Bishop Hill Lewis 2013 as an "outlier"
Apr 19, 2013 Climate: sensitivity One of the strangest things about Dana Nuccitelli's article about the Lewis 2013 paper is its twin-pronged attack - alleging that Lewis misrepresented the match between the mode of his estimate and that of Aldrin et al, and suggesting that the Lewis result is an outlier.
In the graph below, I have redrawn Lewis 2013 and a selection of other papers: Aldrin et al, Forster and Gregory, and Troy Masters' new paper. The IPCC's 2-4.5deg range is shown as the shaded area.
With Lewis's PDF sitting in the middle of the bunch, Nuccitelli's position is shown to be baseless. I've added a line through the mode of Lewis, which you can see matches Aldrin et al almost exactly. So when Nuccitelli says Lewis is misrepresenting the match between his findings and Aldrin's, it's easy to see that this is, ahem, a stretch.
;)
There are other papers that could be shown on the plot - Ring et al, Lindzen and Choi and so on, but I think this handful is good enough to make the point: there is simply no way Lewis 2013 can be seen as an outlier.
Reader Comments (61)
HaroldW, Paul_K
Broke my own rule about driving a calculator after midnight! Subtracted when I should have divided.
The calculation should have been ( (400/200)/(280/200) ) * 4 = 5.71C
Entropic man -
You might want a little more rest. If you attribute a 4 K rise to a change in pCO2 from 200 ppmv to 280, the sensitivity calculation is (4 K)/ log2(280/200) = 8.2 K/doubling.
The primary error is not the arithmetic though, it's the assumption that 4K is a linear response to CO2 forcing, as Manfred pointed out.
the sensitivity calculation is (4 K)/ log2(280/200) = 8.2 K/doubling.
HaroldW
I'm not sure that formula is correct. Even if the rest of your formula is correct it should use the natural logatithm, not logarithm to base 10. That should be (4 K)/ ln2(280/200) =4.12K/doubling.
Perhaps we should leave this to the professionals. :-)
@Manfred
Sounds reasonable.
What provokes the end of an ice age?
EM -
The "log2" was meant to indicate logarithm to base 2; log2(280/200) ~= 0.485, which makes sense as a factor of 1.4 is just shy of half a doubling (which would be at sqrt(2)=1.41).
One can use the natural log (or log10) if one divides by the logarithm of 2 to the same base, thereby converting to doublings. E.g.
ln(280/200)/ln(2) = 0.336/0.693 = 0.485
log10(280/200)/log10(2) = 0.146/0.301 = 0.485
HaroldW, MartinA,
You're getting sucked into Entropic Man's fallacy. The fundamental error is not that EM can't handle logarithms. The fundamental error is one of reversing cause and effect.
Suppose there is a large temperature increase caused by change in received SW - TSI and albedo changes which have nothing to do with any change in CO2. This large temperature change will cause a small increase in Co2 concentration - mostly from ocean outgassing. The CO2 forcing might then add a small increment to the temperature change. If you then assume, as EM has done, that the small change in CO2 is responsible for the entire temperature change, you end up with a stupidly high and completely erroneous estimate of climate sensitivity to CO2.
This is widely accepted mainstream science - not some radical view.
Paul_K,
I agree; see my post of 12:20 PM, and Manfred's earlier. It can't be correct to attribute all of the change to CO2 when even Hansen claims that over half of the change in forcing is due to albedo change from the retreat of the glaciers. Unless one is willing to argue that such feedback remains possible; but the fact is that there is just not much glacier left (compared to LGM).
But while I was at it, I thought it helpful to correct the maths; at least that wouldn't be contentious. Or so I thought.
good efforts from Paul_k and HaroildW but you both know that Entropic man does not bow to greater knowledge.....
http://link.springer.com/article/10.1007%2Fs00382-012-1375-3
Who is this Nutticelli that seems to draw such large amounts of mental energy? Must be a formidable scientist on the AGW-side? No? So why did she - er, he, end up on the dark side? The forcings wasn´t with him?
It is senseless to mention Wikipedia as a source of information on Climate Science. This section of Wikipedia is no more than Connolleypedia (with an M).