date: Tue, 12 Oct 2004 18:41:16 -0400
from: David Rind <drind@giss.nasa.gov>
subject: Re: [Wg1-ar4-ch06] IPCC last 2000 years data
to: wg1-ar4-ch06@joss.ucar.edu

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For the last 1000-2000 years, there are several subsections that are involved -

6.3.2.1
which is the data for the "forcing and response". 
Keith and Eyestein have discussed the climate 
response component (including the spaghetti 
diagram). I've talked with Judith Lean about 
producing a figure for the "Forcing" component, 
which will feature an equivalent "spaghetti" 
diagram for solar forcing and, if we can get all 
the data, for volcanic forcing. We could also 
include trace gas figures, which presumably would 
be "angel hair pasta" diagrams considering the 
smaller uncertainties.

The other sections concerned with the last (in this case ) 1000 years are:

6.4.3.2 Model Evaluations of the last 1000 years
This is a tough section to write, because there's 
literally no way to conclude anything of 
substance. If forced with the "best guess" 
forcings, model responses are on the order of -1 
to -1.5C for the Maunder Minimum. This is 
considerably greater than the estimated 
"response", so at face value it would imply the 
model's are way too sensitive. But...the forcings 
(solar, volcano) could easily be overestimated, 
as will be shown in the forcing diagram. Also, 
the response diagram will show it's uncertain as 
well. So what can we conclude about model 
evaluation for this time period except that the 
forcing and response need to be better 
constrained before the models can be tested 
appropriately.

6.5.8 Climate Sensitivity (including the last 1000 years)
There's a great deal of overlap between this 
section and model evaluation; I've put together 
some paragraphs for both, and they basically say 
the same thing at least where the model part is 
concerned. I don't know if we want to go with the 
repetition, or leave the details in only one of 
the two sections.

David


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