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  1. This is probably the most in-depth effort related to the issue.

    Comment by PaulW — 13 Mar 2014 @ 9:17 AM

  2. Nice initiative.

    Related to that, the International Surface Temperature Initiative (ISTI) is looking for people to visualize our open dataset with global instrumental temperature data.

    Comment by Victor Venema — 13 Mar 2014 @ 9:26 AM

  3. So According to the following graph

    We have nothing to worry about at all. Our current tempts aren’t even at the “climate optimum” or Roman warm period.

    Thus if we have seen similar temps mow, many many times before….

    Every things fine

    [Response: That would be that fallacy I mentioned at the top. Serious points only from now on please? – gavin]

    Comment by JustAnotherPoster — 13 Mar 2014 @ 9:45 AM

  4. Longtime reader, first time comment:

    I’ve been craving something like this myself. I think what most of the highly time-compressed graphs of temperature reconstructions fail to communicate (by design, in many cases!) is the *rate* of temperature change. Sure Earth has been 3, 4, 5, 7+ degrees C warmer in the past, but what’s concerning about even a 3 degree temperature increase is the rate of that increase.

    So my idea: In addition to more accurate data, could a graph be generated plotting the average rate of temp change, say in degrees C/century, over geologic timescales? You could extend the present-day end of the graph with various model projections. Even a low end estimate of the rate of increase under BAU over the next 100 years would be pretty dramatic compared to the stately shifts of the past.

    Comment by Photon — 13 Mar 2014 @ 10:14 AM

  5. It’s a fabulous notion, Gavin — the very thing, I think, at which crowd-sourcing can excel.

    As for rendering the data, once compiled and combined, one picture comes immediately to mind. It is modeled after a depiction of the tree of life I have seen — Harvard’s “Deep Tree” project. It allows one to continue to zoom in to different branches and they expand and provide much, much greater detail as you do. Video here:

    Comment by robert — 13 Mar 2014 @ 10:31 AM

  6. i’ve been attempting the 125k NGRIP/Antarctic (Epica beginning) combo. heavy assumptions regarding the bi-polar seesaw mechanism is necessary to get those aligned well. aligning is pretty easy if one allows ~7000 years of mismacthes, but is this ok, probably not… though there are be reasons why antarctic and Greenland cores might lack layers (no snow (deepest glacial arid climate), all surface melt (Eemian, rapid D-Ö events)) haven’t seen the original full NGRIP record though (used the 50yr), but in the deep Antarctic cores the compression issue is notable.

    as on the series on ice age dating in scienceofdoom-blog ( is stated the lack of accurate timing in the deeper cores is a major hurdle. f.e. is EPICA 750, 800 or 900Ky is not at all clear to me, what with orbital tuning. As I understand it Abe-Ouchi has proposed a promising alternative to traditional dating, whether the mechanism is correct doesn’t matter wrt timing. Suggesting though the el’gygytgyn core to be included (at least to 800ky) and compared to all others to, if it’s been processed already.

    Comment by jyyh — 13 Mar 2014 @ 11:01 AM

  7. This comes from a non-scientist who may be representative of the lowest common denominator.  I hope these comments can help science communicate with folks like me.
    1.  If the graph is to be used for general consumption it should be a simple line graph.  The majority of the population is incapable of readily understanding any other form of graphic representation.
    2.  Wikipedia says that the climate that has existed during the last 10,000 years while civilization has developed is, because earth still has some major ice sheets, a glacial-type climate … that it is nothing like the interglacial climates that have occurred during the Phanerozoic era.  I submit that it serves no point — and even distorts the message of the graph — to include information about interglacial climates on the graph.  
    3.  The title of the graph is very important.  Avoid scientific jargon.  Suggestion: “Graph of the Earth’s Climate Since Animals Became Abundant (excluding the human-unfriendly, hot, steamy times)”.
    4.  The graph should show time on the horizontal axis and important volumes on the vertical.  Again, keep it simple.
    5.  The modern era needs to be contrasted with the entirety of the Phanerozoic.  Even though it’s inelegant, consider scaling the first half of the horizontal axis to show the Phanerozoic up to 10,000 years ago, and the second half to show the modern era.
    6.  The vertical axis should represent the quantities of only the most important factors for humans.  Each could have its own separate colored line.  Suggested entries: temperature, sea level, CO2, ocean acidity, extinctions, ice volume.  These items can be footnoted to show the unimpeachable sources of the data.
    7.  If possible, have the lines show what the quantities were during the Permian and K-T extinctions.
    8.  If someone criticizes the graph for not including inter-glacial data, simply ask, “But why is that relevant?”
    9.  Thanks for the opportunity to add one’s two cents worth.

    Comment by S.B. Ripman — 13 Mar 2014 @ 11:03 AM

  8. I had a go at making a figure along these lines a couple of years back –

    The source is at for anyone who want’s to build on it.

    Comment by Philip Brohan — 13 Mar 2014 @ 11:11 AM

  9. There is an excellent new book about graphical design for the public. Booklet can be downloaded at no cost.
    “Visualizing Oceans of Date: Educational Interface Design”, Education Development Center, Inc, Scripps Institution of Oceanography, It discusses three key theoretical underpinnings and gives specific cross-cutting guidelines for presenting data for non-experts (i.e. the general public). Critical are the schemata of experts vs. non-experts.

    Comment by Joe Witte — 13 Mar 2014 @ 11:29 AM

  10. Another issue is that when people look at what appears to be a noisy modern-day temperature series they fail to grasp that all the wiggles and ups-and-downs in temperature can be understood in terms of known forcing factors, both natural and anthropogenic. In other words, the noise that they see is not really noise.

    I get the impression that the scientists in the know understand that ENSO, volcanic eruptions, wind, tidal effects, LOD, each contribute some factor to the fluctuations, but this point is not coming across.

    So make that point and show that you understand the details, and you have won the battle. The skeptics feed off of uncertainty and doubt, and this would eliminate a chunk of their argument.

    Comment by WebHubTelescope — 13 Mar 2014 @ 11:38 AM

  11. This is a nice and helpful initative. Since I am working more on the communication side, I’d like to make a point on the basic fallacy (thinking that global warming is not a problem because this has ocurred before):
    One problem that fosters this fallacy is probably that there is a wide perception (which is supported by the communication/argumentation of environmental organizations) that the aim of climate change mitigation is to protect climate against human influence, and thus puts the topic in a “green” edge and produces instinctive defensive reactions of the political opponents. But in fact we are not changing climate in a way that it will be “harmed”, since climate itself will cope with anything we do to it and nature will largely adapt, as both have done in the past. The “real” problem is (even if environmentalists do not like that statement) that on the contrary with mitigation we have to protect us against climate change, since a change to some climate states we have seen in the past would be very difficult to cope with for humanity (80m sea level rise e.g. as mentioned by Gavin). Maybe we should rather speak of “impact mitigation” than “climate change mitigation”.
    Coming back to the graph: I’d recommend to include in such a graph kind of a compartment where some of the most important impacts (SLR, extremes, vegetation shifts, etc.) of the temperatures at different times (or time periods) are highlighted. This could maybe support some thinking about the harmlessness of climates that have been seen in the past.

    Comment by Urs Neu — 13 Mar 2014 @ 11:39 AM

  12. My off the top flash was to the g oogle map scale button that jumps an order of magnitude, at a click. May not be of help, or easily done, but …

    Appreciating that the following thought may be off-thread, I wish there were a means of using graphic art to depict the original mystery of the Pleistocene, for those who either never confronted the curiosity, or were born after its resolution. Some way of conveying, at a view, how compelling Milankovitch cycles paced ice advances and retreats, but how physically underwhelming their “nudges” were, in comparison to the planetary response.

    Comment by Dave Peters — 13 Mar 2014 @ 11:46 AM

  13. Can we make better graphs of global temperature history?


    Read “The Authoritarians” by Bob Altemeyer. Free download from:

    First, you have to be their preacher. Then they will believe the last thing you said, no matter how self-contradictory, and they don’t remember anything before that.

    You have assumed that most people are actually smarter than chimpanzees. Baaad assumption. Humans have a language module that chimps don’t. Beyond that, you are on thin ice.

    Comment by Edward Greisch — 13 Mar 2014 @ 11:53 AM

  14. Two general suggestions:

    First, for communicating with a general audience, make the graph extremely simple. Then make it simpler. Once you have made it as simple as you possibly can, make it simpler. All the graphics shown here are FAR too complicated even for an educated and interested general audience.

    Second, if you are trying to communicate with an American audience, PLEASE FOR THE LOVE OF GOD use degrees Fahrenheit instead of degrees Celsius.

    Yes, I know that Celsius is the True Language Of Science. But Americans are conditioned to viscerally “get” degrees Fahrenheit. When you express temperatures — and especially temperature increases — in degrees Celsius, Americans don’t really “get it”.

    If you think it is vitally important to train Americans to use and “feel” of temperatures in terms of Celsius, have at it. But that’s a separate effort from effectively communicating the reality of global warming.

    Comment by SecularAnimist — 13 Mar 2014 @ 12:03 PM

  15. This area has always interested me. I have a bit of a paleoclimate background and it’s weird how the field is so often used as an argument against global warming, when we have so many records showing how extreme climate change can be. I think I saw monkton pull out one of those graphs a few years ago, and completely misrepresent it then.

    For me, the big issue with these longer records is that they are always smoothed out. As humans we care about the decade and centennial scale changes which don’t really show up well. It’s really the abrupt events like the PETM and the end Permian mass extinction that we care about, and they only look like blips on the longer records. The earth tends to heal itself pretty quickly (but not quickly enough for us) after these events so they don’t really register. Take the PETM at 55 million years ago. It’s represented as a little bump on the schematics, so it only looks like a degree or so warming, of little significance, whereas it’s a pretty big event on human timescales.

    For me, any attempt to show temperatures over these timescales should try and represent these rapid events somehow. Because they’re the most analogous and relevant to what we’re likely to see in the future (though of course they’re not perfect). The wikipedia attempt is a decent go, but yeah, it’s not the clearest figure.

    For science communications purposes my favourite figure from paleoclimate is the classic antarctic ice core CO2 record because you can show the big old swings in CO2 between ice ages, draw attention to the significant changes seen over those cycles, then pop on the human contribution at the end to see how big a difference we have made. Then you can talk about how big an impact that could have on the earth. It’s a good way of providing perspective. It’d be nice if we could do similar things with temperature.

    A couple of other points RE: datasets.
    1) Elderfield et al 2012 in Science, have produced a deep sea temperature record covering the last 1.5 million years,. This is better than the pure oxygen isotope record form the oceans because it is independent of changes in ice volume. Although it is just one record from one place, it is in theory a pure temperature signal, and deep ocean temperatures are not too variable spatially.
    2) A standard problem with geological records is that they are sparser going back in time, and it is always important to bear this in mind, given that global surface temperatures are pretty variable. So this is probably an issue patching together the data, e.g. ice core records vs deep ocean temperature. For records where there is overlap there could be some sort of bootstrapping done.

    Comment by JoeN — 13 Mar 2014 @ 12:11 PM

  16. Agree with the concept of SIMPLE. The author NEEDS to become familiar with Tufte’s book on how to make understandable graphs.

    Comment by John Burgeson — 13 Mar 2014 @ 12:19 PM

  17. So color me slow, dense, and generally clueless, but if the points you want to make are about time, heat, sea level rise, and the zone in which civilization thrives best (the agricultural sweet spot or whatever), shouldn’t your graph include and focus on those elements? Straight up so that Joe Bloke doesn’t have to spend his day mapping out the implications of Phd level data p o r n?

    Comment by Radge Havers — 13 Mar 2014 @ 12:29 PM

  18. Gavin: You mention one fallacy people propagate when talking about that graph. However, I think that a similarly common fallacy is to make the claim that the graph shows there is no particular correlation between temperature and CO2 levels.

    The fallacy in that is:

    (1) The data is likely not accurate and resolved enough to even address such a question. [And, as I understand it, the more resolved and accurate the data gets over the last few million years, the more a close correlation is seen.]

    (2) Over long enough time scales that there can be significant shifts in continent locations, solar insolation, …, we would not expect temperatures to correlate so closely with CO2 when there are these other equally important variables that have significantly changed.

    Comment by Joel Shore — 13 Mar 2014 @ 12:29 PM

  19. The wikipedia graphic is probably not too far off the mark as far as I understand the existing data sources. There are huge uncertainties over temperature and CO2 levels in the more distant geological past (pre-Cenozoic) and any graphic would have to reflect that. However, The representation of the Holocene in relation to previous Late Pleistocene interglacials in the black line looks poor – temperatures for the Holocene are fairly typical for a Late Pleistocene interglacial (prior to AGW) and the natural (non-anthropogenic influenced) shape of the interglacial would probably resemble stage 11 at around 400 kyr – though this is somewhat disputed on astronomical grounds. Marine calcite O18 records convolve temperature and ice volume, though there is an attempt to separate these components in Elderfield et al., Science 2012 for the last 1.4 Ma. Nb the temperatures given there are for the southern ocean, not global, just as the Antarctic record is Antarctic not global, though obviously closely connected with global climate. Lear et al., Science 287 (5451): 269-272 show how Mg/Ca can be used to calibrate oceanic temperature over about 50Ma, adjusting the Zachos 2001 isotope composite which is widely used for this interval. Any one record is bound to be a record of a particular place and not necessarily fully representative. A truly long term picture of global climate would be a great thing to have … maybe the best approximation for these purposes would be to plot everything, including the Holocene, on one time scale, then have a “magnifying glass” graphic zoom applied to the Holocene itself to show its currently understood shape so far.

    Comment by Simon C — 13 Mar 2014 @ 12:35 PM

  20. Two quick points, first on “It has been warm before”, Richard Alley explains how it has been to hot to exist in the tropics (28 mins into the video) – and around the areas where we grow most of our crops today. Second it would be really great to have all these graphs released under CC-BY-SA, so we can use them on Wikipedia too (This kind of graph as well).

    Comment by prokaryotes — 13 Mar 2014 @ 12:51 PM

  21. I have a few suggestions:

    1. Whoever eventually designs the graphs should re-read Edward R. Tufte’s classic works on this: Visual Explanations, Envisioning Information, and The Visual Display of Quantitative Information. These are truly magnificent works that teem with ideas for making information easier to grasp.

    2. I disagree with the suggestions that the graph should be made as simple as possible. I think it is possible to make a powerfully expressive graph that is not at all simple. Again, consulting Tufte will surely help in this. Moreover, I think that THREE variables should be expressed: temperature, CO2 concentration, and sea level. This third one will counter the people who assert that the earth has been really hot before, so we have no need to worry.

    3. In agreement with the “simplicity school”, I think that error bars should be left out. Perhaps a graded shading would be adequate. In other words, don’t draw a line, draw a path that is darkest in the center and fades out to gray in proportion to the standard deviation.

    4. If you do present all three variables, then you should use different colors to represent the variables: red for temperature, gray/black or brown for CO2, and blue for sea level.

    I’ll start reviewing Tufte and get back if it inspires any new thoughts.

    Comment by Chris Crawford — 13 Mar 2014 @ 1:00 PM

  22. I regret the cliche, but there is, in fact, an app for that! It’s called EarthViewer, from HHMI:

    It’s got a great interface that allows you to interactively visualize all sorts of things over time. To quote from their website: “From molten mass to snowball earth, EarthViewer lets you see continents grow and shift as you scroll through billions of years. Additional layers let you and your students explore changes in atmospheric composition, temperature, biodiversity, day length, and solar luminosity over deep time.”

    Among other things, you can simultaneously display two stacked plots of e.g., temp and CO2, vs time. The references and raw data used in the app are here:

    Obviously an app is not a graph, so this may not solve the problem at hand, but it’s a very useful and interesting resource nevertheless.

    Comment by David Windt — 13 Mar 2014 @ 1:03 PM

  23. I’d suggest strongly that the ocean’s temperature is the reliable indicator of the thermal balance of the planet, the atmosphere is subject to many more variables and geologists never use it for time-spans less than 30-years because of that.

    So to get the point across to non-geologists that don’t freak out about 400-ppm CO2 being Pliocene Epoch, instead feature ocean temperatures and relate everything back to that because the ocean is the thermal-mass that provides global stability thermally, not the air.

    Comment by tom mallard — 13 Mar 2014 @ 1:09 PM

  24. I’d strongly suggest featuring ocean temperature as the basis of climate change, it’s the thermal-mass that has dominance in thermal balance not the atmosphere, geologists never use global air temperatures for time-spans less than 30-years due to variability.

    So, by graphing ocean temperatures and tying everything else to that, climate change won’t seem so variable as graphing the atmosphere thus far less misleading to people that don’t know what the mean average means or why being cold this winter doesn’t affect the ocean that’s heating up.

    Comment by tom mallard — 13 Mar 2014 @ 1:14 PM

  25. This is a great idea, but it would be a good idea to think hard about simple, but modern computer graphics, rather than 2D static plots, although a good instance of the former should offer easy extraction of good examples of the latter. A current smartphone has more CPU and graphics power than $100K graphics workstations of the early 1990s, so surely we can do better, even in 2D, much less 3D.

    1) I’m very fond of NOAA’s CO2 history, for the nice job it does on timescales.
    I’d probably like it better if there were a slider bar to control the time window, not just a predetermined animation.

    2) I liked Nick Stokes’ presentation of spaghetti graphs, that allows mouseovers to highlight selected lines.

    3) We really, really need to do better with uncertainty. I liked AR4 WG I Fig 6.190(c), which in some ways is far more representative of reality than spaghetti graphs.

    There may be better ways, especially for static graphs. Solomon Hsiang has been doing interesting experiments, as here, or here. He was a recent AGU award winner.
    Getting him involved would be great. For general communication, I really dislike lines with the usual error bars (as they over-emphasize the edges) almost as much as lines with no indication of uncertainty. Sometimes I wish for 2 sliders: one for timespan, and one for uncertainty, if I had to have bars or gray zones.

    Again, if one *starts* with a simple interactive display, with some adjustable parameters and controls, then one can experiment and extract good 2D graphs, and see how they work. It is really hard to create great static graphs that are both accurate and compelling to multiple audiences … but I’d guess that most people will examine such graphs via computer, and even printed images can link to the interactive display from where they came.

    Comment by John Mashey — 13 Mar 2014 @ 1:15 PM

  26. I wonder if it’s “better graphs” that we need, or better narrative “context” for the information people see in existing graphs. Maybe a bit of both.

    “Context” might include:
    * sea levels during prior warm periods
    * some way to convey the scale of “deep time” (e.g. a very long horizontal scroll bar, or indicate the position of the continents, or time before dinosaurs, time before flowering plants, time before ???)
    * rate of change
    * proximity to global extinction events

    Comment by Doug H — 13 Mar 2014 @ 1:19 PM

  27. Please make two graphs, with Celsius and the imperial US F*.

    Suggesting using only linearly spaced datapoints, I think the 50y in NGRIP is good, I realize that in deep time datapoints are far in between, so linearization should be used here to fill in. All the datasets should go to the present. There are two possible points in time where the beginning of the graph should be set on:
    or the more notable

    as these can be seen as the beginning of the modern fauna and flora, the continental distribution that allowed the initiation of the Antarctic glaciations is connected to the former. At least I’ve no interest to destroy all mammals and most flowering plants to get to the Cretaceous again.

    Comment by jyyh — 13 Mar 2014 @ 1:21 PM

  28. Graphs and charts are an important tool in demonstrating time scale to events. Visual impacts are more easily and quickly understood than lengthy dissertations.
    That said, vast time temperature charts loose their impact in human terms when millions of years are added, they show wide ranging scales that have no relevance to our current situation, and might justify a ho hum response. Perhaps one date set prior to human existence and a larger data set displayed since the dawn of man, emphasizing the beginnings of the
    industrial revolution onto today’s warming world. The idea being to show the depth of understanding throughout history, while emphasizing today’s current temperature analysis.

    Comment by WJ Long — 13 Mar 2014 @ 1:36 PM

  29. When I was younger I lived in Tasmania where treeferns still exist —vestiges of the Upper Carboniferous. I recall walking among the ferns and thinking what it was like when the land creatures were mostly just arachnids and amphibians and trees were giants. This makes me think, why are the CO2 and O2 levels of before, and directly after the Carboniferous Rainforest Collapse being used as an argument for why 400 ppm and rising, CO2 is OK today? (mostly by posters to mainstream news articles) If anything the opposite seems true. Seem to me, as a novice, that the time scale of adding CO2, like with the evolution of fungus in the Carboniferous, allows for migration or evolution. I also do not see a lot of talk about where land masses were during —in size and/or latitude— various events. Also how can we understand paleoclimate —especially the Cretaceous–Paleogene boundary— unless we can fully understand ocean currents now and then.

    Comment by Eliot Walter — 13 Mar 2014 @ 1:37 PM

  30. Thoughts on Timescales

    If we take 150years as the period of reliable direct temperature records ( 1850-ish) then this should be the first timescale chosen. After that scale at orders of magnitude ( 1500, 15k, 150k,1.5m etc.) showing the previous scale as a different colour at the end. This would avoid any issues with cherry picking.

    There may be better intervals which reflect proxy series which are relevant to specific time periods ( e.g. ice cores do not fit very well with these intervals and neither do social history proxies). However a consistent set of intervals is a good and simple presentation style… not logarithmic only linear for all graphs

    Comment by Colin Aldridge — 13 Mar 2014 @ 1:53 PM

  31. #10 WebHubTelescope :”… and you have won the battle”.
    I have posted that idea many times … to no avail! In “The Guardian” three weeks ago:
    “I really CAN´T UNDERSTAND the stubbornness of skeptics when arguing that evidence of man caused climate change is not real, because most changes always happend, long before industrial revolution, due just to Nature …
Can´t they understand that both agents can act simultaneously?
And that the result of adding the effects due to ever, man produced increase of CO2 to natural OSCILLATIONS can´t be different than what we are seeing?

    Have a look to:
Is not clearly showing that, though there are natural oscillations, they are going upwards?
And something similar can be seen relative to other global warming consequencies.
Let us consider the sheer issue of the so called current warming hiatus.
    Have a look to any mean global temperature graph:
Despite all oscillations, is not QUITE CLEAR that after each that could trigger skeptics, temperatures carried on rising? 
And that IS due to underlying, continuous GHG warming!
So far, nobody has given any other sound, possible reason”.

    Comment by Rafael Molina Navas, Madrid — 13 Mar 2014 @ 2:28 PM

  32. I have a worry that some of the ambition behind this project may be asking too much for a single graphical representation.

    If you stick with a comparison of present global temperature records with various palaeoclimate temperature reconstructions, graphically it would be down to a reasonably simple decision about how to present a few decades of data on a graph that also presented data spanning tens or hundreds of millions of years.
    A log scale would be the first choice for a scientist but there are drawbacks. It would flatten trends on the expanded bit, be difficult to scale time & greatly confuse those not comfortable with log scales.
    An alternative would be a series of graphs as per Hansen & Sato 2011 Figure 1 (Tiny version of it here) but with better indication of how the separate graphs link together. A single graph with three, four, five expansions would not be too challenging for public consumption as long as the expansions are in equal steps. (20ky, 3.2My, 540My looks an interesting choice.)
    A single graph should still work with uncertainty data being included as long as there is not much overlapping (ie multiple data sets covering the same time period), but a single graph is now be on the verge of becoming too ‘busy’.

    So I would certainly warn that superimposing CO2 data onto the same graph (or graphs) would start to make things a lot more difficult, although not immediately insurmountable.
    And adding Co2 data would also start to kick off questions like ‘Why ppm? Why not forcing?’ And perhaps then ‘Why not add solar forcing as well?’
    So my view would be that if more than temperature (or proxies thereof) are to be plotted, it would be worth asking “What is this/these graphics being produced for? Who is the audience? What is the take-away?”

    Comment by MARodger — 13 Mar 2014 @ 2:47 PM

  33. Your effort to clarify the rise and fall of interglacial sea levels might be aided by explaining climate dependentt shifts he amount of water residing on land, for example in evaporite basins, dty lakebed and other aquifers and cycles of hydration in rock and mineral weathering .

    Comment by Russell — 13 Mar 2014 @ 4:30 PM

  34. I made that Wikipedia graph Gavin, after Rob Rohde (perhaps wisely!) refused to try. It’s cobbled together from six different Rohde graphs (using his actual graphics) plus one pinched from Royer et al 2004. I’m happy to admit that it’s a piece of c**p; but there was little else similar at the time. Yes, the splices are weak, as the text notes, “The relativities are very approximate.”

    BTW, there is no logarithmic scale there at all, and you’re not the first to make that mistake. The time scale is multi-linear in seven different segments; the scale just expands at each vertical line. To my (admittedly odd) brain, that makes perfect sense…

    We want to display data over a very long period of time, but we know progressively more about more recent times, and are much more interested in those. How best to do that? One can do multiple pull-outs at larger and larger scales (a la Hansen), but that always looks awkward to me. The alternative is to use some sort of periodic scale change, which is what I attempted. Perhaps it would be better if the changes were more regular and more obvious.

    Dr Rohde’s graphical skills are considerable, and need to be roped here.

    Comment by GlenFergus — 13 Mar 2014 @ 5:06 PM

  35. Interesting challenge. Existing data has different time spans and resolution. There is monthly data from the present, but not back millions of years. There is overlap asking to weight the data. A graph has to fit the publisher’s needs and the audience’s demand, small ones for mobiles, huge for print, appropriate colors for color blind, Fahrenheit for the American, logarithmic scale and error bars for the literate, last 150 years to document industrialization, last 10,000 for civilization.

    Targeting the one and only chart appears unfeasible and is actually not needed. An interface on top of the data, letting everyone select or produce a chart might please and attract more users.

    A data structure to start with would cover a value, a dimension, the time span and attribution per data point. And then a method/program would solve the overlaps, probably the most difficult part, producing charts from the result the fun part. It could be started with a simple Google spreadsheet. However, someone should select editors, and curate data sets otherwise editing wars will follow.

    It’s a serious community effort, but the most trustable temperature record would change a lot. The more people recognize it the less time is spent discussing cherry picked ones.

    Comment by Arcticio — 13 Mar 2014 @ 5:39 PM

  36. I would also add to your list of data that of Anderson et. al. 2013, for the period 1730-1990:
    Anderson, D. M., Mauk, E. M., Wahl, E. R., Morrill, C., Wagner, A. J., Easterling, D., & Rutishauser, T. (2013). Global warming in an independent record of the past 130 years. Geophysical Research Letters, 40(1), 189-193.

    It’s a good proxy-data fill-in to use in place of the more recent parts of the Marcott dataset, as Anderson has many more proxies and is resolved finer in time. It does require some processing to create a global record from his data, but I’ve already done so and can provide it if anyone is interested.

    Comment by Keith Pickering — 13 Mar 2014 @ 6:17 PM

  37. On wood for trees I make graphs that have different colors for ENSO neutral, La Nina, and El Nina. I go by the classifications here. You could also use underlying color bands.

    Comment by JCH — 13 Mar 2014 @ 7:03 PM

  38. Examples of excellent graphs

    Comment by prokaryotes — 13 Mar 2014 @ 7:26 PM

  39. My favorite colors and style which is similar to

    Comment by prokaryotes — 13 Mar 2014 @ 7:55 PM

  40. I am surprised that you have used Robert Rohde’s graph of phanerozoic temperatures, as it is essentially based on Viezer et al (2000), without taking into account the pH correction as detailed in Royer et al (2004). A far better graph would be that used by Royer in a 2008 non-peer reviewed article, but based on Royer et al (2004)

    Comment by Tom Curtis — 13 Mar 2014 @ 9:07 PM

  41. Out of interest, Royer et al’s reconstruction appears to be qualitatively supported by analysis of fossil reefs (see figure 2):

    Also of interest is the temperature record for the last 3.5 billion years (Fig 15):…2007.pdf
    Jaffre et al do not apply a pH correction, but at the resolution of their graph, I doubt that is important.

    Comment by Tom Curtis — 13 Mar 2014 @ 9:11 PM

  42. Speaking of temperature history… what’s the chance you could put together a graph or analysis of Arctic (or north of 60) warming? I’ve downloaded the binary file for zonal data from GISS for 1880-2012, and will try to do my own analysis, but I bet you could do a better job.

    This is something I’m interested in because the best I can come up with is 1.9 degrees from 1875 based on AR5 discussing the linear trend in warming, in turn based on Berkryaev et al. But a linear trend is not necessarily the best way to analyze a time series which has accelerating warming… so I’d also like to see a “last decade vs. first decade” analysis. I think the information could be pertinent to discussing Arctic amplification…

    I realize that you don’t have spare time to do random analysis, but… maybe this is something you’d be interested in as well.

    Comment by MMM — 13 Mar 2014 @ 10:34 PM

  43. Maybe overlaying multiple scales of temp, CO2, sea level rise, extinctions and numbers of repetitions of the same denying delayalist post about it was warmer back in the good old days would make it clearer. And you could put in some wavy time travel sound effects.

    Comment by J4Zonian — 13 Mar 2014 @ 11:46 PM

  44. I’m very interested in seeing this happen. I’d really like to see a way of presenting the data such that you could tease out how the periodic stuff and the odd extreme event contribute to the global values.

    I love the way some of the above have timelines of “events” – eg: Pinatubo, Krakatoa.

    Photon (#4) – I agree with you on rates-of-change…maybe that should be made understandable rather than absolute values – or perhaps a parallel plot.
    As a reasonably math literate layperson, I find myself explaining that “nothing is decreasing, just the rate of change has decreased”; using more specific language (derivatives, gradients, etc) just results in more glazed eyes.

    Philip Brohan (#8) – R is doing a nice job with that graph. I like your choice of scaling too; although it looks like it’s in the same “multi-linear” camp as GlenFergus? Will raid your git repo and see if I can understand your R. Hey, after C++, how hard could it be ;)

    Comment by Happy Heyoka — 14 Mar 2014 @ 12:31 AM

  45. to keep datasets manageable for amateurs like me, I’d suggest about 4000 datapoints as a maximum for each set. for the set having the longest sensible span (420Mya, when life went terrestrial) this would mean 1 data point per 100000years and the Pleistocene would seem near linear.

    Comment by jyyh — 14 Mar 2014 @ 2:14 AM

  46. FWIW, I think an animation with the “expanding x-axis”, as seen in NOAA’s CO2 history (see John Mashey #25) is the way to go. You can make the axis linear, but expand it at an exponential rate. If we’re going into deep time (as I think we should) then I would suggest two y-axes: one for temperature, and one for *forcing* (rather than CO2 ppm) which better reflects contributions of both CO2 and solar.

    Comment by Keith Pickering — 14 Mar 2014 @ 10:30 AM

  47. You should go back to the Silurian at a minimum as that is the star of land based life forms. Might also be interesting to see a comparison of bio diversity and extinction events.

    Comment by J. C. Seery — 14 Mar 2014 @ 12:16 PM

  48. This is a great idea and a group of us ( are in the process of putting something together for CO2 using the latest published data. We will hopefully be able to post something soon.

    Comment by GavinFoster — 14 Mar 2014 @ 12:17 PM

  49. FYI, I would be willing to do the graphing as it is what I do (engineer). My biggest problem in doing this (which I have tried before) is a) finding available data sets and not just graphs and b) having someone evaluate the validity of the data sets (climatology isn’t my field of expertise). Sorry for typos in previous post, trying to do too many things at once.

    Comment by J. C. Seery — 14 Mar 2014 @ 12:58 PM

  50. I may have missed it, but is there a reason why the PAGES2K data is not used for the 2000 year global temperature reference?

    [Response: It’s not a global time series. – gavin]

    Comment by Flakmeister — 14 Mar 2014 @ 2:35 PM

  51. Well, of course Horace Mitchell and his scientific visualization studio at Goddard MD should be the best person in the world for something like this:), but Eli has a couple of ideas. Now if he only could draw. . .

    Comment by Eli Rabett — 14 Mar 2014 @ 3:32 PM

  52. FYI, proxy temp anomaly data for 1730-1995 derived from Anderson et al. 2013 can be found at:

    Comment by Keith Pickering — 14 Mar 2014 @ 3:41 PM

  53. Hi Gavin and Sou,

    This is a good idea in essence, but I am not sure it will bring anything new to the discussion. Having a better historical reconstruction is a very good idea.

    However, the problem is that the graphs are produced by scientists, and are interpreted by scientists who have an understanding of the science and explanations behind their construction and most importantly the results. The general public can see historical trends, but without understanding the science, can easily jump to the wrong judgment or conclusions as to what is presented and why it looks the way it does.

    Would a new reconstruction demonstrate that past temperatures were no higher or CO2 concentrations were no higher than current? No. Monckton et al would still use this information to hoodwink people, as they have been doing.

    It is therefore easy to see why somebody may jump to the conclusion that temperature has been greater in the past, or CO2 concentrations have been greater in the past, as they clearly have been. The reasons why this is the case, and whether this could be presented graphically, needs to be captured.

    As Keith #46 rightly states, forcing is a critical issue. But then the question is how to capture and present such data?

    One option could be to take the current solar energy flux and backcast global temperatures based on the historical CO2 concentrations, and planet albedo if this can be estimated, to show how warm it would have actually been historically, if the Sun output had been the same as is present. Therefore showing a greater correlation between CO2 and solar influence over the lifetime of the Earth, possibly, although there will be many other factors.

    Personally, I would think a graph showing the timeframe of modern man (say the last 250k years) would be also beneficial to focus the mind, as this is something that people can grasp far easier than millions of years ago. But that is not saying that far longer back in history should also be captured.

    Comment by Dan — 14 Mar 2014 @ 3:58 PM

  54. You might add a line in the graph giving the estimated number of species or families (though the latter may need more explanation for most viewers). This would go some way to countering the meme I have often seen in denialist posts that a warmer world would automatically have more ‘life.’

    Comment by wili — 14 Mar 2014 @ 4:40 PM

  55. I have tried a somewhat novel approach – a user-adjustable graph. Mouse clicking stretches the time scale from hundreds to millions of years. The graph can be dragged, and the temp scale varied. It’s a bit rough at the moment, but I’m hoping to improve. I did a post here.

    [Response: Thanks! – It’s a nice concept, but obviously needs some work. Note that there are scalings and baselines that need to be thought about (for instance, you are plotting LR04 upside down since temperature is inversely proportional to d18O). – gavin]

    Comment by Nick Stokes — 14 Mar 2014 @ 7:05 PM

  56. The proposal is very good and has the potential to be built upon to provide greater clarity on other matters of urgency.

    The graph which is an attempt by some editors at Wikipedia to produce a complete record for the Phanerozoic (as shown in Gavin’s post) sets the scene for a vertical line on the right-hand-side of the graph, if by 2100 the rise in temperature is 4-6 degree C above pre-industrial. That then shows clearly that the rate of temperature change in the coming decades has never previously been experienced, if you compare it to what has gone before. If the derivative is then determined and, for example, extinction data (eg as indicated at ) are plotted against it, the starting point which is the temperature graph can evolve to illustrate impacts. In the case of extinction intensity versus temperature change, there is a strong correlation between extinctions and change in temperatures. Life does not like sharp changes.

    In essence, therefore, the temperature graph could be the first step in an endeavour to create a open-source system that allows people to explore potential impacts. It is the potential for ordinary people to be able to explore impacts for themselves that could emerge as the value-add of the endeavour.

    Comment by Name — 14 Mar 2014 @ 7:30 PM

  57. The link for GISTEMP is dead. I think it should be

    [Response: Yes – thanks. – gavin]

    Comment by Vince — 14 Mar 2014 @ 8:16 PM

  58. Re- Comment by Eli Rabett — 14 Mar 2014 @ 3:32 PM, ~#51

    Hi Eli. I don’t have any ideas but am pretty competent with Adobe Illustrator. I have made thousands of teaching illustrations, but in my biological specialty. Steve

    Comment by Steve Fish — 14 Mar 2014 @ 9:28 PM

  59. Thanks, Gavin for letting me off the hook:) Now I can take it off the back-burner and will monitor progress here.

    I’m not sure if this has been mentioned already – Kevin Anchukaitis @thirstygecko pointed me to this paper by James Hansen, Makiko Sato, Gary Russell and Pushker Kharecha, which has a data supplement with this txt file:

    It may be of value in this exercise.

    [Response: It’s linked above. – gavin]

    Comment by Sou — 14 Mar 2014 @ 9:39 PM

  60. Even many people who follow climate issues quite closely will have no idea what “d18O” means. I would advise converting it to the estimated temperatures with a note that you are using this measure as your proxy here.

    Comment by wili — 15 Mar 2014 @ 12:50 PM

  61. Different graphs and or pictures are good at different times. Didn’t a senator recently tell us that things were fine with high CO2 in dinosaur times, without mentioning that his state was under water at the time?

    Perhaps there could be a graph (along with some pictures) showing the area of the continental US on the same chart as CO2.

    Comment by Pete Dunkelberg — 15 Mar 2014 @ 5:37 PM

  62. Good initiative! For the context I also think it is important to include projections into the future in the graph. This strengthens the staggering perspective of what we are doing to the planet.

    My favorite climate graph of all time does exactly this. It is from the U.S. 2009 National Climate Assessment, and shows CO2 concentration from 800,000 years ago into 2100. The axes are linear and without any cutoffs. Simply amazing in its simplicity and so very powerful. It can be found here and is free to use:

    Otherwise I like Hansen & Sato’s graphs, e.g. in the paper referenced by Sou above.

    Comment by perwis — 15 Mar 2014 @ 9:28 PM

  63. One alarming aspect of Climate Change is the rate of change of CO2, sea level rise, global temperature. Is there any way to extract from the data the rate of change of CO2 vs. time and rate of change of temperature, like ppm CO2/20 yrs or degrees /20 years? CO2 and temperature might have been high long, long ago, but the rate of change was very different back than from what it is today. And a high rate of change leads to more unpredictable weather — ask any farmed how important that is.

    A gray range showing upper and lower limits with the average line in the middle is always more readable than a graph full of error bars, but still captures the uncertainties in the measurements.

    Shouldn’t there be graphs of CO2 vs. time (left axis) and sea level vs. time (right axis), with a dashed line showing where sea level is in 1900 and 2000? Sea level rise is the most immediate attention-getting issue for a lot of people living near a coastline.

    NASA’s global temperature map is an excellent graphic of where climate change is going in time while showing the variations:

    Some places are hotter and colder but you can see that the average of the whole map is obviously getting hotter with time. With one look you can see both the average and how much variation there is, though it is only really effective as a video.

    Maps like this should be kept as up-to-date as possible.

    Climate data is inherently noisy. Just because there are a lot of ups an downs does NOT mean that we can’t see where things are going.

    Comment by ardavenport — 16 Mar 2014 @ 12:09 AM

  64. Many Americans are incapable of understanding simple graphs, and unable to do
    basic arithmetic, so things have to be made simple, simple, simple.

    1: Follow the Wikipedia graph model
    Temperature is the most important scale, and the time scale must be compressed.

    2: Expand the last 100 years

    3: Expand the Pleistocene segment so that the transition into
    regular cycles of glaciation can be seen.

    2: Place a dot at time = 0 so that the current temp can be seen
    Label it as such with an arrow.

    3: Place a dot at time + 100 showing where the models place global temps
    in 100 years. Another where the final equilibrium temperature falls.

    Label as such with an arrow.

    4: Left hand side show dt ‘F inset dt ‘C

    5: Show error bars.

    6: Draw several lines downward at times of major biological events both
    evolutionary, and cultural labeled by number.

    7: Include some text for each numbered event available as a
    text caption.

    8: Put the image in the public domain.

    Comment by Vendicar Decarian — 16 Mar 2014 @ 11:15 AM

  65. A real simple suggestion: In any graph showing global temperature over time,
    insert a horizonal line at the current average global temperature, so that the public can clearly see how,say, the temperature during the MCA compares to today’s temperatures.
    Also, something that I found useful in a debate I found myself in: When someone makes the claim that Mann et al removed the Medieval Warm Period, draw a horizontal line from the peak temperature of the MWP time period. People can look right at a graph and not understand what it shows.

    Comment by Dallas Dunlap — 16 Mar 2014 @ 11:53 AM

  66. My apologies if this has already been brought up. provides an excellent means of generating temperature charts.

    Comment by Villabolo — 16 Mar 2014 @ 3:44 PM

  67. It would be great to include ‘consequences’ and ‘feedback’ graphs. One of the most dramatic of these is the loss of Arctic sea ice, especially volume, and especially contrasted with expected/modeled values as recently as 2007.

    Comment by wili — 16 Mar 2014 @ 4:06 PM

  68. Coming up with more precise temperature charts won’t solve the basic problem, which is media corruption. Six media companies (soon to be five) control 90% of content. They smirk at the public interest, and answer only to advertisers. We will continue to see inaccurate charts, or decent ones buried on page 17.

    These companies get away with it because they are only called out on lightly read blogs or stuffy academic analyses. We can’t have a democracy if the people remain uninformed about matters of life and death.

    The solution is to establish a robust media monitoring organization that is focused on climate. Bad actors would be linked and humiliated, in detail. It’s an idea I’ve floated for a couple of years, without success. If anyone knows of possible supporters of this notion, I can be reached at

    Comment by Mike Roddy — 17 Mar 2014 @ 8:56 AM

  69. Producing accurate charts won’t help, because six (soon to be five) media companies control 90% of content. They answer only to advertisers, smirk at the public interest, and would only publish an accurate chart if it appears on page 17. The truth has become a harmless byproduct of geeks like us.

    Media critics dwell on lightly read blogs, or in stuffy academic analyses. The American public is far less informed on these issues than the people of, say, Uruguay or Latvia.

    We urgently need a climate change media monitoring organization that is funny and aggressive. Americans don’t see the truth because nobody is calling out those who are concealing it from them. I floated a plan to do something about this situation, but it went nowhere (“It’s already being done”), etc. A recent survey showed that climate change ranks #14 out of 15 concerns for the American public. Whatever we are doing is failing. If anyone knows of a person or organization willing to support this effort, I can be reached at

    Comment by Mike Roddy — 17 Mar 2014 @ 9:06 AM

  70. There’s a basic rule in education that every teacher learns the hard way, no matter how well educated one may be:

    You have to know where your student is at, and you have to recognize that it isn’t where you are at. (The more educated and specialized you are, the more that is true, especially in trying to connect with ‘the public’.)

    Scientists are human, and they can exist in their own bubble, and be parochial, and have a kind of tunnel vision. What impresses one’s peers may not really be useful in changing the mind of a hypothetical unbiased reader.

    The problem with ‘better graphs’ to counter ‘phony graphs’ is that the point of the phony graphs is not to convey information but to ‘look sciency’; to elevate the phony arguments and create a false equivalence ‘controversy’. (Remember “teach the controversy” for Evolution?)

    I wonder if rather than calling in the graphing experts, sympathetic marketing types would be more useful in structuring an explanation. Kudos to Edward Greisch @13 for mentioning Altemeyer’s decades of research, depressing though it may be.

    My experience with ‘not the best’ students is that they can access and internalize a narrative about physics with good quantitative understanding, but only if they can relate to that narrative.

    How about beginning at the beginning, with the *measurements* and what they mean rather than ‘data’– in other words, a series of slides illustrating *the science* that culminate in a nice graph. We need to face the fact that most people don’t have a clue what the global average temperature represents in the first place; statistically sophisticated arguments, however prettily presented, are not going to have much resonance.

    Comment by mgardner — 17 Mar 2014 @ 9:38 AM

  71. I read most of the comments. I swear!

    I would strongly suggest that any chart which extends back more than 10KY very clearly note that civilization didn’t exist. For that matter, list the dominant life forms.

    Comment by FurryCatHerder — 17 Mar 2014 @ 11:34 PM

  72. Ok, a first try at tidying that old WP graph:

    1. Hansen version of Zachos doesn’t fit, at either end (that shown is arbitrarily halved).
    2. What is the preferred estimate of global temps from L&R?

    Comment by GlenFergus — 18 Mar 2014 @ 9:35 AM

  73. > dominant life forms
    Those that change (or maintain) the climate system, and
    those that could be lost under current anthropogenic mismanagement,
    for example:
    Caldeira and Wickett, 2003, cited by 1500 subsequent papers

    Comment by Hank Roberts — 18 Mar 2014 @ 9:41 AM

  74. Mike et. al.,
    The reason that climate change ranks so low among Americans has little to do with educating the people. Rather, people care less about those issues which interest or affect them less. It is also too long term for them to care. Many people can’t see past next week, let alone next year, decade, or century. Regarding news, the missing Malaysian jetliner has the monopoly on that at the moment. Even the Crimean election was relegated to the back pages.

    Comment by Dan H. — 18 Mar 2014 @ 10:23 AM

  75. Speaking of graphs, the Mauna Loa CO2 graph has risen dramatically recently. CC has a story on the first days above 400 this year we’ve just had turning soon into the first month ever above that mark.

    My calculations (which please do re-check for me, someone) are that we have just had the first 7-day period this year (11th-17th) during which the official current daily numbers average above 400.

    Comment by wili — 18 Mar 2014 @ 1:12 PM

  76. @70: We need to improve our arguments. In particular, we need to give up the idea that the dispassionate presentation of data and logical argument will persuade the general public.

    Data and logical argument address the intellect, but (for most people) leave the emotions untouched. Not one person in ten thousand looks at, say, Euler’s Identity and feels amazed.

    Rather, emotions rule most peoples’ lives, with the intellect following behind and assembling the debris into arguments supporting what the emotions have already decided.

    We must, therefore, address the emotions.

    Which means we must tell a story.

    It should be a story about a few people whom the viewer gets to know, not about multitudes who lose their faces in the scrum.

    It must be a story of peril and descent into darkness, but also one of hope and recovery.

    And it must be in the form that best reaches the emotions of the most people.

    Which means it must be a video.

    Got screenwriters?

    Comment by Meow — 18 Mar 2014 @ 4:55 PM

  77. Revised…

    1. That would be, doesn’t fit at one end. Hanson & Zachos ≠ Royer et al
    2. I used method from Hanson, Sato, Russell and Kharechka (2013), for consistency with 1.

    Comment by GlenFergus — 18 Mar 2014 @ 5:42 PM

  78. Re:70

    You can’t teach the willfully ignorant. In this instance, willfully ignorant American Republicans, and Conservatives in general.

    You can only convince those who are honest and willing to learn.

    Chipms don’t understand tables very well, and Average American Chimps are only marginally capable of comprehending the most simplistic graphs. Their minds are so polluted and thoughts so discordant that logical argument is mostly lost on them.

    A simple graph is the way to go.

    Wood for trees is a useful tool but it’s failure is in not providing error bars, and statistical confidence limits.

    As a result, it is therefore often hijacked by cherry pickers.

    The York plotter…

    Is good, but it doesn’t allow you to provide a simple link to any given plot. You have to rely on the apes to plug in some settings that you give to them second hand.

    A graphic is a good compromise, and has other utility like being able to be placed as a graphic in a web page, or used as a reference in a real publication.

    Comment by Vendicar Decarian — 18 Mar 2014 @ 6:57 PM

  79. Re: 68,69 Bad actors

    An organization of 1000 people to monitor and respond to articles linked by the major “bad actors” – Dr*u*ge Report, etc., would be sufficient to take the wind out of the sails of the American Conservative Lie Machine.

    But given a few more years, that wind will be lost due to the change in climate itself.

    Have your lists ready when the revolution comes.

    Comment by Vendicar Decarian — 18 Mar 2014 @ 7:01 PM

  80. Here:

    Royer et al (2004) and Hansen/Zachos don’t agree; not even remotely:

    My     Royer 2004    Hansen/Zachos
    60          2.28                  10.39
    50          1.40                  12.98
    40          0.33                    8.6
    30         -0.05                    5.0
    20         -0.29                    5.34
    10         -0.08                    3.66
    0            0.00                    0-ish
    Re-reading Royer, their adjusted Veizer T is meant to be a low-latitude shallow sea estimate. Is there grounds to factor it towards something more “global”, say x 2? (It would still be far away, but less so.)

    Comment by GlenFergus — 19 Mar 2014 @ 5:13 AM

  81. It would be very nice to see a graph of global temperature versus time reaching back over at least a thousand years with all methods for data collection and correction and data sources spelled out in detail. It may be necessary to have different time scales also since the number of data points per unit time was lower in the past, and higher in recent times.

    Comment by Dan Wang — 19 Mar 2014 @ 2:39 PM

  82. It has now been been 6 days since Edward Greisch posted his comment at #13. It appears that his comment has been ignored while most have immersed themselves in the minutiae of graph creation.

    I think Greisch point is, “How do you preach NOT to the choir but to the non-choir?” This is a much more difficult problem than preaching (or graphing) to the true believers, i.e., the choir. (See Eric Hoffer on the notion of true believers.)

    The recent AAAS initiative, “What do we know” may be a good step in the right direction without any graphs at all “assuming that most people are actually smarter than chimpanzees”. One can hope.

    Comment by BillS — 19 Mar 2014 @ 8:17 PM

  83. dominant life form is a pretty hard thing to determine in paleontology, but how about something like this? (rights to alter the image afterwards reserved)

    Comment by jyyh — 20 Mar 2014 @ 2:31 AM

  84. I seems like you are trying to display trend information to non-climate scientists. You should get input from the audience, and I am one of them. But I have looked at lots of these graphs.

    The graphs should be simple, intuitively obvious, and a bit entertaining.

    They should not be misleading.

    You might want to work with commercial graphic designers, who are experts at getting ideas across to the public.

    Some rules I would suggest are:

    1) There should be one line for each concept – temp. CO2, sea level, etc. Lots of lines for different estimates looked cluttered.

    2) To get a single line, one should use a commonly accepted notions of averaging. I would suggest the median estimate for each observation. Also, possible is the average, dropping highest and lower figures.

    3) The graphs should not include measures of uncertainty, such standard deviations. If the stand deviations are very large, the data series should not be used. Otherwise, text describing the graph can give rough descriptions of the uncertainty.

    4) There should be separate graphs for long and short time periods. Log graphs are not intuitively obvious.

    5) The graphs should not include technical words – especially the geological periods.

    6) The graphs should supply internet links to more detailed graphs and data descriptions. The major reason for this is so someone intending to mislead cannot use simplifying aspects of the original graphs to do so.

    Comment by thomas marvell — 20 Mar 2014 @ 6:02 PM

  85. Logarithmic scales in particular are a potential problem. I have a demonstration of some of the main issues here:

    Comment by Jim — 20 Mar 2014 @ 9:11 PM

  86. The rate of change of atmospheric CO2 since industrialization is unprecedented over that period for which we have reliable data. We know theoretically and can demonstrate experimentally that CO2 has a positive RF; other things being equal, more CO2 means more warming. Statistics have nothing to do with the demonstrable RF effect of CO2. Statistics come into play because of the “other things being equal” qualification with regard to the attempt to measure CO2-caused warming.

    My point is that perhaps one graph or chart is insufficient for the purpose of relating CO2 to a reconstructed graph of temperature. Perhaps a set of graphs showing CO2, TSI, aerosols, clouds, etc., might be useful as overlays — a sort of pictorial PCA?

    Comment by Richard Badalamente — 20 Mar 2014 @ 10:19 PM

  87. Looks like my earlier comment was lost in the ether, but not to worry. I’ve been playing around with the idea of presenting multiple linear timescales on a single interactive graph here (simple proof-of-concept only). It could help with avoiding log scale, but only over a couple of orders of magnitude I guess. An expandable time-axis slider might be a better approach. Making graphics interactive also lets you keep them clean and simple but embed additional detail (references, links to datasets etc.) directly into the figure.

    Comment by Dieter — 20 Mar 2014 @ 11:51 PM

  88. The Wikipedia graph has been updated. (The graphic in the OP is now the new version. The old one is here.)

    Comment by GlenFergus — 20 Mar 2014 @ 11:51 PM

  89. fixed a couple of types in the wikipedia image explanation, thank you for updating.

    Comment by jyyh — 21 Mar 2014 @ 1:07 AM

  90. Glen Fergus, on the updated Wiki graph, you’ve expanded the Royer 2004 temperatures by 2 times. While that makes the numbers closer to what temperatures were more likely to have been, the explanation that they were meant to represent shallow tropical oceans is not correct. They were meant to represent global temps. The issue with Royer 2004 is that they use a 50 million year smoothing routine (following on what Veizer did) which downplays the changes that occurred in the Cretaceous, the Permian, the Ordovician etc. I think the values produced by Rohdes directly from the Veizer isotopes is more representative. Just use Rohdes’ values as they are smoothed over 3 million years which then starts to capture more realistic temperature variations.

    In addition, the Hansen 2013 temperatures from 5.3M to 65M years ago are meant to be polar oceans rather than global temperatures. They have to be scaled back by 50% to be more representative of global temperatures. The Eocene should not be warmer than the Cretaceous, Antarctica did not glaciate over 33.6 Mya with global temps at +5.0C from today. The values should also be detrended at the same rate that Veizer and Royer and Rohdes have done over time because the isotopes suffer from diagenesis over time.

    Comment by PaulW — 21 Mar 2014 @ 7:30 AM

  91. On the new-version Wikipedia graph, I think the ‘blobs’ to mark the temperature rise of 20th/21st century are a big improvement for putting geological temperature record in the context of recent changes. I was toying with a slightly different idea to do the same thing – a shaded band across the whole graph showing the temperature increase since 1900 and another shaded band showing the projected RCP8.5 range for 2100 – so the second of these would be something like this (although a red shading may be more appropriate).

    Comment by MARodger — 21 Mar 2014 @ 9:46 AM

  92. Thank Pauls, I really would like to get it right, and definitely need help with that…

    Royer et al 2004: The rock record of glacial deposits can only be qualitatively compared to other records of climate, such as CO2. It is within this context that the low-latitude paleotemperature data of Veizer et al. (2000) and Shaviv and Veizer (2003), based on the shallow-marine δ18O carbonate record of Veizer et al. (1999; Fig. 3A), is so appealing.

    That says tropical (or at least subtropical) seas; do they change that by their re-interpretation? The objection to Veizer et al (plotted by Rohde), as I read it, is that they didn’t correct for CO2, pH and Ca++, so get it badly wrong (??)

    Hansen et al 2013: “Our first estimate of global temperature for the remainder of the Cenozoic assumes that Ts = Tdo prior to 5.33 Myr BP, i.e. prior to the Plio-Pleistocene, which yields a peak Ts of approximately 28◦C at 50MyrBP (figure 4). This is at the low end of the range of current multi-proxy measures of sea surface temperature for the Early Eocene Climatic Optimum (EECO) [79–81].

    That says global. How do you tell it is meant to be polar SST before 5.3 My? I agree it sure looks high. Maybe you could email me: Gmail gergyl.

    Comment by GlenFergus — 21 Mar 2014 @ 7:44 PM

  93. MARoger: Nice. Doesn’t need to be red; can be a mistake to overstate IMO.

    Comment by GlenFergus — 21 Mar 2014 @ 7:57 PM

  94. In #55 I linked to an experiment with user-adjustable graphs which could adapt to widely varying time scales. I’ve now embedded this in a general climate plotter. It adds a few paleo datasets and allows mixing of different types, with an adjustable third axis. There’s still lots to be done on the actual data.

    Comment by Nick Stokes — 21 Mar 2014 @ 9:24 PM

  95. GlenFergus, Veizer and Zachos’ isotopes come from all over the world. They are really a collation of every study from every drilling program that they could get their hands on. And there are literally 18,000 datapoints in Veizer’s database and 14,000 in Zachos’.

    And then the question is how does one turn the isotope database into a global temperature estimate. There are formulae available to do that. The isotopes do vary with temperature based on location, proximity to the ocean, and especially with latitude.

    How does one take 18,000 isotopes from all over the world which have also moved over time with continental drift and Ph factors and diagenisis. We calibrate the whole database to known temperatures from other periods. Ph is not actually an issue because the whole database needs to be consistent with what we know.

    We know the last glacial maximum was around -4.5C, it was about +2.0C in the Eemian interglacial for example.

    We know that tropical oceans today can get to 32.0C or 17.0C warmer than the global average temperature. Did Eocene tropical oceans really get 16.0C higher than today’s 32.0C. That would be far too hot for complex life-forms. There are almost no animals that can live in a 48.0C ocean. Eocene temperatures seem to be about +6.0C compared to today based on the best estimates.

    We also know we had ice ages during the Carboniferous and the Ordovician as parts of Gondwana transited the south pole. Global temperatures had to be similar to today for large glaciers to survive for tens of millions of years at a time. etc.

    Comment by PaulW — 22 Mar 2014 @ 8:10 AM

  96. Here is just one example of a deliberate misuse of charts. (Its so easy to do!)

    For a while WUWT was choosing to link to this chart on their side bar as an example of their being “fair and balanced” by sharing real Arctic sea-ice-extent information with their visitors;

    But here is another chart that most of us would agree is far more useful;


    Comment by Pete.W — 22 Mar 2014 @ 9:37 AM

  97. Here is a graph for the past 3 Ma that I had put together for my own purposes (teaching and a book I am working on):

    The graph would be easy to extend to 5.3 Ma with the Lisiecki and Raymo (2005) benthic d18O stack, and to 65 Ma with the Zachos et al. (2001) data, with similar rescalings to estimated global temperatures as in this graph.

    Figure caption: Estimated global- and annual-mean surface temperatures over the past 3 million years. The temperatures are expressed as anomalies relative to the mean for 1961–1990. (a) Temperatures of the past 11.3 kyr, inferred from a variety of globally distributed temperature proxies. The orange line on the far right shows the smoothed direct temperature measurements from [NASA GISS]. (b) Temperatures of the past 420 kyr, inferred from the relative abundance of deuterium 2H to hydrogen 1H in an Antarctic ice core. (c) Temperatures of the past 3 Myr, inferred from the abundance of the oxygen isotope 18O relative to 16O in the calcium carbonate shells of benthic (bottom dwelling) foraminifera, recovered from ocean sediments. Shading in all panels indicates rough estimates of 95% confidence bands.

    Details: The temperature reconstruction in panel (a) is from Marcott et al. (2013). The temperature reconstruction in panel (b) is based on the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core (Jouzel et al., 2007). The temperature anomaly of snow formation that Jouzel et al. estimated from the relative deuterium abundance in the ice is divided by a factor 2 to obtain an approximate global-mean surface temperature anomaly. The factor 2 accounts for the polar amplification of global climate change and is estimated from climate model simulations (Masson-Delmotte et al., 2010). The temperature reconstruction in panel (c) is based on the relative 18O abundance in the shells of benthic foraminifera, recovered from ocean sediments at sites distributed around the globe (Lisiecki and Raymo, 2005). Bintanja and van de Wal (2008) used a land ice model to deconvolve the effects of ice volume and temperature on the relative abundance of 18O in foraminifera shells. The resulting deep-sea temperature anomaly inferred by Bintanja and van de Wal (2008) was multiplied by a factor 1.59 to obtain an approximate global-mean surface temperature anomaly that matches the temperature anomaly inferred from the EPICA Dome C record in the period of overlap in a least-squares sense (cf. Masson-Delmotte et al., 2010). The confidence bands are approximations based on published uncertainty estimates: In panel (a), they are from Marcott et al. (2013); in panels (b) and (c), they are 2 K wide, roughly taking into account measurement uncertainties and the uncertainties in obtaining the estimated global-mean surface temperatures from the inferred Antarctic and deep-sea temperatures (Masson-Delmotte et al., 2010).

    The confidence bounds are rough, basically educated guesses based on various published sources of uncertainty. I would be interested in improving them.

    Comment by Tapio Schneider — 22 Mar 2014 @ 11:33 AM

  98. Paul, pH is the key confounding effect investigated by Royer et al 2004. Have you read the paper? The section headed “The effect of seawater pH on the δ18O of marine carbonate“?

    I see Zachos et al 2006 (ref’d by Hansen et al 2013) has early Eocene mid latitude SSTs of ~26-33°C (excluding the error bars). Hansen et al’s global estimate for then is ~28°C (which I plot as +14°C vs a 1960-1990 mean of 14°C). That strikes me as potentially a little high, but unlikely way out.

    Are there similar estimates from the mid Cretaceous? I mean from plaktonic forams, not brachiopod shells? Maybe Bice et al 2006? Anyone know this literature?

    Comment by GlenFergus — 22 Mar 2014 @ 6:38 PM

  99. In case iy has not been proposed I would put Hans Rosling’s Mind the Gap software to yhe task. This is orecisely the kind of challenge that it was designed for.

    Comment by Bill Bunting — 22 Mar 2014 @ 7:29 PM

  100. Re:91

    I think the change showing the bar representing projected temps is a good one.

    People still need some events on the chart to give them a feel for how long ago those 500 million years represents.

    Extend the box vertically and add some date sign posts.

    1: Emergence of land plants.
    2: Emergence of land animals.
    3: First mammals.
    4: First Birds.
    5: First Primates.
    6: Dinosaur extinction
    7: Emergence of modern humans
    8: Industrialization

    In addition the left should be augmented with an additional box that has a scale of 200 years.

    Comment by Vendicar Decarian — 22 Mar 2014 @ 11:36 PM

  101. Generating a *quantitative* global temperature record for the Phanerozoic will be difficult, especially for the pre-Cretaceous. Veizer is the only one bold enough to try so far, I think. His shallow-ocean compilation (mostly from the tropics) contains a +8 per mil drift over the Phanerozoic. He normalizes this with linear regression, and assumes the residuals reflect a true temperature signal. But whatever controls the long-term drift (diagenesis, ocean-water d18O, whatever) can also explain–at least in part–the residuals, yes? And then there’s the whole business of scaling tropical SST to global surface temperature.

    The goal of our pH correction in 2004 was not to produce a quantitative temperature record. Our goal was to show that the correction produces a record that is more in line with the robust but qualitative temperature record from glacial evidence. We never intended our record to be used as a quantitative record of temperature. Qualitative maybe (there is a temperature signal in there somewhere), quantitative no.

    There are some good pre-Cretaceous temperature records out there, but they tend to be for only short intervals. Perhaps the clumped isotope techniques will continue to develop…

    Comment by Dana Royer — 23 Mar 2014 @ 12:46 PM

  102. It will be challenging not only present the data, but also to calibrate the different data sets. The reason is that there don´t exist a common definition of “global average temperature”. Therefore, it will be very hard to calibrate the values of global average temperature between the different data sets.

    The term “anomaly» does not help either, because there do not exist a definition of “normal global average temperature”. This is obvious because the “normal global average temperature” cannot be defined if the “global average temperature” isn´t defined.

    This is not a significant issue if we only regard the trend of “average temperature” in one single data set.
    However it will be a significant issue when trying to use different datasets to produce a common historical record. How can a historical record of a measurand be produced if the measurand hasn’t been properly defined?

    My point is that to calibrate the different data sets, a common definition of the “global average temperature” is required. Further, the actually used measurand in all data sets will have to be transposed to an estimate of this new definition of “global average temperature”.

    Comment by DF — 23 Mar 2014 @ 1:12 PM

  103. Great idea,
    Maybe need separate discussion bins,
    One on terminology /labels, such as should we use hot/cold vs warmer/cooler, should we include terms such as phanerozoic, what is best summary language to use for uncertainty (over these vast timescales), etc, how to suit the target audience,

    Good luck with a useful initiative

    Comment by Mary voice — 23 Mar 2014 @ 4:08 PM

  104. A group of us palaeoclimatologists (Gavin Foster, Dana Royer and Dan Lunt) have put together a plot using Dana’s compilation of CO2 over the last 450 million years, including the historic period and some RCP scenarios for the next 200 years. The plot and some text about it can be found here ( We have also calculated climate forcing from CO2 and changing solar output which puts the business as usual scenarios in some geological context.

    We all think coming up with a global temperature record to compare to this type of CO2 dataset would be great. We would like to add a few words of caution though – reconstructing global temperature is not easy (e.g. see Lunt et al., 2012) which is why such a record for the Phanerozoic doesn’t really exist in the peer reviewed literature. The paleoclimate community is moving in this direction but its slow progress involving lots of people and loads of data. As others have noted here simple scaling from a benthic or planktic d18O record is likely to be very inaccurate as the influence of ice on d18O of seawater (d18Osw) changes through time, the overall d18Osw changes on long timescales through geological process, diagenesis modifies carbonate d18O and importantly the relationship between deep (or surface) water temperature and global temperature is not a fixed constant (e.g. think how latitudinal SST gradients change through time). That being said, provided these caveats are noted, it is possible to use d18O-based approach to provide a good schematic global climate history but we caution it’s not likely to be an accurate record of global temperature.

    A valuable dataset that is robust and doesn’t require any tricky geochemistry (other than for determining sediment age) but illustrates the state of the climate well is the latitudinal extent of glacial deposits that Crowley put together (Crowley, T.J., 1998, Significance of tectonic boundary conditions for paleoclimate simulations, in Crowley, T.J., and Burke, K., eds., Tectonic Boundary Conditions for Climate
    Reconstructions: New York, Oxford University Press, p. 3–17). Combining this with the d18O-based schematic would be quite a nice illustration of changing climate state through time.

    Comment by Gavin Foster — 24 Mar 2014 @ 7:26 AM

  105. This is not a graph of climate data, but it is a really simple real world example of how short term trends can be misleading (called by some the ‘escalator effect’).

    Comment by Andrew — 24 Mar 2014 @ 1:26 PM

  106. Unfortunately bad graphs are like naked pictures. Once they are out there, they will never go away.

    Comment by Chris — 24 Mar 2014 @ 2:31 PM

  107. I heard the most simple argument for action. It was a professor from U of Idaho Geology on the radio. His math was elegantly simple:

    At 500 billion tons of C02 in the air – we’ll cook ourselves off the planet
    We are at 370 Billion tons of C02 right now.’
    We spew out 10 billion tons of C02 out each year.’
    We have less than 13 years.

    That’s bumper sticker size. And that could be nationwide in a month for under $1-Million bucks.

    dave petersen

    Comment by Dave Petersen — 24 Mar 2014 @ 10:12 PM

  108. Re post 104, above, their constructed Fig. 2 at:

    Is the most telling I have seen. Hansen and several others , and the Ipcc, have been elaborating the forcing argument for several years and the faint sun paradox has been discussed also, but to see the net result in a graph with the RCP pathways added, shows just how radical the future forcing could be. May I suggest it would need work to become not just a graph for scientists but one for general consumption/understanding.
    Yes, it is not a temperature graph, but very relevant to all the discussion in this thread.

    Comment by Mary voice — 26 Mar 2014 @ 4:35 PM

  109. Attempting to fit several records in similar style to the wikipedia image, that is multilinear scale, but expanding it out so almost every datapoint is visibly present… currently the image is about 26000*700px. Marcott et al has separated series for NH, tropics and SH. Next record to incorporate in this megalomaniac image, would be a similar, more detailed record, of the more recent times, bronze age, iron age or after ancient history (535 and all that). are there some publicly available?

    Comment by jyyh — 27 Mar 2014 @ 3:22 AM

  110. tried to fit the wikipedia-image ( in the same chain of images (currently at 27000 pixels wide), I believe these reconstructions are pretty accurate. This leads to problems in the intermediate sets of data, which have to be adjusted a bit downwards (~0,2 -~0,6 C) to get smoother transitions between data sets all the way back to 64Mya. Of course the datasets from far back are obtained from different areas thus they are not uniform in their represatation of global temperatures. F.e. Using NGRIP to pose as global temperature is a bit false since the tropics didn’t cool as much. It appears that I’ve missed inserting EPICA between the NGRIP and Raymo series, this might lessen the adjustments a bit (expanding the width of the image to 30000 pixels :-D), still to be added is the instrumental series, probably it would be best to use biannual to monthly values so the final width of the image would probably be ~33000 pixels (some labels needed). There’s probably no paper in the world that would print such a disproportionate image (aspect ratio ~50:1).

    But this series spanning the recent 2000-year period is though a bit problematic, since I’ve not found the datasets involved. A recent poor/bad version of the image here (comments regarding the datasets welcome, if I get this finished I might do a version without the goofy text insertions):

    Comment by jyyh — 27 Mar 2014 @ 10:29 PM

  111. This 10 year old Wikipedia graphic does more harm than good.

    Comment by Vendicar Decarian — 29 Mar 2014 @ 2:59 AM

  112. @111 Go back and read the Summary page for the graph. Read it all. See the cautions, methods, sources, links. This work is helpful, informative and exemplary for its transparency.

    Get the purpose of the graph. The graph is meant to be “a fair representation of the range of reconstructions appearing in the published scientific literature.”

    “However, since this plot is a fair representation of the range of reconstructions appearing in the published scientific literature, it is likely that such reconstructions, accurate or not, will play a significant role in the ongoing discussions of global climate change and global warming.”

    A nice statement of probability, that. Prescient.

    Comment by patrick — 29 Mar 2014 @ 5:49 PM

  113. Also: the page in question says this figure is part of a series of plots created to illustrate changes in Earth’s temperature and climate across many different time scales. Nine are linked. The 500 Myr time-scale work in this series figures in this post as an example of one of the ‘better’ graphs.

    Comment by patrick — 30 Mar 2014 @ 2:22 AM

  114. #104; Gavin Foster:

    I’m very pleased to hear you’re working on it. As an outsider looking in, I observe: a) the achievements of the last 30 years in quantifying palaeoclimate are simply stunning; and b) there’s miles to go yet to build a coherent picture.

    Some examples:

    1. LGM temperature. Hansen 2013 briefly touches on this. Global estimates seem to range from about -3 to -6°C … or is that -12°C (see NGRIP in Shakun 2012). “Minus 12” as a global average got a run in a popular BBC television production last night (Ice Age Giants). What’s a mere pleb to think?

    Seriously guys, this thing is just a few years back. It’s plain embarrassing. And very important to AGW context.

    2. Eemian peak. This one is not so bad, but we do seem to keep changing our minds every year or so. Higher and higher appears to be the game.

    3. Oligocene reglaciation. I was short with PaulW above, but his point is valid enough. The Hansen interpretation of Zachos looks too warm.

    4. Cretaceous temperatures. Dana Royer says that his were only meant to be qualitative (and definitely not global); fair enough. I understand the problems with calcareous δ18O (long term baseline changes; sample “changes in storage” over a hundred million years). It needs an answer though.

    Comment by GlenFergus — 30 Mar 2014 @ 7:46 PM

  115. To be clear, it is useful to be able to say something like:

    If we keep burning fossil fuels, global warming this century is likely to be as large as the increase since the peak of the last ice age, 20,000 years ago. Back then, New York was under a mile and a half of ice.

    That is basically sound I think, with just a touch of (warranted!) exaggeration. Importantly, it supplies context for those who won’t grasp the importance of a small numerical increase. But it fails when the likes of Dr Alice Roberts* (and practicing geologists I know) claim the LGM was -12°C.

    (* In Ice Age Giants, episode 2. I haven’t checked the transcript, but she definitely says “global”, not polar or local.)

    Comment by GlenFergus — 30 Mar 2014 @ 11:34 PM

  116. Vendicar Decarian @111.
    It’s an interesting point you make. The graph on wiki you highlight dates from December 2005. It appears to be a subtle bit of propaganda but, in my view, damage-wise it is probably the page it appears on at Wikipedia that is the more damaging. That asserts of the data in the graph:-
    “These reconstructions indicate:- (A) Global mean surface temperatures over the last 25 years have been higher than any comparable period since AD 1600, and probably since AD 900. (B) There was a Little Ice Age centered around AD 1700. (C ) There was a Medieval Warm Period centered around AD 1000, though the exact timing and magnitude are uncertain and may have shown regional variation” I see such poorly qualified statements as useful solely for MWPEs & LIARs & those of similar ilk.
    Yet this statement is referenced (not unreasonably) to the NRC (2006). Perhaps the Wiki page needs updating. Didn’t the UN IPCC recently publish something on this subject?

    The graph is the work of a Robert A Rohde and contains some very odd plotting.
    The 2004 plot is probably global HadCRUT3 while the proxies are NH, so not a good start. The black trace is probably the global HadCRUT3 10-year running average. Given the accuracy of HadCRUT3 (compared with the proxy accuracies), I see no rationale for not extending the black plot up to 2004. Perhaps Robert A Rohde thinks global temperatures are about to crash back down a couple of tenths of a degree. (Of course NH temperatures have dropped a bit in recent years but not by that amount.) Also strange (if it is global HadCRUT3) is the high position for the 1940-1970 inflection which is way too high, perhaps a move to diminish the comparative size of the recent warming.

    Within the rest of the plots, there is also some strange graphing at work. (See here for the Wiki graph’s legend.) The red curve that gives most visual impact is Moberg et al (2003) but far too droopy at its early end. Both this plot & Mann & Jones (2003) (the light green plot) appear in AR4 figure 6.10. Note on the AR4 graph the two plots are crisscrossing each other at AD600. Yet Robert A manages to separate them by some distance.
    The other plot (yellow) stretching back to AD200 is the NH reconstruction of Mann & Jones (2004). Robert A has manages to achieve some serious errors to engulf his plotting of that trace.

    All in all, I can but assume that Robert A is doing his best to produce a graph with an eccentuated MWP & LIA while providing as few hockey-stick type characteristics as possible. Bad Robert A!!

    Comment by MARodger — 31 Mar 2014 @ 7:48 AM

  117. Thanks Glen Fergus for the note on Oligocene. NGRIP is a nice and notably detailed record but all too jagged in my opinion looking at global tempereatures, one has to take the Antarctic record in consideration too and smooth the record to get it closer to global values i think. By how much, I have no clear idea yet. The Oligocene initiation has likely the same problem but in opposite direction, the Antarctica likely had a sudden (in geological terms) drop in _surface_ temperatures on the onset, even though the ocean temperature records show it to be more gradual (I believe, so it looks on Hansen 2013). Antarctica and surrounding areas are c. 4% of the planet surface and a drop of 10 degrees average there should show in the record. The same could happen on some northern areas when Pleistocene glaciations began, or a bit earlier. Fully agree that “a) the achievements of the last 30 years in quantifying palaeoclimate are simply stunning”. The Raymo (can’t spell the ‘Lisckeiesci’) series is, I understand, almost solely of the ocean sediments or corals so it could be adjusted to be a bit jaggier, to represent the polar variation more, maybe?

    So, the image linked in #83 should be reworked on times after Antarctic glaciers began to form. I should’ve guessed.

    Comment by jyyh — 31 Mar 2014 @ 8:36 AM

  118. That’s a touch harsh, MA. You impute malice to what was probably just a bit of graduate student ill-judgement, a long time ago. Whilst Rohde has published with Ms Curry, I sincerely doubt that he shares her opinions. The opposite, more likely.

    Comment by GlenFergus — 31 Mar 2014 @ 4:51 PM

  119. MA and Glen Fergus raise an important point: the 1,000 and 2,000 year graphs were done a decade ago, but they remain the main illustration for Wikipedia articles on the topic, including the Hockey stick graph and the Hockey stick controversy. More than a dozen reconstructions have been published since then, as listed at,000_years

    For a while the articles were illustrated with IPCC figures, but these were deleted as not being available under a free license, and a plea to the IPCC for permission to use the graph was turned down.

    So if anyone can produce updated graphs, please publish them with a suitable license (such as Creative Commons Attribution-Share Alike 3.0 which retains copyright and requires attribution, but allows commercial use) so that editors such as myself can upload the files, or better still register at and upload them yourself. A basic outline of how the graphs were made would be needed.

    Examples of useful files are the 2,000 year graph at the RealClimate: Paleoclimate: The End of the Holocene article, and the 1,000 year graph at which were both made by Klaus Bitterman.

    It would be a terrific help to science communication on Wikipedia to have up-to-date graphs available to illustrate articles.

    Comment by dave souza — 1 Apr 2014 @ 3:53 AM

  120. Re #111, Vendicar Decaria, what would be a better graph for Holocene temperature reconstructions? Anyone? Overview of mentioned graph

    Comment by prokaryotes — 10 Apr 2014 @ 12:09 PM

  121. I have been long time lurker on this blog and fascinated with the great work that people do here. I also happen to be a Microsoft employee. Some quick thoughts from a climate science common person that is really perplexed why the average U.S. citizen hasn’t grasped the urgency of demanding action from our elected public officials.

    Like in post #76 I agree that we haven’t made this personal enough to the average citizen AND we haven’t allowed them to visualize it. What makes something personal to them? I would argue the following:

    • Weather disasters
    • Price of food because of draught flood
    • Increase cost of insurance premiums because of weather disasters
    • Increase medical costs
    • Hunger

    While I am not a climate scientist, or a scientist at all, my understanding is that climate change has, is and will increase the frequency of floods/droughts, intensity/frequency of extreme weather events and intensity/frequency of fires.

    Thus, if we could get people to visualize some of this where they live it may help with the emotional connection they need to demand action.
    To me this is one great big business intelligence problem and Microsoft has some incredible technology that may be able to help.

    Give this URL a watch (about 20 minutes long) and come back…. Think about the prison scenario in terms of extreme weather frequency – over time.

    If people think this is a good idea, I could make a run pulling a small sample data to illustrate the point.

    That being said… perhaps this idea is already being execute on.

    Comment by Tim Reckmeyer (aka T-Rex) — 11 Apr 2014 @ 4:23 PM

  122. First, of course, keep all graphs simple. In line with that, do not show more than two lines on any one graph. Three or more lines gets VERY confusing VERY quickly!
    Second, use graphic lines (solid, dotted, dashed, little squares, little triangles, etc.). Keep in mind that many people have defective color perception, and your color coded graph will NOT be looked at by most of them, simply because they can not differentiate between the colored lines you used, and the graph is absolutely useless and meaningless to them!

    Comment by Jon Gates — 11 May 2014 @ 7:11 PM

  123. About 1 in 10 males have one of the common forms of red-green colour vision deficiency. I don’t, but I have colleagues who do. My policy has been to try to avoid using red, green, orange and orange-brown traces of similar width and style on the same graph panel. Do you have trouble reading the new Wikipedia graph above? I’d be interested to know. Can you detect the red line within the orange in the first panel (they’re Dana Royer’s colours!)?

    Complete avoidance of colour coding (or double-coding using line styles and symbols) seems OTT to me. There are colour palettes that minimise difficulty for those with the common colour vision deficiencies, for example:

    Those sort of responses won’t help people with other, rarer colour vision problems, but the extent to which one should degrade general appreciation of a graphic to cater for a tiny minority is a difficult question.

    Comment by GlenFergus — 12 May 2014 @ 2:07 AM

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