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request from IPCC-TAR, CO2 chapter



Dear OCMIP-participants:

For the CO2 chapter of IPCC's Third Assessment Report, we are planning to
include a figure of estimated oceanic and terrestrial uptake of CO2 from
1990 to 2100, including global warming feedback. After weighing the pros
and cons of several scenarios (including S650), we find that the scenario 
which suits best our purpose is IS92a. In this e-mail we ask if you, as
OCMIP-2 participants, would be willing to run this scenario using your
ocean models.

The rationale for the choice of IS92a is threefold. First, atmospheric CO2
associated with this scenario does not level off before 2100. This
continual increase allows us to argue that the eventual reduction in CO2
uptake caused by climate change feedback is not due to the stabilization
of atmospheric CO2, but to warming of the ocean and circulation effects. 
Second, at least three of the published studies on the impact of global
warming on CO2 uptake by the ocean used this scenario. Finally, IS92a is
used by terrestrial models to compute their CO2 uptake, including global
warming feedback. Homogeneity in the scenarios would make the figure more
easily understandable for the reader.

As you may know, IS92a is an emission scenario. To compute the ocean
uptake of CO2, we would provide the atmospheric CO2 concentration 
associated with this scenario. Your results would be needed by the end of
1999, with the possibility of including entries after that only if time
permits. 

The OCMIP modelers will be acknowledged and listed in the IPCC report as
"contibuting authors". We sincerely hope that you will agree to 
participate on this figure, in spite of our late request.

Best Regards,
Corinne Le Quere                                                      
for IPCC TAR, Chapter 3 (The carbon cycle and atmospheric CO2).