Contribution to the UNFCCC assessment of the Brazilian Proposal, 
using the “Java Climate Model”
(Preliminary experiment, submitted 31st May 2002)

Dr Ben Matthews,
Klima und Umwelt Physik,
University of Bern, Switzerland
ben@chooseclimate.org

Prof Jean-Pascal vanYpersele
Institut d'Astronomie et de Géophysique, 
Université Catholique de Louvain,  Belgium
vanypersele@astr.ucl.ac.be 

(from July 2002 Ben Matthews will also be working in Louvain)
About the model
The calculations specified for the preliminary experiments were made with Java Climate Model (JCM).

This model is coded in Java and works with an interactive graphical interface in a web browser.
The most recent version, adapted for this experiment, is now online at:
www.climate.unibe.ch/~matthews/jcm/	
Other versions are at: climatechange.unep.net/jcm/ 	and  www.chooseclimate.org/jcm/	

The model is accompanied by extensive web documentation. 
The source code is also linked from the documentation.
A package for use offline may be provided on request.

The carbon cycle and atmospheric chemistry calculations are as Bern-CC model, with the exception that the biosphere sink is still a 4-box model (a reduced form of LPJ-DVM is under development here in Bern).
The climate response is calculated using an UDEB model, with parameters as specified in IPCC-TAR-appx9.1. 
Both SRES and stabilisation scenarios are included, and it is also possible to investigate the distribution of emissions among 12 regions.

You can explore the effect of changing many parameters, both scientific uncertainties and policy options, simply by adjusting graphical controls on the plots. The instant response helps to demonstrate the cause-effect relationships, and the sensitivity to assumptions. Tabulated numerical output is also available (as used for this submission).

Attribution calculations, as proposed by the Brazilian proposal, may be sensitive to many uncertainties, feedback processes and risk/value judgements. It is important that these are not hidden inside a “black box”, but are made transparent and subject to global discussion. It is hoped that the JCM may provide a useful tool to enable more people to explore such questions, complementing this assessment process. 
Specific Experiments
Three experiments were made, all using SRESA2 scenario and climate parameters for HadCM3.
•	Simple experiment: Only CO2, CH4, N2O, specified aerosol, no chemistry feedbacks, high land-use.
•	“Hadley” experiment: All gases (inc F-gases and O3), specified aerosol, feedbacks, historical CO2 fixed.
•	JCM default setup: All gases, SRES aerosols, solar/volcano forcing, feedbacks, lower land-use.

One data file, one gif graphic, and one parameter list is provided for each of the above experiments 
jcm_simpleexp.txt, 	jcm_hadleyexp.txt, 	jcm_default.txt,
jcm_simpleexp.gif, 	jcm_hadleyexp.gif, 	jcm_default.gif, 	jcm _plotlegend.txt 

More details are written at the top of each data file, including the options changed from default JCM setup.
Using the model online
It should be possible to reproduce the same data and graphics submitted here, using the model on the web. 
You can also experiment with many other combinations of options.

First open www.climate.unibe.ch/~matthews/jcm/	
It works in most browsers /systems. However the “java virtual machine” in NS4.x on Unix is very slow. 

Select “SRES no-climate-policy scenarios” from the Mitigation menu (top) and choose A2 from the SRES Menu. HadCM3 should also be selected from the GCM-fit menu on the temperature plot.
The temperature-baseline arrow should be shifted to 1760. 

Other changes are specified in the submitted text files.

For the purposes of this experiment, various extra options were added. In order not confuse other users, these options are only visible at the “experimental” complexity level (menu at top).

Information about the curves, scales, options, controls, pops up as you move your mouse about. Use the plot and layout menus to see other graphs. Note also “view graph data” and “list of parameters” (plot menu).

Documentation page regarding these experiments will be added soon, including a script to automatically set up the model with the options used to generate the data submitted here.

(Note: if the online version changes later, a link will be added to the version used for this experiment).

For further information please contact Ben Matthews as above.