A Few Things Ill Considered

A layman's take on the science of Global Warming featuring a guide on How to Talk to a Climate Sceptic.

Thursday, June 22, 2006

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Hockey Season Finally Over?

As followers of the climate change debate may recall, Science Committee Chairman Sherwood Boehlert (R-NY) requested a report from the NAS on the rather convoluted, contentious and cantankerous controversy surrounding the Infamous Hockey Stick graph and its conclusion that late 20th century warming and temperatures were likely faster and higher than any other period in the last 1000 years.

Well, the report is out and it seems to be a fairly strong vindication of Mann et al. There is some more fuzzy language that will surely be seized apon by some but there is certainly nothing to support the allegations of errors, omissions and frauds that have been thrown around. The main conclusion is that many other studies support these same findings and that this is not a central issue in the present and future of climate change.

Real Climate has more details and quotes here. Roger Pielke Jr. seems to agree, which is by no means a given in climate change issues.

Is Hockey Season finally over? I guess that depends on whether or not your interests are social, scientific, or political.

Labels:

posted by coby @ 6/22/2006 11:22:00 AM  

25 Comments:

  • At June 22, 2006 12:40 PM, Blogger Co2emissions said…

    Just what I needed - what timing!

     

  • At June 23, 2006 2:26 AM, Blogger Heiko said…

    I haven't really followed the hockey stick discussion much, and I like your FAQ entry on it, but I did notice this passage:

    It was important in that it overturned the concept of a global Medieval Warm Period warmer than the 20th century and a pronounced Little Ice Age, both long time (cautiously) accepted features of the last 1000 years of climate history.

    It is interesting that the report says:
    http://dels.nas.edu/dels/rpt_briefs/Surface_Temps_final.pdf

    Large-scale surface temperature reconstructions
    yield a generally consistent picture of temperature
    trends during the preceding millennium,
    including relatively warm conditions centered
    around A.D. 1000 (identifi ed by some as the
    “Medieval Warm Period”) and a relatively cold
    period (or “Little Ice Age”) centered around
    1700. The existence and extent of a Little Ice
    Age from roughly 1500 to 1850 is supported by
    a wide variety of evidence including ice cores,
    tree rings, borehole temperatures, glacier length
    records, and historical documents. Evidence
    for regional warmth during medieval times can
    be found in a diverse but more limited set of
    records including ice cores, tree rings, marine
    sediments, and historical sources from Europe
    and Asia, but the exact timing and duration of
    warm periods may have varied from region
    to region, and the magnitude and geographic
    extent of the warmth are uncertain.

    The Mann reconstruction appears much flatter than other reconstructions before 1900, and it seems that NAS see pretty good evidence for a "Little Ice Age" and reasonable evidence for a "Medieval Warm Period" (though they think it's plausible that the last 25 years were warmer than any comparable period during the last 1100 years).

     

  • At June 23, 2006 6:33 AM, Blogger coby said…

    Thanks, Heiko.

    I think MWP and LIA are still useful and descriptive denominators, it is just their global extents and degrees of divergence that have been revised. The LIA remains globally well supported but not well synchronized and not so cold as once thought. The MWP was likely quite warm in western europe, but there is much less indication of this feature in the rest of the world.

    I beleive it is likely that the Hockey Stick shows less variability than there actually was, other reconstructions seem to show this, but the major findings were the most important (ie how the late 20th century fits in).

    The big noise started because of the previous view of the last 1000 years as presented in the SAR. Here is a comparison graph:
    http://en.wikipedia.org/wiki/Image:Ipcc7.1-mann-moberg.png

     

  • At June 23, 2006 7:24 AM, Blogger Heiko said…

    Thanks, that's a pretty nice graph.

    It's interesting that if one splices on the last 25 years, even using the data from the previous IPCC report, 1998 would come out as the highest in a thousand years (though only just beating out the MWP maximum, and there's no indication on interannual variability in the early IPCC graph).

    At any rate, it seems there's plenty of work left to do to clarify past temperature trends further.

     

  • At June 24, 2006 2:15 PM, Anonymous Anonymous said…

    Hockey Season finally over? I'll say. Take a look at the graph from the NAS report.

    http://darwin.nap.edu/books/0309102251/html/2.html

    Can someone point out the hockey stick for me?

    Further on, the NAS report states:

    "Even less confidence can be placed in the original conclusions by Mann et al (1999) that "the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millenium."
    http://darwin.nap.edu/books/0309102251/html/4.html

    The strongest words the NAS can find for Mann's work is to call it "plausible". That is hardly a strong scientific endorsement.

    Paul G.

     

  • At June 26, 2006 7:05 AM, Anonymous Anonymous said…

    Is Hockey Season finally over? I guess that depends on whether or not your interests are social, scientific, or political.

    Coby, I have as much a scientific interest in climate change as anyone else but it doesn’t seem to me that after the NAS report the “Hockey Season is over” at all.

    Even if one were to follow just the (rather predictable) interpretation of that report by RC, it’s quite obvious, especially in the comments to the posts, that they are not very happy with it.

    If, for the sake of balance, one looks at other websites, such as Motl’s
    http://motls.blogspot.com/2006/06/nas-schizofrenic-climate-report.html
    or the directly concerned McIntyre’s
    http://www.climateaudit.org/?p=715
    the conclusion is that everybody feels vindicated by this politically worded report.

    When I read the report from the link you have provided yourself: http://www.nationalacademies.org/morenews/20060622.html and the most relevant parts of it therein, my opinion as regards what the main conclusion is also differs quite radically from yours.

    1) The main conclusion, I’d say, is that the global temperature of the last decades is very likely higher than that of any comparable period since the depths of the LIA. Hardly surprising, isn’t? BTW, the authors continue considering both the LIA and the MWP as valid concepts, contrary to Mann et al.

    2) Even though they have little confidence in temperature reconstructions previous to AD 1600 and very little for those previous to AD 900, the authors consider that Mann et al’s claim of the last decades being warmer than any such period in the past millennium is nonetheless plausible. Well, so do I. That is a possibility that, with our current knowledge, cannot be ruled out. But the confidence in this claim is small. This could actually be the wording of a standard skeptic position…

    3) Mann et al’s claim that the ’90 and 1998 are record-breaking decade and year in the context of the past millennium are dismissed, given the uncertainties.

    Apparently, there’s further criticism of Mann et al in chapters 9 and 11 but I haven’t read them.

    Contrary to what’s being said, I do personally consider that paleoclimatology is a key element of the current GW debate. It goes to the very root of the issue: is the warming we are observing now something unprecedented? Are we perhaps looking just at natural oscillations (maybe even pure statistical noise) that we don’t fully understand? If we were to find out that similar or warmer conditions existed not so long ago (for which we would miss an explanation with the variables we now consider) where would the all-important role of man-made GHGs go?

    Finally, I find it very relevant that, once again, it’s just the last decades that seem to stand out as a potential proof of man-made GW. The warming that took place at the beginning of the 20th century, which was similar in intensity to the current one, was essentially natural in origin. Had nature not have produced it, the current warming would be nothing but an irrelevant spike that would leave us within the boundaries of the last 400 years and plausibly below those of the last millennium.

     

  • At June 26, 2006 9:12 AM, Blogger Luboš Motl said…

    Dear Mikel,

    I am often pleased how smart and reasonable people discuss on these forums. Except for a few places where the discussion is extremely politicized and emotional, it seems that people start to understand the reports and each other.

    I also agree with you that paleoclimate has been the strongest evidence that the humans are doing something unprecedented with the Earth - that the current changes exceed those that appear on the timescales of millenia. It is really the only known reliable method to estimate the natural variations that can be much smaller or much greater than the human influence.

    Although I've asked this question to 21 people who claimed that there also exists some other evidence that we're doing something substantial, neither of them has so far given an answer.

    It is pretty likely that such an alternative paper does not exist. If it did, the evil skeptics ;-) would have attacked it as much as they (we) did attack the hockey stick chart. :-)

    All the best
    Lubos

     

  • At June 26, 2006 1:29 PM, Blogger coby said…

    Mikel, I agree that this report will not put an end to this issue, so the answer to the post's title is "no", I was more optimistic after initial review of other people's impressions. However, after more first hand investigating, I stand by my conclusion that it is much more favorable to Mann et al than ClimateAudit and Smokey Joe Barton. This is because in my mind the single important accusation from Climate Audit was that this study was the result of errors and bad judgements at best and scientific fraud at worst. This is clearly not the conclusion of this report. It is just another scientific paper whose general conclusions have been upheld as time passed.

    The report also confirms that this is not the cornerstone of climate change science that it is often seen to be.

    I think you mischaracterize people who consider the hockey stick a reasonable reconstruction (with limits and uncertainties like all reconstructions) by thinking that implies that MWP and LIA are phantoms. It is simply that, especially in the MWP, the anomaly was not as global and synchronized as today's temperature trend is. The Report in Brief has soundbites that bear that out.

    "little confidence" in pre-1600 periods is your words AFAICT. The report merely says "less confidence" than the last 400 years, a bit of a no-brainer really, no information for anyone in that. Mann et al's claim of record breaking warmth in late 20th century is not dismissed, it is characterized as plausible. Not a ringing endorsement, I grant you that, but not a dismissal by any means. It is just one study, it is a pretty cautious but still reasonable way to describe any single study that presents new and surprising findings. You then look to other studies for confirmation or refutation.

    I disagree that paleoclimate is essential for understanding climate today. It is informative, but not explanatory of current climate change, nor predictive of future climate change. I do not accept the "it could be natural" position as anything but a hand wave and an appeal to the "we don't know everything, so we don't know anything" argument. Natural does not mean magic, show me the cause and the mechanism. The fact is we already have one in hand that is consistent with all the available evidence and physical theories.

    There is one thing I will grant that could be learned from evidence of a comparable change to what we expect by 2050 or 2100 having occured in the recent past and that is about the resilience of biosphere. Such a big temperature change so recently would be evidence that the biosphere may be much more resilient than thought.

    Early 20th century warming was around .4oC in three decades, late 20th century is .6oC in three decades and a bit more now and almost certain to continue. Early 20th century was also about half anthropogenic.

    Thanks again for the substantive comment, though we may have trouble bridging this gap!

     

  • At June 27, 2006 3:20 AM, Blogger Heiko said…

    The warming that took place at the beginning of the 20th century, which was similar in intensity to the current one, was essentially natural in origin.

    Coby gave a good link showing that greenhouse gas warming was 0.81 W/m2 in 1944. That's one third of the 1998 value and hardly negligible.

    the resilience of biosphere.

    But what's gonna happen concretely? Grass or wheat or pines aren't going to stop growing because of climate change. Their growth doesn't depend on other species. As long as they've got nutrients, water and sunlight they'll grow, no matter how many species of moss disappear in Spitzbergen.

    I also don't find it credible that we couldn't save polar bears or penguins. Even if their food were to run out, we could feed them ourselves.

    I'll grant you that a particular moss species in Spitzbergen might be wiped out by invasive species assisted by climate change. But what's the concrete impact on people, beyond anecdotes about pine beetles and the West Nile virus?

    I don't see any moral obligation whatsoever to preserve species as such. People are perfectly entitled to feel differently. Many people disagree about whether fetuses are humans or a bundle of cells that doesn't need any protection.

    As long as species have zero impact on humans (including the esthetic, one species of moss will do just as any other to make Spitzbergen look pretty for tourists), I couldn't care less about their survival.

     

  • At June 27, 2006 5:51 AM, Blogger Co2emissions said…

    There have been a couple of studies recently that show the limiting factor on CO2 fertilisation is soil nitrates. If they remain the same, plants cannot take advantage of the CO2-enriched atmosphere.

    Climate Change Surprise: High Carbon Dioxide Levels Can Retard Plant Growth, Study Reveals

    The prevailing view among scientists is that global climate change may prove beneficial to many farmers and foresters -- at least in the short term. The logic is straightforward: Plants need atmospheric carbon dioxide to produce food, and by emitting more CO2 into the air, our cars and factories create new sources of plant nutrition that will cause some crops and trees to grow bigger and faster. But an unprecedented three-year experiment conducted at Stanford University is raising questions about that long-held assumption. Writing in the journal Science, researchers concluded that elevated atmospheric CO2 actually reduces plant growth when combined with other likely consequences of climate change -- namely, higher temperatures, increased precipitation or increased nitrogen deposits in the soil.

    and

    Planting trees 'will not cancel out climate change'
    Plant growth in a changing climate will be limited by nitrogen available in soils, say researchers Catherine Brahic
    13 April 2006
    Source: SciDev.Net

    Attempts to limit climate change by planting trees to absorb carbon dioxide from the atmosphere could be futile, according to two studies published this week. It had previously been suggested that rising concentrations of the gas would boost plant growth and, with it, the amount of carbon dioxide plants absorb. But two US-based teams - led by Johan Six of the University of California at Davis and Peter Reich at the University of Minnesota - say this is a false hope. Insufficient amounts of nitrogen gas*, they say, will limit plant growth regardless of how much extra carbon dioxide is available.

    * (I can only assume they mean fixed nitrogen, as the gas is 80% of the
    atmosphere at ground level - one more example of scientifically
    illiterate reportage, perhaps)

     

  • At June 27, 2006 7:54 AM, Blogger Heiko said…

    Unfortunately, that's press reports about the studies, rather than the studies themselves.

    The first report claims that the study shows an increase of 33% in plant growth with carbon dioxide alone, 84% with increased precipitation, temperature and nitrogen, and 40% with all four factors combined (ie extra precipitation, nitrogen, temperature and CO2).

    They surmise that this, on the face of it, strange result may be due to other factors, such as potassium, becoming limiting.

    There have been a couple of studies recently that show the limiting factor on CO2 fertilisation is soil nitrates.

    But, assuming the press report is vaguely accurate, the first study does not show that. It actually shows that when adding extra nitrogen, temperature and precipitation you get 84% extra growth, while this goes down to just 40% extra growth when also adding doubled CO2.

    The other study actually shows the opposite, namely that adding CO2 increases plant growth up to a limit imposed by nitrates, and if nitrates are then also added, growth gets enhanced even more.

    These are terrible press reports, the journalists clearly don't understand the science well, but they do their level best to make the results sound alarming.

     

  • At June 27, 2006 9:51 AM, Anonymous Anonymous said…

    Thank you Lubos, if you’re still around.

    I wonder how you manage to run so many blogs, take part in other people’s debates, contribute to Wikipedia,…and then do your highly qualified work!

    I found it very reassuring to receive support from someone like you.

    Mikel

     

  • At June 27, 2006 10:01 AM, Anonymous Anonymous said…

    I think you mischaracterize people who consider the hockey stick a reasonable reconstruction (with limits and uncertainties like all reconstructions) by thinking that implies that MWP and LIA are phantoms.

    Let me just quote Jones and Mann: “‘‘Medieval Warm Period’’ and ‘‘Little Ice Age’’ are therefore restrictive terms, and their continued use in a more general context is increasingly likely to hamper, rather than aid, the description of past large-scale climate changes. We recommend that paleoclimatologists avoid the use of such terms and instead refer to anomalous climate periods by calendar dates, as is the practice in the description of more modern climate changes.”
    ftp://holocene.evsc.virginia.edu/pub/mann/JonesMannROG04.pdf

    Mann et al's claim of record breaking warmth in late 20th century is not dismissed, it is characterized as plausible.

    I used the “dismissed” verb for Mann et al’s claim regarding the ‘90s decade and the year 1998. But I’m willing to compromise to a less severe characterization of those 2 particular claims in the report, if you want.

    I do not accept the "it could be natural" position as anything but a hand wave… Natural does not mean magic, show me the cause and the mechanism.

    I see it just the other way around. After an unprecedented scientific/political effort, a large group of climate scientists have indeed come up with a plausible explanation for the observed warming of the last decades. Not all relevant scientists are in agreement with it and it does not explain everything (which is why we keep discussing in this blog) but it may be the least implausible explanation science can produce at the moment: the recent warming is mainly driven by anthropogenic GHGs. Incidentally, this explanation has the advantage of accommodating very well to the expectations raised when the IPCC body was created (there may be a big problem and we developed societies are causing it) and also to the political agendas of the left, environmentalists, capitalism-haters, USA-haters, etc.

    Now, does this all mean that this explanation must be blindly accepted just because it is the most elaborated one? Hardly. I think that it is perfectly legitimate to be skeptic about it without the need to produce any alternative explanation that you perfectly know I don’t have. Do we know what causes the ENSO events, the hurricane/monsoon intensity oscillations, the glacial cycles, the dinosaurs extinction, the cause/s of cancer? No, there are many things that we don’t know. There may equally be more or less plausible theories for these phenomena but accepting them blindly would be the contrary of a sound attitude towards science.

    Early 20th century warming was around .4oC in three decades

    The global average temperature experienced an increase of +0.57 C between 1910 and 1944:
    http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/annual

    Early 20th century was also about half anthropogenic

    I’m very curious about where you get this estimate from. Certainly not from the IPCC. Even your Wikipedia article from the observations/sensibility post shows a scant 0.1 C warming due to GHGs for the period in question together with a small negative forcing from sulphate aerosols. The Crowley dataset, which I still don’t know what relevance has, also shows a stable amount of GHG forcing for this period. This figure may be more helpful to compare both variables:
    http://www.junkscience.com/MSU_Temps/CRUglobalan.png

     

  • At June 27, 2006 11:14 PM, Blogger coby said…

    Mikel,

    Thanks for the Jones and Mann quote, I stand corrected. I think they will remain useful terms myself, though can agree with the "restrictive" characterization.

    "After an unprecedented scientific/political effort, a large group of climate scientists have indeed come up with a plausible explanation for the observed warming of the last decades."

    I think you should have a look at this history of global warming here. It did not start with a UN bent on world domination.

    CO2, a greenhouse gas, is accumulating in the atmosphere causing an enhanced greenhouse effect. This is hardly an elaborate eplanation. Granted it is not so simple as "it's just happening". There is another side of the "it's natural" argument that a new theory must deal with: why is CO2 rise *not* increasing the temperature?

    The global average temperature experienced an increase of +0.57 C between 1910 and 1944:
    http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/annual

    I'll accept .5 in that analysis, .4 in GISS, but I won't accept drawing a line from highest single year to lowest single year because interannual variation is too chaotic.

    As for 50% anthropogenic early 20th century warming, I don't know where I got that idea and it doesn't look like my attribution link supports that, so consider it withdrawn.

    BTW, the artful choice of scale does not escape my notice in your junkscience link!

     

  • At June 28, 2006 6:25 AM, Anonymous Anonymous said…

    Coby, it’s always a pleasure debating with an honest person like you (especially when you decide to agree with my arguments:-)

    I don’t really see any UNO attempt to dominate the world. But let’s imagine, for example, that that some scientists convinced enough politicians to create an IPCC-like International Panel to decide whether the modern way of life is the essential cause of the ever-growing rates of cancer. I suspect that 15 years afterwards we would end up with a very similar outcome. A lot of studies and mounting evidence showing how diverse contaminants in industrialized societies lead to increased cancer rates, appeals to stringent regulation, a lot of hype in the media with each new finding/report,…and a less vocal minority of sceptics claiming that a lot of uncertainties remain and that cancer is an age-related disease so, as long as we keep living longer, higher cancer rates are pretty much unavoidable…hope not to have gone too far with my rudimentary example of how predictable certain things are.

    I'll accept .5 in that analysis, .4 in GISS, but I won't accept drawing a line from highest single year to lowest single year

    So when you chose “3 decades” for your 0.6 C figure, weren’t you equally arbitrary? The fact is that, for whatever reasons, the average temperature of the earth surface rose 0.57 C between 1910 and 1944. Period. Either “something” caused that and, not being man-made GHGs or (obviously) sulphate aerosols, it would be quite safe to call it a natural phenomenon or perhaps it was just a meaningless variation in an essentially flat curve moving around 13-15 C or thereabouts since the beginning of the Holocene.

    why is CO2 rise *not* increasing the temperature?

    I don’t think there is any discussion about the rise of CO2 (all things being equal) causing a surface temperature increase. Lindzen estimates 2xCO2 should raise temperatures by about 1C and I think Michaels is speaking about a 1.5 C sensibility right now. The problem arises, I believe, when strong feedbacks, “masking” effects of aerosols and volcanoes and other uncertain assumptions are fed into computer models to generate catastrophic scenarios for the near-medium future.

    the artful choice of scale does not escape my notice in your junkscience link!

    Yes, it is because of the scaling tricks that I’m not very fond of graphs and prefer data sets myself. But could you explain what exactly you find misleading in the scaling of this graph? Thanks.

    One last point. Paleoclimate is essential to the AGW debate, in my view. Different causes may produce similar results, alright. But if we happened to find strong evidence that, say 1K years ago temperatures were as high or higher than the ones predicted for the coming decades (not implausible as yet) we would have at least 2 major problems with the AGW theory: 1) According to the forcings commonly considered (for example in Crowley’s data set) there would be no explanation for such a phenomenon. 2) No big evidence exists of any catastrophic events for humankind because of warming in that or any other period. This just but an example of how paleoclimate can have a serious impact in the GW research, which is why I guess it has such a relevant position in the IPCC papers.

     

  • At June 30, 2006 2:00 AM, Blogger Glen said…

    Coby,
    For what it's worth, here's where that "it was based on one tree" claim likely came from:

    "McIntyre and McKitrick went back to the source of the Gaspé series and then to the archived data at the World Data Center for Paleoclimatology. "We found that although the Gaspé series begins in 1404, up until 1421, it is based on only one tree. Dendrochronologists (tree ring researchers) generally do not use data based on one or two trees. The original authors only used this series from the 1600s onwards in their own temperature reconstructions. This series should never have been used for the 15th Century, let alone counted twice and extrapolated"

    To read the last few climateaudit.org posts, the hockey stick is probably dead but doesn't know it yet. I liked this chart and the associated pdf report.

     

  • At June 30, 2006 7:15 AM, Blogger coby said…

    [Mikel, sorry for the long delay in responding, I had this mostly written 24 hours ago but first I thought I had posted it already, then I thought it was lost when Outlook crashed but it was auto-saved after all. Anyway, here it is!]

    for whatever reasons, the average temperature of the earth surface rose 0.57 C between 1910 and 1944. Period. Either “something” caused that and, not being man-made GHGs or (obviously) sulphate aerosols, it would be quite safe to call it a natural phenomenon

    Well, if you insist on looking at individual years and *not* smoothing the data at all, then given that interannual variability can quite easily be .15oC, we can take .3oC away as it is meaningless chaos and not indicative of a trend. That leaves us with only .27oC rise over that ~3 decade period that needs any forcing explanation. There was in fact an increase in solar at the beginning of the century so yes, we had a small natural temperature rise. That is taking your approach of dismissing GHG forcing. AGW theory does not deny that there are natural forcings, on the contrary it attempts to identify and quantify as many as we can and assess their roles in observed trends and future projections.

    The problem arises, I believe, when strong feedbacks, “masking” effects of aerosols and volcanoes and other uncertain assumptions are fed into computer models to generate catastrophic scenarios for the near-medium future.

    In general, it is quite incorrect to say that feedbacks are fed into GCMs. They are the result of the physical principals out of which the model is built. eg Water vapour feedback is not made up and then plugged into a model to make the temperature projections higher. Equations about evaporation rates and convection patterns and temperatures are built into the model and then the output, not the input, is a feedback driving temperature higher. These models, with the resulting feedbacks, mimick observations and are consistent with physics and are therefore useful tools in trying to understand both what is currently happening and what will happen in the future.

    Similarily, the uncertainty in aerosols is mostly in the data (and then cloud effects), the "masking" effect is a result of the model's physics it isn't just parameterized and fed in.

    could you explain what exactly you find misleading in the scaling of this graph?

    I find it misleading to make the bottom of the x-axis 0 ppm as this is not a possible value in any relevant timeframe. The range that the graph needs to cover is preindustrial 280 ppm to the current value of 380. That is a spread of 100 pts not counting an upper and lower buffer. They set the x-axis from 0 to 550, fully five times more than what the data requires.

    I have seen people present similar optical illusions with temperature, showing degrees Kelvin and starting the x-axis at 0. It makes the rise from ~288 to ~289 look pretty small. Only effective when your audience is naive, and not far above an outright lie, IMO.

    [paleoclimate]
    Paleoclimate is more important for prediction than it is for explaining what is happening now. The exception is finding reliable data from the past that clearly violates the basics of current atmospheric or oceanic science. That would obviously entail going back to the drawing board. (Grant hungry researchers would love that to happen, no?). Simply finding recent past periods with similar anomalies (not only to what we have observed, but what we expect to come) does not tell us more about what is happening now, though it might reassure us about the negative effects we expect. The past can provide some examples of what to expect in the future, the PETM for instance.

    Actually, rereading your last paragraph, we seem to mostly agree about that.

     

  • At July 01, 2006 12:12 PM, Anonymous Anonymous said…

    given that interannual variability can quite easily be .15oC, we can take .3oC away as it is meaningless chaos and not indicative of a trend. That leaves us with only .27oC rise

    Coby: I’m not following you here.

    a) Further up you spoke of early 20th century warming being about 0.4C. All I’m saying is that from through to crest (approx.) it was ~0.57C, which is comparable in size to the so often mentioned warming of the “last decades”.

    b) Most definitely, this warming could most be internal variability or chaos. That’s the point I’ve been trying to make. But this would apply to both warming periods, wouldn’t it? Applying the same filters you have just used, what would be the substantive warming of the “last decades”?

    c) Where do you get those 0.15C and 0.3C figures from??

    d) Lindzen has recently made a very interesting point in his last published article saying that, as long as we don’t know what the climate internal variability is, trying to attribute observed temperature changes to this or that forcing is an impossible task. I believe this ties in very well with this discussion and also with the discussion on paleoclimate.
    http://meteo.lcd.lu/globalwarming/Lindzen/no_consensus.html

    The range that the graph needs to cover is preindustrial 280 ppm to the current value of 380…not far above an outright lie, IMO.

    Showing the 0 value on the X axis is customary in algebra. In this case the graph covers the 0 – double CO2 range, approximately. This gives us a very visual representation of what the current ~30% rise amounts to and how it has evolved over time.

    If anything, this graph exaggerates, as usual in this context, what the real temperature variations have been. The impression you get is clearly that the global temperature of the earth has gone up and down dramatically during the plotted period. But the fact is that it has oscillated smoothly around the 14C value, not one single year below 13C or above 15C (or even close to those values). Taking again 0C at the X axis and say 30C as the upper limit, we would indeed see a basically flat curve…and that’s fortunately what has actually happened and the reason why nobody would have noticed the allegedly unprecedented warming, if we didn’t have the observations record.

    Paleoclimate

    I put an example of how paleoclimate can also be crucial for explaining what is happening now (or at least ruling out certain hypothesis). Until recently it was widely accepted that temperatures in the MWP were higher than the current ones. Even the first IPCC papers supported this notion, which is why Mann et al was such a breakthrough. However, if we were to return to the prior estimates (and efforts are being made in that direction), we would have no way of reconciling it with the way usual forcings are thought to have operated: nothing in the Crowley dataset we’ve been discussing with Heiko, for example, could explain it.

     

  • At July 01, 2006 4:37 PM, Blogger coby said…

    Mikel,

    Too many numbers and approaches. I was trying a hypothetical acceptance of your desire to use individual years as trend defining data points. Forget all that. Bottom line is I do not accept your statement that the global average temperature rose .57oC in the early part of the 20th century. You must use some kind of smoothing to have a meaningful climate indicator. In your preferred dataset it is .5, in the GISS analysis it is .45

    Re Lindzen's point, what do you think he means by "climate internal variability"? I though that refered to how much climate can vary without any forcings.

    As for Lindzen, the more I read of his latest writings, the less respect I have for him. He employs all the cheap tricks of shills like John Stossel. Sad, really, I think he was a respectable scientist before.

    Re graphs of CO2, I think you are defending the indefensible. There is no reason that seeing the 0 gives us any better information. Why not show the scale from 0 to 1000000, the full range of theoretically possible values? Have a look at this graph, it has visual impact in a completely justifiable way.

    As for exagerating or minimizing the current temperature trend through choice of scale, it really depends on wether or not 1oC is a large change to occur over one century and all evidence suggests that it is. The other reasonable criterion for scale choice is the range of values you need to cover. 0oC and 30oC are way out of the picture.

    Paleoclimate:

    Yes, we could find something that defies current theory. So far we have not and at this point it seems unlikely that any of the basics will be overturned.

    Don't forget that the SAR graph of the last one or two K yrs was not based on any kind of rigorous analysis at all, AFAIUI. I think the most likely impact of finding that the MWP was more pronounced than currently thought is that the models will have proved too insensitive to forcings. This implies that the future climate response will be larger than currently thought. Unless of course this hypothetical finding comes with new data showing a currently unknown significant forcing to explain it.

     

  • At July 03, 2006 4:26 AM, Blogger Mikel Mariñelarena said…

    Coby:

    It’s interesting to see how long we both spend arguing on the very same data, graphs, sentences,… it’s quite clear that our inability to bridge the gaps you mentioned earlier stems from our a priori positions. You have already decided that what appears to be the position of a majority of experts (a large climate sensitivity to GHGs and catastrophic scenarios for the future) must be right.

    9 times out of 10 I would also bend to the opinion of the majority of experts on any scientific issue, unless the issue was politicised. As it happens, AGW is a very highly politicised issue, deals with uncertain predictions based on computer models (rather than observations) and there is a substantial minority of experts, including some IPCC contributors who don’t agree with this position. They also seem to make a lot of sense when I read them and their admittance that we may much know less than we think is one I very much sympathise with, whatever scientific field we’re talking about.

    When I decided to start posting in Real Climate a few months ago, I was actually quite willing to change my mind, which was leaning towards the skeptic position at the time. I must say that having seen how the “majority experts” defend their views has reinforced my initial stance.

    early 20th century warming

    You may refuse to accept my through to crest approach but the fact remains that the average global temperature in 1909, according to the widely respected HadCRUT diagnostics, and subject to the uncertainties expressed by themselves, was 13.44 C and that of 1944 was 14.01 C. You seem to think that by smoothing the data statistically you are eliminating the chaotic component from the data series and arriving at some “meaningful” trend explainable by known forcings. By smoothing the data, as the word says, all you get is a smoother curve without less spikes produced by inter-annual variability. But the chaos component may equally persist in the trend and account for most, if not all, of the variation. That is my point.

    I think you are defending the indefensible.

    I only took 2 years of statistics and another 2 of econometrics at university. But I think it’s quite safe to say that there’s no such thing as one “correct” range of values for any given graph. In the graph I gave the basic facts that were being represented were that a) CO2 concentration has risen slowly to ~30% above pre-industrial times and b) No precise correlation can be seen between this steady rise and the uneven global temperature record. In the graph you gave the idea to convey is that current CO2 levels are higher than in the last 400k years. Mission accomplished, too.

    Re Lindzen's point, what do you think he means by "climate internal variability"?

    The same as you.

    As regards your lack of respect for him, I cannot comment. You’re not very specific and I don’t know who John Stossel is. I found out about his article, not surprisingly, through someone who was also criticizing him bitterly in a personal way, and doing so after having totally misunderstood one of his points. I found the whole article very interesting.

    the SAR graph of the last one or two K yrs was not based on any kind of rigorous analysis at all, AFAIUI

    Do you think that the IPCC SAR used blatantly inaccurate analysis? I rather think that they used what was the best scientific knowledge at the time. This was later overturned by new studies, most notably the Mann et al one, but we seem to have agreed that the debate goes on.

    he most likely impact of finding that the MWP was more pronounced than currently thought is that the models will have proved too insensitive to forcings. This implies that the future climate response will be larger than currently thought.

    You see? You always manage to come to the same conclusions :-)

    Anyway, I find it useful to argue with a staunch but knowledgeable and honest “global warmer”. I learn a lot.

     

  • At July 05, 2006 9:36 PM, Blogger coby said…

    [Hi Mikel, it was either this very short and very late response, or admitting I would never have time to reply at all. I hope any unfinished themes will be picked up again in later threads]

    Do you think that the IPCC SAR used blatantly inaccurate analysis? I rather think that they used what was the best scientific knowledge at the time.

    Are those two mutually exclusive? :-) But seriously, I think it was really a scientific WAG (and I'm sure it would have been clearly indicated as such) though I don't have a copy of the SAR to see exactly what they said about the graph, which I have seen. There are plenty of things in the TAR that are clearly indicated as being very poorly understood. Sometimes the best scientific knowledge is actually quite poor.

    Anyway, I find it useful to argue with a staunch but knowledgeable and honest “global warmer”. I learn a lot.

    I think that's what we are both here for!

     

  • At July 11, 2006 4:58 AM, Blogger Mikel Mariñelarena said…

    No worries Coby. We all have so much to do. And it should be fun to debate, not a pressing obligation.

    Actually, I found out this morning that I do know who John Stossel is. Just didn’t remember his name. I read a brilliant article by him translated to Spanish about the Hooters restaurant chain being harassed by Fed regulators. And that’s in Republican USA. I wish we had a group of Stossels in socialist Spain!
    http://www.missloumagazine.com/stossel.htm

    Anyway, going back to your lack of respect for Lindzen, I have been reading a lot of personal abuse against him because of his article in the link above. I must say I was sad to see you joining the chorus at a particular website.

    One of the various mistakes that fuels the outrage you guys are directing at him seems to be that you think he’s saying that satellites show no atmospheric warming. Well, that’s just not so.

    I remember that some time ago Lindzen was complaining about the big efforts that were being dedicated to correct the observational data, just because it didn’t fit the models’ expectations. He argued, not unreasonably, that the scientific process had traditionally worked the other way around.

    As it turned out, those efforts eventually had some success and the MSU data were corrected to show some warming, albeit less than surface records. Since (by then) not all models showed more warming aloft than on the surface (which I wouldn’t call a strong sign of reliability in the models) the gap between models and observations closed just enough to make both statistically compatible. However, an inconsistency remains for the tropical troposphere, where observations and model results continue to be in contention.

    This is clearly what Lindzen is speaking about. Note that he used the past in his sentence “satellite data showed no warming” and then he goes on “The report showed that selective corrections to the atmospheric data could lead to some warming, thus reducing the conflict between observations and models descriptions of what greenhouse warming should look like.” He concludes (again, not unreasonably in my view): “That, to me, means the case is still very much open.”

    I hope not to ever get so biased as to misread what alarmist scientists say and start attacking them personally based on my own mistake. My brief interaction with some of them at RC showed me that they can be *very* arrogant and unpleasant. But the fact remains that they are top quality professionals who are dedicating their careers to the study of a very complex subject. On that basis, I will always feel, as a layman, interested in what they have to say.

     

  • At July 29, 2006 9:26 PM, Anonymous Anonymous said…

    Coby,

    love your blog. Up here in Alberta a new group of climate skeptics are up and runnging. here's the link:

    http://www.friendsofscience.org

    have a look at the myths and facts section.

    thank goodness we have people like you working to counter this slop.

    p

     

  • At July 29, 2006 10:00 PM, Blogger coby said…

    Thanks for the feedback! I know about FOS...ugh. I grew up near Calgary (Bragg Creek), so feel some responsibility ;-)

     

  • At August 01, 2006 4:28 AM, Blogger Peter K. Anderson said…

    There is little that can be validly noticed from the 'hockey stick' plot, the methodology to produce it was flawed, showing clear indications of predetermination in it's consideration of 'data' dropping 'outrider points' when those very points are strongly indicative of short term fluctuations of temperature in an 'experiment' looking for 'the casual process' only shows that the 'casual process' had already been decided on beforehand. Testing a 'hypothesis' in a VALID manner does NOT include 'fitting' the data TO that hypothesis...

    There cannot be considered a 'greenhouse effect' in any serious consideration of ["important climate related issues"] as there is NOT such a process present within the biosphere when is noticed the materials actually present, these materials REAL behaviours AND the situation these materials are placed within. Numerous 'interpretation errors' have included into the 'greenhouse theory' the 'use' of Energy that in actuality existents as secondary photons, but is (incorrectly) being given 'treatment' as 'representative of heat'.

    This Energy, as presented in these (reemitted) photons is the Energy within the Cascade of Photons existing within the boundary of the Atmosphere. This Energy doesn't however represent a 'temperature' of the surrounding and SEPARATE molecules. The Energy of secondary photons wasn't related in its production to the Temperature of the original molecule to begin with and isn't 'blackbody' sourced or derived in ANY (valid and real) manner. See again the outlines at link (*) and notice that the Quantum Wave-Kinetic ('heat inducing') and Photonic (involving remittance of secondary Photons) interaction sets and are all part of the 'Interactions with Photons' Science.

    The 'demonstrative greenhouse model' presents not the reality we observe but only a (very expensive) 'computational processing' of disassociated OPINION.

    The persistent reoccurrence of the 'hockey stick theatre' is made only at times when the 'greenhouse platform' finds itself needing a 'blind' to hide its lack of substance ,and 'real world performance', behind.

    Advocacy is NOT an action of the validation processes of SCIENCE.

    Your's,
    Peter K. Anderson a.k.a. Hartlod(tm)
    From the PC of Peter K Anderson
    E-Mail: Hartlod@bigpond.com

     

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