GOP presidential candidate Jon Huntsman expressed skepticism about the science on climate change, so now all GOP candidates are on the record as doubting either that the planet is clearly warming, or that people are responsible for most of the warming.

Of all the GOP candidates, Huntsman had been the most supportive of action on climate change: in 2007, as governor of Utah, he signed up his state for a cap-and-trade system for greenhouse gas emissions.

There has been an increase in climate skepticism in the past year and a growing reluctance to say anything about climate, especially among Republicans. The turning point—argued the National Journal’s cover story, “Heads in the Sand“—was the