Discrepancies in CO2 Reporting

CO2scorecard.org has released a report (PDF) showing that different sources arrive at sometimes very different estimates of carbon dioxide emissions for different countries.  The figure above comes from the report and shows various estimates of 2006 US emissions.

The report concludes:

Policy implications are quite serious because the empirical discrepancies in the current annual CO2 emissions estimates far exceed the annual reduction targets generally proposed by policy instruments like the cap‐and‐trade program or national commitments.

I come to a different conclusion -- namely, that the uncertainties in data provide (yet) another reason to disfavor top down programs focused on scheduling annual, national commitments to carbon dioxide reductions.  If you want to measure progress towards stabilization, then a far more meaningful metric will be the proportion of energy generation from carbon free or carbon neutral sources.  Efforts to measure decarbonization of the economy depend on having a consistent set of estimates over time, and so are less impacted by the presence of different estimates and methodologies.

I am all for improved measurement, which in this case would be useful for carbon cycle science.  But to suggest that climate policy is being held up by CO2 measurement uncertainty says more about the shortfall in policy design than anything else.