The new average annual temperature number is in, or at least a preview of it, since we poor muddling humans still have to live through the month of December, 2012. The new datum is estimated to be 14.45 degrees Celsius (absolute) or (as published in this article here) about 0.42 degrees Celsius above the 1961-1980 average.
In our Lean and Rind climate modeling exercise, AAT was pegged to the 1951-1980 average, which is a slightly lower baseline number than the 1961-1980 one. Without going back to the data set and recalculating, I might guess that the L & R number for 2012 will end up at about 0.44 or 0.45 degrees Celsius.
In the article they cite both La Niña and anthropogenic sulfate aerosols as reasons for the cooling, both of which are included in the L & R independent variables. If you remember, La Niña is the cool variant of the ENSO cycle, while anthropogenic sulfate, primarily from coal, is one of the eight Hansen et al 2007 variables included in our index of anthropogenic effects.
A hint (A big hint!): This article would make a great final exam question. I might take the article, or a paraphrase thereof, and ask you to interpret the results using the L & R framework for decadal scale change.
Or I might give you the 2012 L & R parameters (ENSO, VOLC, SOLAR, and ANTH) and the L & R 2009 multiple regression equation, ask you to calculate the expected 2012 AAT, compare to the actual, and explain the difference, if any.
Hmmm. Choices, choices.