"The risks associated with doing business as usual are a much greater concern than the risks associated with engaging in ambitious but measured response efforts. This is because many aspects of an 'overly ambitious' policy response could be reversed or otherwise addressed, if needed, through subsequent policy change, whereas adverse changes in the climate system are much more difficult (indeed, on the time scale of our lifetimes, may be impossible) to 'undo.' "For more: NPR's Top U.S. Scientists To Nation: Global Warming. Really. We Are Not Kidding - or Skeptical Science, National Academy of Sciences on Climate Risk Management - or Climate Progress, National Academy of Sciences slams climate disinformation campaign, flawed media coverage:
...“Many factors complicate and impede public understanding of climate change”:
"Most people rely on secondary sources for information, especially the mass media; and some of these sources are affected by concerted campaigns against policies to limit CO2 emissions, which promote beliefs about climate change that are not well-supported by scientific evidence. U.S. media coverage sometimes presents aspects of climate change that are uncontroversial among the research community as being matters of serious scientific debate. Such factors likely play a role in the increasing polarization of public beliefs about climate change, along lines of political ideology, that has been observed in the United States."
Or see the report itself.