Gas-CAP uses CO2 only as the basis for emissions and atmospheric concentrations calculations. Other greenhouse pollutants (CH4, O3, BC, N2O, HFCs, PFCs, SF6) are excluded from the calculations.
This CO2-only focus is not because other pollutants are unimportant, but because of data availability and the desire to provide a simple tool in v1:
- Data availability:
- Emissions data for the non-CO2 GHGs is available only through year 2000; CO2 data is available through 2005 for land use (Houghton 2008) and through 2004 for non-land-use (WRI 2008).
- Calculator simplicity:
- In v1, we are testing the usability and usefulness of a user-driven targeting tool. Because the addition of multiple pollutants will complicate the tool, those pollutants have been excluded from v1.
Note, some nations have higher proportions of non-CO2 greenhouse emissions than others. For a country with large non-CO2 emissions, a CO2-only analysis may understate the country's greenhouse impact.
[1] IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.)