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Detection, attribution, disintegration

James Annan hit the climate blog headlines the other day, with a post that not only wrote off the possibility of high climate sensitivities but also revealed that one climate scientist had been so sure of the omerta among his colleagues that he openly admitted to lying to promote political action on climate change.

Annan has now written another potentially blockbuster post, which discusses recent publications in the area of detection and attribution (D&A) - the bit of the climate change science that assigns guilt. What Annan reveals is that the studies that have supported the claim of "the majority of recent warming is manmade" are fatally flawed.

I've been fairly critical of the conventional D&A approach in the past, primarily on the grounds that the null hypothesis of no anthropogenic influence is always false a priori (and therefore a failure to detect an anthropogenic influence is always a matter of insufficient data). These recent papers point to another, arguably more terminal, problem. Attribution will inevitably fail as the anthropogenic effect increases!

Read the (relatively technical) reasons why here.

As Annan explains, this is going to leave D&A specialists with a headache to rank alongside the one being ensured by the climate sensitivity team.

It will be interesting to see how the D&A community addresses this problem. Atribution of the observed changes to GHG and other influences was touted as a major step forward when it was first achieved, so it would surely be rather embarassing to lose the ability to do this. It looks a bit like they are trying to just ignore it for now, but that can't really be tenable as a long-term strategy.

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Reader Comments (120)

Entropic man - Feb 21, 2013 at 9:17 PM |

"The 21st century pause in measured global temperature rise may be due to the extended solar cycle 24 minimum and the weakness of cycle 25."

O, I do hope and trust that you are wrong!

Feb 21, 2013 at 10:54 PM | Registered CommenterGreen Sand

Entropic man whistles past the graveyard of the heat, if it hasn't been spirited from it's augured tomb to deep space. When, dear Entyone, will that heat come out?

Your sea level rise is a joke. Pay attention to TonyB.

Feb 22, 2013 at 12:32 AM | Unregistered Commenterkim

Feb 21, 2013 at 9:17 PM | Entropic man

"Support from this comes from the continued rise in sea level.Since the 1997/98 El Nino sea level has risen at an average of 3.2mm/yr. That's 50mm in 16 years."

Sea level will rise a meter in just 320 years. Beach front property must be worthless.

Feb 22, 2013 at 2:09 AM | Unregistered CommenterTheo Goodwin

@entropic man

'Since the 1997/98 El Nino sea level has risen at an average of 3.2mm/yr. That's 50mm in 16 years.'

Just to point out that 50 mm in 16 years equates to about 300 mm (one foot) in a century.

Will somebody please try to convince me that a sea level rise of less than three inches (75 mm) per human generation is going to produce the end of civilisation as we know it?

For calibration, one standard British housebrick laid with mortar is about three inches deep.

Feb 22, 2013 at 5:20 AM | Unregistered CommenterLatimer Alder


'Alternatively, the heat may still be accumulating, but in areas where we do not have temperature monitoring. The deep ocean below 2000M is a possibility, beyond the depth range of the ARGO buoys'

H'mm. How very convenient that it's there ..but just hiding somewhere where we can't measure it.

The theory might be even a bit plausible if somebody could propose a mechanism by which it got there without showing up in either the atmosphere or the shallow ocean on it's way past to the deep and stygian depths. Any ideas?

Perhaps it is another facet of that mysterious (and unknown elsewhere) climatological force of 'teleconnections'?

Or perhaps my little dog ate it along with his 'good boy chewie'............

Feb 22, 2013 at 5:28 AM | Unregistered CommenterLatimer Alder

No I didn't!

You are always blaming me for things that are nothing to do with me!

I may be only a Dachshund but I'm not stupid. But you humans just love your fantasies.....'The cheque's in the post', 'Of course I'll still love you in the morning'.....'the heat's in the deep ocean...' get real!

I haven't seen your boring inedible and unfindable 'missing heat'. You want it - you go and find it. Because if you can't even my simple doggie brain tells me it ain't there.

Wake me up if and when it appears..or at 'walkies' time.

Feb 22, 2013 at 7:07 AM | Unregistered CommenterLatimer's Dog

Alexander, I take the point that you didn't play the man, but even if you play the ball, if 20 other people all play balls at him simultaneously, then get nippy when he can't respond to each one adequately (in the eyes of the asker) then it can get a bit fraught. Combine that with his probably contractual obligation not to bring his employer into disrepute, and it's a recipe for stress all round.

Feb 22, 2013 at 9:53 AM | Unregistered CommenterTheBigYinJames

After Climategate, it became apparent that "climate skeptic" = "loony" no longer cut it.

The Met Office clearly decided it needed "to engage with skeptics". I wondered if Richard Betts, with his undoubted tact and diplomacy, was put forward for the role by the Met Office management.

I think there is a fundamental disconnect between engaging in open discussion with sceptics on scientific matters and being, at least to some extent, a spokesman for a propaganda organisation. So I can imagine, that, to someone having faith in the objectivity of the Met Office's science, the reaction of posters on BH would have been disconcerting.

The Guardian, Monday 28 September 2009
Met Office warns of catastrophic global warming in our lifetimes

"We've always talked about these very severe impacts only affecting future generations, but people alive today could live to see a 4C rise," said Richard Betts, the head of climate impacts at the Met Office Hadley Centre, who will announce the findings today at a conference at Oxford University. "People will say it's an extreme scenario, and it is an extreme scenario, but it's also a plausible scenario."

The Met Office scientists used new versions of the computer models used to set the IPCC predictions, updated to include so-called carbon feedbacks or tipping points, which occur when warmer temperatures release more carbon, such as from soils.

When they ran the models for the most extreme IPCC scenario, they found that a 4C rise could come by 2060 or 2070, depending on the feedbacks. Betts said: "It's important to stress it's not a doomsday scenario, we do have time to stop it happening if we cut greenhouse gas emissions soon." Soaring emissions must peak and start to fall sharply within the next decade to head off a 2C rise, he said. To avoid the 4C scenario, that peak must come by the 2030s."

Feb 22, 2013 at 2:58 PM | Registered CommenterMartin A

Wow, Martin, did you just find that or have you had it tucked away since Sep 09?

Feb 22, 2013 at 5:38 PM | Registered CommenterRichard Drake

I was looking at a page on Judith Curry's blog, having googled "engage with skeptics", and there was the link. It was not in my "Met Office Propaganda" file.

It's interesting that the Met Office's pages on Climate don't seem to have been updated for a couple of years now (typically, since March 2011).

I have the impression (partly from what RBetts has said) that the Met Office's line has morphed into "we just do climate science; we don't tell govt what to do".

But if you look at AVOID, it is pretty clearly the Met Office's "advice to govt on what to do" branch - eg AVOID's chief scientist is a Met Office employee etc. Just take a look at their series of reports.

Feb 22, 2013 at 6:35 PM | Registered CommenterMartin A

Great work Martin. It will be amusing and instructive to do a gallery of Before and After Climategate for many characters, like Mike Hulme, one day. I still like Richard but this has to be chalked up as embarrassing. Meanwhile I'm back to lurker mode for a while. Have fun.

Feb 22, 2013 at 7:47 PM | Registered CommenterRichard Drake

Martin, that is an interesting find. I would be interested to see your Met Office propaganda file. The layest addition is a new project called My climate and me, a series of short videos to mislead and brainwash young people. I rather lost my temper with them on twitter today over this.

Feb 22, 2013 at 10:18 PM | Registered CommenterPaul Matthews

"The theory might be even a bit plausible if somebody could propose a mechanism by which it got there without showing up in either the atmosphere or the shallow ocean on it's way past to the deep and stygian depths. Any ideas?"

Feb 22, 2013 at 5:28 AM | Latimer Alder

You might like to read up on the process of deep column formation around the Greenland Gyre, which acts as the source for the thermohaline circulation. I've given you links to a review article and, for those with a less technical interest, the Wikpedia page. In the latter, look at the section Formation of Deep Water Masses

Feb 22, 2013 at 11:33 PM | Unregistered CommenterEntropic man

Oh come on, quoting Skeptical Science was bad enough, but Wikipedia? Really?

The "encyclopedia" which anyone can edit, provided your POV agrees with the clique who "own" the article in question.

Feb 23, 2013 at 12:42 AM | Unregistered CommenterNW


I might be tempted to put it this way:

A: Either Kevin Trenberth got his maths a little bit wrong, which is entirely plausible given that the IPCC freely admit they have very little knowledge of the overwhelming majority of the (allegedly) known 'forcings'. People with appropriate humility would accept this position and not blather on about travesties.

B: Or, he nailed it exactly, and all the 'missing' heat, which, again, bear in mind, falls over the entire surface of the earth, is teleconnectedly focused at a single point and is whisked away from ALL of our measuring equipment to lurk maleveolently in the deep ocean, rewriting physics as it goes.

My training suggests A., but feel free to further defend B.

Feb 23, 2013 at 10:27 AM | Registered Commenterflaxdoctor


Feb 23, 2013 at 11:01 AM | Unregistered Commentersplitpin

EM - Did you read the summary on p51 of the 1992 review article you linked? Did you understand it? Have you looked up the current status of the Argo floats around Greenland using the Google Earth KMZ link on the Argo home page?

Feb 23, 2013 at 3:35 PM | Unregistered Commenternot banned yet


Weaver & Hughes, my first link, is the paper you should be reading. I falil to see the connection to Skeptical Science.

Say No To Fearmongers

The scientific undrstanding of these processes is incomplete, but not negligible. People with appropriate humility would not reject it out of hand.

Feb 24, 2013 at 12:35 AM | Unregistered CommenterEntropic man

"The scientific undrstanding of these processes is incomplete, but not negligible. People with appropriate humility would not reject it out of hand."

Entropic does irony?

Feb 24, 2013 at 8:18 AM | Unregistered Commenternot banned yet

not banned yet

Weaver & Hughes are right. If variation in the rate of heat uptake into the thermohaline circulation a) has a large global effect on temperature, and b) is cyclic over the long term; it would be possible to misattribute its effect to cAGW.

Unfortunately the long term record needed to identify such cycles is particularly sparse in this region. The only research I've seen is a couple of speculative papers on the AMO with limited data and loose statistics.

One thing I've been pushing for among the sceptics who wave natural variability and cycles at me is links to quality research to back it up their claims, but they never have anything concrete.


Thanks for the ARGO link. I was particularly intrigued with 6900613. This buoy monitored the sea off SE Greenland from 2008 to 2010. It showed warming down to 1600M in 2008 associated with high salinity. By 2010 it showed cooler deep temperatures and lower salinity, suggestive of lower energy flow into the THC.

Given the time I could have great fun following this up in detail. There looks like enough information from the network to construct energy content/ time data for water entering the THC.

My ready-reckoner GISS global temperature graph

shows an increase in temperature anomaly from 0.49C in 2008 to 0.66C in 2010, while heat flow into the THC dropped. There's a research topic for someone there, checking a possible inverse correalation between global temperature and thermohaline heat uptake.

Feb 25, 2013 at 12:20 AM | Unregistered CommenterEntropic man

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