As the United Nations climate change summit in Copenhagen heads into its final week, nearly half of Americans — 49% — say they are only slightly or not at all concerned about climate change, while 35% are somewhat or highly concerned, a new Zogby Interactive survey shows.

Zogby's latest polling shows an increase in those who hold this view compared with 2007, when 39% said they were slightly or not at all concerned about climate change and 48% said they were somewhat or highly concerned.

Intensity of concern about global climate change has shifted over the past three years in favor of those who are not at all concerned — 27% held this view in 2007, compared to 37% who say the same now. Fewer now say they are highly concerned — 20% today compared to 30% in 2007.

This latest survey shows more than two-thirds of Republicans (68%) and 46% of political independents say they are "not at all concerned" about global climate change and global warming, compared to just 7% of Democrats. Thirty-eight percent of Democrats are highly concerned, compared to 4% of Republicans and 14% or independents.