date: Thu, 24 Sep 1998 12:01:13 +0200
from: Fortunat Joos <joosatXYZxyzmate.unibe.ch>
subject: fix to co2 emissions and carbon cycle simulations
to: firstname.lastname@example.org, email@example.com, stockeratXYZxyzmate.unibe.ch
Just two quick comments on the recent mails by David and Maria and Michael Prather
>(David and Maria:) our recommendations are the following:
>* Impose a "fix" on the 4 Markers to account for the differences in
>the 1990 values (make them consistent with the observed data). One
>possibility is to use the fix suggested by Wigley (Wigley, Nature 390,
>1997): Use observed emissions to 1996 (as far as data is available),
>linearly extrapolate these to 2000 (under the assumption that this is better
>projection than the corresponding Marker projection) and then use Marker
>changes from 2000.
This fix is not big science and will have a marginal impact on
projected CO2 given the overall scenario uncertainties. E.g. it is not
really relevant whether emissions in 2100 are lets say 13.9 or 13.6
GtC/yr and we should not spend to much time on this issue. However, to
avoid a mess and annoying discussions and recalculations somebody,
e.g. the scenario group, must do this simple fix for all groups.
Presently only the values for the year 1990, 2020, 2050 and 2100 are
on the web site. Values for the other years e.g. similar to the table
provide by Naki for B2, should be made available for all scenarios.
>Finally we think it would be very useful for 1 or 2 GCM modellers, 1 or 2
>atmospheric chemistry experts and 1 or 2 scenario development experts to
>attend the next SRES full author meeting (7-9 October 1998 - Beijing,
>China). In that meeting the provisional scenarios will be discussed hence it
>will be appropriate to present the points raised here and to discuss the
>needs and preferences of the GCM community.
>Our suggestions would be:
>GCM modellers: G Boer, J Mitchell, J Meehl?
>Atmospheric chemistry: F Joos, S Smith?
>Scenarios: M Hulme?
>Are any of you able to attend the SRES meeting at such short notice? We
>realise this may not seem like a high priority but we believe the scenarios
>issue is critical for the TAR and if we can resolve it in this way it will
>be well worth the investment in time.
Sorry, but I do not see how I can make it to Beijing given all the
ongoing obligations here in Bern as well as next weeks Vienna IPCC meeting.
>(Michael:) Step-1: Generate the major forcing from B2 scenario. Limit
>the RF to major gases:
> CO2 - WGI-Ch.3 (Prentice) to map emissions to CO2 (ppm)
We are ready in Bern to project CO2 concentrations for all of the
Marker scenarios using
1) the Bern model as used in SAR
2) the Bern model as updated to include an energy balance model to
project global SST and mean surface air temperature as well as sea
level rise for prescribed climate sensitivities (dT2xCO2). SST is then
used in the calculation of surface water CO2 partial pressure. Also
included is sediment-ocean interaction. The temperature feedback on
sea water carbonate chemistry is important for long term projections.
3) the 2.5-d physical-biogeochemical model of Stocker et al and
Marchal et al. that allows us to study the interaction between the
carbon cycle and changing thermohaline circulation.
With best wishes, Fortunat
Physics Institute, KUP, Sidlerstr. 5, CH-3012 Bern
Phone: ++41(0)31 631 44 61
Fax: ++41(0)31 631 44 05