According to this article in Milenio, the IPCC used only mathematics and did not include the Sun in their scenarios.
Auguring brief era of ice in 2010
Researchers from the UNAM considers erroneous reports on global climate change
An expert from the National Autonomous University of Mexico predicted that in about ten years the Earth will enter a "little ice age" which will last from 60 to 80 years and may be caused by the decrease in solar activity.
Victor Manuel Velasco Herrera, a researcher at the Institute of Geophysics of the UNAM, as argued earlier during a conference that teaches at the Centre for Applied Sciences and Technological Development.
Velasco Herrera [Victor Manuel Velasco Herrera, a researcher at the Institute of Geophysics of the UNAM] described as erroneous predictions of the Intergovernmental Panel on Climate Change (IPCC), pursuant to which the planet is experiencing a gradual increase in temperature, the so-called global warming.
The models and forecasts of the IPCC "is incorrect because only are based on mathematical models and presented results at scenarios that do not include, for example, solar activity," said the specialist also in image processing and signs and prevention of natural disasters.
If Herrera is correct, then the IPCC is woefully incompetent to make any sort of predictive claims at all. To ignore the Sun's contribution to the temperature of the Earth is sheer ignorance.
It may be that we need to INCREASE our carbon footprints, rather than reduce them.