In the new report the IEA projects that by 2030 the world will be emitting about 45 Gt (gigatonnes) of carbon dioxide. Yet, in 2008, just 4 years ago the IEA was projecting 40 Gt CO2 for 2030 (see it at p. 11 at this PDF).
Where did the extra projected 5 Gt CO2 for 2030 (just about equal to an extra United States) come from over the past 4 years?
It came from a systemic underestimate for future emissions that is built in to almost all such exercises. The IEA assumed in 2008 that future emissions would grow from 2005 to 2030 at 1.5% per year. Actually, from 2005-2010 emissions increased by 2.4% per year (data from PBL in this PDF). The 1990 to 2010 average was a 1.9% increase per year, and 2009 to 2010 was a whopping 5.8% increase.
Thus, in 2008 the IEA used a low-balled 1.5% annual rate of increase in projected emissions to 2030. In the years since, actual emissions have increased by much higher than this rate, which means that the new 2012 projection for 2030 needs to start at a higher starting point than was projected just several years ago. Hence, in the new 2012 report the IEA has quietly increased the 2030 level of emissions o 45 Gt from 40 Gt. I actually anticipated this revision almost exactly when the 2008 IEA report came out.
So, based on this experience, what rate is the IEA now using to project emissions from 2015 to 2030 under a business as usual scenario?
1.3% (45 Gt CO2 in 2030, 37 in 2015)
So much for learning from experience.
Such estimates matter because all of the estimates of cost of emissions reductions and level of policy effort required that derive from the IEA projections are contingent upon an assumption of a rate of emissions growth that is much lower than observed in recent years and decades.
This repeated failure to accurately describe the actual magnitude of the emissions reduction challenge occurs so widely that it is the systemic failure of policy analysis of CO2 emissions reductions. We repeatedly trick ourselves into thinking that the task is easier than reality shows.
Unless things change in how such analyses are done, we should expect that future IEA projections will be revised upwards and the charade to continue. A more technical explanation of this dynamic can be found here in PDF and an alternative approach to policy analysis of emission reductions can be found in TCF.