PRINCETON, NJ -- Americans are less likely than now (50%) they were two years ago (61%) to believe the effects of global warming are already occurring. This shift is most evident among political conservatives, 30% of whom believe the effects are already happening, down from 50% two years ago. There has been essentially no change in liberals' views over this time.

And though wide ideological differences remain, both liberals and conservatives are more likely now than they were in 2008 to believe the seriousness of global warming is exaggerated in the news.

Gallup has documented a sharp drop in concerns about global warming on a variety of measures over the past two years. With only a few exceptions -- most notably ideology and age -- the decline in concern is evident among all key demographic and attitudinal subgroups. The following summarizes changes in views of global warming among key groups.

Political Party

Though ideology and political party are related, ideological and partisan groups do not show the same patterns of change in their views that global warming's effects have begun to happen. Whereas conservatives show a great deal of change in their attitudes and liberals almost none, all three party groups show similar declines over the past two years, between 6 and 10 percentage points.

The net effect is that Democrats (66%) are now twice as likely as Republicans (31%) to believe the effects of global warming are already underway. Independents' views (56%) are closer to Democrats' than to Republicans'.

"In addition to political liberals, young adults are the other major subgroup that shows no decline in the belief that global warming is already affecting the environment."

There are similarly large party differences on whether the seriousness of global warming is exaggerated. Two-thirds of Republicans, compared with 25% of Democrats, hold this view. All three groups are more likely now than they were in 2008 to believe the news media exaggerate the seriousness of the issue, including a sharp 19-point increase among independents. As a result, independents' views on this matter are now closer to Republicans' than to Democrats'.

Age

In addition to political liberals, young adults are the other major subgroup that shows no decline in the belief that global warming is already affecting the environment. Meanwhile, there have been double-digit declines over the past two years among Americans aged 30 and older in the belief that global warming's effects have already begun.

All age groups are more likely now than they were a few years ago to say global warming's seriousness is exaggerated, but the gain is proportionately less among young adults.

Gender

Women have typically expressed greater concern than men about the environment. While both groups express less concern now than they did in 2008, the decline has been somewhat greater among men. Thus, the gender gap on both measures has expanded, from 6 points to 14 points on whether the effects of global warming are occurring, and from 14 points to 17 points on whether the seriousness of global warming is exaggerated.

Orientation to the Environmental Movement

As one would expect, those who describe themselves as "active participants" in the environmental movement (19% of Americans), or who say they are "sympathetic" to it (42% of Americans), generally express greater concern about environmental problems and support for policies designed to remedy them. However, even among these generally pro-environment groups, fewer now believe that the effects of global warming are occurring than did so in 2008.

Those active in or sympathetic to the environmental movement are also more likely now to believe the news media exaggerate the seriousness of global warming, but there has been a greater increase in that belief among those neutral or unsympathetic to the movement.

Knowledge About Global Warming

The 26% of Americans who say they understand the issue of global warming "very well" are significantly less likely now than they were in 2008 to believe the effects of global warming are occurring today. Views among those who say they do not understand the issue well (18% of Americans) are similar now to what they were two years ago.

Since 2008, more conservatives have said they understand the global warming issue very well while the percentage of liberals and moderates who claim a high level of knowledge about it has stayed relatively flat. The greater professed understanding among conservatives may account for the decline in the percentage of the highly knowledgeable who claim the effects of global warming are occurring.

All three knowledge groups show similarly large increases in the belief that global warming's seriousness is exaggerated.

Bottom Line

There has been a significant shift in Americans' views on global warming in the past two years to a position of lessened concern compared with two years ago. Global warming attitudes have become more politically divided over time, and while the shifts toward diminished worry are evident among all party groups, ideological liberals' views have been more stable than conservatives' or moderates' views. Given that conservatives outnumber liberals in the U.S. population by roughly 2 to 1, any significant change in the former group's attitudes toward global warming is enough to move the needle on global warming attitudes among all Americans.

Survey Methods

Results are based on telephone interviews with a random sample of 1,014 national adults, aged 18 and older, conducted March 4-7, 2010. For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is ±4 percentage points.

Interviews are conducted with respondents on land-line telephones (for respondents with a land-line telephone) and cellular phones (for respondents who are cell-phone only).

In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.