Americans are broadly skeptical when it comes to climate change — but apparently not when it comes to the scientists who overwhelmingly say it exists.

About 64 percent of Americans think scientists are neither liberal nor conservative, according to a Pew Research Center survey released Monday. That's roughly the same as when Pew asked the question in 2009.

As with most political issues, perceptions shift along ideological lines — although Americans at both ends of the conservative-liberal spectrum tend to agree that scientists lean somewhat more liberal than conservative.

And there's no escaping the fact that in the United States, climate change is a political issue.

According to a Pew survey in July, one in 10 conservative Republicans say the Earth is warming because of human activity. That's almost the mirror image of liberal Democrats (78 percent) who say the same thing.

When we hear that carbon dioxide levels in the atmosphere have surpassed the ominous threshold of 400 parts per million, people tend to interpret what that means — and by extension, how we should handle it — through their ideological prisms. If you're a conservative, you're more likely to believe humans aren't the main culprit. If you're a liberal, you're more likely to believe they are.

Which makes the findings of this Pew survey even more surprising. There's bipartisan consensus that the scientists aren't injecting politics into the debate. So why the doubt about what scientists say is happening to the Earth?

One explanation: Americans are misinformed about just how much scientists agree on climate change. As Wonkblog and Washington Post polling guru Scott Clement have noted in recent years, Americans seem to underestimate the global scientific community's consensus that climate change is happening because of humans.

[This map of climate change attitudes around the world might surprise you]

Here's what Americans think about that near-consensus:

• 57 percent: The number of Americans who think scientists generally agree on that fact, according to a 2014 Pew Research survey
• 64 percent: Americans' average estimate of how in-agreement scientists are that climate change is caused by humans, according to a 2012 Washington Post-Stanford University survey (which phrased climate change as "global warming.)
• 53 percent: The number of Americans who say scientists who find that humans cause climate change are doing so based on scientific evidence. (About one in three suspect political motivation.)

But here's what scientists actually say: Between 84 to 97 percent of the global scientific community says humans are causing climate change. That's based on a 2009 Pew Research survey of members of the American Association for the Advancement of Science and a 2013 review of nearly 12,000 climate change-related papers.

So there's a big gap in Americans' understanding of the scientific community's consensus and the scientific community's actual consensus on climate change.

Dana Nuccitelli, one of the authors of that 2013 review, thinks that misunderstanding correlates directly with Americans' belief in what causes climate change: If the scientists we trust are apparently unsure of whether climate change is happening, then why should we be?

Of course, that's not the case among the scientific community.

Pew's study of scientists' trustworthiness reveals just how many hurdles climate change activists are facing to get the public on their side: When politics isn't a roadblock to Americans' willingness to act on climate change, misunderstanding is.

Scott Clement contributed tot his article.