A detectable pattern of climate response to a
specific forcing, i.e., climate changes that show a pattern that is unique to a specific climate-change driver.
A key skeptic argument derives from the application of the fingerprint method.
How Do We Know? Physics, Forcings, and Fingerprints
Richard Alley talks to leading climate scientists who explain the reasoning that led the IPCC to conclude that humans are "very likely" the cause of most of the current warming. Note that the video doesn't really get going until about 4:25.
1. Click here to read an article about the hunt for the elusive fingerprint.
2. "Many papers indeed have claimed to find a human 'fingerprint', but upon close examination the evidence is simply consistent with human caused warming — while conveniently neglecting to point out that the evidence would also be consistent with naturally caused warming. This disingenuous sleight-of-hand is just one more example of why the public is increasingly distrustful of the climate scientists they support with their tax dollars." ( Roy Spencer in "Ben Santer’s “damage control” on UAH global temperature data")
3. Click here to read Skeptical Sciences detailed arguement for why they believe that the human fingerprint in global warming has been found.