Jeff Id has an excellent post on IPCC AR5 use of the highly flawed Steig et al 2009. Despite Steig’s efforts to block the publication of O’Donnell et al 2010, O2010 shows clearly that whatever is new in Steig et al 2009 is not only incorrect, but an artifact of flawed math and whatever is valid was already known.
As Jeff observes, Steig coauthor Josefino Comiso (who was very uncooperative, to say the least, in providing data underpinning Steig et al 2009) is Coordinating Lead Author of AR5 Chapter 4 on the cryosphere, where Steig et al 2009 is cited, but not O’Donnell et al.
AR5 chapter 10 cites Steig et al 2009 four times, without any citation of O’Donnell et al 2010. Jeff quotes the following from AR5:
It was concluded that the pattern of mean surface temperature trends in both West and East Antarctica are positive for 1957–2006, and this warming trend is difficult to explain without the radiative forcing associated with increasing greenhouse-gas concentrations (Steig et al., 2009).
As readers of CA and tAV are aware, Steig’s methodology smeared warming from the Antarctic Peninsula into other parts of Antarctica. Jeff observes of the IPCC draft (with considerable frustration):
That last sentence is too much for me. The positive trends are very easy to explain – bad math!!
In Chapter 5 (Paleoclimate), Steig et al cited as authority for polar amplification. In this case, they have a placeholder noting O’Donnell et al 2010 as follows:
[Reference needed: O’Donnell et al., ?]).
O’Donnell et al 2010 was the only reference among the 1000 or so citations for this chapter where the authors had not bothered locating volume citation information. It was the only reference returning the term “null” as follows:
O’Donnell, R., N. Lewis, S. McIntyre, and J. Condon: Improved methods for PCA-based reconstructions: case study using the Steig et al. 2009 Antarctic temperature reconstruction. Journal of Climate, 0, null.
One doesn’t get the impression that the IPCC authors had read, let alone assimilated, the findings.
Check out Jeff’s post.