Martin Manning and Greg Bodeker

1
New Zealand SCM results for the UNFCCC SBSTA
assessment of contributions to climate change

• 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 CO2 emissions.
• Discrepancies between Stern and Kauffman CH4
  emissions used in Phase 1 and EDGAR.
• Suggests need for re-examining emissions data
  before their use in attribution.

3
Concentrations
Emissions

• For CO2
• 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 CO2
  solubility
• Only parameter adjusted is effective air-sea
  exchange coefficient used 0.07/year rather than
  1.04/year.

4
Concentrations
Emissions
Biosphere
Atmosphere
Fab
Fba
Fao
Ocean
5
Concentrations
Emissions

• Issues for carbon cycle modelling
• Regional attribution of changes in CO2
  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 pCO2
  or NPP according to the attributed change in the
  driving factors.

6
Concentrations
Emissions
For CH4 and N2O Integrated the ODE for time rate
of change of CH4 and N2O using a fixed methane
lifetime of 10 years and a fixed N2O lifetime of
114 years.
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Radiative Forcing
Concentrations
Components for CO2, CH4, N2O and sulfate aerosol
assumed to be additive. RFCO2 5.35 ln pCO2/
pCO2(0) RFCH4 0.036 ? (?CH4 - ?CH4(0) )
CH4 N2O term RFN2O 0.12 ? (?N2O -
?N2O(0) ) CH4 N2O term RFsul f
Esul i.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 ls and ?s from fit to HadCM3
stabilisation experiment as provided on web page
by Jason Lowe (UKMO).
9
Case I Attribution of emissions to regions from
1890 to 2100
Case II Attribution of emissions to regions from
1890 to 2000
Results
10
Outstanding issues

• Treatment of emissions pre-1890.
• Inadequacies caused by constant CH4 lifetime.
• Treatment of bunker fuels.