Santer: Climate Models are Exaggerating Warming – We Don’t Know Why

Ben Santer’s latest model/observation comparison paper in PNAS finally admits what climate realists have been been saying for years — climate models are exaggerating warming. From the abstract:

On average, the models analyzed … overestimate the warming of the troposphere. Although the precise causes of such differences are unclear…

Their figure above shows the massive model fail. The blue and magenta lines are trend of the UAH and RSS satelite temperature observations averaged by latitude, with the Arctic at the left and Southern Hemisphere to the right. Except for the Arctic, the observations are well outside all of the model simulations. As they say:

The multimodel average tropospheric temperature trends are outside the 5–95 percentile range of RSS results at most latitudes. The likely causes of these biases include forcing errors in the historical simulations (40–42), model response errors (43), remaining errors in satellite temperature estimates (26, 44), and an unusual manifestation of internal variability in the observations (35, 45). These explanations are not mutually exclusive. Our results suggest that forcing errors are a serious concern.

Anyone who has been following the AGW issue for more than a few years remembers that, Ross McKitrick, Stephen McIntyre and Chad Herman already showed climate models exaggerating warming in the tropical troposphere in their 2010 paper. Before that was Douglass, and in their usual small-minded way, the Santer team do not acknowledge them. Prior to then a few studies had differed on whether models significantly overstate the warming or not. McKitrick found that up to 1999 there was only weak evidence for a difference, but on updated data the models appear to significantly overpredict observed warming.

Santer had a paper where data after 1999 had been deliberately truncated, even though the data was available at the time. As Steve McIntyre wrote in 2009:

Last year, I reported the invalidity using up-to-date data of Santer’s claim that none of the satellite data sets showed a “statistically significant” difference in trend from the model ensemble, after allowing for the effect of AR1 autocorrelation on confidence intervals. Including up-to-date data, the claim was untrue for UAH data sets and was on the verge of being untrue for RSS_T2. Ross and I submitted a comment on this topic to the International Journal of Climatology, which we’ve also posted on arxiv.org. I’m not going to comment right now on the status of this submission.

Santer already had form at truncating inconvenient data, going back to 1995, related by John Daly. It is claimed that he authored the notorious “… a discernible human influence on global climate”, made in Chapter 8 of the 1995 IPCC Report, added without the consent of the drafting scientists in Madrid.

As John Daly says:

When the full available time period of radio sonde data is shown (Nature, vol.384, 12 Dec 96, p522) we see that the warming indicated in Santer’s version is just a product of the dates chosen. The full time period shows little change at all to the data over a longer 38-year time period extending both before Santer et al”s start year, and extending after their end year.

It was 5 months before `Nature’ published two rebuttals from other climate scientists, exposing the faulty science employed by Santer et al. (Vol.384, 12 Dec 1996). The first was from Prof Patrick Michaels and Dr Paul Knappenberger, both of the University of Virginia. Ben Santer is credited in the ClimateGate emails with threatening Pat Michaels with physical violence:

Next time I see Pat Michaels at a scientific meeting, I’ll be tempted to beat the crap out of him. Very tempted.

I suppose that now faced with a disparity between models and observations that can no longer be ignored, he has had to face the inevitable. That’s hardly a classy act. Remember Douglass, McKitrick, McIntyre and other climate realists reported the significant model/observation disparity in the peer-reviewed literature first. You won’t see them in Santer’s list of citations.

Failing to give due credit. Hiding the decline. Truncating the data. Threatening violence to critics. This is the AGW way.