But Bob Tisdale would rather not believe it. He’s posted at WUWT his reason for believing it may well have been January 2007 instead. “The Bob” is always good for a laugh.
And what, readers may well wonder, is his reason? The U.K. Met Office, publishers of the HadCRUT4 data set, include uncertainty values with their temperature estimates — specifically, a 95% confidence range. Temperature anomaly for February 2016 is estimated at 1.057, but the lower limit of the 95% confidence range is 0.921. For January 2007 the estimate is 0.832, but the upper limit of the 95% confidence range is 0.977. Since the upper limit at the earlier time is higher than the lower limit at the later time, the Bob has sufficient reason to think it “may or may not have been” bigger back then.
You can see it with your own eyes:
A thin blue horizontal line marks the lower limit for February 2016, and by golly the red dot (upper limit) for January 2007 is above it.
The sketchy nature of his reasoning can penetrate the minds of discerning readers without the use of a howitzer. For January 2007 to be greater than February 2016, the earlier value would need to be near the upper limit of its range and the later value near its lower limit. Either unlikely event alone, won’t do the trick; you need both unlikely events to make it work.
This is clear even to some readers of WUWT, as one says:
Nick Stokes March 30, 2016 at 10:09 am“It is a fact that the error bars overlap, but the headline is misleading.”
seaice1 is right there. Once you take account of an error distribution, you can always say any two numbers “may or may not” have a different order. You can’t be certain of anything, anywhere. But the probability can be very lop-sided, as here.
Just saying the 95% CI’s overlap doesn’t say much. There is, let’s say, a 2.5% chance that 1/2007 was over 0.98. And a 2.5% chance that 2/2016 was under 0.92. Those are both unlikely events, and if independent, the chance of both happening is 0.0625%. The probability of order change would be higher because there is a small overlap in the range, but you’d have to figure out how much higher, which is not done here. And dependence, if any, will reduce that further.
I bothered to “figure out how much higher,” and the chance of both happening turns out to be 0.013. If we require 95% confidence (the standard which “the Bob” seems to have adopted as the “may or may not have” threshold) to declare February 2016 truly higher than January 2007, then contrary to Tisdale’s belief, we’ve reached statistical significance — in fact we made 98.7% confidence.
I was also amused by the first comment on that post:
Marcus March 30, 2016 at 5:53 amBob T, when Trump or Cruz is elected as POTUS, I will put my vote in for you as nominee for Science Advisor to the president ! …
I’d say Bob Tisdale’s standard for quality science is an ideal match for either Donald Trump or Ted Cruz.
If you like this, join others in supporting this blog and donate at Peaseblossom’s Closet.
Open Mind 
Yeah, the joint p-value. That was the 1st thing that popped into my mind. But too dumb to figure it out myself.
But I was pretty sure that you would inform us correctly. Thanks.
I should note that Nick Stokes, while a reader of WUWT, is not in any way a denier. Rather he accepts the science of AGW, and has a very good blog on global temperatures. His persistent reading and commenting on WUWT does, however, show him to have masochistic tendencies.
And he works tirelessly on WUWT, sewing doubt among the Wotbots. Good on him.
Second that. I don’t have the stomach for such an Augean task.
With limitless patience, economy of discourse, teflon suit for insults and most importantly his skill, Stokes is an excellent contributor there. He and Zeke Hausfather are good role models for how to engage in hostile territory.
I came early to get a good seat…something tells me this is going to be an extremely interesting thread and wondering bob is going to be shown some actual fact based science from the reality based universe. Any early number on the betting line that it all goes over his head in the wingnut alternate reality (war for short) called Watts Up With That?
Actually there’s another issue. The uncertainties in the temperature data are highly correlated. Comparing the distributions for the two months without taking into account which ensemble member is which ignores this correlation. That’s the whole point of providing an ensemble rather than just monthly uncertainties.
I haven’t checked the monthly data, but on the basis of my previous work with the ensemble trends I’m very confident that the high 2007 and low 2016 values come from different ensemble members. I suspect that the fraction of the ensemble for which Jan 2007 was hotter than Jan 2016 is precisely zero.
Your suspicion is correct. In fact, no ensemble member shows Feb 2016 as less than 0.194 K warmer than Jan 2007, let alone cooler than it. And in every single ensemble member, Feb 2016 sets the record for highest temperature.
Can one of you please define what ‘ensemble’ means in this context? How many ensemble members are there in HadCrRUT4?
Mark, from HadCRU FAQ.
Why can I not exactly reproduce the hemispheric and global averages for HadCRUT4 and HadSST3 that are given here?
Both these are ensemble datasets. This means that there are 100 realizations of each in order to sample the possible assumptions involved in the structure of the various components of the error (see discussion in Morice et al., 2012). All 100 realizations are available at the above Hadley Centre site, but we have selected here the ensemble median. For the gridded data this is the ensemble median calculated separately for each grid box for each time step from the 100 members. For the hemispheric and global averages this is again the median of the 100 realizations. The median of the gridded series will not produce the median of the hemispheric and global averages, but the differences will be small.
Ensemble members can be accessed from this page.
Here’s another link answering the question more directly, Mark.
https://climatedataguide.ucar.edu/climate-data/global-surface-temperature-data-hadcrut4-and-crutem4
This web site is awesome. By a country mile the most comprehensive list of climate data sets I’ve ever seen, with explanatory summaries and external links. Good catch-all for the Climate Data Links section.
https://climatedataguide.ucar.edu/climate-data
I was intrigued with this aspect of HADCRUT4, as I’d been unaware of it previously. Unfortunately, the Morice et al paper is paywalled, and I didn’t find a PDF version. After a bit of poking around on the net, I found a nice succinct poster discussion:
Click to access Morice_EarthTemp_Edinburgh_2012_Poster.pdf
Basically, if I’ve got this right, ‘realizations’ means using different estimates of relevant errors—the famous ‘bucket versus intake’ bias, for instance–combined in various ways, to arrive at different error corrections (and hence anomalies). That way, it’s possible (if, I suspect, pretty damn finicky) to figure out relationships between sources of error, and to constrain uncertainty better.
There’s a PDF of the paper here.
Ah! Thanks!
The other message within that Wattsupian wordage from Bob “always good for a laugh” Tisdale is that the present up-tick in global temperature appearing on the records over recent months is nothing unusual.
To illustrate this normality Tisdale plots the 1997/98 temperature record against the present 2015/16 data and shows the up-tick is simply the expected result of the El Nino playing out across the Pacific.
Such a comparison (as Tisdale demonstrates with his figure 2) only makes sense if you accept there has been a 0.386ºC rise in global temperature since 1998, equal to 0.2ºC/decade of global warming over the last 18 years. So presumably over the next couple of decades of “the pause” (Bob “Always good for a laugh” Tisdale is happy to tell us“the pause” will last a total of 20 to 35 years) we can expect similar rates of global warming. Presumably, after that time AGW will return from its “pause” and all hell will break lose.
“Presumably, after that time AGW will return from its “pause” and all hell will break lose.”
LOL. I guess ‘all heck’ is breaking loose at present.
Nick Stokes: “And dependence, if any, will reduce that further.”
This is not insignificant, I imagine. Is there any way to get an idea of the dependence? Of course, if there was an obvious systematic dependence then HadCRU would take it into account already, so maybe there isn’t.
“This is clear even to some readers of WUWT, as one says…”
I think Nick Stokes will be offended by that characterization. He’s an Australian scientist and he does a fair bit to counter denier garbage.
The word ‘even’ may have misled – ‘reader’ is not a characterization after all. I’ve no doubt Tamino knows who Nick Stokes is, and equally sure Nick would take no offence.
Agree. Stokes, Hausfather, Mosher (who’s evolving as a result of his research), and others.
Nick Stokes runs very good climate site, with tons of useful data and by any measure he is as far from beeing climate denier as the host of this site.
Check moyhu.blogspot.be to see it for yourself.
“Bob T, when Trump or Cruz is elected as POTUS, I will put my vote in for you as nominee for Science Advisor to the president ! …”
Is Tisdale even American? Can’t seem to find any biographical info… which makes me wonder if his credentials are as thin as his reasoning.
He’s American (you can hear him speaking on self-made videos).
People have often asked about his credentials but none have been found, to my knowledge. Desmogblog do not have a listing for him, which is unusual. Looks like they could find out little about him either. Safe to assume he has no qualifications specific to his climate topics.
Yes, I was surprised not to find him on DSB. Apparently, a ‘man of mystery.’
Tisdale has updated the post to reflect, and respect, Stoke’s comment. Might be worth updating that here, too.
JMA have released Feb data for 2016 in the last couple of days.
http://ds.data.jma.go.jp/tcc/tcc/products/gwp/temp/feb_wld.html
Another record-breaker.
February was “+0.62°C above the 1981-2010 average (+1.04°C above the 20th century average), and was the warmest since 1891.”
According to Barry’s link, January was 0.52 C so February ws the highest on record by 0.10 C.
February was the 2nd highest anomaly in the JMA record over the 1981-2010 average. The highest anomaly in the JMA record for that baseline was December 2015 (0.66C). December and February anomaly are tied (1.04C) per the 20th century average.
In terms of absolute temps July is the hottest month globally, about 3C warmer than January, so the warmest absolute monthly temperature in the JMA record was probably July last year (eyeballing the graphs). Not especially meaningful WRT climate – just to keep things clear.
February marked a full 30 years (360 months) since the global average surface temperature was below the 20th century average (NOAA temp record). 30 years is the classic climate period. By that designation we are now living in a different global climate to the one in which I was born.
And we should have the March anomaly from UAH soon. It’ll be interesting to see if it remains extreme, or if there’s some weakening to just ‘hot.’
March RSS anomaly is also out. Highest March.
Top 3 anomalies are:
Feb 2016 : 0.978
Apr 1998 : 0.857
Mar 2016 : 0.842
During the very strong el Nino 1997/98, monthly anomalies in the satellite record peaked in April ’98. Not inevitably going to be the same for this year.
UAH (Beta 6.0 version) March anomaly is out, Doc. Slightly down from the Feb anomaly, warmest March, and statistically tied for the second warmest month for the whole record.
http://www.drroyspencer.com/2016/04/uah-v6-global-temperature-update-for-march-2016-0-73-deg-c/
The ‘official’ version, 5.6, is not yet updated. Should be some time over the next week.
Thanks, barry. I’d actually noticed that after I commented. So, a little ‘weakening’, but not much.