...sorry, meant to write "About PDO, Lags, Cycles and Hysteresis"
In another article here, a certain WUWT commenter, Professor JP, took me to task for quoting him. Quite right too. But that one line of mine resulted in something of real value. The Professor obviously forgave me because he was kind enough to give me a lengthy lesson on climate sciency stuff. For free. I didn't have to pay a cent. I was a bit nervous at first because I've heard awful stories about gravy trains and the billions of dollars climate sciency people charge everyone. For a minute I wondered if I'd end up roast meat under a pile of brown sauce. But no. Not a penny did he charge.
Now I wouldn't have written this up as an article, but the Professor was so insistent that I learn and he was so gracious in imparting his years of climate sciency knowledge that I just have to share. (Don't you just love it when people say "share". Makes you feel all gooey and warm and fuzzy in your mouth.)
Now I'm always willing to learn new things and I read his comments over and over to make sure I didn't miss a thing. It's not often I get offered personal tuition. RealClimate is one place but there are always such a lot of other people in the classes there. (I've been honoured by other renowned scientists here as well, but none who have written so much detail as Professor JP.)
From kettles and ice blocks to the PDO
After some wonderful lessons on the basics of kettles and ice blocks (I learnt some really good stuff - like ice blocks melt if you take them out of the fridge and water in a kettle won't boil unless you heat it, while seawater doesn't need heat, it expands by magic - did you know that?), the topic shifted to the PDO. This lesson was so informative I just have to share. (There's that word again.)
Here is how it started. Professor JP was explaining why it took so long for the warmer sun in the 1950s to heat up the earth in the 1970s. It's called "waiting for homeostasis" and has something to do with boiling kettles. But then it turns out it wasn't the sun after all that heated up the earth. It was the PDO. (I looked that up. PDO stands for Pacific Decadel Oscillation. See I'm not as dumb as I look!) Anyway, Professor JP wrote:
As for why the Earth started heating up in 1978, that is pretty obviously due to the PDO going into its positive phase (the previous 30 year cooling period was coincidentally during the PDO's negative phase).
And this is where lags come in again:
The PDO is clearly one of the long-term lags in climate that I was speaking of.I got curious about these 'lags' and asked:
Just how long is that "lag" supposed to be?To which the Professor replied:
A reasonable guess would be the length of a half-cycle or two - 30-60 years.
That's wonderful news. The scientists have narrowed the uncertainty right down to half a cycle or two or 30 years or sixty years. Still, not being at all knowledgeable like the Professor, I had another couple of questions:
And when is the earth going to get back to temperatures of the 1960s? Maybe the PDO only heats the earth but doesn't cool it? Is that what you are arguing?
Unfortunately Professor JP only had time to answer the second question, so there's still a big gap in my knowledge. Not that I'm complaining, you understand. Heavens above, it was so generous of him to tutor me at all. Anyway he scolded me and told me to pay attention (justifiably - I was starting to race ahead a bit) and wrote:
Not at all, it cooled during the 30 years of the last negative cycle, which I believe I already said. Are you even bothering to read my posts?
The instantaneous laggy PDO
So there you have it. The PDO warms and cools the earth with either a 30 year lag or a 60 year lag, which I'm told is a half-cycle or two, and instantaneously too like in the previous negative phase. If you do the sums you'll see the Professor means that the PDO has a 60 year cycle. In other words the PDO is a 30 or 60 year laggy sciency thing that acts instantaneously. He then generously added more words of wisdom:
I wonder since you haven't mentioned hysteresis, but I assumed someone quietly told you that you were ridiculously wrong on it or you finally realized it yourself.Well, I did try to read his posts and I did make a reference to hysteresis, but I can't really blame him for missing that bit. Professors are very busy at doing PDO climate sciency stuff, and boiling kettles and so forth, I'm sure.
Oh and please, if you can't see what is wrong with the skeptical science page on it then there is no hope for you. Their graph is so blatantly stupid the way it applies linear trend lines to a cyclical phenomena that a grade school kid could see the error.
Given Professor JP's insistence that it's now the PDO that is causing global warming, I sat up and took notice. The way he writes with such certainty, he's obviously a highly qualified expert in the field of hysteresis, PDOs, lags and kettles. It was with some trepidation that I ventured forth, however. If a renowned climate expert like JP can't figure out if this PDO lag is 30 years or 60 years, I thought to myself, then what hope does a humble blogger have. And I couldn't figure out if the lag only applied to the warming phase, because I thought he said the cooling phase brought instant cooling but the warming phase takes 30 or sixty years. In any case, I put aside my fears and decided to give it a go.
Here's the result. You can click the animation to enlarge it:
|Sources: JISAO and NASA|
What do you think? I reckon Professor JP is incredible. It sure looks like the negative phase cooled the earth instantly. Well okay, it didn't cool it exactly but at least it looks like it stopped it getting hotter for a while. Fine, whatever you say. It didn't completely stop it from getting hotter but you've got to admit it didn't warm quite as much. And 'not warming as much' is pretty close to being the same thing as 'cooling', sort of, if you squint a bit. Okay, if you squint a lot and shut your eyes and imagine. Anyway the warming phase really gave such a jolt to the earth that it's still getting hot, even though the PDO has turned negative. That's pretty powerful stuff.
I figure I'm still much dumber than the Professor though because I can't see the lags working very well. Nor can I see the PDO's 30 year half cycle or the 60 year full cycle. It goes up and down for sure, but I must have forgotten how to do sums because I just can make them all add up to either 30 or 60, no matter what I do. It's just me I'm sure. He probably knows as much about climate science as his fellow Professor David Archibald, or even more. I don't know that he knows as much as Ronald A. "it's the insects" Voisin. But that's doubtless a matter of opinion. Whatever, I know I'll never get to the level of any of them.
On "blatant stupidity"
BTW here is the SkepticalScience chart. As the good professor said, how "blatantly stupid" of them to compare linear trends instead of cycles.
I'll send an email to Mr John Cook Esq (proprietor of SkepticalScience) and tell him to change the chart. Of course he wouldn't listen to a humble blogger. I'd better tell him Professor JP, the expert in half cycle or two PDO's, hysterical lags and kettles, is personally tutoring me. That should impress him no end.
As the Professor suggested, all you have to do is show cycles. I couldn't draw the spokes but I did manage to draw the shape of the wheels. You can see how bigger and bigger wheels can be made to fit between the lines and are pushing up the temperature. It's a tri-cycle. It all makes sense now. You just wait and see. I'll bet in no time at all, SkepticalScience will replace their "blatantly stupid" chart with this one below. It's prettier for one thing. Don't you like pink?
|You had the Marcott wheelchair, now here's the HotWhopper tricycle|
Gotta go now, the kettle's boiling at last. (I've only been waiting forty years. It was only after the tip from the Professor that I figured out you have to apply a source of heat before the water boils. After I did that, it took no time at all. Nary a lag to be seen.)
|Anyone for a nice hot cuppa?|
PS While you're sipping your tea (milk and sugar?), you might enjoy reading another version of the PDO, this time with clouds and magic fairy dust.