> The MSU record is now fairly consistent with the sfc. At least since 1979, you
> probably can't get away with lowering the trend too much. And there is the
> marine record too.
I've got to think of James Annan's work on climate sensitivity and in
how far we can apply the same logic to temperature increase. If we
have a number of sources of information on temperature trends that are
independent of each other, each with a large uncertainty range, we
should be able to get a much narrower uncertainty range for the
combined total.
I must say that what I've read so far about adjustments applied to
both satellite and surface data (eg the impact of time of day reading
of thermometer shifts in the US introducing an artificial cooling)
makes me quite wary of the large impact hitherto unrealised systematic
biases can have.
I'd agree with William that since 1979 it should be quite unlikely
that the trend is mismeasured too much, for the Arctic we've not got
surface stations, satellite measured temperatures, baloons and sea ice
extent (and good observations to work out how much of the sea ice
extent changes has to do with local temperatures).
Pre 1979, I've got this suspicion that the temperature record is
comparatively very poorly constrained, and could be thrown by as much
as 0.4C by a hitherto undiscovered systematic bias in say Siberian
surface stations in the period 1860 to 1960. Or would there be
sufficient independent information (say on sea ice extent on the North
Siberian coast or glaciers; or from climate models that give good
theoretical grounds why 2C more in Siberia in 1860 than actually
recorded, and 1C less than actually recorded in 1960 just doesn't
work and so forth) to reduce that uncertainty sufficiently to say
1979 was at least 0.2C warmer than 1860?
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