Strategies of Communication on Climate Change

Friday, May 10, 2013

Communicating climate change in ONE graph

It is sometimes said, that one (good) picture is worth of thousand words. Let's try to do that experiment. Let us have the instrumental temperature record since 1880 till present, coupled with paleoreconstructions of global temperatures using various "proxies" during the last 540 millions years, and add to that the boiling-frog (i.e. business-as-usual) scenario with policy unrestricted GHGs emissions:

*This graph show the reconstructions of global temperature during the last 542 millions years, together worst case temperature rise by the end of this century following the 8.5 RCP (Representative Concentration Pathway) scenario (van Vuuren et al., 2011). 8.5 is amount of additional radiative forcing (in W/m2) relative to the preindustrial period. Global temperature rise of » 4,7°C (8,5°F) is taken from the latest draft report of U.S. Global Change Research Program (p33, PDF). Also note that the scale of x-axis is varying, and that such rapid current+projected temperature rise did not occur during this period. Source of the graph: Wikipedia.

Thus even if we consider large uncertainties of the paleoclimatic temperature record, going anywhere close to the “worst case” scenario would, in the long term, completely deglaciate our planet. Climate change itself would probably not allow such dramatic rise of global temperature, not seen for tens of millions of years, but this is clearly something we would collectively like to avoid. 

A comment by Ugo Bardi:  This post by Alexander Ac is a good example of the subject of this blog. We are trying to "package" the information on climate change in ways that are not only understandable, but also direct and effective. This "one graph" summary of climate change goes in the right direction, but I would like to add a caveat. 

We shouldn't forget that most people, out there, are not able to read even simple x-y graphs. This specific graph, with a variable x scale, is not easy to read and will be confusing for people who never learned the specific "graph language" that scientists find so obvious. Still, this graph may be a winning weapon to penetrate the "climate illiteracy" that affects a good number of scientists and professionals who are not specialists in climate. 


  1. For those interested there is also graph of the "global surface temperaure" during the last 65 millions years published in Hansen et al., 2012

    Similar graph as that presentented in the blog readars can find here - it shows higher global surface temperatures prior to the Pliocene era, still projected temperatures by the end of the century would be highest in around 35 millions years.

  2. The graph
    It is unfortunately not easy to understand, if you have no scientific background. Lots of information packaged there, very interesting if you have some background in the climate problem, very difficult to unravel if not, I fear.

    The projected temperature rise is in the future, so one can always dismiss it ("it has not yet happened, it will not happen").

    If you have some scientific background, and just a glimpse at the problem, it is terryfying. Not only for the part that is shown, but for the (unknown, really unpredictable) part that is not, atthe right. What will happen after 2100? It is really unlikely such a rapid rise will just stop there. Where it will stop? At +6C? +10C? No way to survive in summer except, maybe, at really high latitudes. And Antartica unfreezing would rise the sea level really a lot.

  3. The graph is more related to global warming, it cannot model climate change per se since climate need a more holistic and systemic approach. As you can see the main values are Temperature and Time, which are not enough to describe Climate Change but shows incredibly well the Antropocene fast raise of T mainly due to GHG emitted by modern human behave

  4. What's impressive in Alex's figure, anyway, is that 4 degrees higher (and it looks like we are set for that value, at the very least) corresponds to the complete melting of all permanent ice on the planet's surface. Now, that would correspond to about 70 meters rise of the ocean level

    Now, that has to be taken with a lot of caution, of course. The world was different 30 million years ago; temperatures are not rising uniformly everywhere, and it is to be seen how long it would take for the Anctarctica ice cap to melt completely. But it is perfectly correct to be scared about these data.

    The problem is one of communication: if you mention 70 meters of sea rise to people who are not familiar with these things, they'll either think you are a madman or they'll run away while plugging their ears with their hands (the "force push" effect). So, these data are interesting if you discuss with someone who can actually understand the graph and who has some knowledge to appreciate the various points involved with these paleo-climatic reconstructions. But for all the others we must use different methods

  5. I am not a scientist but I can see that the line is going up quickly and that looks scary. I recently read an interview with Anthony Leiserowitz that really helped me understand some key points. He uses analogies and refers to concrete things (like you did with your ice house). My favourite example:

    Think about when you get sick and you get a fever, okay. Your body is usually at, you know, 98.7 degrees. If your temperature rises by one degree you feel a little off, but you can still go to work. You're fine. It rises by two degrees and you're now feeling sick, in fact you're probably going to take the day off because you definitely don't feel good. And in fact, you're getting everything from hot flashes to cold chills, okay. At three you're starting to get really sick. And at four degrees and five degrees your brain is actually slipping into a coma, okay, you're close to death.

  6. I agree with most of the comments, this scary graph is not for people with lack of scientific background (and even for some scientist would be difficult to grasp!). However, it still is very valuable when arguing with negationists that pretend to have some scientific knowledge.

    And by the way, I'd like to propose a topic for a future post, is it worth to discuss with negationists?

    1. Yes, Angel, this is a fundamental problem - although not THE fundamental problem. Denialists are a hindrance, but not the major cause of the lack of "traction" of the climate message. If we can frame the message right for normal people, then denialists will simply be ignored and their position consigned to the dustbin of wrong ideas.

      This is a point that I hope we'll be able to discuss with this blog. Maybe we can make an open thread on the subject, but we have to wait for the blog to gain a stable audience. Or maybe you have a post to submit, please send it to me

  7. Dm, thanks for a nice interview!

    Angel, well, it depends, if the person has a sincere will to understand the topic, then yes, otherwise it is a waste of time.

  8. For communication on climate change, most probably not everything works the same for everybody, but it seems to me that one way of bringing it is to NOT talk about temperature at all in the beginning, and start more with below graphs for instance :
    (the top two on extemely sudden and regular CO2 rise)

    Or :

    Then not avoiding to say that climate science is extremely complicated, and is an on-going body of knwoledge about a single very complicated object (atmosphere, oceans, biosphere, ice, currents, clouds, etc) object and a single experiement.

    But that the CO2 green house effect is well known (and can be replicated in a lab 10 000 times), and that it results in a positive delta of energy that the "earth + atmosphere" now receives.

    James Hansen, or somebody else forgot who, is using the number of Hiroshima bombs this energy delta corresponds to to give an "image", forgot how much, ah yes 400 000 according to below :

  9. a nyt new..