date: Fri, 24 Jul 1998 17:42:05 +0100
from: Sarah Raper <s.raperatXYZxyz.ac.uk>
subject: naki's emissions data
The emissions data sent out by Naki seem to me to be deficient
for a number of reasons ...
(1) CO2 emissions need to be split into fossil and net
deforestation in order to do carbon cycle modeling.
(2) My crucial point about consistency with 'observed'
emissions has been ignored.
(3) CH4 emissions in 1990 are grossly out of budget balance -
even worse that in the IS92 scenarios.
(4) 1990 SOx emissions are too low compared with Steve Smith's
corrected GEAI data.
(5) Global SOx emissions are useless -- it is essential to
have a global GRIDDED data set. This is what we have done
at NCAR. We are willing to make these data sets available
In addition, there were some scientific flaws in the letter from
Watson et al. For example (read the SAR!) it is not possible (and
not necessary!!) to devise a CO2 emissions scenarios from first
principles that will stabilize CO2 concentrations. The E-C link
depends on the carbon cycle model used -- and I do not believe
that all of the emissions generating groups have the same model
(or that they have the Joos model in particular). What we did in
the SAR is start with the CONCENTRATION profile and derive the
emissions, which requires specifying a particular net deforestation
scenario. It is possible to do a similar inverse calculation to
what was done for the SAR with an energy-economics model -- this
is what Steve Smith has done to derive 'our' stabilization cases.
I doubt that anyone else has done this -- but perhaps I am
Even if I am underestimating people, I can't see how anyone
can have done this properly, since no-one has updated concentration
stabilization profiles (i.e., profiles that are consistent with
observations through the 1990s). Again, I've made the offer to
distribute these already.
As a final painfully obvious point, modelers DO NOT NEED CO2
emissions data for a stabilization case, since we already have
the concentrations! It is the concentrations that go into the
model!! The reason why an energy-economics model is needed in
such a case is in order to get consistent emissions for non-CO2
gases, especially SO2.
You might guess from the above that I was very disappointed by
the material distributed by Naki. Please think about the points
made above and try again. This is really important data and 'we'
can't afford to have it open to the elementary types of criticisms
Constructively (albiet bluntly) yours,
| Dr S. C. B. Raper |
| Climatic Research Unit |
| University of East Anglia |
| Norwich |
| NR4 7TJ |
| Tel. +44 1603 592089 |
| Fax +44 1603 507784 |