Not everyone agrees:
"The salient facts are these. First, the accepted global average temperature statistics used by the Intergovernmental Panel on Climate Change show that no ground-based warming has occurred since 1998. Oddly, this eight-year-long temperature stasis has occurred despite an increase over the same period of 15 parts per million (or 4 per cent) in atmospheric C02.
Second, lower atmosphere satellite-based temperature measurements, if corrected for non-greenhouse influences such as El Nino events and large volcanic eruptions, show little if any global warming since 1979, a period over which atmospheric C02 has increased by 55 ppm (17 per cent)."
http://www.ourcivilisation.com/aginatur/hotair.htm