The Sun is the most spherical object in the known universe. It's just one giant circle.
For the past week, climate denialati have been breathlessly awaiting the "BIG NEWS" being dribbled out on the well-known skeptical climate blog run by Joanne Nova, aka Australian blogger JoNova. Never one to pass up hype, JoNova describes this work (by her better half, Dr. David Evans) as "a major advance", "extraordinary", and "a creative idea that breaks the current paradigm."
After six postings and 12,000 words, we now haven't seen new posts on the subject for two days, so it's safe to say that the BIG NEWS is complete, at least for now. And what's there is a model, which has only one input: Total Solar Irradiance, or TSI.
And all you need to know is this key sentence, which is found near the top of part 2:
We are envisaging some sort of black box, whose input is TSI and whose output is temperature.
Aaaaand
there's the problem in a nutshell. Evans
starts by assuming the result he wishes to demonstrate: that Sun drives global surface temperature. And from here on out we're on a gigantic 12,000 word
circular argument, bringing us right back to where we started.
And it's not just a side issue: the circular argument is in fact his entire thesis. At no point does Evans allow, nor even consider, that there might be any other drivers of surface temperature.
And it just gets worse: the "unexpected" discovery at the heart of this whole thing is that -- now hold on to your hats -- the Sun has an 11-year cycle, but surface temperature does not! (Yes, I know: hard to believe! Especially considering the assumption of the result we started with. This means Evans is going to have to work extra special hard to come up with a solution to close that circular argument; but don't worry, he's up to the task.)
Now, Dr. David Evans is not an actual climate scientist. He's a mathematician, with a special interest in Fourier transforms and signal processing. And, as my Daddy used to say, when the only tool you have is a hammer, every problem looks like a nail. So the solution Evans comes up with is a "notch filter", that is, a mechanism that filters out a specific wavelength from a signal, while leaving all other wavelengths alone.
At this point, any real climate scientist would simply throw up his hands (or more likely, throw away Evans' paper). Because the lack of a strong solar signal in surface temperatures has been known for a very long time now, and the reason for that has been known almost as long. It just takes the ocean too darn long to heat up, or cool down, in response to a very weak (0.1% of solar output) signal like this. To use Evans' signal-processing analogy, for signals of this amplitude the oceans act as a low-pass filter, with a break frequency that's longer than 11 years. If the signal amplitude were stronger, like we see when a big volcano cools the whole planet, the oceans act faster; but the teeny-tiny solar cycle signal is simply sunk too deep in the ocean noise that our climate system is full of.
But Evan's zero-dimensional model is also a zero-noise model: he simply doesn't take this into account. In fact, JoNova addresses just this in a supplemental post (in which she replies to a critical appraisal of the "notch filter" model by physicist Lubos Motl):
The data most definitely does not suggest a low pass filter with a 20 year break point. (If it did, the lines in the graph Lubos reposted twice would be flat lines to 20 years, then bend down with a 45 degree decline to zero from there in the shorter frequencies.)
Well, no. The data would only show that kind of behavior
if solar forcing were the only thing driving temperature. (In other words, the assumption of the result has circled around and bitten them in the backside yet again.) It's entirely possible that short-term frequencies can still exist in surface temperature, even with a long-term break frequency on solar inputs, if those shorter frequencies are the result of non-solar inputs -- a rather obvious fact that somehow escaped Evans and Nova during their 18 months of research.
But wait, it gets worse! It's not hard for an electrical engineer to build a notch filter. But how does the natural world conspire to create a notch filter on solar forcing? Any inquiring scientist would want to know. And Evans tells us: it's a mysterious Force X, which he cannot describe other than its ability to create solar notch filters.
It might as well be Fairy Dust.
In classical logic, when you start with a given assumption and argue forward to reach a conclusion that is false or illogical, that is proof that the initial assumption was wrong. In this case, Evans has argued forward to reach an unfalsifiable (and therefore unscientific) conclusion that Force X exists. It doesn't. Evans' original assumption -- that global surface temperature can be modeled from solar inputs alone -- has been nicely disproven by Evans himself.
Links
Evans part 1
Evans part 2
Evans part 3
Evans part 4
Evans part 5
Evans part 6
Lubos reply
