Don J. Easterbrook, a retired professor from the Dept. of Geology, Western Washington University, in Bellingham, WA sent Anthony Watts a brief analysis of the effect of the PDO on climate:
Dr. Easterbrook’s analysis (PDF). The analysis included two figures: a) a graphic illustrating the PDO over time, and b) Dr. Easterbrooks projection for temperatures. Otherwise, there is very little narrative.
I took the liberty of organizing the two figures into 1 figure, manipulating the widths of the graphs to align years; I also slapped a “eyeball-best-fit” regression to estimate the magnitude of overall warming Dr. Easterbrook is projecting.
What I note about Easterbrook’s projection:
- Easterbrook is projecting cooling for several decades. This will be followed by renewed warming.
- His overall projection appears to be warming at a rate of roughly 0.7 C/century. (My estimate is based on the “calibrated eyeball method”.
- The graphic would suggest Easterbrook attributes the recent rapid warming was due to the super-position of the PDO warming phase and roughly 0.7 C warming. So, I would infer he is suggesting the PDO has a cooling effect of a bit more than 0.7 C/century. (Note, my calibrated eyeball also seems to detect a slight deceleration in warming predicted by his graphic. You may tell me what your calibrated eyeball says.)
- According to the graphic, it appears he expects the effect of PDO index to lead the effect on the GMST by a slight amount.
- The graph includes other wiggles. The text of Dr. Easterbrook’s analysis doesn’t provide suggestions as to the source of the wiggles.
I guess I could ask Dr. Easterbrook for more details, but mostly, that’s what the graphic seems to convey. Overall, this would seem to place Dr. Easterbrook in the “Lukewarmer” category: That is people who believe there is an overall warming trend, but that it’s not very strong.
I suspect we’ll get more than 0.7C of warming during the next century, as the physical arguments for GHG’s having a real warming effect seem pretty sound to me. Also, the argument that the earth’s climate system has a moderately large response time (as in at least 5 years) seem sound. So, I do expect more warming from 2000-2100 than occurred from 1900-2000.
It would be interesting to read additional comments by Dr. Easterbrook. I would consider emailing, but since he sent his analysis to Anthony, I suspect he’ll pop in at the Easterbrook post at “WattsUpWithThat?”. If so, the conversations over there should be interesting.
I’ll be checking for comments as Anthony approves them, and suggest you all go there too!
Blog note
Roughly 10 comments were auto-moderated last night. I released them all from moderation, and I’ll be checking to make sure certain names are whitelisted in SpamKarma. I use SpamKarma, which tends to be “suspicious” when newer commenters suddenly post a sizeable number of comments. Eventually, it “learns” who the frequent commenters are, and lets them through. However, I can also place people on a whitelist, and will do so. This should help with the over-aggressive moderation.
Meanwhile, I’m busily reading things, and have a full check list of self-study assignments. But, it may take a bit of time before I actually do the analysis on the stratospheric temps, or more solar. (There is a lot of stuff to read, I need to attend to learning ARMA and I need to look at some of the interesting Model E results Steve Moscher found.)
What is temps return to 0 anomaly (or even -1 anomaly)? I find it incredible that scientists have not even considered this. Its always assumed its going to go up….when historically its gone up and down and this trend is simply confirming this. What if it really goes down and down -10?
lucia, your point 5: source of other wiggles. They are just the wiggles from the previous cold period shifted over. this is a common and probably valid approach as it preserves some of the statistical properties of the curve.
Leif– I think you’re right. The wiggles just look transposed.
It seems Dr. Easterbrook did jump into comments at WattsUpWithThat?
At (08:02:10) , Don Easterbrook posted:
Lucia,
You have stated in several of your posts, as you do above, that the physical arguments of GHGs having a warming effect appear sound to you. What appears to me to be forgotten is that the “GHGs [let alone man-made CO2 specifically] cause global warming” hypothesis is precisely that, a hypothesis, and one which, the IPCCs efforts notwithstanding, has not been proven. Also, it appears to me that elementary physics tell us that the “greenhouse” effect of CO2 is on a log scale and thus has specific limits that fall well short of those ascribed to their effect by e.g. Hansen or the IPCC.
Fact is, there is a rapidly growing body of data and analysis that strongly suggest the AGW hypothesis is fundamentally flawed. For instance, what to do with the demonstrable fact that as CO2 ppmv values continue to rise ALL relevant temperature metrics from SSTs, deep ocean temperatures, land surface and lower troposphere temperatures have leveled off or fallen for a decade now? The lower troposphere temperatures are particularly confounding in this regard as AGW proponents have held them up as the proverbial “canary in the coal mine”. However, not only is this temperature metric not increasing at a rate of 30% over land surface temperatures as per the IPCCs GCMs, it is in fact falling [-0.3C between Jan-March 2008 alone]. All of this can not have been caused by one old fashioned La Nina.
Don Easterbrook is certainly not alone in cautioning that any further warming is not CO2 driven. In my view, the hypothesis which needs to be falsified first and foremost is the one that states that variations in relevant temperature metrics are primarily caused by natural, cyclical, systemic fluctuations.
I look forward to your comments.
Tetris–
I haven’t forgotten that the enhanced greenhouse effect is a hypothesis. But, in science, (and politics, life etc.) one is permitted to assess the physical arguments in favor of a theory and lean toward or against believing the hypothesis even before it is tested.
But, I also am underneath it all, strongly inclined towards empiricisms. So, I do believe hypotheses need to be tested. My general sense is: quite a bit of the warming we have seen since the 70s is likely do to GHG’s. Is it all the warming? Probably not. As for percentages: I honestly don’t know.
What I do see — and this is unfortunate– is much of the testing and verification in support of attribution is fairly hand waving. (This is not, by the way, unique to climate science. There are many, many handwaving proofs in all fields. Don’t let engineers tell you there has never been any in engineering publications for CFD. There were loads of “Here’s the predictions; here’s the data. Eyeball. Looks good to me!” type papers. There is even value in that! But, it’s not the sort of things that really tests alternative hypotheses realistic very strictly.)
JM–
The baseline is irrelevant when determining the trend. Period. I set things to a common baseline for the purpose of plotting.
I realize you don’t understand the simple fact that rebaselining is unimportant. However, since you don’t believe me, Arthur or the variety of other people who have told you so here, I don’t suppose we will convince you.
Possibly, you will convince Tamino to redo the whole thing rebaselining appropriately under your guidance, but I’m not going to waste any more of my time discussing the non-importance of rebaselining when determining the trend.
Lucia,
a paper by Gerhard Gerlich and Ralf D. Tscheuschner
http://arxiv.org/pdf/0707.1161
appears to falsify the enhanced greenhouse effect that is the basis of the warmer projections. I honestly am not capable of evaluating it, but, they appear to have some real issues with the basic physics. Maybe you could take a look at it?? I saw one blog series on it, but, the warmers mainly were attacking the average global temperature claims instead of the issues with GHG’s.
I too thought there might be more response to this paper when it first came out last July, not that I saw any considered refutation. Lubos Motl has just written about the basic CO2 equation at
http://motls.blogspot.com/2008/05/average-temperature-vs-average.html
which seems to have a the point that quibbling about the “average Global Temperature” is a waste of time and effort, as the global heat budget has little correlation with it, in that a minor increase over a century in the aGT can just be marked down as changes in temperature distribution. (My comment, from an entirely non scientific interpretation).