Correspondence in Nature

I have a short Correspondence in Nature out today on China's and India's claimed business-as-usual rates of decarbonization. For non-subscribers here is the text:

Decarbonization figures for India and China unconvincing

SIR — In their Opinion articles, Rajendra Pachauri (Nature 461, 1054; 2009) and Jiahua Pan (Nature 461, 1055; 2009) include figures that show business-as-usual perspectives on India’s and China’s emissions growth in coming decades. Both figures indicate that the two countries’economies have already made the transition to high rates of decarbonization. This would put them in a very strong position in international climate negotiations, but I find the figures unconvincing.

India’s five business-as-usual projections include different assumptions of annual rates of decarbonization, from 1.0% up to 3.3%. Four of these greatly exceed the 1987–2006 average of 1.1%. The single business-as-usual projection for China suggests an annual rate of decarbonization of 6.5% per year to 2030, which is almost three times the 1987–2006 average. China’s emissions grew by 12.2% per year from 2000 to 2007, and under business-as-usual are now expected to grow by only 2.5% per year to 2030.

If India and China have indeed already implemented policies that will decarbonize their economies by 3% per year and more, then it would be very good news indeed, as global rates of about 5% (or more) per year would be necessary to achieve an 80% emissions reduction below 1990 levels by 2050, assuming modest economic growth. But if India and China are overoptimistic about future rates of business-as-usual decarbonization, then the challenge of stabilizing concentrations of carbon dioxide will be much greater.

Either way, projections of business-as-usual decarbonization from any country that are at rates three times higher than recent historical averages should be greeted with appropriate scepticism.

Roger A. Pielke Jr.
Center for Science and Technology Policy Research
UCB 488 University of Colorado
Boulder, Colorado 80309-0488, USA
e-mail: pielke@colorado.edu