Bishop Hill Did the IPCC just blink?
Jul 18, 2013 Climate: sensitivity The wave of new evidence of low climate sensitivity, the existence of which is denied by the CCC's David Kennedy and downplayed by Julia Slingo, has presented the IPCC with a dilemma. They could try to bluff it out, an approach that could be terminal given the widespread reporting of the new science in the media. Alternatively they could 'fess up. This too could be extremely damaging, but perhaps might not be the end of them.
Being good bureaucrats they have gone for the option that is most likely to lead to their survival. At least that is what I surmise from a posting at the Economist, which has managed to get its hands on a table from the IPCC's Fifth Assessment Report. According to the article, a draft of the WG3 report reveals that
at CO2 concentrations of between 425 parts per million and 485 ppm, temperatures in 2100 would be 1.3-1.7°C above their pre-industrial levels. That seems lower than the IPCC’s previous assessment, made in 2007. Then, it thought concentrations of 445-490 ppm were likely to result in a rise in temperature of 2.0-2.4°C.
Now of course, it's draft and its WG3, not WG1, so we have to be cautious. But there is at least a possibility that they are going turn down the alarm somewhat.
Reader Comments (51)
EM, I know what a null hypothesis is. I am comparing real measurements, such as they are, with my null and the CS hypothesis. I've been going on about it for months. Nobody has ever come on and justified the CS hypothesis at all. That there is some number associated with a doubling of CO2 which regardless of other factors will be added to the global average temperature, per doubling. Not just once. It is not apparent to me why this should be so, so my null is that it is not a valid concept. It is no good looking at historical global temps, taking away every other factor you can think of (and some you can't measure, and some you just made up out of thin air) and saying the result is CS. It doesn't matter whether Trenberth does it, or Lindzen, or Lewis or Scaffeta. There will always be a bit left over, positive, negative or zero, which you can label the CS. It's a get out of jail free card, a fudge factor. The sum will always produce a result, you'll get a paper or several out of it, but it may well be rubbish.
Your claim that for an Oxfordshire housewife to make such a suggestion, to put it out for discussion on a blog read by a few hundred is a threat to the planet, is the purest theatrical alarmist bollocks. If it's wrong, why after repeated attempts does no-one take me aside and explain it all, justify the concept? And avert threat to mankind?