Those who reject the scientific consensus that the world is warming due to human activity often point to what is referred to as the "warming hiatus," a period of years in which global temperatures have remained relatively flat -- high, but flat.

Scientists don't see this as refuting the idea of climate change (and recently offered a possible explanation for it). But there is a hiatus that they should be concerned about. In Gallup polling, the number of people who say they are worried a "great deal" about global warming has been essentially flat since 1989 -- despite the increase in research about the problem.

Gallup released the latest in its annual survey on Wednesday, noting that concern about climate change had dropped slightly. Over time, the trend is clear: flatness. (The dotted line below shows the trend.)

There are peaks and valleys, as you might expect. There was an increase in concern in the late 1990s and again with the release of the Al Gore documentary "An Inconvenient Truth" about a decade ago. As recently as Monday, Sen. Lindsey Graham (R-S.C.) blamed Gore for making the issue more partisan. "The problem is Al Gore has turned this thing into a religion," Graham said to an audience at the Council on Foreign Relations. More accurately, Gore brought the issue to a national audience, galvanizing the political opposition.

You can see the slow turn in opposition to addressing climate change in Gallup's polling. As Gallup notes, that change is heavily partisan. Democrats are slightly more likely to say they're concerned about warming. Republicans are much more likely to say they aren't.

The trend on those saying they worry "not at all" about climate change has risen since 1989. The hiatus in global warming opposition is a myth.