Media coverage surrounding the release of the IPCC report in September may be the explanation for the shift of more previously uncertain people into disbelieving climate change, Leiserowitz told LiveScience.
While the report made a strong case for human-caused climate change, most media coverage focused on the question of whether there has been a "pause" in global warming.
In fact, some research does show a slowdown in how fast temperatures are rising, if not a pause. Scientists theorize the slowdown could be the result of decades-long climate cycles playing out against a background of long-term warming.
But a study published online in November 2013 in the Quarterly Journal of the Royal Meteorological Society suggests that even that slowdown may be an illusion, caused by gaps in temperature data.
Nevertheless, the media framing of the story may have contributed to more doubt among those who were not firm in their convictions, Leiserowitz said.