Global Warming: The Smoking Gun?

Dr. Roy Spencer has a comment on the recent research reported by Dr. James Hansen.

In summary, the recent study by Hansen et al. indeed presents one possible interpretation of the available evidence, but it is a very human-centric one that assumes that natural decadal- to century-scale climate fluctuations are not to blame for at least some part of what has been recently observed. Or, using the 'smoking gun' metaphor, it isn't yet clear whether mankind is the perpetrator, Mother Nature is an accomplice, or vice versa.