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The weirdest millennium

Filed under: — stefan @ 29 May 2007

Much research effort over the past years has gone into reconstructing the temperature history of the last millennium and beyond. The new IPCC report compiles a dozen reconstructions for the temperature of the Northern Hemisphere (including of course the original “hockey stick” reconstruction, despite opposite claims by the Wall Street Journal). Lack of data does not permit robust reconstructions for the Southern Hemisphere. Without exception, the reconstructions show that Northern Hemisphere temperatures are now higher than at any time during the past 1,000 years (Figure 1), confirming and strengthening the conclusions drawn in the previous IPCC report of 2001.

Fig. 1: Figure 6.10 (panel b) from the paleoclimate chapter of the current IPCC report (see there for details).

“Climate sceptics” do not like this and keep coming up with their own temperature histories. One of the weirdest has been circulated for years by German high-school teacher E.G. Beck (notorious for his equally weird CO2 curve). This history shows a medieval warm phase that is warmer than current climate by more than 1 ºC (see Figure 2). So how did Beck get this curve?

Fig. 2, modified from E.G. Beck (we added the green parts).

The curve is a fake in several respects. It originally is taken from the first IPCC report of 1990: a scan of the original is shown in Figure 3. At that time, no large-scale temperature reconstructions were available yet. To give an indication of past climate variability, the report showed Lamb’s Central England estimate. (Unfortunately this was not stated in the report – an oversight which shows that IPCC review procedures in the early days were not what they are now. We will post in more detail on the history of this curve another time.)

Fig. 3. The past millennium as shown in the first IPCC report of 1990, before quantitative large-scale reconstructions were available. This curve was based on Lamb’s estimated climate history for central England.

But Beck did not stop at simply using this outdated curve, he modified it as highlighted in green in Figure 2. First, he added a wrong temperature scale – the tick marks in the old IPCC report represent 1 ºC, so Beck’s claimed range of 5 ºC exaggerates the past temperature variations by more than a factor of three. Second, the original curve only goes up to the 1970’s. Since then, Northern Hemisphere temperatures have increased by about 0.6 ºC and those in central England even more – so whatever you take this curve for, if it were continued to present, the current temperature would be above the Medieval level, as in the proper reconstructions available today. As this would destroy his message, Beck applied another fakery: he extended the curve flat up to the year 2000, thereby denying the measured warming since the 1970s. With this trick, his curve looks as if it was warmer in Medieval times than now.

When approached directly about these issues, Beck published a modified curve on a website. He changed the temperature range from 5 ºC to 4.5 ºC – but he shortened the arrow as well, so this was just cosmetics. He also added instrumental temperatures for the 20th Century at the end – but with his wrong temperature scale, they are completely out of proportion. (In fact his version suggests temperatures have warmed by 2 ºC since 1900, more than twice of what is actually observed!)

Beck goes even further: in a recent article (in German), he has the audacity to claim that his manipulated curve is right and the more recent scientific results shown by IPCC are wrong. And for years, he has offered his curve on an internet site ( that distributes teaching materials for schools, with support from German school authorities. It is quite likely that his fake curve has been shown (and will continue to be shown) to many school children.

507 Responses to “The weirdest millennium”

  1. 101

    Re #73,


    The glaciers in the Alps show several retreats and advances in the Holocene. Wood from trees growing far higher than today (and human bodies) are now released by retreating glaciers. That points to higher temperatures and/or less precipitation in the past. One investigation on that subject points to the possibility that Hannibal could get over the Alps without problems, because there were no ice barriers…

    Some references:

  2. 102
    Tim Jones says:

    Ref comment #2:
    “It worries me that we (i.e. our politicians) are not going to address the issue of climate change in time to avoid serious consequences. Institutions like the Wall Street Journal and people like Beck are not helping the issue.”

    Seems to me there’s an even more insidious level of abrogation of responsibility at play here. To wit:

    CLIMATE: NASA chief questions need for action on warming
    Lauren Morello, Greenwire reporter

    “NASA Administrator Michael Griffin questioned the need today for action against global warming in a taped radio interview that aired just ahead of President Bush’s announced effort to help forge a new international agreement for curbing greenhouse-gas emissions.

    Griffin told National Public Radio he has “no doubt that a trend of global warming exists” but said he is unsure that it is “a problem we must wrestle with.”

    The majority of scientific evidence supports observations that the Earth’s average global temperature has warmed by about 1 degree Celsius over the last century, Griffin said.

    “Whether that is a long-term concern or not, I can’t say,” he said. “I don’t think it’s within the power of human beings to assume that the climate does not change, as millions of years of history have shown.”

    Griffin further addressed climate change in a statement released by NASA today in response to the NPR interview.

    “NASA is the world’s pre-eminent organization in the study of Earth and the conditions that contribute to climate change and global warming,” Griffin said in the statement. “It is not NASA’s mission to make policy regarding possible climate change mitigation strategies.”

    In response to Griffin’s interview, House Science and Technology Committee Chairman Bart Gordon (D-Tenn.) issued a statement questioning whether NASA is adequately carrying out its scientific duties related to climate change.

    “Based on NASA’s own five-year budget plan, the agency will be unable to start any of the new Earth observations initiatives recommended by the National Academies for the foreseeable future,” Gordon said. “That’s not going to get us where we need to be in our understanding of climate change. NASA needs to do more.””

  3. 103

    I hate to break a thread, but the new millennium just got weirder.

    Where is RealClimate with the Michael Griffin – James Hansen thing?

  4. 104
    Bill Barney says:

    I’m wondering if anyone here has a reaction to Michael Griffin’s comment on NPR today that

    “I would ask which human beings â�� where and when â�� are to be accorded the privilege of deciding that this particular climate that we have right here today, right now is the best climate for all other human beings. I think that’s a rather arrogant position for people to take.”

    I heard this on the radio this morning and was astonished. My take is here (and I gave a plug):

  5. 105
    Bill Barney says:

    I don’t think I can edit my comment, but the a?? characters are supposed to be em dashes…. looked OK in preview…

  6. 106
    unconvinced says:

    I know I seem to be nit-picking on various comments, but I feel you need to be careful and precise in what you say, lest these comments come back and bite you on the nether regions! In that context…

    Gavin, in response to #83 says “Thus the couple of tenths of deg C that are in dispute here are simply just not that relevant for the questions of future climate.” This is a rather dangerous position to take because sceptics would suggest that “If a couple of tenths of a degree C is not relevent to future climate, then why the fuss about the couple of tenths of a degree C rise that happened over the 20th C?”. Please be more careful.

    [Response: The warming over the last hundred years is significantly more than ‘a couple of tenths of a degree C’ – i.e. 0.8 deg C (and counting), but the issue with climate change is not that the last hundred years have been disastrous, but that the future continuation of this process may be. And there, we are taking about mutliple degrees. -gavin]

  7. 107
    Jomathan Gradie says:

    Can you provide us with the most useful action can individuals take to counter the comments by NASA Administrator Michael Griffin? Is there someone (significant) at NASA we can email to register our displeasure? Should we contact our congressional representaitves? Which ones are most significant with respect to this issue?

  8. 108
    dhogaza says:

    “I would ask which human beings – where and when – are to be accorded the privilege of deciding that this particular climate that we have right here today, right now is the best climate for all other human beings. I think that’s a rather arrogant position for people to take.”

    Yet deciding that a significantly warmer earth is best for all other human beings (which is what doing nothing amounts to) is not an arrogant position to take, apparently.

  9. 109
    Neal J. King says:

    Since the topic of “global warming on other planets” has emerged again, I would like to mention a point I noticed.

    If GW is happening on another planet, the effect could be related to the issue of proximity: being closer or farther away, as a function of phase in the orbit. In effect, a “seasonal” issue (although I guess planetologists like to use that term for effects due to axial tilt with respect to the ecliptic plane; I’m using it here to refer to expected changes over the course of a planetary year). But if the effect is happening within a seasonal timeframe, then you can’t prove that it’s anything other than a seasonal effect, so it’s not evidence of extra-terrestrial GW.

    On the other hand, if it happening on a timescale that exceeds the planetary year; and if it dominates the seasonal changes, then whatever is causing it must have a greater effect that the seasonal changes. In particular, if it is laid at the door of increase in solar luminosity, then that increase has got to be a bigger effect than the natural change in solar intensity due to the changing radius: If the effect of the “GW” is bigger than the effect of the seasons, the cause of the “GW” must be bigger than the cause of the seasons. This puts a lower limit to the required change in luminosity required to explain the “GW” on other planets.

    But the seasonal variation is well-knowns: Since
    TSI is proportional to luminosity/(orbital_radius)**2,
    the fractional variation of TSI is (2*delta_r)/(average_r), which is
    4*(aphelion – perihelion)/(aphelion + perihelion).

    The two candidates of interest (because of observed time frames of the putative “GW” events) are Mars and Jupiter. When you do these calculations, you find a required change in solar luminosity of 37.4% and 19.7% respectively. However, since TSI as measured on Earth has only varied in the range of about 0.1% since 1988, you can’t possibly seek an explanation of these non-seasonal behaviors in the Sun.

    So, in summary, GW on Mars and Jupiter certainly cannot be blamed on the Sun; and events on the other planets can credibly be attributed to merely seasonal variation.

  10. 110
    John Mashey says:

    re: #100 (re #73, and check #93 for edit fix)

    Ferdinand: yes, what they say is completely consistent with the Holzhauser paper which goes back to 1500BC. The Hormes Unteraar Glacier paper covers earlier periods, although the latest one meshes with the earliest period on the Holzhauser paper.

    Is your argument that it was warmer than currently during some periods before 1500BC?

    If so, we agree 100% … of course, there should have been warmer periods back then. See: Brian Fagan, “The Long Summer” for example.

    I haven’t found a handy chart of typical solar insolation In Switzerland (~47 degrees N), but:

    a) Based on normal orbital cycles, and eyeballing a few charts, I see that the typical July solar insolation at 30 degrees N should have fallen from a peak ~550 W/m^2 10,000 years ago to ~ 475 W/m^2 now. These would be less in Switzerland.

    b) Of course, there would be imposed the usual 11-year jiggles, plus any Maunder Minimum equivalents to drop the temperatures, plus any other of the usual effects.

    c) But still, one would expect that even with the usual jiggles, overall natural temperatures should have shown a slow cooling trend last 10,000 years, i.e., especially more than 3500 years ago, there should have been warmer periods, simply because the typical insolation should have been higher.

    c) But, the Unteraar is heading up the hill just like the Great Aletsch, see:

    d) Hannibal crossed the Alps Fall 218BCE, in middle of a long Aletsch retreat period centered on 1AD in Holzhauser Fig 5, and people still debate his exact route:, maybe thsi research will produce results.
    But for now, if they went via the route occupied by Montgenevre … via Googlemaps, the village is along one side of the pass, and the ski resort is across the street, so I doubt there are “ice barriers” these days, although they certainly get snow.

    Anyway, all of this perfectly consistent with natural cooling (with jiggles) over millennia, shorter earlier glaciers, longer recent ones … except recently, when the glaciers turn and retreat, heading soon (decades, at current rate, for Aletsch, anyway) further up than any time in last 3500 years…

  11. 111
    Lawrence Brown says:

    It’s mind boggling that the NASA Administrator would make a statement that he’s unsure that climate change is a problem that must be dealt with. What is he thinking? That if we don’t worry about it will go away? I can’t understand how someone in his position, wouldn’t know about the problems that are being confronted today from the effects of climate change, such as native residents of northern Canada and Alaska,dealing with the adverse effects of melting permafrost. The residents of low lying islands in the Pacific Ocean are seeing the results of rising sea levels at this very time. There are many other detrimental effects that have been documented on this site, before, such as dying coral reefs,and the loss of reflecting ice and snow, both at high altitudes and in the polar regions, reducing the Earth’s albedo, which leads to more heating.
    I suppose we shouldn’t be too surprised. The foot dragging by this administration’s political appointees, as opposed to career professionals, in the scientific area, has been evident from day one.

  12. 112

    Some misinformation about Antarctic ice appears in this thread, so far uncorrected, I think. Specifically I believe Eric’s reply to #4 is incorrect.

    The West Antarctic ice sheet is not particularly melting; it is warming up a bit, it is softening a bit, the ice shelves holding it back are retreating, all of which causes the ice to flow faster. If we get the several meters of West Antarctic driven sea level rise it will predominantly be because of what amounts to a mechanical failure of the ice sheet.

    Glaciers flow downhill and warmer glaciers flow downhill faster. Above a certain flow rate there is no equilibrium with precipitation and the glacier vanishes. The West Antarctic can be considered a few huge glaciers, and this idea holds for them as well.

  13. 113
    Philippe Chantreau says:

    RE 89: I ran into someone like that Kenny. All you have to do is conduct your own quick research. and NASA are the good, readily available sources for the layman.

    Any assertion that outer solar system planets could be warmed by the sun in a significant way appears unfounded. The kind of solar output variation necessary to warm up Pluto or Neptune would be very noticeable to us. Keep in mind that no variation in solar output was ever actually observed until the age of satellites. The gas giants are mostly driven by their internal heat. In the case of Jupiter, the internal heat effect is far beyond any other input (see Most outer planets’ climates are a matter of educated guesses since there has not been enough observation to cover even 5 “years” of it. In other words, we don’t exactly know what the “climate” of Saturn or Neptune is really like and we are not in a position to say affirmatively that it is changing. As an example, Pluto takes 248 years to revolve around the sun. Any latest observation on those planets is likely to be the best to date, making comparison inappropriate, and will be a punctual observation, i.e. not a long term trend. In any case, these planets’ and their atmosphere are so dfferent from ours that any comparison beyond a specific point is very hypothetical.

    There is a lot of noise about Mars, it is quite undeserved. Mars’ seasonal cycle naturally exposes it to more intense southern hemisphere summers, which are not entirely compensated by its northern hemisphere winters, hence a natural deficit in southern carbonic ice (see NASA, good discussion on that). How much of an anomaly the recent southern hemisphere CO2 ice deficit constitutes is debatable. Furthermore, dust storms appear to be a major driver of Mars weather and short term climate. Lastly, the correlation between Mars and Earth is actually weak to non existent; what the Mars-global-warming proponents ignore or leave in the dark is that the recent warming trend (if there is such a thing) is quite recent. Mars went through a signficant cooling period after the Viking landings in the 70’s, while Earth’ climate was doing its upward temperature spike.

    Last but not least, Venus, close to the Sun and sporting enormous GH effect, does not show signs of “global warming” like Pluto. Asserting that a solar output variation capable of warming Pluto would leave Venus alone does not seem to make much sense.

  14. 114
    Timothy Chase says:

    John Mashey (#73) wrote:

    What exactly would you do different if today:

    T1000AD > Tnow ( a little cooler today) OR
    T1000AD == Tnow (same) OR
    which shows the Great Aletsch Glacier’s advances & retreats [a long glacier, which tends to smooth out short-term fluctuations, and is only now responding to 1980s temperatures.

    (emphasis added)

    That is pretty much the same which is happening to approximately 90% of all glaciers.

    For global glacier mass balance, see the chart at:

    State of the Cryosphere: Glaciers

    I think everyone should also keep in mind that even if we were to hold constant the amount of greenhouse gases which are already in the atmosphere, the temperature would continue to rise for some time to come.

    Please see:

    Even if we could have stopped any further increases in all atmospheric constituents as of the year 2000, the PCM and CCSM3 indicate that we are already committed to 0.4 and 0.6 C, respectively, more global warming by the year 2100 as compared to the 0.6 C of warming observed at the end of the 20th century (Table 1 and Fig. 1B). (The range of the ensembles for the climate model temperature anomalies here and to follow is about +-0.1 C.) But we are already committed to proportionately much more sea level rise from thermal expansion (Fig. 1C).

    How Much More Global Warming and Sea Level Rise?
    Meehl, et al
    Science 18 March 2005:
    Vol. 307. no. 5716, pp. 1769 – 1772

    Yet we have actually increased the rate at which we are dumping CO2 into the atmosphere…

    For more on this, please see:

    CO2 emissions from fossil-fuel burning and industrial processes have been accelerating at a global scale, with their growth rate increasing from 1.1% y^-1 for 1990â??1999 to >3% y^-1 for 2000â?? 2004. The emissions growth rate since 2000 was greater than for the most fossil-fuel intensive of the Intergovernmental Panel on Climate Change emissions scenarios developed in the late 1990s.

    Global and regional drivers of accelerating CO2 emissions
    Raupach, et al
    Proc Natl Acad Sci U S A. 2007 May 22; [Epub ahead of print]

    In an effort to downplay the seriousness of today’s climate change, contrarians will argue that some glaciers were smaller a thousand years ago, but given the way things are looking, our surpassing this is a foregone conclusion. Their argument might be carry some weight – if glaciers were to miraculously freeze where they are now. As things are, it is about as relevant to the current state of our climate and the direction that it is headed as the seasons of Pluto.

  15. 115
    Philippe Chantreau says:

    RE #89 continued: About solar output variations, a lot of denialists like to refer to the Sulanki paper (2004, I think). It is quite helpful that this paper is actually available online as a PDF file (I found it easily with Google). The conclusions section is very clear as to how much of the current warming can be attributed to solar variation and it is no more than 30 %. This would be under the extreme assumption that previous temerature changes would be entirely due to solar output, a scenario that is virtually impossible.

    I also read about Neptune that the supposedly increased brilliance is in the blue spectrum, which would correspond to an amount of energy that simply makes no sense. I haven’t verified that with any more credible source, however.

  16. 116
    Julian Flood says:

    Re 36: > … global warming art etc link

    I have reservations about this graph (is it HADCRUT3?) as it fails to verify my own particular theory of global warming. This theory predicts that there should be an SST pulse starting in late 1939 and tailing off after the battle for the Atlantic is won. A study of the rise rate — grab a passing student someone — should confirm that the various effects of oil/surfactant spill are what is causing our current warming. But look at the graph — it begins to rise before 1938 which presents a problem.

    Now look at the raw data before the so-called ‘bucket’ correction is applied: this correction was imposed to allow for the differing methods of measurement before engine intake thermometers were installed, raising SSTs before 1938. IMHO, it should be looked at again: it was originally accepted as it enabled one of the GCMs to forecast land temperatures correctly and, while it may have achieved this aim, it fails the test of the kreigesmarine signal.

    ‘You cannot experiment with the climate’. How many times have you heard that? Well, Donitz and his kreigesmarine did and the signal and response is there to see. Do you know what it looks like to me? It looks like a tiny version of the PETM.

    More details of the AGW theory of surface pollution on my website at floodsclimbers.


  17. 117
    SomeBeans says:

    #99 Timothy Chase
    Cheers – that’s what I was looking for!

  18. 118
    Julian Flood says:

    Re 61: “In Fig 1 there is a distinct peak in the temperature curve in the WW II years. Has any consideration been given to assigning a forcing factor for warfare and the MIC’s?” Harold Pierce Jr

    On the basis of that bulge I have constructed a theory of global warming that explains much of our current problem. Briefly, oil spill and surfactant pollution alter the properties of the ocean surface, reducing cloud formation, lowering albedo and changing oceanic nutrient flows. It’s on my floodsclimbers website. No-one takes it seriously, of course, but it’s amazing how many predictions it makes about the process of AGW, even the isotope smoking gun. I’ll not hold my breath about a grant, though — I’ve watched a student struggle to finish a thesis on phytoplankton carbon fixation without a grant and that’s about as cutting edge GW stuff as you can get. No chance, then, for something as off-the-wall as this theory.


  19. 119
    nicolas L. says:

    re: 89

    About Martian warming, I found a french article talking of it, I’ll try to make a ruff translation (here’s the source anyway for all french lovers :) ):,climatique,sur,mars,,.aspx

    “Planet Mars is heating. It’s surface temp. would have increased by 0.65°C during the 20 last years, says Lori Fenton, from Carl Sagan Center, California.Comparing maps of the planet albedo, from Viking probe between 1976-1978 and from Mars Global Surveyor between 1999 and 2000, the scientist discovered many regions of southern emisphere darkened with time. And, like earth, the darker a region is, the more it “captures” heat.
    Why those austral regions became so dark? Lori Fenton says the clear dust recovering those areas have been swipped by solar induced winds. And this process started to spiral out of control: upon the darkened areas, atmosphere began to heat, making the winds blow stronger, swipping away even more dust.
    To estimate global increased of temp. on Mars surface considering the surface of darkened regions, the american scientist used some models used notably for earth weather predictions. From its results, and if warming doesn’t stop, Mars polar sheets could disappear in 500 years. It’s unlikly to happen, commented many planetologists, considering the large number of phenomenas that could inverse this tendency, for exemple large scale dust storms.”

    I didn’t manage yet to find the original work from Lori Fenton, but if someone finds it I’d be glad to read it.
    So what can we conclude from the martian warming? Not much apparently, as it seems to be due to some very specific regional phenomena (the dust deposits), and that the main factor here is albedo, not solar radiation. Secondly, this is based on a ruff 5 years-long collect of data, on an overall 20 years period… Not much to make a robust trend, is it?
    Each planet is working its own way on this solar system, due to its atmosphere, specific climatic phenomenas, orbit, size and so on and so on. So when one tells you that because there is a warming on Mars or Neptune (I wonder how relevant it is to compare the atmosphere of a telluric planet with the one of a gaz planet :) ), this can only be explained by fluctuations in solar radiation and therefore it also explains earth warming, I think you can consider this person as pretty ignorant about everything concerning climate AND astronomy.
    And if you wanna be a little sarcastic, you can always say that if there was actually a trend of global warming concerning all of the solar system, you should observe it on all the planets, and not only 3 :)

  20. 120
    PaulM says:

    #92: There is no generally accepted view on what caused the MWP and LIA. Some have pointed out that the peak of the LIA coincides roughly with the ‘Maunder minimum’ in the late 17th century during which there were virtually no sunspots – but note the word ‘coincides’. Others say that the climate is a complex system that fluctuates in a rather irregular way and it is wrong to ask for a ’cause’ of each maximum and minimum.

  21. 121
    pete best says:

    This website has been very good at putting the case for AGW and defying the contrarians and denialsists but that battle seemingly seems to be over no with the current administrations admission on AGW being real and worrying. What seems to be happenning now is that the worlds economies seem to want to limit climate change to 2 degrees C or 500 ppmv or CO2 which although possible still seems unlikely.

    Can real climate not run an article on what the consequences are for a average warming of 2 degrees C and when it is likely to happen and how likely it is that we can achieve this.

    President Bush keeps on harping on about breakthrough technologies but no one seems to know what they are and how long it will take to deploy them in order to achieve the desired results. Is the Bush administration stalling and providing a smoke screen in order to continue their quest for the continuation of the fossil fuel age ?

  22. 122
    ghost says:

    RE: 121 Perhaps, but it’s equally likely in my view that the go is a Rovian attempt to take the issue away from the Democrats. Sort of “Don’t worry about GW–we’ve addressed it, and it’s not an issue anymore. Move along now. Nothing to see here. There are no droids here.” Or, toward another movie theme, “Earl explained it to me: we plan ahead, that way, we don’t do anything right now.”

  23. 123

    Re: Pete Best, If governments just dont get it re: climate change, then it up to us and business to take the initiative and take the lead. We dont have time to wait for governments to argue as to the ways to tackle climate change without effecting one’s economy. They dont seem to get the seriousness if the situation. The US and many world economies wont survive anyway if climate change gets out of hand. It will be the countries that can survive on less that will triumph. If Bush took this as seriously as the threat in the corny movie ‘independance day’ we might get some action…he must realise that this threat is absolutely no less in magnitude only in slow motion. If we fail, our young children now may never be given the chance to be grandparents.

  24. 124

    This is interesting…ninemsm conducted a survey which stated: ‘Should the Australian economy come before climate change’..the majority of the resondants said ‘NO’. I would guess that’s the same in the US and europe. Good sign!! Shows people’s concern is growing.

  25. 125

    Re 121, see the Two Degrees chapter of Mark Lynas’ 2007 book, SIX DEGREES.

  26. 126
    Rod B says:

    catman (306), what is perfectly obvious to some just might not be so to others. This might or might not make us sceptics (…but still looking) stupid. And don’t use the old argument that ‘we took a vote and AGW won by a large majority — so that settles the science’.

  27. 127
    Timothy Chase says:

    Re William Calvin (#123)

    Good book? Does he seem credible and do his claims seem to be backed up by the science?

    I was a little worried about that. Real Climate seems right on target and has the expertise up the yin-yang, but some articles by others are legitimately regarded as alarmist or at least uninformed.

    I guess I should just check it out and put the preconceptions in the circular file…

  28. 128
    Warren says:

    With the exception of the black curve (Instrumental, HADCRUT2v), the shape of the family of curves in Fig. 1 seems to match Beck’s curve (Fig. 2) quite well (ignoring scale). I’m not familiar with the derivation of each of the other curves in Fig. 1, but is it possible that low temporal resolution of these other estimates could be masking significant spikes in the past that we are only now able to resolve by better instruments and records? In other words that the current hockey stick is an artifact of improved temporal resolution in the recent past compared to the poor resolution of the distant past climate? I’m not an AGW denier and not trying to make bold claims, I’m just trying to understand the significance of the data in this chart.

    [Response: Most of the records shown in the IPCC graph (Fig. 1) have annual resolution (as you can obtain e.g. from tree ring data). The curves shown are of course smoothed versions; that applies both to the instrumental record (black curve) and the reconstructions. -stefan]

  29. 129
    Timothy Chase says:


    My post above…

    I meant to respond to William Calvin (#125) regarding Six Degrees.

    My apologies to both William Calvin and Lawrence Coleman.

  30. 130
    nicolas L. says:

    re: 126

    maybe we should put it this way then: “we looked at the opinion of the climate scientists , and AGW won by an overwhelming majority… so that settles the science” :)

  31. 131
    pete best says:

    Re #123, Politicians that rely on lobbying (the USA) and other countries relying heavily on fossil fuels (ie Australis, China and India to name a few) have a vested interest in maintaining the status quo. Painful decisions need to be made regarding energy efficiency and alternative technologies but the coal and Oil industries have a large grip on political thinking in many countries and the economy could suffer under these new initiatives.

    AGW is an inconvenience for them and they really cannot see how to reduce their CO2 footprints by 60 to 80 percent in order to limit AGW to one or two degrees. Moving away from Oil and coal to renewables and sustainables is a new world to them, one in which they might not be able to control it all.

    As Gavin Schmidt and James Hansen have stated recently we could first deal with aerosol and soot emissions first and then CO2 next, stop cutting down rain forests and use land differently in order to give ourselves a chance or then reigning in CO2 emissions but there was no evidence of any of that is Bush’s speech, just rhetoric really and stalling tactics.

  32. 132

    Re #120 The climate is a complex system, but that does mean that it is wrong to look for the cause of each maxixmun and minimum. What is wrong, is to look for one cause that explains all maximums and minimums, or even just all minimums.

    The Little Ice Age (LIA) began in the 14th Century, long before the Maunder Minimum. It seems to have started because of the drawdown in CO2 as a result of the increase in fallow land after the depopulation caused by the Black Death. A couple of hundred years later, in the middle of the LIA, the Dutch had their hottest temperatures ever recorded before 1998. Then the solar cycle brought the the Maunder Minimum and the Dutch spent their winters skating on the canals, and Londoners were building bonfires on the frozen Thames.

    The most likely cause of the Mediaeval Warm Period (MWP) was the spread of the Anglo Saxons who cleared the forests in order to farm it with their iron ploughs. Their descendants in the USA and Australia had the same effect in early 20th Century, culminating with the Dust Bowl.

    It is not a matter of arrogance to claim that Man has changed the climate in the past. It is arrogance to think that we have learnt from our past mistakes and that any changes we may make in the future will be for the good of mankind :-(

  33. 133
    Timothy Chase says:

    Rod B (#126) wrote:

    catman (306), what is perfectly obvious to some just might not be so to others. This might or might not make us sceptics (…but still looking) stupid. And don’t use the old argument that ‘we took a vote and AGW won by a large majority — so that settles the science’.

    In all honesty, I don’t think that the contrarians look stupid at all – well, perhaps some, but not any that come here – at least that I have noticed. Moreover, I most certainly don’t believe that contrarians have “evil intentions.” Well, perhaps a few, but not here.

    However, personally, there is something which I entertain as a hypothesis of sorts – namely, that many people in different areas of their lives and to different degrees tend not to recognize a fairly fundamental principle: identification precedes evaluation. This is the principle underlying the fact that ad hominem attacks and appeal to emotion are fallacious forms of reasoning.

    It is something which one violates when one refuses to accept the evidence and where it leads because it would call into question what one believes even with regard to oneself – and one recoils from the consequent anxiety. It is something which one violates when one places loyalty to a group above one’s perception of the truth with regard to any subject. And it is something which one violates when one endorses the view that there are different logics for different people – dependent upon their race, religion or economic class.

    Now in my view, some contrarians are simply uninformed. Others in one way or another to one degree or another violate the principle that identification precedes evaluation – given the weight of the scientific evidence. Moreover, I believe that the group which is simply uninformed is rapidly shrinking.

    Where I would place particular individuals is another matter – and ultimately it would be up to each individual to make this judgment for themselves.

  34. 134
    catman306 says:

    Sorry about my tone, Rod B. I had just heard the head of NASA’s interview on NPR and was livid. Since I knew more knowledgeable people would be responding to him (and are they!), there was more emotion in my response than was warranted.

    Climate change shows itself as extreme weather events because climate is average weather and any average is changed either by many small changes or fewer large ones. So if you watch the kind, number, and intensity of extreme weather events you may loose some of your skepticism.

  35. 135
    John Mashey says:

    Re: #73,#93 (me); #101 (Ferdinand Englebeen); #114 (Timothy Chase)

    “In an effort to downplay the seriousness of today’s climate change, contrarians will argue that some glaciers were smaller a thousand years ago, but given the way things are looking, our surpassing this is a foregone conclusion.”

    I’d assumed #101 was of that sort, or at least I’ve gotten similar arguments elsewhere. [Ferdinand: have you had a chance to study the Holzhauer paper, and did these arguments make sense, or not?]

    This does remind me of the value of complementary orthogonal approaches:
    1) “Horizontal”, like, which
    gives a broad global view with clear current results, needed to see the current big picture and avoid problems with the randmoness of individual glacier configurations and local differences. Unfortunately accurate broad records (especially for mass balance) just don’t go back very many decades.

    2) “Vertical”, like the various glacier-length studies of Aletsch, focus on a single example for which there is:
    a) Excellent data over last 100 years.
    b) Pretty good data over last 1000-2000 years.
    c) Some data over thousands of years before that.

    and whose behavior seems reasonably representative; I especially like the longer glaciers’ effect of doing their own curve-smoothing, so one need not argue about that.

    For some people, I think the “concreteness” of a single example is useful, simply because they can *see* the difference in the photographs. While there may be some uncertainty in parts of reconstructions , there’s no room for argument about how mass-balance measures are done, how accurate they really are across numerous glaciers, etc, etc, because one is dealing with the visible effects of one glacier.

    Of course, a) and b) are consistent with the view that unusual warming is happening:

    the glaciers are
    1) melting as fast or faster than they have for thousands of years, and at least from eyeballing the global mass-balance charts, and a sampling of the Swiss glaciers, many retreats have been accelerating … and given the response time lag, the longer ones haven’t even noticed the last 10 years’ heat.

    2) have already retreated to levels not seen for thousands of years, equivalent to times whose typical insolation should have been higher.

  36. 136
    Michael Gell says:

    The timescales for delivery of effective action may be much less than 10 years (circa 4000 days).

    The following is an extract from the summary of the report â??High Stakes. Designing emissions pathways to reduce the risk of dangerous climate changeâ?? by Paul Baer and Michael Mastrandrea. (All temperatures below are in Celcius.)

    â??The research concludes, based on a reasonable set of assumptions, that to have a â??very low to low riskâ?? (calculated as a nine to 32 per cent chance) of exceeding the 2°C threshold, global emissions of carbon dioxide (CO2) would need to peak between 2010 and 2013, achieve a maximum annual rate of decline of four to five per cent by 2015-2020, and fall to about 70 to 80 per cent below 1990 levels by the middle of the century. This would need to be matched by similarly stringent reductions in the other greenhouse gases. These calculations are based on scenarios in which atmospheric concentrations of CO2, which stand at 380 parts per million (ppm) today, peak at between 410-421ppm mid century, before falling to between 355-366ppm by 2100. This in turn is based on the understanding that CO2 concentrations can be reduced by lowering annual emissions below the level of CO2 which is absorbed by global carbon sinks, which currently take up approximately half of the CO2 emitted annually by human activity.â??

    The report can be accessed at the following link

    This type of report is very useful because it provides a time framework on which mitigation efforts should/could be implemented. Other studies indicate similar results.

    Specifically (but roughly speaking), one can take this type of emissions pathway assessment for a given target temperature and define what emissions reduction needs to be delivered.

    One degree
    If people target for a 1 degree warming, then (roughly speaking) emissions should peak within the next 1000 days, and be reduced from then; one degree may, however, already be an option which we have thrown away.

    Two degrees
    If people target for a 2 degree warming, then emissions should peak within about 1000 to 2000 days (i.e. between 2010 and 2013, as quoted above), and be reduced from then at rates described in the report.

    Three degrees plus
    If people target for a higher than 2 degree warming then â?¦

    So how does one work out what level of warming one should target for or what one thinks others should share?

    For this, a useful document is the book â??Six degreesâ?? by Mark Lynas. Information about the book can be seen on Markâ??s website The IPCC report is another useful source.

    The book is an interesting compendium of degree-by-degree analysis as one goes from one degree, to two degrees, to three degrees, etc. Mark gives some summaries of what to expect at each degree on his website.

    If one goes through each degree one can ask: â??what sort of an economy might operate at that degree?â?? or â??what sort of life might people have in a world at that degree?â??. This is the sort of analysis that business and industry should be doing. Corporate executives would do well to read each â??degree chapterâ?? (the book is highly readable) and ask themselves: â??can my business and industry operate at that degree and is my board prepared to disclose to the world, including to investors, shareholders, customers and the media, what degree the business / industry is targetting?â??.

    Specifically every business and industry should be going through their own systems and supply chains in detail, including plant-by-plant analyses and building a realistic assessment of the situation that has been created or that might occur at each degree. It is through this sort of detailed analysis that a more realistic risk landscape can be established, let alone navigated.

    So where are we. In very simple terms, we may be at a point where we can choose which degree we wish to have. However, if we wish to choose one degree then we have about 1000 days to have got our combined act togther and have peaked the emissions or we may already have missed it. If we wish to choose two degrees then â?¦ (see above).

    So what about BAU? The climate systems that people are attempting to model are hugely complex and it is not surprising that climate modelling endeavours remain an ongoing developmental effort. However, people do develop an intuition about the systems they focus so much of their life studying and when an expert, such as Hansen, steps forward and says above the â??reticentâ?? crowd, that even though he doesn’t have fully-developed ice sheet disintegration models to back him up, that the BAU scenario may give rise to a 5 metre sea level rise by 2100 ( ) then from the point of view of business and industrial risk assessment, which is but one point of view, there are important considerations in terms of emission pathways that are now being chosen.

    Also, given that climate scientists were taken aback by the disintegration of the Larsen B ice shelf, it might be reasonable to expect that other disintegrations may occur which come as a surprise, even to climate experts. Hansenâ??s scenario is therefore instructive to work through and back from in substantive detail because it provides a quasi â??boundary conditionâ??, if one does accept that it may be a worst case scenario, for connecting through comparative scenario sets and metricating risk typologies, accumulations and flows over the coming business cycles. If one takes the 5 metre SLR rise as an estimate, and if one then analyses representative individual supply systems across the global economy including coastal plant-by-plant bases and hazard-by-hazard bases and builds up risk profiles through multi-sector mappings and connectivities, it soon becomes clear that structural instabilities, including system-wide shocks, resonances and autocatalytic formations, are the norm as various event horizons in relevant scenario sequences gain sharper focus. Business and industrial risk managers should take note.

    Risk managers should be developing highly detailed models around specific plants and supply networks out into the future because the risks (and liabilities) associated with BAU are both enormous and material. In analysing and modelling the response of business and industrial systems to varying degrees of climate change, abrupt changes to global supply systems, industrial processes and plant operations are endemic. In other words, structural instabilities, shocks and risk cascades are the BAU norm. We see that quite explicitly in analyses and nonlinear dynamical simulations of projected economic, industrial and business processes and market formations.

    We are at a point of structural instability right now and the timescale to choose which branch which we wish to move along is very short. Right now, that is over the next 1000 to 2000 days, we will either have moved industrial and economic systems onto the safest trajectory that we can, given the situation we have created, or the world system will have taken the branch to higher temperatures. Whichever branch is taken the message is absolutely clear: present systems, in the way they are built, configured and operated, cannot be a part of a sustainable future.

    Business and industrial leaders should be prepared to state what degree they are targeting.

  37. 137
    Tim Jones says:

    It’s going to be interesting to see how this shakes out… Jim Hansen is as appalled at Griffin’s ignorance as many of us have been… livid. (This is a guy who’s going to administer an effort to send people to live on the moon???)

    NASA Scientist Critiques Bush’s Strategy
    Hansen also takes issue with NASA administrator Michael Griffin’s views on global warming during an interview with Madeleine Brand. Griffin told NPR’s Morning Edition that he isn’t sure global warming is a problem we must tackle, a view Hansen says is “remarkably uninformed.”

  38. 138
    Timothy Chase says:

    Re John Mashey (#135) on glaciers

    Seems like an accurate assessment, and try as I might, there isn’t really much that I can add to it as I believe you more knowledgeable than I am.

    Concrete examples obviously help, likewise charts which show the problem as it exists at a much broader level help, and ideally one should have both. If limited to text and hyperlinks, I would include a very brief description regarding a few points on the chart – to illustrate the trend – as there will be people who will at least act as if they don’t know what you are talking about and didn’t even seem to realize that the link was there. However, if the description is too long, the point is likely to be lost in the text for some more careless readers.

    One other point: a great many people might not understand the practical importance of glaciers.

    Glaciers permit precipitation to be preserved rather than lost to the soil. Their yearly, dependable melt provides much of the world’s population with fresh water throughout much of the year. Without glaciers there will be severe water shortages – so there is a genuine urgency to this issue. A catastrophic melt may mean that a great many people will drown in a flood within a given year or another, but the possibility of extreme and enduring water shortages over vast regions and the consequent reductions in agricultural output are far greater concerns.

    I don’t mean to reduce this to body counts, but I suspect that ultimately this is in large part what it comes down to.

  39. 139
    Timothy Chase says:

    PS – to my post above

    When projections of the number of people affected by one disaster or another are made, I think it may be easy to lose sight of the fact that such people are individuals.

    Having been in the Navy, I may be a little more sensitive to this in some ways. I briefly knew a girl in Madagascar living in little more than a shack. She was taking calculus. She and her friends offered to let me join them for dinner. Their island was hit by several hurricanes last year. The Atlantic was quiet, but the Pacific had a record year. I knew a guy who everyone called “chief” even though he was only a first class pettiofficer. But he was a chief – in Samoa. His island had essentially been in the stone ages at the beginning of the twentieth century, but on board ship he was an electronics technician – and just about the sweetest guy you ever met. And there were many others.

    Even at my current job I have the chance to meet and work with people from many parts of the world. A number of them are from China and Taiwan. Others are from India. I know a former mathematics professor who grew up in Tibet. These people might not be directly affected, but people that they care about probably will be.

  40. 140
    JimO says:, All of what you say seems so logical and clear but similar projections in the past where so far off and it it seems so very complicated that I cannot support acting on the current knowledge.

  41. 141

    Actually, the last 20 years have been predicted fairly accurately, given what we knew just in the ten years previous to that.

  42. 142
    Kroganchor says:

    I am a skeptic. Not being sufficiently educated to understand the science, I must form an opinion from the conclusions of others. And present company excepted, there are lots of skeptics.
    However, it seems that within a decade the temperature record will confirm or confound the AGW hypothesis.
    If confirmed, there will be a capitulation of opinion, and the leaders of the world will take action in several ways. First by accelerating the development of nuclear power generation, High taxes on fossil fuels, and if the situation is severe enough, the Russians’ diabolical plan of a million tons of aerosols into the atmosphere.
    If temperatures don’t confirm and cause some real pain,-well then good luck convincing the world that something serious needs to be done.
    Solar, wind, & conservation is just a sideshow that we ought to be doing anyway just out of common sense.

  43. 143
    Timothy Chase says:, All of what you say seems so logical and clear…

    What parts?

    … but similar projections in the past where so far off…

    Which projections?

    How long ago?

    What were computers like then?

    How much peer-reviewed scientific literature backed those projections?

    How much support was there in the science community?

    How much evidence did they have at the time?

    … it seems so very complicated that I cannot support acting on the current knowledge.

    How much time have you spent attempting to understand the issues?

    … and out of curiousity, where are you posting from?

    Come to think of it, I most certainly would not ask you to act on the current state of your knowledge. In fact, I would rather you didn’t. I would only ask that you don’t get in the way of those who are clearly far more knowledgeable and informed than yourself.

  44. 144

    I am a skeptic. Not being sufficiently educated to understand the science, I must form an opinion from the conclusions of others.

    That makes you a denier. A skeptic must present evidence to back up their claim of skepticism.

  45. 145
    Kroganchor says:

    No. I am not a denier. I just don’t think that the evidence is conclusive, at least not to a layman.

  46. 146
    ray ladbury says:

    My 2 cents on the whole flap with Mike Griffin. I’m somewhat limited in what I can say for various reasons. However, I can attest that the man is not an idiot. He may be somewhat narrowly focused, and I am pretty sure he has not thought through the consequences of climate change in much detail. He is totally focussed on his mission of getting astronauts back to the moon–and he really doesn’t want to think about much else. He is convinced that that is the only way NASA will survive–that otherwise it will die the death of 1000 budget cuts. In my opinion, it was probably inappropriate for him to answer the question the way he did, but let’s face it, his opinion is representative of that of many engineers–who also haven’t thought the problem through, but still feel they SHOULD have an opinion on the matter. The quickest way for a scientist to look like an idiot is to venture opinions outside his realm of expertise. Unfortunately, when scientists (or engineers) become public figures they are often asked to do this and few are wise enough to resist the temptation.

  47. 147
    Mel Alstadt says:

    “The weirdest millienium?” Weirdest one out of how many? Two? Where’s James Annan on probability theory when you need him? Has this proposition passed peer-review?

  48. 148
    mark s says:

    Hi all,

    i’ve got a copy of the Mark Lynas book, and i have to say that i think it is pretty convincing, with one or two minor reservations.

    Unfortunately the book is not out in the US til January 2008(!), so i guess i will have to wait a while to see Realclimate’s reaction, which is a pity. If any of the US based moderators would like my copy, i would be more than happy to send it to them, free of charge.

    I believe his previous book, High Tide, was well recieved, and i think that ‘six degrees’ answers some of the questions most of us are currently asking ourselves. Of course Mark Lynas is a journalist, but his attempt to review the published evidence seems thorough, referenced, and reasonably measured.

    Lynas’s website says that National Geographic have bought the tv rights to ‘six degrees’, which reinforces my feeling that he has produced a timely and interesting book. Also, the recently published IPCC WG3 SPM (which we know to be a conservative analysis), included a table(p23) very similar to the one in Lynas’s book.

    Perhaps the most striking parts of the book, are those suggesting that 2deg of warming (which seems to be the limit of our ambitions, currently) will be enough to start the feedbacks that will lead to 3,4 and 5 deg.

    I feel that it is important to point out that i am only a very interested (and reasonably well read) laymen, but i am alarmed by the speed with which events seem to be overtaking us.

  49. 149
    Julian Flood says:

    Re 144: I think you may have that the wrong way round. A sceptic is unconvinced, a denier is determined in his views. The way you treat the two should be different: for a sceptic you need to politely present adequate, well argued and unabusive evidence supporting the case you are trying to make. For a denier you need to point out the errors in the evidence that he is using to form his wrong opinion. Incidentally, I see no reason for either word to be pejorative, they are simply descriptive of an attitude to a proposition. It’s a shame that people try to use them as terms of abuse.

    You will notice, of course, that this argument goes both ways and would, in an ideal world, lead to a polite discussion between both factions (the alarmists and the denialists) while the sceptics look on waiting to choose who wins.

    To see what I mean, read the discussions involving JD (is that Jim Dubhia?)and Judith Curry at The Other Place. They are models of politeness, even when abused. Politeness will win over converts, bullying and hectoring will not.

    I came into this affair convinced that we were facing a major crisis. Now I’m sure that global warming is happening, that it’s anthropogenic (but not so sure that other explanations might not change my mind) and that we should think about solutions. However, I see enough problems with the science — some of the science is truly terrible — that I’d be very very slow to expend billions, let alone trillions, on ameliorating one contributory factor. That’s scepticism.

    If I had my hands on the budget then I’d spend billions on data collection and publication. The fact that this is not being done makes me wonder about motives and whether a push for the security of low oil consunption is not a driver of government priorities — the public will take nuclear power if it’s frightened of global warming and not otherwise.

    Open source data will end up convincing me. It will have to be good stuff, transparent in collection and dissemination, not hoarded by gurus who hand down their conclusions from on high, expecting me to take it or leave it.

    My journey to knowledge continues. Does anyone know of a good source for isotopic changes during historical periods up to today? I’m looking for a graph where I can see the trends and so on — one picture is worth a thousand words — with more complicated details of annual and geographical variation*. For some reason the name ‘Eric’ springs to mind!

    *I would expect a difference in isotopic response to volcanic eruptions higher or lower in zinc and chromium leachate.

  50. 150
    John Mashey says:

    re: #142 & #144

    We continue to have problems with definitions, and we should be gentler. I follow Stephen Schneider’s kind lead here, who had no problem with me being somewhat skeptical years ago, given that I was clearly willing to listen and study a wide range of sources.

    We have the following problem:

    a) A few people are paidup members of the denialist industry, and some of them know enough about the science to be able to generate masses of plausible-sounding controversy, using well-honed PR and lobbyist tactics … at least somewhat successfully, just as the tobacco companies still do OK, 40+ years after “The Surgeon General has determined…” These are clearly “denialists” or “”deniers”, not skeptics.

    b) Some people happen to encounter enough of this early, and get anchored on these beliefs, and it does take serious effort to wade though it, and watch these sources long enough to understand how the end result never changes. This often happened when somebody got turned off by some of the early extreme alarmist doom-saying & press pieces [I certainly got turned off once or twice that way], or gets irked at movies like “The Day After Tomorrow”, or thinks that Crichton is credible on this.

    People are often susceptible to this for economic, political, philosophical, or ideological reasons. Oddly, people who are quite rational skeptics on many topics are also susceptible, because many such topics have one group with strong beliefs supported by pseudoscience, opposed by skeptics using science. But this one has two groups with strong beliefs, plus a third group using science. People turned off by one extreme can rebound over into the other, thinking they are being normally skeptical, whereas they are now adopting a 100% certainty in the other direction. Confusion is always easier to create than clarity.

    b1) Some seem to make a career of digging up every contrarian cherry-pick, repeating every old argument, post such everywhere, etc, and I think “denier” fits them also.

    b2) But some admit to not knowing or understanding much about it, and it is not completely irrational to think that human modification of climate seems an “Extraordinary claim that requires extraordinary proof”.

    Of course, the proof by now is very solid, but I don’t think that’s instantly obvious to the casual observer, and the real deniers are good at stirring up confusion, and tarring lots of people as alarmists., and playing to non-science motivations.

    Anyway, I’d suggest being gentler with somebody in b2) than in b1) or a), because b2) might be willing to learn if they don’t get turned off. I don’t know of an accepted term for b2), and it is sometimes hard to distinguish b1) from b2) at first. I think “Start Here” is a good resource, but I’m not yet sure there is a solid educational strategy for people who are willing to learn, but with different levels of background and misinformation.