Wait a Second...How Can We Be Responsible for 110% of the Warming?!

In a recent post, I marveled at David Pakman's surplus of patience for denier ignorance. Well, he's got nothing on Gavin Schmidt, who very calmly and meticulously deconstructed a ridiculous Judith Curry blog post last month about how much of the observed modern warming she believes can be attributed to human emissions/activities. Though I must admit Schmidt's high-octane mathematical expertise can leave me in the dust rather quickly, it's a fascinating read, and I encourage you, dear readers (all five of you), to dive in and tough it out until the end. Your knowledge of the climate change issue will likely double by the time you finish, whether or not you understand every last bit of it. Through it all, Schmidt shows the patience of a saint as he quite graciously entertains and rebuts line-for-line, more or less, Curry's absurd lukewarmer madness that it's a 50/50 human/natural variability split since 1950. I mean, Judith can really bury her head in the sand when she wants to, because at the very least it is three-quarters our fault.

Head on over and come back when you're done, because I want to address one remarkable-looking claim Schmidt makes, almost offhand, since for him and many climate experts it's probably just a throwaway, take-it-for-granted point. G'head, I'll wait here.

Back? OK, good. Look again at this graphic that he posted early on in his Curry blog-post takedown:


The probability density function for the fraction of warming attributable to human activity (derived from Fig. 10.5 in IPCC AR5). The bulk of the probability is far to the right of the “50%” line, and the peak is around 110%.

Schmidt correctly argues that Curry has no right to be puzzled about other scientists not agreeing with her wishful-thinking 50/50 split, because the vertical black dashed line representing her belief barely falls within the probability density function bell curve, and in fact the likeliest attribution level for human influence is 110%.

Now, while I'm certain that you, dear readers, are aware that I give 110% every time I sit down to update my blog, you may still be wondering how the freakin' freak-athon it is possible for anyone to be responsible for 110% of anything.



What does it even mean to attribute 110% of something, such as the modern observed warming?

Well, the fact of the matter is we not only can be responsible for 110%, but if you look at Schmidt's graphic closely, we can also be guilty of bringing about 115%, 130%, and even 150%! And the answer to this seeming mathematical impossibility is, I think, binary, the first part being common knowledge in the climate science community as well as the climate blogosphere, and the second part being pure conjecture on my part (I have not read the idea I'm about to put forward anywhere, and I am only assuming it to be the case, so I will take my lumps if I'm totally wrong).

OK, so...let's start the explanation with the factual part that ain't just my guesswork. Curry's 50% natural causes is horribly wrong, so horribly wrong in fact that the real effect of combined natural forcing (Milankovitch cycling, volcanic eruptions, solar activity, etc.) may have been to gradually cool the planet since before the Industrial Revolution, or about when our GHG emissions began overwhelming that non-anthropogenic trend and warming everything up, let alone since 1950 when our influence on the climate really started kicking in. That is, whenever you choose to start looking forward in the recent temperature record (Schmidt and Curry opt for 1950), the natural component may be negative, even, oh, -10%. Therefore in order to account for all the warming we see, humans would have to have contributed over 100%. Get it?

The second part is where I stick my neck out and probably meet with the guillotine. So be it. And I bring your attention to the "observed" portion of the phrase "modern observed warming." Ordinary people going about their daily lives and even scientists in the laboratory performing experiments or out in field conducting research are aware only of what they can observe, but that does not mean they notice all that there is to be observed! An easy illustration of this would be running through a crowd and noticing that you, like the big, inconsiderate, rushing jerk you are, knocked over ten people, but, in your mad, dashing hurry, failing to catch that they accidentally pushed over another ten when they toppled. So, whereas you only saw ten people fall down, you were really responsible for 200% of that total kissing the pavement. A rather classic and illuminating example of our limited observational skills from within the field of climatology itself is the Cowtan & Way study which filled in many "blank" areas of the globe where we cannot acquire firsthand surface temperature readings. Though we cannot witness or record the warming taking place in, for instance, the "Arctic hole" directly, that does not mean there is no warming occurring there. So while we all talk about 0.8C worth of warming happening since about 1880, there may have been more (most of it occurring since 1950, hence Curry and Schmidt's preferred starting point), and we most likely are also responsible for some or all of that unknown amount, and therefore to accurately predict what percentage we can, well, pat ourselves on the back for, we may have to go beyond 100% of the warming of which we are cognizant and for which we have empirical evidence.

There you have it, 110% human responsibility is now explained. And even if I'm wrong about the second conjectural speculation bit that I must admit I have not seen any climate scientist mention as part of their attribution calculations, the first part is quite satisfactory and sufficient as far as explanations go. As Gandalf would say, "Of course, of course! Absurdly simple, like most riddles when you see the answer."