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.
8 comments:
I could be wrong but it appears to me that BP's numbers don't include US Carbon Sinks and the other numbers do.
http://epa.gov/climatechange/emissions/downloads10/US-GHG-Inventory-2010_Chapter7-LandUse.pdf
"Land use, land-use change, and forestry activities in 2008 resulted in a net C sequestration of 940.3 Tg CO2 Eq."
The problem here derives from the supposed emissions being calculated based on whatever assumptions one makes in the process. These are quite arbitrary and, clearly, as is attested by the huge discrepancies, questionable. Emissions should be measured, not calculated, and furthermore they should be measured against absorption that occurs naturally within the country. It is, in the end, the net production of CO2 that matters. If a country absorbs naturally all CO2 produced, then where's the problem? Yet, I have never seen any estimates or measurements of CO2 absorbed. So, with half of the equation missing, how can one possibly devise any sensible policy regarding CO2 for starters?
I've said before: The more people use oil and gas the less burden they put on the forests.
The BBC has this interesting comment today:
The UK government's chief environment scientist has called for more openness in admitting Britain's apparent cuts in greenhouse gases are an illusion.
Robert Watson says that if emissions "embedded" in imported goods are counted, UK emissions are up, not down.
He says the same syndrome is true for other rich nations which offshored manufacturing industry.
That means developing countries - particularly China - are blamed for goods they buy for export to the West.
He said: "At face value UK emissions look like they have decreased 15% or 16% since 1990. But if you take in carbon embedded in our imports, our emissions have gone up about 12%. We've got to be more open about this."
See the whole story here
I agree that any policy that relies on great precision has problems.
However, I doubt that a shift to share metrics helps. The aggregate emissions numbers are mostly derived from energy accounts, i.e. energy by source x emissions factors. The uncertainties are more in the energy flows than in the emissions factors, so share measurements are likely to be just as uncertain as aggregate emissions. To aggregate shares across regions or sectors, you end up having to weight by energy anyway, so you're back where you started.
Also, shares are not always a reliable indicator of the emissions trajectory. Shares can easily go up at the same time as aggregate emissions, if energy demand goes up fast and shares are small.
Gustav, there are quite a few accounts of net emissions. Many of the US state GHG inventories include them, for example.
All the more reason to use McKitricks idea to base the carbon tax on temperature rise rather than CO2 level.
Besides your proposed metric of "the proportion of energy generation from carbon free or carbon neutral sources" you'd also need the total amount of energy generated to arrive at a meaningful estimate of the (change in) emissions.
They could be reduced by substituting dirty for clean energy or by using less energy. Both aspects should be taken into account if you don't want to rely on top down emissions estimates.
Bart
-7-Bart
Thanks, I agree ... this is technically correct. However, I find it implausible that the world will consume less energy anytime soon, hence my emphasis on the generation side.
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