Why isn't a TCR type of simulation, but instead using
actual history and 200 year projected GHG levels
in the atmosphere, that would produce results similar to a TCR simulation (at least for the AGW temp increase that would occur when the CO2 level is doubled) and would result
in much less
uncertainty than ECS (as assessed by climate model dispersions), a more appropriate metric for a 300 year
forecast, since it takes the climate more than 1000 years to equilibrate to the hypothesized ECS value, and we have only uncertain methods to check the computed ECS value with
actual physical data?
Sampling errors estimated from different reanalyses and from seasonal
forecasts yield qualitatively comparable spatial patterns,
in which the
actual values of
uncertainties are controlled by the magnitudes of synoptic variability.