The added greenhouse gases from human activity clearly have a role in increasing the heat content of the climate system from what it otherwise would be. However, there are other equally or even more important significant human climate forcings, as I summarized in my 2005 post and in the 2009 article
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union.
We now know, however, that the natural variations of atmospheric and ocean circulation features within the climate system produces global average heat changes that are substantially larger than what was known in 2005. The IPCC models have failed to adequately simulate this effect.
END OF STORY.
BTW: "... natural variations of atmospheric and ocean circulation features..." = CLOUD COVER VARIATIONS, OCEAN CURRENT VARIATIONS, AND el NINO EFFECTS ETC.