There's a three-pronged answer to this, as I see it.

First: there's a tacit moratorium on partisan-coded issues around here which do not directly concern the science of rationality or (to a lesser extent) AI. Even those on which a broad consensus exists: the reasoning most often given is that a vocally partisan position on such topics would position LW to attract like-minded partisans and thus dilute its rationality focus. The politics of religion is something of an exception; it's essentially treated as a uniquely valuable example of certain biases, though I suspect that status in practice has more to do with the grandfather clause. Anthropogenic global warming is not a uniquely valuable example of any bias I can think of; it's a salient one, but salience often comes with drawbacks.

Second: LW is not a debunking blog, nor a forum dedicated to cheering scientific consensus over folk wisdom, and it should not be except insofar as doing so serves the art and science of rational thinking. There's considerable overlap between LW's natural audience and that of sites which are devoted to those topics, which has on occasion misled (often ideologically opposed) newcomers into thinking it's such a site, but even if a general consensus exists that LW's theory and practice tends to lead to certain positions, it behooves us to guard against adopting those positions as markers of group identity. The easiest way to do that is not to talk about them.

Third, and probably most embarrassingly from the standpoint of healthy group epistemology: by the last census/survey LW is disproportionately politically libertarian, though adherents of that ideology are an absolute minority ([left-]liberalism is slightly more popular, socialism slightly less, other political theories much less). The severity of, proper response to, and to a lesser extent existence of anthropogenic global warming remains an active topic of debate in libertarian circles, though less so in recent years. Higher sensitivity to AGW than to other conservative-coded positions may in part be a response to these demographics.