China has committed to cutting its carbon intensity by 40 to 45 percent between 2005 and 2020. So 40% would be enough to keep its commitment. But "intensity" = emissions / GDP, so intensity is reduced by increasing GDP, and China plans to increase that dramatically.
So what was expected before China made its non-binding pledge? The U.S. Dept. of Energy estimated that in May 2009, and predicted that, you guessed it, China would reduce it's emissions intensity by 45 percent. China has pledged to do almost, but not quite, as well as DOE was expecting them to do anyway.
But is DOE's prediction of a 45 percent intensity drop actually something that could happen with no effort? As the numbers below show, during the previous 15 years, when China was making very little effort, it actually did reduce emissions intensity by 44.42 percent.
India, played it a little safer. It pledged to do half as much as it expected to do anyway.
Of course this intensity game is nothing new. Then President Bush used it on Valentines day 2001, when he promised to cut U.S. emissions intensity between 2000 and 2010 by 18 percent. That was two percent more than what we did in the previous 10 years without trying.