Story Highlights "Concerned Believers" at 50%, up from 37% in 2015

"Mixed Middle" falls to 31%, well below recent high of 45%

"Cool Skeptics" remains smallest group at 19%, down from 26% in 2015

WASHINGTON, D.C. -- With a record number of Americans sounding the alarm on global warming, the share of the U.S. population that Gallup categorizes as "Concerned Believers" on climate change has consequently reached a new high of 50%. This is up slightly from 47% in 2016 but is well above the 37% recorded only two years ago.

While the half of Americans classified as Concerned Believers take global warming very seriously, the other half are split between what Gallup calls "Cool Skeptics" and the "Mixed Middle." The percentages of Americans falling into these last two groups have declined in recent years as the ranks of Concerned Believers have swelled.

Once the largest category of Americans on global warming, the Mixed Middle has ratcheted down from a recent high of 45% in 2012 and now ranks second, at 31%. Cool Skeptics have always been the smallest global warming segment, but at 19%, their numbers are diminished from 26% in 2015 and the high point of 28% in 2010.

These groupings stem from an update of a statistical cluster analysis of its global warming questions that Gallup first reported in 2014. The analysis is based on four questions that measure Americans' beliefs and concerns about climate change, and that Gallup has now asked together 10 times since 2001. The latest results are from the March 1-5, 2017, Environment poll.

The questions tap the following views on global warming:

Concern: How much Americans worry about global warming or climate change -- a great deal, a fair amount, only a little or not at all.

How much Americans worry about global warming or climate change -- a great deal, a fair amount, only a little or not at all. Seriousness: Whether the seriousness of global warming is generally exaggerated, underestimated or assessed correctly in the news.

Whether the seriousness of global warming is generally exaggerated, underestimated or assessed correctly in the news. Cause: Whether global warming is mainly the result of pollution from human activities or mainly from natural causes.

Whether global warming is mainly the result of pollution from human activities or mainly from natural causes. Threat: Whether Americans believe global warming will pose a serious threat to themselves or their way of life in their own lifetime.

As shown in the accompanying graph, 100% of Concerned Believers worry a great deal about global warming and think human activity causes global warming. Two-thirds in this group also expect global warming to pose a serious threat in their lifetime, while none believe that news reports exaggerate the problem.

On the flip side, Cool Skeptics uniformly believe the news about global warming is exaggerated, while none worry a great deal about climate change. Also, none think the problem will pose a serious threat in their lifetime or blame human activity for the earth's warming.

Those in the Mixed Middle express some combination of views on the four items. Overall, the slight majority blame human activity for the problem, and just above half worry about it a great deal. At the same time, half also think the seriousness of global warming is exaggerated, and only 29% believe global warming will pose a threat in their lifetime.

Concerned Believers Tilt Democratic, Female and Young

In line with the strong partisan differences Gallup finds in Americans' responses to individual questions about global warming, the global warming groups are highly differentiated politically. Nearly half of Concerned Believers, 47%, identify as Democrats, whereas 61% of Cool Skeptics are Republicans and the Mixed Middle is more independent than anything.

Concerned Believers are also weighted a bit more toward women and young adults, while the profile of Cool Skeptics skews decidedly male and older.

As Gallup found in 2014, education is not a strong discriminator between Concerned Believers and Cool Skeptics. Roughly four in 10 people in each group are college graduates. Lack of a college education is, however, strongly associated with being a member of the Mixed Middle. In other words, as Gallup has found previously, being a college graduate is associated with having more hardened positions on global warming.

Political and Demographic Composition of 2017 Global Warming Groups Concerned Believers Mixed Middle Cool Skeptics % % % Republicans 9 32 61 Independents 44 46 36 Democrats 47 22 3 Men 44 48 64 Women 56 52 36 18 to 34 37 25 12 35 to 54 30 34 32 55 and older 33 41 57 College graduate 36 21 41 College nongraduate 64 79 59 Gallup, March 1-5, 2017

Implications

There has long been a disconnect between the high proportions of Americans who believe global warming is real and even ascribe it to human activity, and the low priority Americans give to global warming as a policy issue and a factor in their vote. This is largely explained by the relatively low percentages of Americans who consider global warming a serious threat in their lifetimes or who say they worry a great deal about it. That may be changing, however, as 50% of Americans now take all aspects of global warming seriously -- classifying them as Concerned Believers. That contrasts with most years from 2001 through 2016, when Gallup found the majority qualifying as Mixed Middle or Cool Skeptics on the issue.

A number of factors may influence Americans' attitudes about global warming, including the prominence of various pro- and anti-global-warming arguments, the sitting president's stance on the issue, the perceived reliability of climate science data, the state of the economy and unseasonably high or low temperatures leading up to Gallup's annual Environment poll. Any of these could cause the ranks of Concerned Believers to expand further or shrink in the coming years, but for now, they represent the single largest global warming opinion group.