Must have PPT #1: The narrow temperature window that gave us modern human civilization

I am starting a new feature and a new category here on Climate Progress for Must-have PowerPoint Slides. I’ll begin with my favorite new slide, which shows just how stable the climate has been over the 10,000-year period that allowed modern human civilization to develop and flourish (click figure for larger version):


The slide is a must-have because it captures the risk we are taking while also providing a quick visual rebuttal to a very common denier talking point, one that NASA administrator Michael Griffin of all people repeated last year (see “And the Moon is Made of Green Cheese“):

To assume that [global warming] is a problem is to assume that the state of Earth’s climate today is the optimal climate, the best climate that we could have or ever have had and that we need to take steps to make sure that it doesn’t change…. I guess 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.

Seriously! Needless to say, his employee, James Hansen rightly called those remarks “ignorant and arrogant.” He might have added “suicidal.”

So I had to have this slide after I saw it in a recent presentation from my friend Bob Corell, chair of the Arctic Climate Impact Assessment and now Director of Global Change Programs at the Heinz Center.

And it’s not just Griffin pushing this nonsense. One of the Cato Institute climate experts currently debating the online, Indur Goklany, just advanced the following argument against my call to stabilize at 450 ppm or less:

there is no guarantee that stabilizing CO2 at 450 ppm would optimize human or environmental well-being. For all we know, stabilizing at 750 may be more optimal.

For all we know, Cato Institute might be funded by manufacturers of flood levees and desalination plants. Seriously, where does Cato find these guys? You can read my full reply to his absurd and disingenuous arguments here (“Goklany Okay with 250-Foot Sea-Level Rise“). I used Correll’s figure in the reply, which was a major inspiration for me to finally get off my butt and start this feature. [Note to self: Actually, you stayed on your butt the entire time you wrote this post.]

One key explanatory background note if you use the slide: The IPCC forecast of a total of 2°C to 3°C is based on stabilizing atmospheric concentrations of CO2 around 550 ppm (a doubling from pre-industrial levels of 280), up from 385 today. The “band of uncertainty” involves the uncertainty about the climate sensitivity to a doubling of CO2 (absent the slow feedbacks). But as I have noted here before, the longer-term climate sensitivity to a doubling is probably much higher (see “Another “Must Read” from Hansen: ‘Long-term’ climate sensitivity of 6°C for doubled CO2“). In any case, we are headed to much more than 550 ppm this century. As the IPCC’s latest assessment makes clear, anything other than a sharp and rapid reversal in greenhouse gas emissions trends risks warming this century of 4°C or more (see “Is 450 ppm politically possible? Part 0: The alternative is humanity’s self-destruction“).

More about the Must-have PPT Slides Feature

I have accumulated a lot of good slides and figures over the years, but I don’t give many talks anymore for a lot of reasons. Air travel sucks, it generates a lot of carbon, it takes me away from my daughter, and talks to even a few hundred people aren’t a good use of my time because this blog reaches more than ten times that number of people every day.

So the point is, my slides mostly go to waste, and I hope some of you out there who are giving talks or blogging or just emailing friends can use the figures. I’ll try to post one a week. I certainly welcome readers posting their favorite slides or figures, and I may feature the best ones.

I have named the category “Best PPTs” so it would appear at the top of the category list.

58 Responses to Must have PPT #1: The narrow temperature window that gave us modern human civilization

  1. gaiasdaughter says:

    Am I reading the graph right? Was there less than a two degree difference between the medieval warm period and the little ice age? That really brings into focus the dangers of the world warming “by just a degree or two”!

  2. Lamont says:

    What is up with the supposed conservatives adopting moral/ethical relativism and radicalism?

    “Maybe 450 ppm is a lot better! Lets try it and find out!” is not a conservative position. That is radical experimentation with the climate.

  3. thingsbreak says:


    The “angry red chart” from the recent CNAS climate war game probably falls into this category. It also allows me to segue into pointing out that RP Jr. is still harboring quite the grudge, and Manzi in the comments has gone after you for your take on BAU temp.

  4. Brewster says:

    One problem with your statement that this blog reaches so many people, Joe.

    You are quite correct, but by and large this blog is just preaching to the choir, myself included.

  5. Andy G says:

    I’m one of those guys who gives presentations ( , and your best PPT’s is appreciated. But to use it folks like me could use access to a higher resolution version of the image.

    It also is important when doing this to have good references for the slide data. I don’t see that on the slide or in your text…the “medieval warm period” seems pretty large, suggesting this is a north atlantic reconstruction and not a global reconstruction.

  6. Daniel Haran says:

    I’d add that a clear license would be good too – Creative Commons, Attribution – Share Alike (applied to only that slide!), perhaps?

  7. CalDem says:

    second the clear image and references as well. is there any way to just post the ppt slide?

  8. Adrian says:

    Fascinating and disturbing. Really puts those other quotes in context, thank you.

    @Brewster – nothing wrong with preaching to the choir. It educates the choir who can then better proselytize to the wider world. I don’t think it’s entirely true that just the choir comes here any more than just the choir saw “Inconvenient Truth” or attend any in-person lectures. Joe’s blog is a great and growing resource for dealing with “sceptics”.

  9. aga says:

    This is a devastating chart and many thanks for it. I will happily make copies and distribute it to all and sundry but, cheeky though it may be, third the request for bullet-proof references.

    FWIW, as I bash this out I am listening to yet another weird torrential downpour in Tokyo.  We have had many this summer. Why didn’t anyone warn us?

  10. oku says:

    May I ask what is the source of the temperature? It does not have any error bars, and looks awfully certain. Although it is not easy to see, it almost looks like the medieval warm period was warmer than now, which does not match the IPCC chart. This is a common denialists point.

  11. Joe says:

    I am going to ask my technical folks and Bob Corell about the answer to some of these questions.

    Things — Nice slide. I might convert it to a JPEG.

  12. Ed Davies says:

    I’d like to second/third…. the requests for data sources, etc. The choir needs backup for their own preaching.

  13. Ron Broberg says:

    4th: We need data sources. Can’t be flashing temp charts without being able to cite their origins.

  14. Dano says:

    I also give presentations and 141kb is not enough resolution for a large screen. I like to have 600+kb minimum for .ppts, and with this 141kb its doubtful I can take it into Photoshop and make it much better for it to work. Bottom line: 600kb minimum for wall-size screen.

    I’ll likely be using this .jpg in some way in a presentation in ~ weeks, higher res or not.



  15. ClaudeB says:

    Contrary to what other people say, Joe is not only preaching to the choir. I’ve stumbled onto this blog a month ago, and I appreciate the style and contents of this site. I even bought Joe’s book :)

  16. David B. Benson says:

    As we leave the comfort of the Holocene on our climate adventure, we risk leaving agriculture behind.

    As measured for the GISP central Greenland ice core temperature proxy, the temperature anomalie for the entire Holocene is just 3.2 K; the minimum occurred during the 8.2 kybp event, rose to the regional maximum about 6–7 thousand years ago and was, on average, declining so that around 1750–1850 CE was the coldest century during the Holocene. Since then the globe was been in the Anthropocene.

    And yes, Joe, your MWP reconstruction is much more prominent than I can find in the GISP data. There the climatic optimum was about 2 K warmer than during the MWP; it in turn was only 1+ K warmer than during LIA.

  17. Saint says:

    Joe: Glad to see that, with this chart, you’ve now rejected the Hockey Stick and rediscovered the Medieval Warm Period and Little Ice Age. Now that’s what I call climate progress!

    [JR: Nice try, Saint. This is a generalized figure for presentations — not a detailed scientific analysis like the Hockey Stick. The Hockey Stick has been vindicated by major peer review from the National Academy of Sciences. It can’t be rejected by anyone who accepts the scientific method.]

  18. David B. Benson says:

    Here is the citation to the data for the Holocene that I use.

    Alley, R.B.. 2004.
    GISP2 Ice Core Temperature and Accumulation Data.
    IGBP PAGES/World Data Center for Paleoclimatology
    Data Contribution Series #2004-013.
    NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

    In it, both the MWP and LIA are rather small pertubations during the coldest millenium of the entire Holocene.

  19. Saint says:

    Joe: Nice try, yourself.

    Are you saying that a generalized figure in a presentation doesn’t have to be accurate? That’s what it sounds like your saying–a bit much, even for you, Joe.

    And the National Academies report to which you refer was a demolition of Mann’s work, as any fair-minded reader of the report would conclude. To suggest otherwise is to turn the report inside-out.

    [JR: I thought you were a serious guy, but now I see you are just a garden-variety denier. The Corell PPT is of course a generalized figure because there is no precise temperature reconstruction for the planet for the past 10,000 years. I’ll post his sources when I get them.

    That said, I am stunned you think this PPT represents rejection of the Hockey Stick. First off, the Hockey Stick is a Northern Hemisphere graph (!), whereas the PPT covers the whole planet. Second, the Hockey stick recognizes the Medieval Warm Period and Little Ice Age.

    Third, you assert “the National Academies report to which you refer was a demolition of Mann’s work, as any fair-minded reader of the report would conclude.” Gosh, I wonder how “Nature” magazine came up with the headline ”Academy affirms hockey-stick graph.”

    My long-standing policy is that I don’t keep reprinting long-debunked disinformation, such as the notion that the Academy did anything but affirm the graph.]

  20. David B. Benson says:

    At 400 ppm CO2, Greenland all melts?

  21. David B. Benson says:

    Saint — There is no single, agreed upon method to present a global paleotemperature record; different regions were warmer or cooler in different millennia.

    That said, there is ample evidence that some regions are no warmer than at any time in the past 5–7 thousand years. Here is the latest:

  22. Saint says:

    David: I agree there is no single method to present the data, which is why I find it surprising that Joe would recommend a chart that is clearly at odds with the same Hockey Stick he has defended vigorously (if, it must be said, in a losing cause). Either Joe believes the MWP and LIA occured, or he doesn’t. I don’t think it’s too much to ask for a little consistency.

  23. red says:

    NASA Administrator Griffin is first and foremost an engineer (he has a boatload of engineering degrees) and secondly a manager. He’s not a scientist of policy maker. I’d take his comments as just coming from off the top of his head on a subject that he’s not tremendously concerned with one way or the other.

    His great ambition is getting people to the Moon, to Mars, eventually to settle the solar system. Those are goals I support. Unfortunately, his method is to more or less reproduce Apollo on an even bigger scale. Unfortunately, in his implementation that means really big, expensive, rockets designed and operated by NASA. As we know from numerous examples (Shuttle, ISS, X-33, X-34, any number of other cancelled programs) NASA isn’t too good at building or selecting contractor designs for working, safe, economically sustainable rockets or human-carrying spacecraft. Even Apollo got cancelled because it was too expensive, so I don’t see this new version working out … and unfortunately all the good things that came just from doing Apollo like exciting a generation to learn math and science and creating new space capabilities aren’t going to happen this time because it’s too close to being a repeat.

    In the meantime, the expensive NASA manned rockets are taking lots of funding from science satellites, planetary probes, and data analysis, which NASA usually does a good job of. Unfortunately that includes just about everything that’s used by the types of science discusses on this blog. It’s too bad Griffin can’t just give some comparatively cheap incentives to private enterprise to supply his manned rockets and spacecraft and actually give a boost instead of a cut to NASA science with the saved funds.

  24. John Mashey says:

    If people haven’t read Bill Ruddiman’s Plows, Plauges, and Petroleum, it’s well worth a look.
    Among other things, his (well-supported) hypotheses explain;

    1) Why the Holocene looks different from other interglacials that one would otherwise expect to be similar based on Milankovitch.

    I.e., CO2 should have been going down, but then human agriculture changed that, and methane should have been going down, but rice paddies + animal herding changed that.
    i.e., 5000-7000 years ago.

    2) Where the CO2 (and hence temperature jiggles) over last 2000 years come from: human plagues => reforestration of farmland => Cooler

    between Roman and MWP

    and (several periods) during LIA.

    3) it is actually *totally* irrelevant whether or not the MWP was (at most) a little warmer than now or not. It doesn’t make *any* difference to the current temperature, or to the path of temperature in the future.

    But it any case, it probably wasn’t warmer, at least as seen in UK. One good set of evidence can be seen from the location of British vineyards, which ebbed and flowed over the last 2000 years, as well-established by Richard Sellley’s delightful “The WInelands of Britain”. Selley is a geology professor with a wine avocation, and this stuff is well-researched.

    See his map, but note that it’s a little out of date. There are already a few vineyards in Yorkshire, which is around the line he originally projected for 2050. i.e., the wineries are already substantially North of the MWP limits…

    Actually, he’s now worried that by 2080, the Southern areas of UK will no longer be very suitable for wine, because it will be too hot. Selley thinks that by 2100, Loch Ness, Scotland should host a fine winery, but that wouldn’t compensate us for the damage to Napa & Sonoma out here in CA.

  25. jorleh says:

    Be sure there will be a bitter war with deniers. To speak science with them is out of question, I have noticed. Even deniers with some education don´t no anything of the mechanisms of the climate change. If they knew, they would not be deniers, of course.

    The really evil and immoral deniers with some kind of science like some Bjoern are not the problem, they are so few. It is the ignorant mob, who pick out our bad politicians and most of these after the elections are deniers, accordingly.

  26. John Hollenberg says:

    I just noticed that arctic sea ice extent has declined below 2005, and is now (just barely) in second place after 2007. The only question remaining is whether the 2007 record will be broken this year. Have to wait a few more weeks to find out:

  27. Ron Broberg says:

    Here is the citation to the data for the Holocene that I use.

    Alley, R.B.. 2004.
    GISP2 Ice Core Temperature and Accumulation Data.
    IGBP PAGES/World Data Center for Paleoclimatology
    Data Contribution Series #2004-013.
    NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

    The same as found here?

    If so, everything to the left of 10K years seems a little iffy … the drops in the noaa chart are more like 20C, not 4 or 5C …

    Don’t me to be nitpicky, but …

  28. David B. Benson says:

    Ron Broberg — I take the Holocene as beginning at 10428 ybp, 428 years longer than many. The Younger Dryas is, at least by me, considered to be pre-Holocene. But yes, all the Greenland ice cores (which were drilled deep enough) show the huge drop and subsequent rise of the regional temperature during Younger Dryas.

  29. Hal says:

    Thanks to ALL of you who have contributed to this dialogue. It has shown me (once again) how little I know and how strongly dependent my understanding of all this is on the wisdom of my choice(s) of guru(s)/sources. I am just a dumb architect, or former architect, who has been trying to convey to the building design community, especially those with a modicum of concern about the environments inside their buildings and the impacts of their buildings on the environment around them and around the Earth, what I have been able to understand about climate change and its impacts on buildings. More recently, I have presented a paper on the two-way relationship between buildings Indoor climate and climate change Fundamentally, I am trying to motivate them to take the problem seriously, and I am not sure that even a global average CO2 concentration of 350 ppm would produce a stable climate. I have never seen any evidence to support that notion.

    Since many of the mitigations and adaptations for the projected changed climate scenarios are centered around shelter indoors, if the indoor environment is unhealthy or dangerous, where can we run? Where can we hide. But I digress.

    What I wanted to say when I started this rambling post was that I can’t dissect all the disagreements I just read and come to any conclusions at all. Help me, please. I just don’t know enough. It would be really great for someone like me if some ones like some or all of you could get your collective act together and give me and my ilk a digested rendition of what is known and what is unknown, what is uncertain and the bounds of the uncertainty, the major limitations in terms of data, and the gross and detailed summary of the controversy and disagreement that generated the posts above this one.

  30. Hal…

    Have you read Heat by George Monbiot? He prose is so luminous that and conversational that it was easy to read, and that was great, because it’s hard to read. I’m ordering Joe’s book and a few others so I, too, can have the answers I need when the debates start.

  31. David B. Benson says:

    Hal — 350 ppm is a fine interim goal, but eventually we will want to have CO2e at about 290 ppm.

  32. Saint says:

    Joe: I know the Hockey Stick is for the Northern Hemisphere. Your chart, however, is a bit more difficult to discern—it’s not described as global and every geographic reference is to the Northern Hemisphere (Mesopotamia, Greenland, and Europe ). So now that you have confirmed it’s global, I’m curious: I’ve heard it said repeatedly by the RealClimate folks and others that the MWP was limited to the Northern Hemisphere—more probably the North Atlantic—yet here it is labeled prominently on your global temperature chart. See the source of confusion? A little more coherence wouldn’t go amiss. It may seem a small point, but if the chart is not supposed to be an accurate representation of global temperature change, then it should indicate this.

    The National Research Council report I read (to say nothing of the Wegman report) vindicated McIntyre and McKitrick’s criticisms of Mann’s methods and results. Mann et al. concluded (in the NRC’s words) “that the Northern Hemisphere was warmer during the late 20th century than at any other time during the past millennium.” The NRC report, however, found something different: (1) there is high confidence that today’s global average temperature is higher than at any time in the past 400 years (not surprising given that this time period encompasses the LIA); and (2) “less confidence can be placed in large-scale surface temperature reconstructions for the period from A.D. 900 to 1600,” owing largely to increasing uncertainties as one goes further back in time (the challenges of using tree ring proxies also gets quite a bit of coverage in the report). In other words, the data don’t support Mann et al.’s headline-grabbing conclusion. Maybe in the circles you move in, that’s affirmation. That a writer for Nature spun the results differently is mildly interesting—I could dig up articles with much different takes on the study: So what? We’ll have to agree to disagree.

    And finally Joe, I don’t recall denying anything. Consider me an equal opportunity skeptic. Cheers.

  33. paulm says:

    here is also a good resource site for graphs etc…

    Global Warming Art

  34. John Hollenberg says:

    Hal, good places to start are Joe’s book “Hell and High Water” and reading the Summary for Policy Makers for the IPCC 4th assessment report:

    From that link you can select either the Summary for Policy Makers (SPM) or the full report.

  35. David B. Benson says:

    Saint — There is liminological evidence for both MWP and LIA in Patagonia. That’s global enough for me.

    There is much more evidence, recently acquired, that in various regions in is now warmer than at any time in the past at least 5000 years. Here is one of the many such reports from Alaska, Britich Columbia, the Alps and maybe even Greenland (not sure about that):

  36. Ron Broberg says:

    Hal, I second the previous suggestions.
    You have asked for a lot … a whole lot.
    You’ll have to read a lot … a whole lot.
    Bottom line is for every piece of evidence presented by the warmers,
    there is a counter-argument from the deniers.
    Some of those arguments have merit. Many do not.
    But there is no single theory presented by the deniers
    which fits the evidence better than Anthropogenic Global Warming Theory.

    Here is my short version of that. I provide a *very* brief citation for each point. Many, many, many more exist for each point.

    [1] Humans add CO2 to the atmosphere
    Global, Regional, and National Fossil Fuel CO2 Emissions

    [2] The CO2 content of the atmosphere is increasing
    CO2 Concentration at Mauna Loa Observatory, Hawaii

    [3] CO2 is a greenhouse gas (a gas which helps warm the surface of the earth)
    Radiative Heating Due to Increased CO2: The Role of H2O Continuum Absorption in the 12-18um range.
    Kiehl, Ramanathan, 1982

    On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground
    Svante Arrhenius, 1896b,

    [4] The temperature of the earth is rising
    GISS Surface Temperature Analysis

    Temperature (Hadley Center Research Unit – HADCRU)

    [1] -> [2]
    The Global Carbon Cycle: A Test of Our Knowledge of Earth as a System
    Falkowski, et al, 2000

    [2]+[3] -> [4]
    Radiative Transfer Within the Earth’s Troposphere and Stratosphere: A Simplified Radiative-Convective Model
    Ramanathan, 1976

    Global climate changes as forecast by Goddard Institute for Space Studies three-dimensional model
    Hansen, et al, 1988

  37. Koen says:

    Ron’s text is most impressive for the dates of his citations. One more proof that “climate change” is a scientific “consensus” since about the early eighties.

    History shows us it takes about years to revert an “industrial” process (asbestos, leaded gasoline, tobacco, ..), so I have been claiming for the last ten years or so that a global policy reversal will probably also take 50 years, which leads to a worldwide change by 2030.

    Only, it seems we don’t have that much time left.

  38. What, Me Worry? says:

    We’ve found a parameter that can capture in a single value, the dirunal, seasonal, and latitudinal variation in the earth’s temperature. And we have the ability to not only calculate this parameter for our current conditions, but to determine its value tens of thousands of years back into the past. And we can make a graph of this value on a must have power point slide to illustrate that a 10,000 year range of this value “gave us” modern civilization.

    I am curious though, about how this graph would look if projected back over the 100,000 years of H. sapiens evolution, or the 1,000,000 years of Homo xx evolution, or the 10,000,000 of great ape evolution.

    I haven’t seen any climatic estimations (eg. Antarctic Dome C, Greenland ice cores, deep sea benthic oxygen) that go much further back than 1 million. What I have seen of such records, indicates a definite cyclical pattern, and a sense that the past 10,000 years have been relatively warm.

    So if modern civilization does depend on climate, then it rests on a shaky foundation. But humans seem to be pretty adaptable. And I’d bet that they will manage outside of the window illustrated on your graph.

  39. John Hollenberg says:

    > But humans seem to be pretty adaptable. And I’d bet that they will manage outside of the window illustrated on your graph.

    I would manage if my house burns down, but that doesn’t mean I am going to leave candles burning unattended in every room every night, while canceling my homeowners insurance. We need to use the same prudence to avoid the potential for radical climate change, and keep our “insurance” (mitigation of climate change by limiting CO2 emissions) current. As with any insurance, the price will be cheap by comparison if the worst climate changes (like the melting of the Greenland glaciers) come to pass.

  40. David B. Benson says:

    The is good reason to think that almost the entire Greenland ice sheet will melt at 400 ppm.

    7 meters to sea highstand.

  41. Andy G says:


    The Union of Concerned Scientists has a breadth of summary information available:

  42. Ronald says:

    Humans are adaptable and can manage? Global Warming?

    Sure we can adapt to Global Warming. When the forests in the west look like the deserts of Arizona and California, instead of building with wood from trees, we’ll build houses like they do in Iraq, rocks and mud and cement.

    Who needs a grass lawn anyway. Gravel and sand is just as good.

    Sure solved the biofuel problem now that the farm fields are barren.

    Prairie dog stew isn’t my first choice but people can get used to it.

    The dehumdifiers we have running work well with solar power and give us just enough water for our drinking and since we use greywater to water our food lawn, we got enough to eat. Had to kill the dog, he was getting into our prairie dog supply.

    yep, humans will manage and adapt.

  43. Hal says:

    Thanks very much to Richard, David, Paulm, John, Ron, and Andy for your suggestions addressing my plea for help. (Excuse me if I left someone out.)

    Actually, I have read most of what you all suggested – I bought Monbiot from a Canadian source before it was for sale in the USA, watched the IPCC site carefully at the time of the release of AR4 and downloaded and read everything available as quickly as it was available, and I bought Joe’s book quite a while back. I also find John Hansen’s paper
    in ENVIRONMENTAL RESEARCH LETTERS 2 (2007) 024002 (6pp) doi:10.1088/1748-9326/2/2/024002 “Scientific reticence and sea level rise” a most important document in the conversation.

    I have no doubt that anthropogenic emissions are driving climate change/warming. I don’t think I am needing a primer. What I am interested in is knowing what disagreements may exist among those who are well informed.

    My plea for help was in regard to the disagreements in the dialogue that preceded my post. It looked to me as though there were substantial differences among some of you — I thought I discerned considerable disagreement among you — oku, David, John, Saint… and Joe. Maybe it was just about the level of detail or accuracy of representation, triggered by Joe’s ppt slide. When I saw Joe’s post, I immediately copied the slide and pasted it into a ppt for future use. But then I read your various comments and wondered whether the detail is important enough to need to be included in any presentation. Maybe this is not worth discussing further, but I had the impression there was some controversy among those of you posting here who seem most knowledgeable. I am always looking for the smartest person in the room so I can sit at his/her fit and learn. Things are never so simple.

  44. Jill B says:

    I do presentations within a local government agency – and do a short piece in the beginning on the science before I get into things like inventories and climate action plans…. just trying to bring up the awareness enough so that people can (1) read the newspaper with intelligence and (2) understand the urgency with which we are addressing public policy on a local level.

    I really appreciate this blog as it is helping me to be more articulate in my smaller world. So, please post more slides and yes, with sources of data.

  45. Karen Nyhus says:

    Nature’s Climate Feedback has a nice (new) collection of ‘best climate graphics’ – and lots of follow-up suggestions for more – at

    Joe, will you make your ‘must have’ list a hyperlink so we can come back to it and find the rest?

    Cheers and thanks.

  46. Thanks, Joe — your blog is absolutely great. And your PPTs will be put to good use. I believe that once we have a small army of folks out and about who are well-educated we will start to turn the population around.

    I recall hearing something like 5% of the population can change the minds of 20%, and after that, things change rapidly.

    Let’s hope so.

  47. paulm says:

    Here is an outstanding graphic. Where is the debate. This clearly shows the delta of temp varying with that of CO2.

    Can any confirm that this is accurate?

    temp change rate vs CO2 imbalance

    from post…
    Here’s How You Can Estimate CO2 Climate Sensitivity From Historic Data

  48. cet says:

    evet bencede
    Brewster – nothing wrong with preaching to the choir. It educates the choir who can then better proselytize to the wider world. I don’t think it’s entirely true that just the choir comes here any more than just the choir saw “Inconvenient Truth” or attend any in-person lectures. Joe’s blog is a great and growing resource for dealing with “sceptics super

  49. Jay Alt says:

    Joe –
    This is a beautiful resource I somehow had missed, (having only used this site to view the
    IPCC report WG1 in html format)
    The information is sortable in three different ways.

    Maps and Graphics by UN Enviro Program.

  50. Chris S says:

    I think it would be a good idea to have a ‘one-stop shop’ for this kind of material. Are you planning to add more slides to this resource? In particular I would appreciate a slide of the Kyoto Cherry Tree Festival dates – I recall seeing a graph showing a startling change in the last couple of decades (of a 900+ year data run).

  51. Tim says:

    Joe, what’s the end date for that graph. Is it 2008?

    If not, it would be handy to update it….who has control of it?


  52. Jason says:

    I like this chart too but for a vastly different reason. I’ve been told over and over again, by people who seek to end debates with my by branding me a denier, that the change we’re experiencing has never before happened at such a rate. Yet any fool can plainly see it has. Great illustration to foster debate especially with those who don’t play the denier card.

    Climate change, as evidenced by your graph, is something we will need to understand and adapt to, not something we can seek to prevent or change. Look at your own graph, even if, in the last 100 years, humans have negatively impacted climate cycles, would we be any less likely to see changes?

  53. Chris S says:

    Jason – not sure how you come to that conclusion? (Note the x axis is logarithmic…)

  54. Ed says:

    Just some thought:

    When I kill a guy its called murder, when I kill a million living its called genocide, when I kill myself its called suicide, when millions kill themselves its called ? And when million kill millions of people from unborn generations its called ?

    We will need a whole new vocabulary to describe our current situation. That is what makes me think, does it make you think as well?

    Greetings, Ed