Thursday, August 15, 2013

Climate change: The ETS vs the Inventory

The EPA has released its annual ETS monitoring report, showing that reported gross emissions had risen to 108.8 million tonnes of CO2-equivalent in 2012. The reporting requirements had changed between 2011 and 2012, so we can't really directly compare it to last year's report. However, we should be able to compare it to the 2011 Inventory Report we provided to the UNFCCC, on the basis that ETS reports should accurately reflect emissions (or someone is cheating). To make the figures comparable, we need to remove the 17.352 million tons of deforestation emissions (which are counted separately in the Inventory Report and not fully accounted for under the ETS anyway), which gives us a gross 2012 figure of 91.456 million tons.

In 2011, we reported our gross emissions, excluding forestry, as 72.8 million tonnes. So emissions apparently rose by 18.656 million tonnes last year, or 25.6%.

Where has the apparent increase come from? Agriculture. The Inventory reported that our total agricultural emissions in 2011 were 34.4 million tonnes. The ETS report gives the total for 2012 as 51.4. At this stage its worth noting that the two reports use different methodologies for agriculture - the ETS report is working off tonnes of milk produced / animals slaughtered, while the Inventory uses (roughly) animal numbers times an emissions factor. But again, if the ETS is any good, we'd expect those different methodologies to produce similar results. They don't. So either there was a massive increase in agricultural emissions between 2011 and 2012, or the ETS methodology significantly overestimates those emissions.

Which is correct? We'll know in April next year, when the 2012 inventory is released. The comparison is going to be fascinating...