If you compare the rate of fossil fuel use over time, you'll find that that has also been accelerating tremendously. There are other factors involved, including particulate emissions (mostly from coal) which tended to repress warming trends.

From 1945 - 1975, fuel consumption was roughly doubling every decade. The rate of increase moderated slightly during the 1970s oil crises, but picked up afterward, with China's growth since 2000 being particularly troubling.

http://macaulay.cuny.edu/eportfolios/alternativeenergyinnewy...