"The splice"

An excellent post on some reprehensible shenanigans by the IPCC is here.

Excerpts:

When one gets an inflection point right at the place where two data sources are spliced, as is the case here, one should be suspicious that maybe the inflection is an artifact of mismatches in the data sources, and not representative of a natural phenomenon.
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You can see that almost all of the proxy data we have in the 20th century is actually undershooting gauge temperature measurements. Scientists call this problem divergence, but even this is self-serving. It implies that the proxies have accurately tracked temperatures but are suddenly diverting for some reason this century. What is in fact happening are two effects:

1. Gauge temperature measurements are probably reading a bit high, due to a number of effects including urban biases

2. Temperature proxies, even considering point 1, are very likely under-reporting historic variation. This means that the picture they are painting of past temperature stability is probably a false one.

All of this just confirms that we cannot trust any conclusions we draw from grafting these two data sets together.
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For some reason, the study's author cut the data off around 1950. Is that where his proxy ended? No, in fact he had decades of proxy data left. However, his proxy data turned sharply downwards in 1950. Since this did not tell the story he wanted to tell, he hid the offending data by cutting off the line, choosing to conceal the problem rather than have an open scientific discussion about it.

The study's author? Keith Briffa, who the IPCC named to lead this section of their Fourth Assessment.