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Thursday, September 25, 2014

Judith Curry vanquishes her uncertainty monster

Sou | 3:52 AM Go to the first of 26 comments. Add a comment

Wonderful news just announced. Judith Curry has vanquished her uncertainty monster. She did it with the help of UK financier (retired), Nic Lewis.

Judith and Nic sat down and puzzled over the challenge for a bit. Then they decided to tackle the monster head on. They've announced their victory in Climate Dynamics.

Not only has Judith killed off her uncertainty monster, she's done an about face on her George C Marshall / op ed of just a couple of days ago. She's announced that the impact of all our waste CO2 can indeed be detected - not just on centennial time scales but on decadal time scales, or at least on multi-decadal time scales.

Here you go. According to Judith and Nic, using an energy balance approach and after much protesting of climate models:
  • Median ECS** is, with very little uncertainty, equal to 1.64K (1.05 to 4.05K at 5-95%)
  • Median TCR is, with almost no uncertainty left at all, 1.33K (0.9 to 2.5K at 5-95%)
**ECS is defined as "effective climate sensitivity", on a shorter time scale than equilibrium climate sensitivity.

Oh, and if you're a retired financier, it's okay to publish reviewers' comments.

One more thing. The IPCC is now back in Judith's good books. She even says she uses forcings from the IPCC's AR5 WG1 report. (What would they have done if Judith had succeeded in disbanding the IPCC. Horror of horrors. That uncertainty monster would still be roaming snatching unwary climate scientists.)

Wonders will never cease!

Here's the archive of the WUWT article, which was personally sent to Anthony Watts by the host of his extraordinary dinner, Nic Lewis. Here's the link that Nic provided to his and Judith's brilliant new paper, which has in one fell swoop solved all the world's ills.

PS If I come across as a mite sarcastic, put it down to my being quite underwhelmed by the swings and roundabouts of the past week at Judith's place.

26 comments:

  1. As I can see, what they've done is redo the Otto et al. (2013) analysis using a newer ocean heat content analysis that produces a slightly lower system heat uptake rate. They've also estimated the system heat uptake rate in the mid 1800s at around 0.15 W/m^2 which reduces the net change in system heat uptake rate over the time interval (I have no idea if the mid-1800s value is reasonable or not). So, these changes reduce the median value for ECS slightly, don't change the TCR, and leave the range broadly unchanged because of the large uncertainties. They don't seem to mention Cowtan & Way though (which would increase both TCR and ECS) and they don't mention, AFACIT, the inhomogeneity issue pointed out by Shindell and Schmidt.

    So, it would seem that the median is most likely an underestimate, but the range is broadly consistent with the IPCC range, so what does it mean? It could be lower than we think but probably/maybe not?

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    1. ATTP, since they published nearly-turnkey code, I'd be interested in whipping together a quick re-analysis using Cowtan and Way to quantify the impact it has on their median result.

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    2. The other thing to understand better is their assumption about system heat uptake rate. It is quite a bit lower than other studies. I've just had a look at Balmaseda et al. (2013) and I calculate a higher system heat uptake rate for 1995-2011 than they use. Also, I think that period is more influenced by ENSO and volcanoes than maybe they acknowledge.

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    3. ATTP

      Also, I think that period [1995 - 2011] is more influenced by ENSO and volcanoes than maybe they acknowledge.

      And you are not alone ;-)

      See Vernier et al. (2011) Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade:

      The variability of stratospheric aerosol loading between 1985 and 2010 is explored with measurements from SAGE II, CALIPSO, GOMOS/ENVISAT, and OSIRIS/Odin space-based instruments. We find that, following the 1991 eruption of Mount Pinatubo, stratospheric aerosol levels increased by as much as two orders of magnitude and only reached “background levels” between 1998 and 2002. From 2002 onwards, a systematic increase has been reported by a number of investigators. Recently, the trend, based on ground-based lidar measurements, has been tentatively attributed to an increase of SO2 entering the stratosphere associated with coal burning in Southeast Asia. However, we demonstrate with these satellite measurements that the observed trend is mainly driven by a series of moderate but increasingly intense volcanic eruptions primarily at tropical latitudes. These events injected sulfur directly to altitudes between 18 and 20 km. The resulting aerosol particles are slowly lofted into the middle stratosphere by the Brewer-Dobson circulation and are eventually transported to higher latitudes.

      Dusty cherries.

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    4. "The estimates using the 1859–1882 base period and 1995–2011 final period combination are preferred because they not only involve the highest ΔT and ΔF, but also have minimal volcanic activity and well matched multidecadal variability." although the answers are relatively insensitive to base and final periods. codes, provided. knock yourself out

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  2. Wow! Just wow! Bingo Halls around the world will now echo the new trend, ditch "Kelly's Eye" and resonate with, "Crankety crank. Number One! I can hear an OAS paper coming on."
    Then again, maybe, maybe not. There's a lot of uncertainty in the future of the Heartland-style Bingo Hall callers, as they've been struggling on a decadal timescale, will continue to do so on a multi-decadal timescale and will fade away on a centennial timescale. On that we can be certain.
    GM

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  3. Look on the bright side.

    This paper getting published will seriously dampen all the plaintive wails about how "pal review" presents anything that doesn't support the "consensus" from getting published.*



    *Yeah. Like that's going to happen.

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    1. First McKitrick, now Lewis and Curry decided not to publish in Anthony's new "journal" :)

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    2. if i were a more cynical person, i might suggest that one (and exactly one) paper will ever be published in the OAS journal.

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    3. I wouldn't be surprised if zero papers got published.

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  4. Thanks for the article Sou. The climate cranks are already posting absurd claims about this paper in the comments at The Conversation. They are like goldfish - they can only remember the last post they read.

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  5. So, how much of this paper is Judy's?

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    1. Who knows? Nic got Judith's name on a paper about energy balance sensitivity estimates and Judith got Nic into Climate Dynamics. It's called teamwork :)

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  6. This is not relevant but it puzzles me that Curry was mere days away from publishing an important paper and yet she risked personal and professional diminution by engaging in intellectual congress with that science denial jerk circle at the George C Marshall Institute.
    She appears to have erratic judgment.

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    1. It is relevant. It illustrates that Judith probably views her science as being in a very separate compartment to her disinformation and advocacy.

      Her blog is mostly the latter, not the former. Sometimes, but not all that often, the same people see both and wonder at the huge inconsistencies.

      She'll need to grind up the spin machine to try to make it look as if this paper is consistent with her propaganda efforts. Or at the least not inconsistent. Most of her target (disinformation) audience wouldn't read science so she should be fairly safe.

      I expect she'll leave science behind altogether at some stage, like Richard Lindzen has, so it'll no longer be a problem for her.

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  7. Here are the ECS and TCR numbers from AR4:
    http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8s8-6-2-3.html
    Approved AR5 graphics were unfindable using Google by me. My apologies for that. I don't think AR4 differs materially from AR5 in respect the ECS and TCR numbers associated with the GCMs used.
    Their paper used the AR5 forcing and heat uptake estimates and uncertainty ranges.
    Strategically this was a good choice I feel. Using their data. As was highlighted, their 1.64 and 1.33 numbers might be compared to the AR4 link above. Greater minds than mine will have to decide if it's a fair comparison.

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  8. I notice they have used the period 1995-2011 vs. some time deep in the past. Interesting ... doesn't Curry think we are in the midst of a "pause" in global warming? If so, surely the ECS and TCR numbers from this analysis would represent the lower bound on possible ECS and TCR? Unless Curry now thinks that the period 1995-2011 is not a pause, and is reflective of the entire post-industrial climate response?

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    1. Nice point. Presumably the result, if robust, would be the same using a different period - say 1982-1998?

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    2. I can't be bothered looking, but I wouldn't be surprised if they have not carefully selected the baseline and comparator to ensure maximum plausible warming at the baseline and minimum plausible warming in the comparator.

      A better approach might be to run calculations over all possible 15-year consecutive periods in the post-industrial (e.g post-1950) era, and all possible 15-year consecutive periods in the pre-industrial (e.g. pre-1920) era; or to boostrap many different combinations of 15 year periods.

      Or, since Nic Lewis seems to be fond of Bayesian analysis, to include a prior for TCS/ECR based on the slope of the entire record ...

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  9. @- Captain Flashheart
    "Unless Curry now thinks that the period 1995-2011 is not a pause, and is reflective of the entire post-industrial climate response?"

    There is an argument that can be made for that.
    The 15year(!) period represents the combination of the CO2 induced rising trend which is added to by natural variation in the first half of the period and subtract/negated in the second half.

    But 15 years is really too short a time to assume that natural variation averages out to neutral so that the trend can be unambiguously defined.

    Dr Curry argues for much longer multi-decade 'cycles' of natural variation which can further obfuscate the derivation of ECS and TCR from recent short historical temperature records.
    Then there is the problem of whether such natural cycles can be separated from a trend which can affect the phasing and magnitude of such hypothetical cycles. Lots of room to flag up the 'uncertainty monster'.

    TCR and ECS are important measures. For frogs in a pot of boiling water (who know what setting the hotplate is on} can discuss the size of the pot, how much water is in it and whether it is stirred or has a lid.
    All will affect how fast the water will warm.
    None will alter the end result.

    izen

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    1. Fiteen years is indeed a bit silly, but if we can take 1995-2011 as straddling the PDO shift (is that what you're suggesting? It seems reasonable) then one could do the same across the last PDO shift. More sensibly we could wait till next year and use 1992-2014 data :)

      I imagine the 1995-2011 version will live for ever unchanged in the happy-land of AGW denial. That period was the golden one for AGW denial; things will never be as good for them again.

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  10. Seems the publication Climate Dynamics and the peer reviewers of the Curry/Lewis study consider it to be legit. Climate Dynamics is supposed to be a legit publication so what gives?

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    1. There is no question about it's legitimacy. There will probably be people looking at how "robust" it is, but this is a tricky area to research. It's one of many such studies, most of which are also legit and many of which have different estimates.

      Their estimated range is also in the same ballpark as other sensitivity studies. Their ECS range on the low end is lower than most, at 1.05 degrees, which on face value appears implausible (esp when looking at current and past climate change). But their high end ECS isn't that different from other studies, at 4.05 degrees.

      They seem to be saying their median is also their best estimate, which means it's a bit on the low side compared to most other estimates, including those based on past climate change (paleo studies) and estimates from climate models.

      Interesting but not earth-shattering. The main reason that deniers like it is because it's got quite a low low-end estimate, and a somewhat lower "best estimate", which allows them to spin the low end of the range as fact or at least claim that this study is "right" and all the others are wrong. Mostly without knowing much about the paper at all. That doesn't make it so.

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  11. This supports my contention of Curry being an opportunist, trying to balance promoting her brand with the denial its by "standing up" to the orthodoxy as the rebel scientist pointing out uncertainty and not correcting the extreme deniers on her site, but then if the surface warming comes back in the next few years, she can claim she was just being on the conservative end, and get back into the "fold"

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  12. My view on these sorts of estimates based on modern observational data is that low ECS is incompatible with the paleo record. In other words, we couldn't have had a globally synchronous LGM if the system was insensitive to changes in the forcings.

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    1. ... and we couldn't have had deglaciation under orbital forcing if the climate system is insensitive to radiative perturbation.

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