displayed precisely for this very reason : as the variation, in itself, does not clearly exceed the preindustrial variability , the attribution can be done only by substraction with a supposed “known” background, which is NOT supposed to be fully noisy (it is thus more a systematic uncertainty than a statistical one).

    So the difference is accurately determined ONLY at the level at which the background is well determined – I don’t think that IPCC redactors would contradict me. But the burden of the proof is then transferred to how to justify how well the “natural background” is known. I don’t think that is such an obvious task – of course it is the result of GCM but the problem is how to validate the result WITHOUT the anthropogenic signal since the actual signal is really a combination of both…

    Very honestly, for instance, if I were asked how well the curves fit the 1900-1950 signal, without knowing anything of what is displayed, just “blindly”, I would probably say (at least I think so) : aheem… not so well.

    I try to be very honest in giving this answer, forgetting that I actually know what it is about, and trying to answer like a normal scientist on a ideology-free issue. I think I would answer that on a number of objective reasons :

    * the average slope before 1940 is not very well reproduced

    * the break is not at the right date : there is no theoretical break around 1940 where the observations obviously seem to break , and there is no clear observed feature around 1963 (Agung explosion) where the model break – actually none of the volcanic eruptions shows a distinctive feature, as significative as in the models.

    * it is a rather strange thing to compare the observations with a set of models, or even an average. Usually you compare them to the best one. Comparing to a set of model broadens the span of results and give an impression of agreement “within the error bars”, but actually none of the model (nor the average) seems to provide a really satisfactory fit. And there is an obvious selection effect that on average, the selected published models will be close to the observations, but that the disagreements may more or less cancel statistically : I wouldn’t be surprised if ON AVERAGE, astrological predictions would be shown to give a reasonable rate of various catastrophes, earthquakes,

    and so on …

    So you can argue as much as you want about the inaccuracy of SST measurements, the possible influence of ill-know aerosols or the influence of WWII, and so on…. But I’m only answering a “blind” question about a figure (which I’m totally unaware of how it has been obtained).

    Furthermore if you add the knowledge that models have been “recentered” to fit exactly the average value of the 1900-1950 period, so that the agreement of the average is granted from the beginning, the overall quality of the fit is even more questionable – Note that if it is in the IPCC report, it is probably the best that modelers can produce.

  2. 352
    Gilles says:

    georg :Your example illustrates a case for which 100% (as good as makes no difference) certainty would be insuffient. Why point this out?”

    My point was only that scientific issue of quantifying the likelihood of some quantitative parameter is very different from the issue of whether we should act or not – the latter implying many more considerations that the purely scientific facts. I just gave this example as an illustration : actually the number of casualties , and more the amount of QALYs suppressed by the car crashes are probably the most expensive human cost associated to the use of fossil fuels – although I seldom hear people advocating their suppression just because of that ! usually people ask only for hybrid or electric cars, which wouldn’t solve this issue of course. So it seems that the hundred of millions of foreseen victims in the next century due to car crashes do not count as much as polar bears …

  3. 353
    flxible says:

    car crashes are probably the most expensive human cost associated to the use of fossil fuels – although I seldom hear people advocating their suppression just because of that

    Maybe most juridstictions have mandatory insurance laws because they’ve recognized that risk? Let’s consider the risks of continued FF burning without restriction – maybe we should have some insurance? Note that actual property insurance entities are increasingly avoiding weather related risks.

  4. 354
    Brian Dodge says:

    Back in the early days of electronics, DC power supplies were often filtered but not regulated. The residual power supply ripple would couple into the amplifier chain, resulting in low frequency noise – “hum” – which would interfere with the signal(s) of interest. To be technically more accurate, this hum isn’t noise per se, but an interfering signal; however, random Gaussian noise, pink noise, thermal noise from hot filaments in tube amps, resistor shot noise, and interfering signals from power line pickup, or radio frequency interference from motor brushes, or arc welding, or cell phone towers – all reduce the detectable signal in electronics.
    A. If the signal of interest (e.g. audio) and the interfering “noise” (e.g., cell phone rf) are at sufficiently different frequencies, the “noise” can be removed by low pass filtering.
    B. Since the source of hum in many early electronic amplifiers was well known and quantified -power supply ripple- it was often removed as “noise” by introducing a scaled amount of the ripple into the amplifier chain so as to cancel its effect at the output.

    We can apply the same principles as A to warming caused by CO2 – see [1]; you can see the effect of lowering the passband by increasing the mean samples number in series 3. The limit in low frequency is shown by series 4, whereby all high frequencies are mathematically eliminated, leaving only the expected signal.

    We can also apply the same principles as B to warming. If we detrend HadCRUT, analogous to removing the DC leaving only the power supply ripple, and subtract this (ENSO, PDO, AMO, SSN, Pinatubo, etc) “hum” from the signal+noise of UAH temperature measurements, we can also improve our Signal to Noise Ratio.[2][3a] If we take as our definition of SNR as being equal to the expected signal(OLS range) divided by the standard deviation of the residual[4], the SNR is 3.5. if we remove high frequency noise by 6 month smoothing, essentially leaving seasonal or longer differences but removing short term(e.g.monthly) noise, the SNR rises to 5.1. We also expect from the physics of CO2 infrared absorption and radiation that temperatures would rise proportional to the log of the increase in CO2 concentration. [3b]

    [1] http://www.woodfortrees.org/plot/hadcrut3vgl/from:1900/plot/esrl-co2/scale:0.008/offset:-2.6/plot/hadcrut3vgl/from:1900/mean:36/plot/hadcrut3vgl/from:1900/trend
    [2] http://www.woodfortrees.org/plot/uah/from:1980/plot/esrl-co2/scale:0.008/offset:-2.6/from:1980/plot/hadcrut3vgl/from:1980/detrend:0.487308
    [3] http://www.imagenerd.com/uploads/snr_t_co2_correlation-ceSt1.jpg
    [4] http://en.wikipedia.org/wiki/Signal_to_noise_ratio

  5. 355
    Pete Wirfs says:

    I work for an insurance company. We are constantly re-computing our risk factors based upon the latest empirical data. When the real world changes (highway speed limits, etc.) the results of these computations change and are reflected in the premiums we charge. So our customers are financially bound to predictive calculations that are based upon empirical data. If you choose to purchase a risky vehicle, that choice will be reflected in your premium.

    This is a pretty good analogy to Climate science, except we have yet to assign a financial cost to human decisions that increase our risk. When I drive my vehicle across a bridge I don’t think about the taxes I paid to maintain that bridge. Mankind is now being asked to consider thinking about paying extra for the health of earths infrastructure.

    And don’t forget this popular video regarding global warming risks;
    http://www.youtube.com/watch?v=zORv8wwiadQ

    Pete

  6. 356
    David B. Benson says:

    Brian Dodge (355) — Nice. My filter
    http://www.realclimate.org/index.php/archives/2010/03/unforced-variations-3/comment-page-12/#comment-168530
    is fairly crude, adequate for 13 decaes of data.

  7. 357
    Ray Ladbury says:

    Gilles, The thing you are ignoring is that the character of the signal and that of the noise are very different. The noise is all pretty much short timescale, while the signal persists for decades–or even millennia. That is why we know the role of CO2 in the climate so well–a long-lived, well mixed greenhouse gas stands out like a sore thumb.

  8. 358
    Patrick 027 says:

    Gilles – also note that global average surface temperature is only one of many variables that can be modelled, observed, and analyzed.

  9. 359
    Gilles says:

    358 : Ray : I don’t ignore it, but i don’t know if it is true or not. And that’s precisely the question I asked. Saying that the low frequency noise is much lower than the high frequency means that you have an idea of its power spectral distribution (a blue noise in this case). But it would have exactly the consequence that I said : the natural, preanthropogenic variability at the relevant time scale (decades , centuries , millennia ) , which is precisely related to the amplitude of the FT at this frequency, should be much lower than the observed signal. And it should produce precisely what I said : a modern variation significantly (several sigmas) higher than the previous, natural one, averaged on this relevant time scale. This is all the same criterion, expressed in different manners.

    So your claim is that you KNOW that the level of noise at this relevant scale is much lower than the observed modern variation – my only question is , how do you know that ?

    [edit]

  10. 360

    Bill 346,

    Try looking at the global average, for God’s sake.

  11. 361
    Hank Roberts says:

    > Bill
    > Many mid-USA temp data sets show the same picture as the CET

    Bill, see the Start Here link at the top of each page, and the first link under Science at the right sidebar.

    You’re new; you haven’t read the basic information; you have not taken a statistics class. So you’re repeating one of the elementary mistakes people make, either because you thought of it yourself or read it somewhere else and brought it here thinking it was a clever idea.

    There’s no shame in being fooled once. There’s a big business in fooling people all the time.

    Don’t be fooled again.

    Read the basic Start Here information, and get a basic understanding why you can’t pick numbers happen to like out of a large collection. It’s often called “cherrypicking” — as in picking only the ripe ones off the tree leaving the rest.

    Once you’ve taken Statistics 101, you’ll understand why this is a classic fail. Until then you need to find someone you trust to help you.

    If you’re trusting someone who’s telling you it’s smart to pick just a few numbers out of a large collection — you’re being fooled.

  12. 362
    Gilles says:

    359 Patrick : Of course. My question holds for ANY parameter. Including local ones, since apart from climate scientists and RC readers, most people are only sensitive to what happen around them, not to global averages.

    Of course I wouldn’t deny that they are many local parameters whose variation over 100 years has been much larger than at any other epoch , a lot of sigmas higher, and first demography, with all consequences on land use, pollution, and so on… I wouldn’t swear local temperature is among them.

  13. 363
    Ray Ladbury says:

    Gilles, So YOU don’t know, and therefore you assume nobody else does?

    Have you met the good doctors Dunning and Kruger?

    Gilles, that is what Tamino does. I would recommend perusing some articles at his place. JUST READ. Tamino has a very low BS tolerance threshold, and if you aren’t careful, you could become the subject of a post rather than a commenter.

  14. 364

    RE those that responded re Hansen (#244), thanks for your info. I couldn’t really imagine there was anything to it….

    RE #244 (John Pearson) & “Lynn I expect your poster was wearing “the juice”: http://opinionator.blogs.nytimes.com/2010/06/20/the-anosognosics-dilemma-1/?scp=1&sq=%22the%20juice%22&st=cse

    Liked that “too stupid to know one is stupid” thing. I was discussing “A BEAUTIFUL MIND” with a friend just today, and in that case, which is sort of opposite, the brilliant mathematician, with help from others, was so brilliant that he was finally able to understand he was experiencing delusions, and to some extent figure out what was delusional and what was reality. He was able to do reality checks, and this is key.

    Bec I am not a climate scientist, I’ve had to frequently do “reality checks” about climate change when naysayers do throw all sort of stuff out there. Anyway you look at it, climate change deserves to be treated as reality. There’s just no other way to look at it. The threats are so serious, one does not need 95% confidence, or even70% confidence. I think 10% confidence (which even the worst skeptice or denialist should have, at the very least) is quite enough to mitigate like heck. There is just no other way an intelligent, rational, good willed person can think of it.

  15. 365
    Gilles says:

    RAy : I know ; I tried to ask Tamino some questions, he obviously couldn’t answer. I’ve been ejected from his blog. Even if I was wrong, that’s not my conception of open scientific debate – were I wrong, he could have explained openly why. You can omit the “BS”, I think.

    I don’t assume nobody knows. I just ask questions. Very simple one : is there anywhere a power spectrum of the natural, preanthropogenic global average temperature , or any other climate indicator ? I never saw such a thing, even in IPCC reports, and I doubt very much it exists, simply because of the lack of high quality data (which no one can charge climate scientists for, naturally); but if doesn’t exist, you are simply unable to quantify the current variation, at some definite timescale , with respect to the “usual” former variation at the same timescale. Actually you may notice that in the first introducing post, it is carefully omitted to say that climate scientists think the current variation is highly unusual : the “unusual variation” all relies on models, and extrapolation, not on current measurements. I don’t think I contradict official science by saying that.

    [Response: Any kind of attribution in any kind of system is a function of a model. In particle physics there is a model and they look for deviations from that, so it is in climate science. But given the different sources of data and size of the system, the models and detection of changes are different, though in each case the methods have evolved as a function of the history. It would also be different for epidemiologists, or vulcanologists, or cosmologists. - gavin]

  16. 366
    EL says:

    [Response: I leave that as an exercise for the reader (there are online resources you can use). But this paper is a clue. ;) - gavin]

    I recall reading that you were a math major. How did you ever end up doing what you are doing now?

    [Response: Math --> Applied Math --> Geophysical Fluid Dynamics --> simple climate models --> more complicated climate models. Driven by a combination of personal interests, available jobs and reception. - gavin]

  17. 367
    Brian Dodge says:

    “the “unusual variation” all relies on models” Gilles — 4 July 2010 @ 1:57 AM

    To expand on Gavin’s comment “Any kind of attribution in any kind of system is a function of a model,” let me point out the following:

    One “unusual variation” is in our observation of increasing atmospheric CO2 coming from anthropogenic fossil fuel use, NOT MODELS.
    Another “unusual variation” is the observation of warming in the GISS, HadCRUT, & UAH temperature records, NOT MODELS.

    There may have been rapid climate changes in temperature/CO2 in the past due to supervolcanoes(Toba), asteroid strikes(Chixulub), continental rifting/methane hydrate destabilization (PETM), that have been faster than we see today. We don’t have detailed enough proxy observations to confirm or deny that. SO WHAT? They are irrelevant because they aren’t occurring and can’t explain the changes we observe happening NOW.

    Correlation between the “unusual” rise in CO2 and Temperature doesn’t prove causation; to infer causation requires a model. Every “greenhouse” model since Arrhennius’ first approximation requires that more CO2 in the atmosphere will cause Temperature to rise. Denial of modeling is denial of science.
    Arguing that your prediction of the future is better than IPCC scenarios, based on peak oil/ Hubbert model or trickle down socioeconomic models, is cherrypicking models which agree with your world view.

  18. 368
    Hank Roberts says:

    > is there anywhere a power spectrum …?
    http://www.google.com/search?q=power+spectrum+of+the+natural%2C+preanthropogenic+global+average+temperature

    finds among much else (but also try Google Scholar of course)

    http://www.people.fas.harvard.edu/~phuybers/Doc/mean_variance.pdf
    The spatial mean and dispersion of surface temperatures over the last 1200 years: warm intervals are also variable intervals
    Martin P. Tingley · Peter Huybers

  19. 369
    Hank Roberts says:

    Gilles, what’s puzzling is how you so often ask questions you could answer for yourself, stating your assumption rather than checking it. If you’d instead say you did some searching on your own and what you found and ask questions based on information rather than belief it’d be more interesting.
    http://www.sciencemag.org/cgi/content/full/289/5477/270

  20. 370
    Hank Roberts says:

    http://www.esa.int/SPECIALS/Living_Planet_Symposium_2010/SEMGEUOZVAG_1.html#subhead1
    “… derived from the radar altimeter (RA2) instrument on ESA’s Envisat satellite, illustrating the variations in the surface height on ice sheet from 2003 to 2010. Many glaciers show red values at the beginning and deep blue at the end of the time series, indicating that they are thinning dramatically.”
    hat tip to Mike Allen at Tamino’s

  21. 371
    SecularAnimist says:

    Gilles wrote: “I don’t assume nobody knows. I just ask questions.”

    What you do is write in bad faith in order to deliberately waste people’s time. That is very obviously the sole purpose of your comments here: to impress yourself with your ability to waste people’s time.

    It is surprising that the moderators continue to permit your comments. They add NOTHING OF VALUE to the discussion, they are mere pointless sophistry, and everyone knows it.

  22. 372
    Jeffrey Davis says:

    (actually it is 5.6 sigmas…)

    ~99.9999%

    Nice work if you can get it.

    We went to war over a 2% possibility. So, what constitutes sufficient evidence to act has a lot of variability.

  23. 373
    Daniel the Yooper says:

    Re: SecularAnimist @ 4 July 2010 at 12:31 PM says:

    “What you do is write in bad faith in order to deliberately waste people’s time. That is very obviously the sole purpose of your comments here: to impress yourself with your ability to waste people’s time.

    It is surprising that the moderators continue to permit your comments. They add NOTHING OF VALUE to the discussion, they are mere pointless sophistry, and everyone knows it.”

    Well spoken. And seconded.

    Regards,

    Daniel the Yooper

  24. 374

    Brian Dodge @ 368:

    Arguing that your prediction of the future is better than IPCC scenarios, based on peak oil/ Hubbert model or trickle down socioeconomic models, is cherrypicking models which agree with your world view.

    Uh, no. That would be incorrect.

    In any risk assessment =all= risks need to be analyzed. I happen to think that Gilles is just plain wrong, but I also happen to think that Peak Oil presents a far more serious, and far nearer term, risk than AGW. That the response to the threat of Peak Oil is the =same= as the response to threat of AGW is an added bonus.

    And while I'm in the 'hood, I mention this because some of the IPCC scenarios strike me as so absurd that I feel they are undermining the objectives that are common to both. In particular, suggesting that some of the more outrageous scenarios are even possible implies that someone thinks there is enough oil in the ground to pull them off. Since that serves to argue against Peak Oil (which is better supported than any IPCC model, I might add), I think it harms the long-term objective of getting off our oil addiction.

    This is not either / or. The worst case scenario is we don't act, and we wind up broke, out of fuel, and very warm. And this is a heck of a lot closer to happening than any of the IPCC predicted disasters — http://www.guardian.co.uk/business/2010/apr/11/peak-oil-production-supply

  25. 375
    Gilles says:

    Brian :
    “One “unusual variation” is in our observation of increasing atmospheric CO2 coming from anthropogenic fossil fuel use, NOT MODELS.”

    Probably, yes.


    Another “unusual variation” is the observation of warming in the GISS, HadCRUT, & UAH temperature records, NOT MODELS.”

    Much less obvious, unless you can answer my first question : on which period of time do you have a good statistics of similar variations in the past, to show it’s really unusual ?


    There may have been rapid climate changes in temperature/CO2 in the past due to supervolcanoes(Toba), asteroid strikes(Chixulub), continental rifting/methane hydrate destabilization (PETM), that have been faster than we see today. We don’t have detailed enough proxy observations to confirm or deny that. SO WHAT? They are irrelevant because they aren’t occurring and can’t explain the changes we observe happening NOW.”

    That’s not the point. The point is that if you don’t have enough high quality proxies to measure accurately the variations within 30 years, you cannot firmly claim that the current change is unusual. That’s would be obvious for anybody , for any topics, were it not the GW one.

    “Arguing that your prediction of the future is better than IPCC scenarios, based on peak oil/ Hubbert model or trickle down socioeconomic models, is cherrypicking models”

    that’s slightly OT, but I argue that if the peak oil happens now, then the real world will be out of the set of all SRES model (or out of their convex envelope, if you prefer). That’s factual, there is no cherry picking. I didn’t really make a prediction – I assumed that the global amount of FF extracted would be close to the proved reserves only, without putting any constraint on the economic growth (implying it could decrease). You may or may not believe in it. I just observe that these scenarios do not belong to the set of IPCC ones (the reason is pretty obvious when you think of what the “I” means …. ).

    Hank Roberts : please check out first what a Power Spectral density is …

    J. Davies : as I said , the question of acting or not depends on much more than purely statistical facts. But i’m discussing here only statistics.

    For secularanimist and Daniel : I think the remark I did first about the significance of the current variation was pretty clearly expressed. So it may be right, and acknowledged as such, or wrong, and you can simply explain why (saying for instance : but Gilles, obviously the variation of the last 30 years is xxx °C whereas the standard deviation is only yyyy °C so we’ve got a signal/noise ration of xxxx/yyyy = zzzz. That’s as simple as that – a mere scientific answer.

    Any digression about the reason why I’m asking the question could appear as a way of not answering….

  26. 376
    Patrick 027 says:

    FCH, also somewhat Gilles – remember coal. Tar sands. Etc. (or maybe you did, but some of the conversation seems to imply that it’s all oil).

    Gilles – There is a period of overlap between proxy records and instrumental data. Proxies have issues but nonetheless can provide useful information.

    I don’t know offhand about the rate of warming over the last 30 years relative to other 30-year periods**, but I do know offhand that evidence supports the most recent warmth is unusual for the last several hundred or more years. Consider melt occurence in regions that otherwise have intact ice records (no melting) going back for x years.

    There is also the matter that we understand the underlying physics (or at least a lot of it) behind the behavior. This is where it’s a bit different from theoretical particle physics – findind a new particle or not is testing the underlying physics itself. The level of physics necessary for climate modelling is of the type that can be accepted as established (except for some parameterizations).

    I suspect that, BAU, the rate of warming from 1970 to 2070 could be very unusual for 100-year periods for a long time into the past, though I’d defer to others who have studied climate records in more detail… (the sustained rate of increase in GHG forcing already is quite a bit larger than what occured in at least the last deglaciation – see graphs in ch 6 of IPCC AR4 WGI)

  27. 377
    Patrick 027 says:

    PS Gilles – traffic accidents:

    1. not a specific target of policies/actions regarding AGW, because it isn’t AGW (traffic accidents don’t generally change climate except via resources spent or not as a result; although climate change could affect traffic accidents).

    2. The analogy would be whether or not there is a 99.9…% or x% chance that a policy regarding traffic accidents would be a net good. For example, the law that vehicles should be driven on the right side of the road, the speed limits in various areas generally 15 – 65 mph depending, requirements of insurance, requiring testing and licences, making drunk driving illegal, etc. (George Will had written an article a few years ago comparing possible AGW policy to a global 5 mph speed limit; sure there would be fewer traffic accidents but would the cost be too great (what about lives, health and wellbeing, and wealth benifits from higher-speed transport?) – interesting analogy, but I would suggest that the question may be more like (regarding AGW): should we have an 85 mph speed limit as opposed to a 115 or 155 or 195 mph speed limit? (As of now, their is no speed limit, except in the physical limits of the vehicles – which is a point of contention for you.) Of course, the extent to which an individual can reduce his/her own traffic-risks might be different then that for AGW-risks – the later affecting people who can’t afford a car.)

  28. 378
    ccpo says:

    FurryCatHerder,

    Your position is absurd, and has been thoroughly shown to be so. Understand this: I am a Peak Oiler and pretty much a “doomer,” but I am up to here with this bizarre panting and heaving over Peak Oil vs. Climate Change. It’s like a very liberal and pretty liberal person arguing over whether Dick Cheney ran the WH or Bush did. It simply doesn’t matter.

    We have covered this already, but you appear to be immune to reason. This is the earmark of either ideology or being married to your position. Facts are facts and cannot be denied.

    Fact 1: Peak Oil cannot end civilization short of a full thermonuclear exchange in competition over resources. Climate Change of 6+ degrees pretty much guarantees it.

    Conclusion: Peak Oil does not trump ACC. Full stop.

    Fact 2: The PO as the greater (more imminent) threat requires the dismissal of Rapid Climate Change as being possible. Given we *do* know climate changes up to 7 degrees in a decade or less, it is just wrongheaded to dismiss this from risk assessment. Sorry, but you cannot simply dismiss facts.

    Fact 3: Quit jabbering about IPCC scenarios. They are based on research from 2005 and earlier! That is, they were out of date before being published and are badly out of date now. By the time the next is published in 2012, whether we have passed a tipping point WRT the Arctic will likely be a fact of history. If we have, and I say categorically here and now we have, we are all well and truly fracked with very, very limited choices and options ahead.

    Even if you completely dismiss my contention, you are still stuck with the historical record that shows very large changes in very short periods of time. To continually state climate cannot possibly change so fast nor get as warm as the IPCC scenarios say is to deny reality. That is a fool’s errand. No good risk assessment simply ignores real possibilities! When you do you get the market collapse we just had. That is what they did; they pretended the worst couldn’t happen, thus ensuring it did.

    That is what you are doing.

    FACT 3 Support: http://climatesight.org/the-credibility-spectrum/#comment-3402
    Kate, you and climatesight visitors may be interested in this research article… we show that temperatures 4 to 5 million years ago were ~19C higher than today, at a time when atmospheric CO2 levels were very close to those today (~390ppm vs ~387ppm in 2009 from the Mauna Loa, Hawaii record: http://www.esrl.noaa.gov/gmd/ccgg/trends/ )

    The implication of our research is that we may already have passed a tipping point for major increases in Arctic temperatures due to increasing levels of atmospheric CO2…
    The article is open access, so should be downloadable for free here: http://geology.gsapubs.org/content/38/7/603.abstract

    David

    FACT 4: The scientists have consistently been behind the curve on ACC for years now. Rather than what we not knowing/fully understanding giving us a comfort zone, it is giving us nightmares because at every turn it is far worse than thought just a short time earlier.

    A. Arctic Sea Ice
    B: Ocean heat content
    C: Clathrates
    D: Antarctic melt
    E: CH4 content (Now something like 1.7 after not being more than about 0.8 or so for millions of years.)

    Etc., etc., etc.

    You are playing an intellectual game and ignoring hard facts because they don’t fit your position. Worse, your position helps absolutely nothing except to confuse the situation. The majority of solutions to both PO and ACC are the same. There are but a few PO options that would make ACC worse, but some, really need to be avoided. Thus, we must pursue those actions that successfully address both.

    Stop the madness, man.

    Cheers

  29. 379

    Patrick 027 @ 377:

    FCH, also somewhat Gilles – remember coal. Tar sands. Etc. (or maybe you did, but some of the conversation seems to imply that it’s all oil).

    I’ve not forgotten them in the least. But I also know that if coal were economically advantageous as a liquid fuels replacement we’d be seeing “CoalCo Gasoline”, and I don’t know anyone who is turning coal into gasoline at any level.

  30. 380
    Ray Ladbury says:

    ccpo, Careful about your Fact #1. For the past 50 years, our food supply has been critically dependent on petroleum. Human population would never have had its last doubling if we hadn’t effectively learned to “eat” petroleum by turning it into soy and corn.

    Food insecurity could well spell the end for civilization, whether it arises due to the end of oil, climate change, or (most likely) both. All the more reason why we should be trying to get off of oil, and other fossil fuels ASAP–they’re too valuable to burn.

  31. 381
    SecularAnimist says:

    I have a question about what climate scientists think.

    Occasionally, a commenter will ponder what sort of climate-related event might trigger serious and widespread public alarm about anthropogenic global warming. What might constitute an “AGW Pearl Harbor” or “AGW 9/11″ type of event in the public mind?

    What I would like to know, from the esteemed climate scientists here, is a little different:

    Presumably you folks are well aware of the seriousness and urgency of the problem, so you don’t need a “Pearl Harbor” moment.

    So instead let me ask you, what sort of climate-related event might plausibly occur, which would lead you to say “Oh f***. The s*** has really hit the fan now.” Or the equivalent in more polite language.

  32. 382
    SecularAnimist says:

    There is no need for peak oil to be more than a temporary inconvenience if we do the obvious things that need to be done to prepare for it, which of course closely overlap with the things we need to do to deal with AGW.

    And peak oil is easier to deal with than AGW, because unlike AGW, peak oil does not demand that we immediately end ALL use of fossil fuels. If the only problem were peak oil and there was no AGW, then we could go ahead and burn as much oil as we like, with the only challenge being to reduce our usage as supplies plateau and decline and we transition to other energy sources — including other fossil fuels.

    Absent AGW, then in the worst case where we completely mismanage the peak oil transition, then sure, it might cause major economic disruption, and war, and could be a significant setback to human progress. Perhaps as severe as all the deaths from war and genocide and famine and disease that occurred throughout the 20th century. Maybe even worse.

    But the idea that peak oil would end human civilization which endured for ten thousand years and laid the foundations of all modern science before humans ever burned a drop of oil is absurd.

    AGW is another story entirely. It is already causing costly, destructive problems, and it is absolutely clear that much worse is in store no matter what we do now. Indeed, the effects of AGW that are very likely “locked in” now from the GHGs we have already emitted, will almost certainly be worse than even a very badly managed peak oil transition would cause. And if we don’t take urgent action NOW to quickly end our GHG emissions and draw down the already dangerous anthropogenic excess CO2, then AGW is likely to have horrific effects on the entire biosphere that will go far beyond merely ending human civilization.

    It’s one thing when fuel for the tractors becomes expensive, and then scarce, and then you switch to a solar powered tractor, or a horse. It’s quite another thing when the fields have all turned to deserts.

    And of course, what the peak oil worriers — and the AGW deniers likewise — ignore, is that we have vast, abundant, ubiquitous supplies of FREE solar and wind energy, and we have the powerful, mature and rapidly improving technologies to harvest that energy to produce far more than enough electricity to run a technologically advanced civilization in perpetuity. We already don’t need fossil fuels anymore.

  33. 383

    ccpo @ 379:

    Your position is absurd, and has been thoroughly shown to be so. Understand this: I am a Peak Oiler and pretty much a “doomer,” but I am up to here with this bizarre panting and heaving over Peak Oil vs. Climate Change. It’s like a very liberal and pretty liberal person arguing over whether Dick Cheney ran the WH or Bush did. It simply doesn’t matter.

    My position on Peak Oil is that all of the environmentally harmful solutions to Peak Oil, and here I mean harmful in an AGW sense, are also environmentally harmful to the environment-qua-environment. Strip mining Alberta isn’t all that environmentally friendly, and drilling wells in 5,000 feet of water is proving to be a complete disaster. That people are suggesting detonating nuclear explosives as a way to close an oil well should be an indication of how idiotic things have gotten. Even before the Macado blowout, the environment along the Gulf coastline had been suffering immensely from oil and gas production.

    So, no, I don’t view “working around” Peak Oil by drilling or strip mining as a viable solution. Nor do I think that cutting the tops off of mountains to mine more coal is a great idea.

    But more to the point, “working around” Peak Oil is this massive act of denial that these actions are just plain =harmful=. I drive through Pasadena, TX each time I travel from Austin, TX to New Orleans and it =stinks= from the refineries, and Lake Charles, LA isn’t any better, nor is Baton Rouge, LA.

    Chinese air pollution is so horrible that US spy satellites (and not-so-spyish ones …) can’t see the ground at times. Mexico City has been severely polluted for decades. These are problems we have =today= because of fossil fuels.

    So, no, I’m not suggesting in any way that solving Peak Oil, except by completely abandoning oil as a fuel, is the way to go. And dittos for abandoning coal.

    Fossil fuel production and consumption is pretty much nothing but harmful. Right now we have environmental pollution and destruction. Near term, we have economic impacts as fuel costs continue to rise. And yes, further down the road we have Global Warming.

    As for a major war being fought over oil, I suggest you study the events that led to the United States entering WW II. Reading the article I linked previously would also be instructive, as will reading up on the acquisition of natural resources by China.

  34. 384
    Hank Roberts says:

    > I’m discussing here only statistics

    If you were, odds are the statisticians would reply to your posts.
    You need to learn how to get the attention of the people who know the area you are asking questions about. Best way is to read something relevant and ask the author about how the statistics are done. Search harder.

    http://dx.doi.org/10.1016/S0012-821X(98)00051-X
    http://dx.doi.org/10.1016/S0022-1694(97)00102-9
    http://dx.doi.org/10.1016/S0169-555X(97)00014-7

  35. 385
    Gilles says:

    ccpo : Peak Oil cannot end civilization short of a full thermonuclear exchange in competition over resources. Climate Change of 6+ degrees pretty much guarantees it.

    Conclusion: Peak Oil does not trump ACC. Full stop.”

    Given than nowhere in the world, modern civilisation (as we know it in 2000) exists without oil, whereas it exists under a variety of climate that span much more than 6 degrees (including the difference between California and Alaska ), this assertion needs to be a little bit more elaborated …

    Another thing is that I don’t know any scenario in which we reach 6 °C with a close peak oil. Do you mean that the set of scenarios in IPCC is far from being complete ?

    Now a question : which amount of fossil are we allowed to burn to avoid a catastrophic warming , following you ?

  36. 386
    SecularAnimist says:

    Gilles wrote: “Now a question : which amount of fossil are we allowed to burn to avoid a catastrophic warming , following you ?”

    This is an example of why the moderators should consider blocking Gilles from the site.

    He has “asked” this exact “question” dozens and dozens of times.

    People have answered him dozens and dozens of times.

    He has ignored their answers dozens of times, instead responding with repetitive, fatuous sophistry that is very clearly for the sole purpose of sucking them into long, pointless exchanges, for no apparent reason other than to waste their time.

    He is nothing more than an attention-vampire troll.

  37. 387
    Rod B says:

    ccpo (379), I hope I’m not falling for a practical joke or satire, but I’m a bit perplexed with your response to FurryCatHerder. It sounds like you are saying that the IPCC is all out of date, most climate scientists are way behind the times, and that you and a few others know that global temperatures in the past rose (and therefore can) 7 degrees in a decade, proven in part with, among other things, 3-5 million year old tree rings uncovered from a peat bog in the Canadian Arctic. Your estimate trumps everything else and is the only current bona fide factual evidence. Then you suggest doing the very same thing FCH proposed. Did I read this correctly??

    Do you subscribe to Kate’s idea, supporting your reference at climatesight, that three (and only three?) things need to happen: 1. plant jillions of trees, 2. everyone in the world become farmers, and 3. everyone in the world transport themselves only with walking (doable because now everyone lives in small farm towns — though harvesting the corn, beans, rice, and wheat seem to be a hurdle that is left unaddressed), all within a world economy that never grows or declines?

  38. 388
    Gilles says:

    387 :”People have answered him dozens and dozens of times.”

    Or not…

    more precisely, I would like to know the ratio of the amount we should burn, to the known proved reserves. It’s faster to answer in one line than digressing about why and how you should answer.

    [Response: "should"?? This is a values question masquerading as quantitative science as has been pointed out to you many times. And you wonder why you get a negative reaction? - gavin]

  39. 389
    Brian Dodge says:

    “Peak Oil (which is better supported than any IPCC model, I might add) ” FurryCatHerder — 4 July 2010 @ 5:57 PM
    “…the application of the conventional Hubbert model to these countries is not appropriate and does not yield good forecasting results. The additional production cycles are apparently the result of many factors, reflecting the state-of-the-art technological evolution in the oil industry, government regulations, economic conditions, and political events. The single-cycle Hubbert model does not consider the effects of these factors.”
    http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ef901240p?cookieSet=1

    Both the Hubbert model(s) and IPCC scenarios suffer from the uncertainty introduced by the unpredictability of future human actions, and socioeconomic forecasting even more so. (I wonder if the Hubbert models could be generalized to the growth and decline in production of economic “resources” like Credit Default Swaps? Where would we be if TARP had failed by a few votes?) I agree that peak oil presents significant risks to socio/economic/political stability necessary for the maintenance of civilization, and that its confluence with AGW multiplies the risk that we will find ourselves Hot, Flat, Crowded, Broke, Hungry, Angry, and Out of Options.We will soon be up to our asses in Black Swans. The point isn’t which models are less accurate – all models are inaccurate – but that ignoring some models(or other inconvenient truths, however approximate) for the sake of argument – cherrypicking – decreases the Signal to noise ratio. The more we spec – ialiise and noisily choose sides – IPCC alarmists, Peak Oil doomsayers, Free Market denialists, Enviroterrorists, Wise Use privateers, etc – the more we resemble blind men arguing over how to tame an elephant.

    “But I also know that if coal were economically advantageous as a liquid fuels replacement we’d be seeing “CoalCo Gasoline” FurryCatHerder — 5 July 2010 @ 7:14 AM
    “Given the current technology and the implied capital and operating costs, the short term price outlook and no guarantee of stable if not escalating real prices for tar sands oil, it is unlikely that any further plants will be built.” Brandie et al, “The Economic Enigma of the Tar Sands”, University of Toronto Press in its journal Canadian Public Policy.V8(1982) http://ideas.repec.org/a/cpp/issued/v8y1982i2p156-164.html
    Plus ça change (plus c’est la même chose).

    “ccpo, Careful about your Fact #1[Peak Oil cannot end civilization short of a full thermonuclear exchange in competition over resources]. For the past 50 years, our food supply has been critically dependent on petroleum.” Ray Ladbury — 5 July 2010 @ 7:41 AM
    A simple model for food supply is y= kx+ b, where y is the food supply and x is fossil fuel; the k factor – how much food supply changes with FF use – and b – food supply with k=0 – depend on your definition of food supply – “how many pounds of tomatoes I can grow in my garden”, or “fresh farm raised salmon flown into New York from New Zealand”. BTW If food supply= Gulf seafood, k is negative &;>)

    Likewise, the continuum of civilization ranges from what we have today to Neolithic Stonehenge. A more accurate description than “end” would be “violent, brutal, deadly, tumultuous and unanticipated decline” of civilization. Carl Sagan said “We’ve arranged a civilization in which most crucial elements profoundly depend on science and technology.” Science tells us that technology has limits; the horizon where those limits are appearing isn’t so far away. Even if the prime movers in society become slaves and animals (biofueled!), there will be enough food for some; however, to paraphrase Hunter Thompson, – where civilization ends, some of us enter the food chain, and not always right at the top.

  40. 390
    Daniel the Yooper says:

    RE: Gilles @ 389

    “I would like to know the ratio of the amount we should burn, to the known proved reserves. It’s faster to answer in one line than digressing about why and how you should answer.”

    Here’s a values-answer for you:
    Let know proven reserves = X
    Let the amount we should burn = ?:X (your equation)

    ZERO:X

    Happy?

    ANY additional contributions to CO2 concentrations above current levels may condemn an unknown future quantity of mankind to premature extinction. Some of the lost may be friends and/or relatives of yours (and mine). If you have children (substitute friends/loved ones for lack of children), look at their faces. If, by continuing BAU, 50% of humanity is extinguished (an optimistically low number chosen at random), which of your offspring/friends/etc do YOU choose to die? Remember, this is YOUR choice.

    Based upon what we know, and by what is apparent that we don’t (the as-yet unbounded risks), it is ALREADY too late to quibble over what constitutes an “acceptable” level of fossil fuel consumption designed to preserve our dinosaur-like standard of living. All that is left to “quibble” about is how to minimize the losses to come.

    Consider the consequences of Ballantyne & Greenwood 2010 on our climate in general and mankind in specific before posting a response:
    http://geology.gsapubs.org/content/38/7/603.abstract

    Vampire-Troll indeed.

    Daniel the Yooper

  41. 391
    Patrick 027 says:

    Re 384 FCH “So, no, I don’t view “working around” Peak Oil by drilling or strip mining as a viable solution. Nor do I think that cutting the tops off of mountains to mine more coal is a great idea.”

    It would be nice if everyone was so clear-headed.

    ———-
    Re 386 Gilles Given than nowhere in the world, modern civilisation (as we know it in 2000) exists without oil, whereas it exists under a variety of climate that span much more than 6 degrees (including the difference between California and Alaska ), this assertion needs to be a little bit more elaborated …

    1. We might replace oil – we have choices; some better than others (PS if we reduced our usage a lot, we could use small amounts for a longer period of time with less negative consequences).

    2. If Alaska’s climate became more like California’s, everything wouldn’t just automatically become as it is in California. Species must either evolve or migrate (or both). Infrastructure and budgets have to be reworked. Where do the species in Alaska go? How fast does soil migrate?

    3. People in Alaska (or Canada, or…) benefit from other places (California, the Midwest, etc.) being like they are and vice versa (global circulation patterns, trade, ecosystems).

    2 and 3 – warming of 6, or … let’s say 3 K, globally, … first, that wouldn’t be the same everywhere for all seasons, and second, it’s not the equivalent of moving everybody and everything from one latitude line to another.

    Now a question : which amount of fossil are we allowed to burn

    Rough estimate, based on 280 ppm CO2 preindustrial, ~ 218 Gt C per 100 ppm CO2 (based on atmospheric molar mass 29 g and C molar mass 12 g, g (different g) = 9.81 m/s2, atmospheric pressure 1013 mb, radius of Earth 6371 km), and 3 K warming per doubling CO2, and 385 ppm CO2 now, and setting aside aerosols and CH4, longer-term ice sheet and geochemical feedbacks, etc:

    to limit warming (from preindustrial) to 2 K, we can add about 130 Gt C to the atmosphere, which might correspond to 259 Gt C of emissions, give or take (324 Gt C or 216 Gt C, for airborne fraction of 40 % or 60 %, respectively (numbers chosen for illustrative purposes; I’m not saying that is the range to expect). Airborne fraction might decline as a result of filling available reservoirs’ short-term capacity; however, ongoing slower redistribution of CO2 could increase the airborne fraction if emissions slow down enough (airborne fraction = increase in atmospheric CO2/emission of CO2; it isn’t actually the fraction of CO2 emitted that remains in the air, as that mixes with CO2 already in the air, etc.)fraction.

    For an annual emission of 10 Gt C (near what we’re at now), that’s 22 to 32 years of emissions. Conventional oil could last that long at present usage, right? Coal can go much longer.

    (PS As a society we’ve demonstrated a willingness to damage private property and destroy water quality to get at coal – and natural gas, apparently.)

    For 3 K increase, about 381 Gt C atmospheric gain, maybe 763 Gt (636 to 954 Gt) emissions, or 64 to 95 years at 10 Gt C/year (same formulation as for 2 K).

    For 4 K increase, about 699 Gt C atmospheric gain, maybe 1400 Gt (1160 to 1750 Gt) emissions, or 116 to 175 years at 10 Gt C/year (same formulation as for 2 K).

  42. 392
    Patrick 027 says:

    Re 379 ccpo – I haven’t looked at those links yet, but for the time being I’m presuming 7 K change in a decade, and 19 K warmer than present with roughly the same forcing change relative to preindustrial – these must refer to regional or local changes, right?

  43. 393
    Patrick 027 says:

    … “385 ppm CO2 ”
    I know it’s close to that now; I’m not saying it is that.

  44. 394
    Gilles says:

    Patrick 027 : I think your figures are underestimated, we have already burnt around 400 GtC I think (did you take into account the airborne fraction in the estimate of past consumption?) . Now concerning assertions 1 to 3, I mainly see here just unfounded claim. I can claim that I disagree with you : I think it is impossible to replace oil without seriously impacting the whole economy, and i don’t see how point 2 and 3 justify the idea that the whole civilization would collapse. And last question : where is the cost/benefit calculation showing that 2K is the right threshold ?

    [edit - can we keep the strawman arguments to one-per-post?]

  45. 395

    SA 382: what sort of climate-related event might plausibly occur, which would lead you to say “Oh f***. The s*** has really hit the fan now.”

    BPL: A good bit of Greenland or the Antarctic suddenly splits off and flows into the sea. Or the methane output from the seabeds or permafrost suddenly goes way up. Or droughts hit all over the world.

  46. 396

    The thing that comes before Peak Oil is Frontier Oil: drilling in places previously thought inaccessible.

    Ask BP and the people living around the Gulf of Mexico what that entails (or if you want the wider picture, ask the people living in the Niger Delta).

    All in all the world is going to be a pretty damn unhappy place unless we get our act together fast. What a pity we did not start working on the problem when it first became clear (I would put that c. 1973, when it first became apparent that relying on oil from limited sources was risky; the second warning was when climate change started to look like a real threat, c. 1988). What have we done since? Aside from a few wars to secure oil supplies, pretty much nothing – except attacks on the scientists who are doing a great job of warning us in time of what we need to do.

    For all the slandering of scientists by deniers the simple fact remains that the people under attack (including the maintainers of this site) are our best chance of starting to solve the future energy problem in time. So keep going, don’t let the bad guys grind you down.

  47. 397
    Patrick 027 says:

    Re 395 Gilles –

    I was calculating the additional amounts of C (in the form of CO2, but given in terms of mass of C) that would raise equilibrium temperature relative to preindustrial time (based on 3K/doubling CO2), given the atmospheric CO2 already there (approximately) (and ignoring aerosols, CH4, etc.). In other words, it’s how much more C in addition to what’s there (note that I don’t need to use the airborne fraction to determine the amount of CO2 already added to the atmosphere, because I can just use that value). And then I multiplied that by factors of 2, 2.5, and 10/6, to get a rough sense of how much emission of C that could correspond to (this entails some assumptions about airborne fraction on my part. If we spread out our emissions over time, the airborne fraction would tend to drop because the C already added is still being redistributed (though more slowly) – on the other hand, other effects could increase the airborne fraction, at least in the ‘short’-term). That would be how much we emit from this time forward.

    I didn’t say that a 3 K global averager temperature increase (relative to preindustrial time – we’re roughly 1 K into it) would cause civilization to collapse. Qualitatively, it makes sense to expect the probability of the collapse or partial collapse of civilization to increase with greater AGW, noting that even without any AGW, it would not be zero; however, there is more to the deleterious effects of AGW then collapse of civilization. It’s not all black and white; there are shades of grey.

  48. 398
    Gilles says:

    #398 Patrick, ok if the amount you computed is the amount of CO2 added to the atmosphere, not what we have produced. Actually a 40 to 60 % percent airborne fraction is overestimated, because in a multilinear absorption model like Bern’s one, the fraction of CO2 that will stay permanently in the atmosphere is lower (around 20 %). The 50 % figure is the current one, but it will increase when the production will decrease.

    I agree that it is all shades of grey. We may disagree on the darkness of the shade brought by the total disappearance (or even the fading) of fossil fuel consumption. For a dark enough shade, the problems brought by the change of temperature will keep being immaterial compared to those brought by the decrease of FF consumption. Even if most of you dismiss this possibility, I don’t think it is less likely that the climate change based apocalypse scenarios.

  49. 399

    Patrick 027 @ 392:

    For an annual emission of 10 Gt C (near what we’re at now), that’s 22 to 32 years of emissions. Conventional oil could last that long at present usage, right? Coal can go much longer.

    No, Conventional Oil can’t go anywhere near that long. I don’t even think that Unconventional Oil, in all of its massive abundance, can maintain the current consumption for 30 more years.

    The worst case Peak Oil + AGW scenario is we do absolutely nothing to get ourselves off of our dependence on oil and other fossil fuels. We spend ourselves into a giant whole chasing unconventional reserves. Then, when fuel costs are sky high, we finally “get religion”. Except that atmospheric CO2 is much closer to 450 than today, we’re low on fuel for remediation, low on fuel for =survival=, and the atmosphere has warmed significantly.

    The only course of action that stands a chance is extremely aggressive migration to renewable energy. We need to both conserve what cheap proven reserves we have, and reduce CO2 emissions. The former in case we need the energy to make the switch, the later to avoid the more severe consequences. AGW will get our children and grandchildren. Running out of oil is going to get =us=.

  50. 400

    Gilles @ 399:

    I agree that it is all shades of grey. We may disagree on the darkness of the shade brought by the total disappearance (or even the fading) of fossil fuel consumption. For a dark enough shade, the problems brought by the change of temperature will keep being immaterial compared to those brought by the decrease of FF consumption. Even if most of you dismiss this possibility, I don’t think it is less likely that the climate change based apocalypse scenarios.

    Continued consumption of fossil fuels, at ever higher prices — standard economics for any commodity approaching scarcity — is going to ruin the economy.

    Oil, and even to some extent coal, is a declining resource with fairly inelastic demand. As demand approaches available production, with no reserve production capacity, the price will rise until supply and demand balance. That price depends on who is doing the demanding and how much money (and guns) they have to “demand” they get their oil with.

    My suggestion is that you look at global oil production over the past few (say, 10) years. Then compare that to the ten previous years.

    Oil is done. Fortunately for me, I’ve got solar on the and an electric motorcycle in the garage. I’m hoping to put an electric car in there a bit later. And perhaps a few carbines close at hand.


Switch to our mobile site