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about Gavin Schmidt

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

The AR4 attribution statement

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Back in 2007, the IPCC AR4 SPM stated that:

“Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”

This is a clear statement that I think is very well supported and correctly reflects the opinion of most climate scientists on the subject (and was re-affirmed in two recent papers (Jones and Stott, 2011;, Huber and Knutti, 2011)). It isn’t an isolated conclusion from a single study, but comes from an assessment of the changing patterns of surface and tropospheric warming, stratospheric cooling, ocean heat content changes, land-ocean contrasts, etc. that collectively demonstrate that there are detectable changes occurring which we can attempt to attribute to one or more physical causes.

Yet, in a paper just out in BAMS (Curry and Webster, 2011) this statement is apparently evidence that IPCC is unable to deal with uncertainty. Furthermore, Judith Curry has reiterated on her blog that the term ‘most’ is imprecise and undefined. For instance:

Apart from the undefined meaning of “most” in AR4 (which was subsequently clarified by the IPCC), the range 50.1-95% is rather imprecise in the context of attribution.

However, Curry’s argument is far from convincing, nor is it well formed (why is there a cap at 95%?). Nor was it convincing when I discussed the issue with her in the comments at Collide-a-Scape last year where she made similar points. Since the C&W paper basically repeats that argument (as has also been noticed by Gabi Hegerl et al who have a comment on the paper (Hegerl et al.)), it is perhaps worth addressing these specific issues again.
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References

  1. G.S. Jones, and P.A. Stott, "Sensitivity of the attribution of near surface temperature warming to the choice of observational dataset", Geophysical Research Letters, vol. 38, pp. n/a-n/a, 2011. http://dx.doi.org/10.1029/2011GL049324
  2. M. Huber, and R. Knutti, "Anthropogenic and natural warming inferred from changes in Earth’s energy balance", Nature Geoscience, vol. 5, pp. 31-36, 2011. http://dx.doi.org/10.1038/ngeo1327
  3. J.A. Curry, and P.J. Webster, "Climate Science and the Uncertainty Monster", Bulletin of the American Meteorological Society, vol. 92, pp. 1667-1682, 2011. http://dx.doi.org/10.1175/2011BAMS3139.1
  4. G. Hegerl, P. Stott, S. Solomon, and F. Zwiers, "Comment on “Climate Science and the Uncertainty Monster” J. A. Curry and P. J. Webster", Bulletin of the American Meteorological Society, vol. 92, pp. 1683-1685, 2011. http://dx.doi.org/10.1175/BAMS-D-11-00191.1

Two-year old turkey

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The blogosphere is abuzz with the appearance of a second tranche of the emails stolen from CRU just before thanksgiving in 2009. Our original commentary is still available of course (CRU Hack, CRU Hack: Context, etc.), and very little appears to be new in this batch. Indeed, even the out-of-context quotes aren’t that exciting, and are even less so in-context.

A couple of differences in this go around are worth noting: the hacker was much more careful to cover their tracks in the zip file they produced – all the file dates are artificially set to Jan 1 2011 for instance, and they didn’t bother to hack into the RealClimate server this time either. Hopefully they have left some trails that the police can trace a little more successfully than they’ve been able to thus far from the previous release.

But the timing of this release is strange. Presumably it is related to the upcoming Durban talks, but it really doesn’t look like there is anything worth derailing there at all. Indeed, this might even increase interest! A second release would have been far more effective a few weeks after the first – before the inquiries and while people still had genuine questions. Now, it just seems a little forced, and perhaps a symptom of the hacker’s frustration that nothing much has come of it all and that the media and conversation has moved on.

If anyone has any questions about anything they see that seems interesting, let us know in the comments and we’ll see if we can provide some context. We anticipate normal service will be resumed shortly.

Scientific confusion

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“We have not succeeded in answering all our problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things.”


I read this quote on a wall on Mark Cane’s office at LDEO (Columbia) many years ago and always wondered where it came from. He found it as an epigram in a book on ‘Stochastic Differential Equations‘ by Bernt Øksendal where it is sourced to a sign outside the mathematics reading room at Tromsø University. The actual source appears to be a 1951 report on an education workshop by Earl C. Kelley, a professor at Wayne University (sleuthing by QI).

MJO Conversations

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There is a (relatively) new blog from scientists involved in a big research program (DYNAMO) looking into the Madden-Julian Oscillation (MJO). Called Madden-Julian Conversations, it is run by Adam Sobel and Daehyun Kim (Columbia), Zhiming Kuang (Harvard) and Eric Maloney (Colorado State).



A schematic of the MJO from cmmap.org

The MJO can be seen in eastward propagating systems of rainfall and deep convection near the equator and influencing the Indian monsoon and El Niño dynamics. Each MJO cycle takes around 30-60 days, so these events can be seen in high frequency diagnostics of cloud cover, LW radiation, rainfall etc. The blog goes into a little more detail of what the MJO is (part i, and parts ii, iii, iv and v), (note that is sometimes referred to as the Intra-seasonal Oscillation or ISO), as well as descriptions of the DYNAMO program and what atmospheric scientists working in the field actually get up to.



(but note that apparently a helmet is not actually required for modelers to launch radiosondes).

This is exactly the kind of thing that should become more common – scientists actually showing the world directly what their research involves and the process that we follow to find stuff out. This will make a great backdrop to the rather dryer contributions to the technical literature that will come from this.

NPP lift off

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The launch of the NASA/NOAA NPP satellite seems to have gone off without a hitch this morning which is great news. This satellite has instruments that are vital to continuing data streams that were pioneered on the aging TERRA (1999), AQUA (2002) and AURA (2004), satellites – including the CERES instrument for monitoring the Earth’s radiation budget, a microwave sounder to continue the AMSU data and a visible/IR camera to complement the work of MODIS.

We really need to apologise for the acronym soup though – it is an endemic disease in satellite discussions. Indeed, NPP is a recursive acronym, standing for NPOESS Preparatory Project, where NPOESS stands for the National Polar-Orbiting Operational Environmental Satellite System.

Another satellite mission we’ve mentioned here, Aquarius (launched in June), has recently released its first results on ocean salinity:




The patterns are not particularly surprising, there is higher salinity in the sub-tropical evaporative regions, lower salinity near the equator (because of the rain!), and particularly low salinity near big river outflows (the Amazon plume stands out clearly). However, as we noted earlier, the main interest is going to be in the variability.

Results from the NPP mission will take a while to come out and be cross-calibrated with the existing records, but given other recent disappointments (GLORY and OCO), this is a huge boost to the effort to monitor the Earth System.

Global warming and ocean heat content

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The connection between global warming and the changes in ocean heat content has long been a subject of discussion in climate science. This was explicitly discussed in Hansen et al, 1997 where they predicted that over the last few decades of the 20th Century, there should have been a significant increase in ocean heat content (OHC). Note that at the time, there had not been any observational estimate of that change (the first was in 2000 (Levitus et al, 2000)), giving yet another example of a successful climate model prediction. At RC, we have tracked the issue multiple times e.g. 2005, 2008 and 2010. Over the last few months, though, there have been a number of new papers on this connection that provide some interesting perspective on the issue which will certainly continue as the CMIP5 models start to get analysed.
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References

  1. S. Levitus, J.I. Antonov, T.P. Boyer, and C. Stephens, "Warming of the World Ocean", Science, vol. 287, pp. 2225-2229, 2000. http://dx.doi.org/10.1126/science.287.5461.2225

Greenland meltdown

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After a record-breaking 2010 in terms of surface melt area in Greenland Tedesco et al, 2011, numbers from 2011 have been eagerly awaited. Marco Tedseco and his group have now just reported their results. This is unrelated to other Greenland meltdown this week that occurred at the launch of the new Times Atlas.
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References

  1. M. Tedesco, X. Fettweis, M.R. van den Broeke, R.S.W. van de Wal, C.J.P.P. Smeets, W.J. van de Berg, M.C. Serreze, and J.E. Box, "The role of albedo and accumulation in the 2010 melting record in Greenland", Environmental Research Letters, vol. 6, pp. 014005, 2011. http://dx.doi.org/10.1088/1748-9326/6/1/014005

Resignations, retractions and the process of science

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Much is being written about the very public resignation of Wolfgang Wagner from the editorship of Remote Sensing over the publication of Spencer and Braswell (2011) – and rightly so. It is a very rare situation that an editor resigns over the failure of peer review, and to my knowledge it has only happened once before in anything related to climate science – the mass resignation of 6 editors at Climate Research in 2003 in the wake of the Soon and Baliunas debacle. Some of the commentary this weekend has been reasonable, but many people are obviously puzzled by this turn of events and unsupported rumours are flying around.

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