An expert saying “I don’t know” on the certainty question is an emphatic disagreement with the IPCC 95% certainty.
The IPCC AR5 Statement: “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.
Skeptical scientists, I daresay, would be much less likely to use the keyword phrase “global warming” in the papers they do publish.
What if everything you’ve been taught about the origins of civilization is wrong?
Kuhn’s work shows that a paradigm cannot be disproved, only replaced (details here).
Unless the skeptics form a theory, they’ll remain minor players in the debates — the climate science debate and the public policy debate about climate change (they’re distinct, although often conflated).
[2^] Bart Verheggen, Bart Strengers, John Cook, Rob van Dorland, Kees Vringer, Jeroen Peters, Hans Visser, and Leo Meyer.
(2014) Scientists’ Views about Attribution of Global Warming.