The reason we keep getting double-six

Dr James Hansen had an Op-Ed published in the Washington Post newspaper last Saturday – under the title: ‘Climate change is here – and worse than we thought’. In it he mentions a paper, which was published yesterday (6 Aug 2012) in the weekly Proceedings of the National Academy of Sciences (PNAS) magazine. For those without a subscription, a brief précis of the paper is also available on the Columbia University website.

James Hansen's climate dice

James Hansen’s climate dice

Having emailed Dr James Hansen and pleaded poverty through unemployment, he has taken pity on me and provided me with a PDF copy of the final proof of the article (as approved by him for publication). For this, I am – and will remain- extremely grateful. However, in what follows, so as not to be seen to be taking liberties or risk breaching copyright, I will quote mainly from the Washington Post and Columbia University pieces (rather than the PNAS). As many others have noted, Hansen has a wonderfully down-to-earth way of communicating complex ideas; and his writing often displays a conversational style. He opens his Op-Ed by reminding readers of another very warm summer – 1988 – when he first testified before US Senate about the consequences of humanity’s unabated burning of fossil fuels, to which he now adds bluntly… “I have a confession to make: I was too optimistic.” It was in 1988 that Hansen first introduced the concept of climate dice, to try and help people understand his message: That the change then expected (and now observed) is not the result of natural variability, because the burning of fossil fuels is changing the nature of what is normal. In effect, Hansen was suggesting that normal climate dice would have two sides with a one (representing cooler-than-normal weather); two sides with a three (representing normal weather); and two sides with a six (representing warmer-than-normal weather. Rolling the die again and again, or season after season, you would have an equal chance of throwing a one or a three or a six. However, by upsetting the dynamic equilibrium of our atmosphere by adding CO2 from previously-fossilised carbon, we have now loaded the climate dice so that now only one side is cooler than normal, one side average, and four sides warmer than normal. Even now, we may get the occasional cooler-than-normal summers or a typically cold winter; but the chances of weather being warmer than (what was previously) normal are now much greater. In summarising this newly-published analysis of six decades of global temperatures (co-authored with Makito Sato and Reto Ruedy), which concludes that “for the extreme hot weather of the recent past, there is virtually no explanation other than climate change”, Hansen emphasises that this “is not a climate model or a prediction but actual observations of weather events and temperatures that have happened”. Having looked back over this data (for the northern hemisphere), Hansen et al 2012 finds that extreme hot weather events (greater than 3 standard deviation [+3 StdDev.] warmer than local average) covered 0.1 to 0.2 percent of the Earth’s surface at any one time during the reference period for the study (1951 to 1980). However, while the average temperature has slowly risen over the last three decades, extremely hot weather events now cover 10 percent of the Earth’s surface. This means that, in any given summer, they are between 50 and 100 times more likely to occur than they used to be. Again, this is not a prediction or a model; this is just statistical analysis of weather that has occurred. Our climate is changing – and we will indeed have to live with it or, if we are unfortunate to be in the wrong place at the wrong time, die because of it. As Hansen et al point out; the heat wave in Europe in 2003 killed 50 thousand people. (2012) Figure 2 (2012) Figure 2

The piece on the Columbia University website includes some helpful colour illustrations such as this one (Figure 2) showing temperature anomaly distribution curves. The frequency of occurrence (vertical axis) of local temperature anomalies in the Northern Hemisphere (NH) relative to the 1951-1980 baseline, in units of local standard deviation (horizontal axis). Image credit: NASA/GISS. Hansen et al describe this increase in the frequency of extremely hot weather events as “the emergence of a subset of the hot category” defined as anomalies exceeding +3 StdDev.. Included among these events are the heat wave and drought in Oklahoma, Texas and Mexico in 2011; and a larger region encompassing much of the Middle East, Western Asia and Eastern Europe (including Moscow) in 2010. Hansen et al conclude that widespread reluctance to attribute these events to anthropogenic climate disruption (ACD) is no longer justified. This is because, as already stated, it is now 50 to 100 times more likely that any given event is indeed attributable to ACD. Despite all this, as Hansen et al acknowledge, the distribution of seasonal temperature anomalies (Fig. 2) also reveals that a significant portion (about 15 percent) of the anomalies are still negative, corresponding to summer-mean temperatures cooler than the average 1951-1980 climate. Thus, people should not be surprised by the occasional season that is unusually cool. Cool anomalies as extreme as -2 StdDev. still occur, because the anomaly distribution has broadened as well as moved to the right. In other words, as well as getting generally warmer, our climate now encompasses a wider range of extremes. This is bad news; and saying “it ain’t necessarily so” will not change the probability that it is.


About Rick Altman

Possibly just another 'Climate Cassandra' crying 'Wolf' in cyberspace. However, the moral of the old children's story is that the Wolf eventually turned up!
This entry was posted in Anthropocene, Climate Science, Environment, James Hansen and tagged . Bookmark the permalink.

12 Responses to The reason we keep getting double-six

  1. Lionel A says:

    Someone called “Sou” has posted a link to a PDF of the entire paper (as published by PNAS) on the Real Climate blog.


  2. weatherdem says:

    This paper is one in a growing stack that makes the important point that the observed climate change has happened much faster and in more varied ways than were projected less than a generation ago – quite the opposite condition than most ‘skeptics’ claim. Those changes will continue to occur faster than what most activists predict, in my opinion largely due to the fact that low and moderate emissions scenarios form the bulk of climate analyses. They’re useful in an academic sense, I suppose, but the public needs information based on our high emissions pathway and I don’t think they’re getting it reliably. I expect more papers like this in the future. I await the day when climate scientists, who convinced themselves that nobody would continue emissions when presented with evidence (social science results be damned), realize that they are not ‘alarmists’ if they model actual emissions and likely future emissions pathways. Until policymakers enact robust mechanisms to address mitigation, scientists need to move their focus toward storylines that aren’t roses and sugarplums. The main problem I see with that is the inertia in the climate science arena – they won’t easily give up on some emissions pathways, no matter how fantasy-land they are.


    • Rick Altman says:

      Thanks for all those thoughtful comments, Weatherdem. With regard to the EPW Senate Hearings on 1 August 2012, I have looked at the testimony of Field and McCarthy (alongside Christy last week) and although the former were both very good (especially McCarthy), I can’t help but agree with those who dismiss these Hearings as political farce; given the mutually contradictory truth-claims in the opening statements of Boxer and Inhoffe. Each is entirely convinced they are right; and not open to listening to the other. The Hearing therefore changed nobody’s mind and will make no difference to policy; nor I suspect did it change the minds of anyone outside politics that watched it. Unless, of course, you know differently? What powers to Senate Committees have? What happens when the members of a Committee cannot agree on policy recommendation (as will clearly be the case here)? Surely, majority and minority reports are just a waste of paper?


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  4. Gerald Machnee says:

    Of course James Hansen forgot to compare the 1930’s to the present. Then there is the half a degree that they are adding to the temperatures today. They call it “adjustments.”


    • uknowispeaksense says:

      Gerald, James Hansen in response to criticisms like yours addressed the 1930’s question here. As for homogenisation of temperature data, rather than just throw about one-liners with no substance, why don’t you explain how the methodologies employed to adjust the data are incorrect and explain what you might do differently?


    • Rick Altman says:

      Thanks for sharing your opinion, Gerald. Are you suggesting that temperatures in the 1930s prove that global warming is not happening? Indeed, presumably you would also claim that (even if it was happening) it stopped in 1998? Despite what you may choose to think, CO2 does trap outgoing LWR (fortunately for the development of life on Earth) and more CO2 does trap more LWR (unfortunately for all life here now). Please stop cherry-picking anomalous data to justify an “it must be anything other than CO2” explanation for the recent warming.


    • Rick Altman says:

      As usual, it seems, yet another “skeptic” has disappeared when challenged…


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