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about Gavin Schmidt

Gavin Schmidt is a climate modeler, working for NASA and with Columbia University.

First published response to Lindzen and Choi

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The first published response to Lindzen and Choi (2009) (LC09) has just appeared “in press” (subscription) at GRL. LC09 purported to determine climate sensitivity by examining the response of radiative fluxes at the Top-of-the-Atmosphere (TOA) to ocean temperature changes in the tropics. Their conclusion was that sensitivity was very small, in obvious contradiction to the models.

In their commentary, Trenberth, Fasullo, O’Dell and Wong examine some of the assumptions that were used in LC09’s analysis. In their guest commentary, they go over some of the technical details, and conclude, somewhat forcefully, that the LC09 results were not robust and do not provide any insight into the magnitudes of climate feedbacks.

Coincidentally, there is a related paper (Chung, Yeomans and Soden) also in press (sub. req.) at GRL which also compares the feedbacks in the models to the satellite radiative flux measurements and also comes to the conclusion that the models aren’t doing that badly. They conclude that

In spite of well-known biases of tropospheric temperature and humidity in climate models, comparisons indicate that the intermodel range in the rate of clear-sky radiative damping are small despite large intermodel variability in the mean clear-sky OLR. Moreover, the model-simulated rates of radiative damping are consistent with those obtained from satellite observations and are indicative of a strong positive correlation between temperature and water vapor variations over a broad range of spatiotemporal scales.

It will take a little time to assess the issues that have been raised (and these papers are unlikely to be the last word), but it is worth making a couple of points about the process. First off, LC09 was not a nonsense paper – that is, it didn’t have completely obvious flaws that should have been caught by peer review (unlike say, McLean et al, 2009 or Douglass et al, 2008). Even if it now turns out that the analysis was not robust, it was not that the analysis was not worth trying, and the work being done to re-examine these questions is a useful contributions to the literature – even if the conclusion is that this approach to the analysis is flawed.

More generally, this episode underlines the danger in reading too much into single papers. For papers that appear to go against the mainstream (in either direction), the likelihood is that the conclusions will not stand up for long, but sometimes it takes a while for this to be clear. Research at the cutting edge – where you are pushing the limits of the data or the theory – is like that. If the answers were obvious, we wouldn’t need to do research.

Update: More commentary at DotEarth including a response from Lindzen.

The carbon dioxide theory of Gilbert Plass

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Gilbert Plass was one of the pioneers of the calculation of how solar and infrared radiation affects climate and climate change. In 1956 he published a series of papers on radiative transfer and the role of CO2, including a relatively ‘pop’ piece in American Scientist. This has just been reprinted (as an abridged version) along with commentaries from James Fleming, a historian of science, and me. Some of the intriguing things about this article are that Plass (writing in 1956 remember) estimates that a doubling of CO2 would cause the planet to warm 3.6ºC, that CO2 levels would rise 30% over the 20th Century and it would warm by about 1ºC over the same period. The relevant numbers from the IPCC AR4 are a climate sensitivity of 2 to 4.5ºC, a CO2 rise of 37% since the pre-industrial and a 1900-2000 trend of around 0.7ºC. He makes a lot of other predictions (about the decrease in CO2 during ice ages, the limits of nuclear power and the like), but it’s worth examining his apparent prescience on these three quantitative issues. Was he prophetic, or lucky, or both?
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Unforced variations 2

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Continuation of the open thread. Please use these threads to bring up things that are creating ‘buzz’ rather than having news items get buried in comment threads on more specific topics. We’ll promote the best responses to the head post.

Knorr (2009): Case in point, Knorr (GRL, 2009) is a study about how much of the human emissions are staying the atmosphere (around 40%) and whether that is detectably changing over time. It does not undermine the fact that CO2 is rising. The confusion in the denialosphere is based on a misunderstanding between ‘airborne fraction of CO2 emissions’ (not changing very much) and ‘CO2 fraction in the air’ (changing very rapidly), led in no small part by a misleading headline (subsequently fixed) on the ScienceDaily news item Update: MT/AH point out the headline came from an AGU press release (Sigh…). SkepticalScience has a good discussion of the details including some other recent work by Le Quéré and colleagues.

Update: Some comments on the John Coleman/KUSI/Joe D’Aleo/E. M. Smith accusations about the temperature records. Their claim is apparently that coastal station absolute temperatures are being used to estimate the current absolute temperatures in mountain regions and that the anomalies there are warm because the coast is warmer than the mountain. This is simply wrong. What is actually done is that temperature anomalies are calculated locally from local baselines, and these anomalies can be interpolated over quite large distances. This is perfectly fine and checkable by looking at the pairwise correlations at the monthly stations between different stations (London-Paris or New York-Cleveland or LA-San Francisco). The second thread in their ‘accusation’ is that the agencies are deleting records, but this just underscores their lack of understanding of where the GHCN data set actually comes from. This is thoroughly discussed in Peterson and Vose (1997) which indicates where the data came from and which data streams give real time updates. The principle one is the CLIMAT updates of monthly mean temperature via the WMO network of reports. These are distributed by the Nat. Met. Services who have decided which stations they choose to produce monthly mean data for (and how it is calculated) and is absolutely nothing to do with NCDC or NASA.

Further Update: NCDC has a good description of their procedures now available, and Zeke Hausfather has a very good explanation of the real issues on the Yale Forum.

Updates to model-data comparisons

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Translations: (Italian)

It’s worth going back every so often to see how projections made back in the day are shaping up. As we get to the end of another year, we can update all of the graphs of annual means with another single datapoint. Statistically this isn’t hugely important, but people seem interested, so why not?

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AGU Fall 2009

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16,000 attendees, thousands of cups of coffee and thousands of interesting conversations (and debates) about science.

That would be San Francisco, not Copenhagen of course.

There are a few of the RC crew there, so hopefully we’ll get some updates, but keep track of some other attending bloggers as well:

and the whole AGU blogroll. There are some live webcasts through the week that might be interesting too.

If there are any other attendees reading, feel free to post about any interesting sessions/talks you see. I’ll update the main post with anything particularly noteworthy.

Unsettled Science

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Unusually, I’m in complete agreement with a recent headline on the Wall Street Journal op-ed page:

“The Climate Science Isn’t Settled”

The article below is the same mix of innuendo and misrepresentation that its author normally writes, but the headline is correct. The WSJ seems to think that the headline is some terribly important pronouncement that in some way undercuts the scientific consensus on climate change but they are simply using an old rhetorical ‘trick’.
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CRU Hack: More context

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Continuation of the older threads. Please scan those (even briefly) to see whether your point has already been dealt with. Let me know if there is something worth pulling from the comments to the main post.

In the meantime, read about why peer-review is a necessary but not sufficient condition for science to be worth looking at. Also, before you conclude that the emails have any impact on the science, read about the six easy steps that mean that CO2 (and the other greenhouse gases) are indeed likely to be a problem, and think specifically how anything in the emails affect them.

Update: The piece by Peter Kelemen at Columbia in Popular Mechanics is quite sensible, even if I don’t agree in all particulars.

Further update: Nature’s editorial.

Further, further update: Ben Santer’s mail (click on quoted text), the Mike Hulme op-ed, and Kevin Trenberth.

The CRU hack: Context

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This is a continuation of the last thread which is getting a little unwieldy. The emails cover a 13 year period in which many things happened, and very few people are up to speed on some of the long-buried issues. So to save some time, I’ve pulled a few bits out of the comment thread that shed some light on some of the context which is missing in some of the discussion of various emails.

  • Trenberth: You need to read his recent paper on quantifying the current changes in the Earth’s energy budget to realise why he is concerned about our inability currently to track small year-to-year variations in the radiative fluxes.
  • Wigley: The concern with sea surface temperatures in the 1940s stems from the paper by Thompson et al (2007) which identified a spurious discontinuity in ocean temperatures. The impact of this has not yet been fully corrected for in the HadSST data set, but people still want to assess what impact it might have on any work that used the original data.
  • Climate Research and peer-review: You should read about the issues from the editors (Claire Goodess, Hans von Storch) who resigned because of a breakdown of the peer review process at that journal, that came to light with the particularly egregious (and well-publicised) paper by Soon and Baliunas (2003). The publisher’s assessment is here.

Update: Pulling out some of the common points being raised in the comments.

  • HARRY_read_me.txt. This is a 4 year-long work log of Ian (Harry) Harris who was working to upgrade the documentation, metadata and databases associated with the legacy CRU TS 2.1 product, which is not the same as the HadCRUT data (see Mitchell and Jones, 2003 for details). The CSU TS 3.0 is available now (via ClimateExplorer for instance), and so presumably the database problems got fixed. Anyone who has ever worked on constructing a database from dozens of individual, sometimes contradictory and inconsistently formatted datasets will share his evident frustration with how tedious that can be.
  • “Redefine the peer-reviewed literature!” . Nobody actually gets to do that, and both papers discussed in that comment – McKitrick and Michaels (2004) and Kalnay and Cai (2003) were both cited and discussed in Chapter 2 of 3 the IPCC AR4 report. As an aside, neither has stood the test of time.
  • “Declines” in the MXD record. This decline was hidden written up in Nature in 1998 where the authors suggested not using the post 1960 data. Their actual programs (in IDL script), unsurprisingly warn against using post 1960 data. Added: Note that the ‘hide the decline’ comment was made in 1999 – 10 years ago, and has no connection whatsoever to more recent instrumental records.
  • CRU data accessibility. From the date of the first FOI request to CRU (in 2007), it has been made abundantly clear that the main impediment to releasing the whole CRU archive is the small % of it that was given to CRU on the understanding it wouldn’t be passed on to third parties. Those restrictions are in place because of the originating organisations (the various National Met. Services) around the world and are not CRU’s to break. As of Nov 13, the response to the umpteenth FOI request for the same data met with exactly the same response. This is an unfortunate situation, and pressure should be brought to bear on the National Met Services to release CRU from that obligation. It is not however the fault of CRU. The vast majority of the data in the HadCRU records is publicly available from GHCN (v2.mean.Z).
  • Suggestions that FOI-related material be deleted … are ill-advised even if not carried out. What is and is not responsive and deliverable to an FOI request is however a subject that it is very appropriate to discuss.
  • Fudge factors (update) IDL code in the some of the attached files calculates and applies an artificial ‘fudge factor’ to the MXD proxies to artificially eliminate the ‘divergence pattern’. This was done for a set of experiments reported in this submitted 2004 draft by Osborn and colleagues but which was never published. Section 4.3 explains the rationale very clearly which was to test the sensitivity of the calibration of the MXD proxies should the divergence end up being anthropogenic. It has nothing to do with any temperature record, has not been used in any published reconstruction and is not the source of any hockey stick blade anywhere.

Further update: This comment from Halldór Björnsson of the Icelandic Met. Service goes right to the heart of the accessibility issue:

Re: CRU data accessibility.

National Meteorological Services (NMSs) have different rules on data exchange. The World Meteorological Organization (WMO) organizes the exchange of “basic data”, i.e. data that are needed for weather forecasts. For details on these see WMO resolution number 40 (see http://bit.ly/8jOjX1).

This document acknowledges that WMO member states can place restrictions on the dissemination of data to third parties “for reasons such as national laws or costs of production”. These restrictions are only supposed to apply to commercial use, the research and education community is supposed to have free access to all the data.

Now, for researchers this sounds open and fine. In practice it hasn’t proved to be so.

Most NMSs also can distribute all sorts of data that are classified as “additional data and products”. Restrictions can be placed on these. These special data and products (which can range from regular weather data from a specific station to maps of rain intensity based on satellite and radar data). Many nations do place restrictions on such data (see link for additional data on above WMO-40 webpage for details).

The reasons for restricting access is often commercial, NMSs are often required by law to have substantial income from commercial sources, in other cases it can be for national security reasons, but in many cases (in my experience) the reasons simply seem to be “because we can”.

What has this got to do with CRU? The data that CRU needs for their data base comes from entities that restrict access to much of their data. And even better, since the UK has submitted an exception for additional data, some nations that otherwise would provide data without question will not provide data to the UK. I know this from experience, since my nation (Iceland) did send in such conditions and for years I had problem getting certain data from the US.

The ideal, that all data should be free and open is unfortunately not adhered to by a large portion of the meteorological community. Probably only a small portion of the CRU data is “locked” but the end effect is that all their data becomes closed. It is not their fault, and I am sure that they dislike them as much as any other researcher who has tried to get access to all data from stations in region X in country Y.

These restrictions end up by wasting resources and hurting everyone. The research community (CRU included) and the public are the victims. If you don’t like it, write to you NMSs and urge them to open all their data.

I can update (further) this if there is demand. Please let me know in the comments, which, as always, should be substantive, non-insulting and on topic.

Comments continue here.

It’s all about me (thane)!

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Well, it’s not really all about me. But methane has figured strongly in a couple of stories recently and gets an apparently-larger-than-before shout-out in Al Gore’s new book as well. Since a part of the recent discussion is based on a paper I co-authored in Science, it is probably incumbent on me to provide a little context.

First off, these latest results are being strongly misrepresented in certain quarters. It should be obvious, but still bears emphasizing, that redistributing the historic forcings between various short-lived species and CH4 is mainly an accounting exercise and doesn’t impact the absolute effect attributed to CO2 (except for a tiny impact of fossil-derived CH4 on the fossil-derived CO2). The headlines that stated that our work shows a bigger role for CH4 should have made it clear that this is at the expense of other short-lived species, not CO2. Indeed, the attribution of historical forcings to CO2 that we made back in 2006 is basically the same as it is now.
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Muddying the peer-reviewed literature

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We’ve often discussed the how’s and why’s of correcting incorrect information that is occasionally found in the peer-reviewed literature. There are multiple recent instances of heavily-promoted papers that contained fundamental flaws that were addressed both on blogs and in submitted comments or follow-up papers (e.g. McLean et al, Douglass et al., Schwartz). Each of those wasted a huge amount of everyone’s time, though there is usually some (small) payoff in terms of a clearer statement of the problems and lessons for subsequent work. However, in each of those cases, the papers were already “in press” by the time other people were aware of the problems.

What is the situation though when problems (of whatever seriousness) are pointed out at an earlier stage? For instance, when a paper has been accepted in principle but a final version has not been sent in and well before the proofs have been sent out? At that point it would seem to be incumbent on the authors to ensure that any errors are fixed before they have a chance to confuse or mislead a wider readership. Often in earlier times corrections and adjustments would have been made using the ‘Note added in proof’, but this is less used these days since it is so easy to fix electronic versions.
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