However if «unknown feedbacks» and other forcings can explain an even greater proportion of past temperature changes, then researchers would be forced to suggest climate sensitivity to CO2 is much lower. (landscapesandcycles.net)
It wasn't derived by examining past temperature records, noting a rise, and picking on CO2 as the cause. (realclimate.org)
Because of the divergence, there would be serious doubt about the validity of the proxy data for past temperature reconstruction. (judithcurry.com)