I don’t know what to say

about the latest from James Delingpole at the U.K. Telegraph:

http://blogs.telegraph.co.uk/news/jamesdelingpole/100210866/an-english-class-for-trolls-professional-offence-takers-and-climate-activists/

Who You Gonna Believe?

It seems that Anthony Watts politely disagrees with my post about the connection between oil and gas production and earthquake activity. Actually that’s not a fair portrayal of his post. It’s a hatchet job against me personally. What a nice guy.

Smearing Climate Data

Note: See the update at the end of the post for a test involving 1000 (rather than 100) Monte Carlo simulations.

If a temperature event like we witnessed in the last century — a warming of around 0.9 deg.C in about 100 years — had happened at some other time in the last 11,300 years, would it have left some trace in the recent paleoclimate reconstruction of Marcott et al.?

Too Little Time

Those in denial of global warming and its danger have tried to make a big fuss over what they perceive as a lack of warming recently. How recently depends on just how much they’re willing avoid seeing.

For the Record

Since Anthony Watts has decided to repeat Steve McIntyre’s accusation, I’m posting my response to a previous comment on this blog:

wte9 | April 1, 2013 at 11:40 pm | Reply

“Also for your information, the original version of this post mentioned McIntyre (and linked to his posts) extensively. But prior to posting I decided to remove that, since McIntyre had already fully explored the ‘low road.’”

Can you clarify something: Are you saying you used McIntyre’s ideas, but removed any citations attributing those ideas to him because he was taking the low road? Or are you saying something different? Thanks.

[Response: All I “learned” from McIntyre’s “analysis” is that Marcott et al. had re-calibrated proxy ages, that McIntyre blamed the uptick on the re-dating process, and that he was happy to hint at the possibility of deliberate deception on the part of the authors. The references to McIntyre in my original version were to his insulting tone regarding this work, but I finally decided it was better to ignore that and comment on the science. It now seems that on the “dot earth” blog he chose to accuse me of having “shamelessly plagiarized” his ideas on why the exaggerated uptick occurs in the Marcott et al. temperature reconstruction. He’s wrong.

I didn’t read all his posts about the paper, for two reasons: first, there are so many, and I find them so full of sneering and thinly veiled innuendo that they’re sickening; second, there’s really very little to be learned from him. In my opinion he’s just not interested in understanding the science, he only wants to kill hockey sticks.

I’m hardly ignorant of the effect of station dropout (in this case, proxy dropout) on averaging temperature data, I’ve known about it since long before Marcott et al. was even published. If Steve McIntyre wants to claim that he identified proxy dropout as the reason for the extreme recent temperature uptick in the Marcott paper before I did, fine. It wouldn’t be the first time two different people had the same idea. I congratulate him on his insight. As for his assuming that I got the idea from him and didn’t credit him, it’s no surprise that he would assume the worst possible motives in others.

My opinion: perhaps if Steve McIntyre had been more careful in explaining himself, more interested in communicating reality than in demeaning the results, and less indulgent of his own sneering, people might refer to him rather than me when mentioning the impact of proxy droupout, and the “dot earth” blog might be referring to his posts rather than mine as “illuminating.”

Also my opinion: if Steve McIntyre were really interested in the science rather than just killing hockey sticks, he might have applied the “differencing method” himself and discovered that the uptick is still there (but reduced in size) when the impact of proxy dropout is dealt with, whether one uses the re-calibrated ages or the original published ones.

But that would require him actually to do some science.

Notice that I not only identified (quite independently) the reason for the exaggerated uptick, I also implemented a method to overcome that problem? Notice how I showed the result and compared it to Marcott’s reconstructions? Notice how I computed the result using both the re-calibrated and the originally published proxy ages? Notice how I did so for the same latitude bands as Marcott, and compared those too? Notice how I even did an area-weighting of those latitudinal results? Science.

Notice also that I disputed the reality of the exaggerated uptick in the Marcott et al. reconstruction without once even hinting that the authors had manipulated the data for nefarious purposes?

As for the differencing method, I didn’t credit the inventor (I don’t even know who it is) although I didn’t come up with that one independently. Perhaps McIntyre will accuse me of having “shamelessly plagiarized” that as well.]

Easy Question

A question was asked recently:

Sorry, it’s not about Arctic not Antarctic, but the Arctic thread seems to be already closed for commenting. There’s a thing I can’t understand about Arctic sea ice – how come according to NSIDC the maximum sea ice extent in 2013 was the 6th lowest in satellite history while Jaxa is showing it to be higher than the 2000’s (not even 2010’s) average?

http://nsidc.org/arcticseaicenews/

http://www.ijis.iarc.uaf.edu/seaice/extent/Sea_Ice_Extent_L.png

The short answer is: in the JAXA plot, the line labelled “2000’s Average” isn’t the 2000’s average.

Regional Marcott

We’ve already examined the big picture of global temperature according to the recent reconstruction for the holocene (in particular the last 11,300 years) from Marcott et al. We also took a close look at the recent uptick in temperature. Now let’s see about some of the regional differences indicated by these data.

In their supplemental materials, Marcott et al. included the reconstructions restricted to three very wide latitude bands: the northern extratropics (from 30N latitude to the N.Pole), the southern extratropics (from 30S latitude to the S.Pole), and the equatorial band (from 30S to 30N latitude). These reconstructions are computed using their “Standard 5×5” method. But we noted that they may suffer from a difficulty, that as time marches forward, the drop-out of more and more proxies can lead to spurious jumps in the average temperature. This is especially difficult for the most recent time period, because that’s when there are the fewest proxies remaining (so things are less accurate anyway) and there’s more proxy drop-out.

The Tick

In the last post we looked at the recent temperature reconstruction for the holocene, in particular the last 11,300 years, from Marcott et al. We noted that the changes over most of this very long time span were no bigger, but a lot slower, than the changes over the last century or so. That means trouble.

We also mentioned that the “uptick” at the end of their “main” (the “Standard 5×5”) reconstruction was much larger than in their RegEM reconstruction, and that they had expressed doubt about its robustness. The large uptick at the end (in 1940) is larger than indicated by the instrumental data — another reason to doubt its reality. Let me tell you my opinion why this difference exists. I could be mistaken, but this is what I think.

Global Temperature Change — the Big Picture

There’s a new reconstruction of past temperature covering the last 11,300 years by Marcott et al. (2013, A Reconstruction of Regional and Global Temperature for the Past 11,300 Years, Science, Vol. 339 no. 6124 pp. 1198-1201, DOI:10.1126/science.1228026). Data for their reconstructions, and the proxy data on which they’re based, are part of the supplementary materials.

The Marcott reconstruction has been joined to the Shakun reconstruction prior to that, and the HadCRUT4 global temperature data since, and the projected temperature change under the A1B scenario for the future, by Jos Hagelaars, in order to show us some perspective on climate change past, present and future.

This graph has been dubbed the “wheelchair.” Compared to the past, what’s happening in the present is scary. The future is scary as hell.

Antarctic Sea Ice Gain

We’ve looked at Arctic sea ice data, noting not only its overall decrease but changes in the annual cycle as well. As one reader suggested, let’s take a similar look at sea ice in the southern hemisphere.