1. Martin Manning and Greg Bodeker National Institute of Water and Atmospheric Research Presented at ‘Expert meeting on assessment of contributions to climate change’, Bracknell, UK, 25 to 27 September 2002

2. Emissions Issues:  Regional mismatches between EDGAR and SRES.  Treatment of bunker fuels.  Discrepancies between EDGAR and Marland et al. fossil fuel CO 2 emissions.  Discrepancies between Stern and Kauffman CH 4 emissions used in Phase 1 and EDGAR.  Suggests need for re-examining emissions data before their use in attribution.

3. Emissions Concentrations For CO 2  Use pulse response model of Joos et al. (1996) with separate response functions for ocean and biosphere uptake processes.  No temperature feedbacks on sea water CO 2 solubility  Only parameter adjusted is effective air-sea exchange coefficient; used 0.07/year rather than 1.04/year.

4. Emissions Concentrations Atmosphere Biosphere Ocean Fab Fba Fao Amount of carbon remaining in surface layer after an input from the atmosphere. Return flux of carbon to the atmosphere after input from the atmosphere.

5. Emissions Concentrations Issues for carbon cycle modelling Regional attribution of changes in CO 2 concentrations to changes in regional emissions in the presence of non-linearities  we use the marginal attribution approach of Enting et al. (1998) and attribute the change each year in pCO 2 or NPP according to the attributed change in the driving factors.

6. Emissions Concentrations For CH 4 and N 2 O Integrated the ODE for time rate of change of CH 4 and N 2 O using a fixed methane lifetime of 10 years and a fixed N 2 O lifetime of 114 years.

7. Concentrations Radiative Forcing Components for CO 2, CH 4, N 2 O and sulfate aerosol assumed to be additive. RF CO2 = 5.35 ln[ pCO 2 / pCO 2 (0) ] RF CH4 = 0.036  (  [CH 4 ] -  [CH 4 (0)] ) + {CH 4 & N 2 O term} RF N2O = 0.12  (  [N 2 O] -  [N 2 O(0)] ) + {CH 4 & N 2 O term} RFsul = f Esuli.e. proportional to emissions Again, non-linear relationships mean that for attribution of forcing to each source region we use the marginal approach  contibution to changes in drivers determines contribution to changes in responses.

8. Temperature Change Radiative Forcing Coefficients for l s and  s from fit to HadCM3 stabilisation experiment as provided on web page by Jason Lowe (UKMO).

9. Results Case I Attribution of emissions to regions from 1890 to 2100 Case II Attribution of emissions to regions from 1890 to 2000

10. Outstanding issues  Treatment of emissions pre-1890.  Inadequacies caused by constant CH 4 lifetime.  Treatment of bunker fuels.