SwiftHack / ClimateGate: I'm calling BS on 'expert' McIntyre

I'm calling 'BS' on Steve McIntyre's and the resulting Daily Mail claim that the IPCC is both 'hiding the decline' and hiding the fact that this was done.

For the background science on this issue, see what I wrote yesterday: A ShiftHack Topic: Tree Rings and Climatology

The 'hide the decline' false controversy is nothing more than a widely identifed issue in scientific literature (and elsewhere -- that's for another day) where historicial temperature data derived for analyzing tree rings ceases to be accurate after 1960 in trees looked at in northern areas. We know it's wrong because more accurate instrumental data from things called 'thermometers' say so. So, that data is ignored. Data prior to 1961 widely agrees with instrumental data.

The whole 'hide the decline' issues is officially known as the divergence issue.

The IPCC report clearly discusses the divergence issue on pages 472-473, and explicitly explains that some data is excluded:

...In their large-scale reconstructions based on tree ring density data, Briffa et al. (2001) specifi cally excluded the post-1960 data in their calibration against instrumental records, to avoid biasing the estimation of the earlier reconstructions (hence they are not shown in Figure 6.10), implicitly assuming that the ‘divergence’
was a uniquely recent phenomenon, as has also been argued by Cook et al. (2004a).

This is an ongoing matter and is still undergoing research. This is widely admitted. Thus, it is not some conspiracy. It is explicitly brought up in the IPCC report, and in the papers it cites.

I can perhaps -- barely -- excuse the Daily Mail for messing this up (that article is replete with errors and falsehoods), but not McIntrye. He's supposed to know better. Indeed, all of these papers are relevant to the Mann 'hockey stick' he keeps assailing. Has he not read them?

McIntrye has been on the divergence issue sicne 2005, yet, having survyed his blog posts, he never seems to read the relavant papers, or undertand what they are saying or explain the widely known divergence issue. Or something.

I don't have time to elaborate further today. I will be back.

It is worth mentioning that this is why the CRU scientists dont; want to cooperate with peopel like McIntrye. They aren't so much involved in science as they are misreperesentation and defamation, coupledwith obvious incompetence.

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Update:

The IPCC Third Assessemnt Report (TAR) also mentions the divergence (2.3.2.1 Palaeoclimate proxy indicators), though does not elaborate much:

There is evidence, for example, that high latitude tree-ring density variations have changed in their response to temperature in recent decades, associated with possible non-climatic factors (Briffa et al., 1998a). By contrast, Vaganov et al. (1999) have presented evidence that such changes may actually be climatic and result from the effects of increasing winter precipitation on the starting date of the growing season (see Section 2.7.2.2). Carbon dioxide fertilization may also have an influence, particularly on high-elevation drought-sensitive tree species, although attempts have been made to correct for this effect where appropriate (Mann et al., 1999). Thus climate reconstructions based entirely on tree-ring data are susceptible to several sources of contamination or non-stationarity of response. For these reasons, investigators have increasingly found tree-ring data most useful when supplemented by other types of proxy information in "multi-proxy" estimates of past temperature change (Overpeck et al., 1997; Jones et al., 1998; Mann et al., 1998; 1999; 2000a; 2000b; Crowley and Lowery, 2000).

It does not directly say to truncate the tree ring data as seen on the Hockey Stick, but if you are looking for a reason why the data truncates at 1960, the above is an obvious place to look.

Once I have my hands on all the relevant papers, I will.