Steve McIntyre points out some inconvenient data from Law Dome.
Re-reading Climategate and AR4 Review Comments, I noticed an interesting discussion about handling the Law Dome O18 record – a series used in Mann and Jones (2003) and Jones and Mann (2004) with a very elevated MWP.
The Law Dome O18 series was illustrated in Jones and Mann 2004 as follows (although the digital data for most series in this article was commendably archived, the digital version of the Law Dome O18 series wasn’t. After a couple of years of effort, I obtained it from Tas van Ommen.
AR4 Second Draft Figure 6.11 purported to show the “locations of temperature-sensitive proxy records with data back to 1000, 1500 and 1750″, but, for some reason, didn’t include Law Dome, Quelccaya and other sites. The caption was as follows;
Figure 6.11. Locations of temperature-sensitive proxy records with data back to 1000, 1500 and 1750 (instrumental records: red thermometers; tree-ring: brown triangles; boreholes: black circles; ice-core/ice-boreholes: blue stars; other records including low-resolution records: purple squares). All proxies used in reconstructions [R1] to [R11] of Northern Hemisphere temperatures (see Table 6.1 and Figure 6.10) or used to indicate Southern Hemisphere regional temperatures (Figure 6.12) are included.
The IPCC stated of this data:
Taken together, the very sparse evidence for Southern Hemisphere temperatures prior to the period of instrumental records indicates that warming is occurring in some regions. However, more proxy data are required to verify the apparent warm trend.
But of course, that’s not all there is to see.
Note that the inversion of borehole temperatures raises interesting questions equivalent to principal component retention – see prior posts on this. I’ve asked the Danish institution for the pre-inversion borehole measurements.
Read the complete story here at Climate Audit