Watching Mitt Romney get hammered for daring to suggest that anthropogenic climate change (ACC) is a real problem has, yet again, got me thinking about how to explain to people the generally-held view of the scientific community on this topic.  I think we make something of a mistake when we argue there is a scientific consensus – if we agree with the Miriam Webster definition of consensus, “general agreement: unanimity”, what we have doesn’t quite rise to this standard.  There are a few folks out there that insist that the huge majority of people working on this issue are wrong, and there is really no way to resolve or mitigate the issues of concern that animate many skeptics.  So every time we say consensus, we are opening ourselves up to the criticism that “Person X disagrees,” thus invalidating (for many) the claim of consensus, which then is (illogically) extended to mean that all arguments for anthropogenic climate change are invalid.
However, thanks to Grist, I stumbled across another means of communicating the state of the science of climate change: a very cool visualization of the evolution of the literature on the subject, from 1824 to the present.  The folks at Skeptical Science have divided the climate change literature into three camps: skeptic, neutral and pro-anthropogenic climate change.  They then classified each of the 4811 papers they could find on climate change into one of these three categories.  Now, their classification system is unique and, in my opinion, somewhat problematic in that they have stretched a bit in placing some pieces into the skeptical or pro categories (see their explanation under the animation).  That said, by 2011 their visualization is striking:

Yeah, no matter how you classify things, unless you completely and utterly pervert the literature, this picture is striking.  The vast bulk of the literature either tests a climate change issue without directly addressing the causes of climate change (neutral) or comes down supporting a human cause for (at least some of) observed climate change.  Only 187 papers since 1900 have argued against the idea.  Go to the visualization, and you can drag the slider across the bottom and watch the literature emerge over time.  It has never been a close raise between those who deny the human causes of climate change and those of us who see clear human causes – the pro-anthropogenic climate change crowd wins by a mile.
Is this consensus?  No.  But does it help people see that the dissent in the scientific literature is diminishingly small and always has been?  Less than 4% of all articles published on climate change argued against human causes.  If unanimity is the standard, then we need to start questioning a lot more than climate change . . . like gravity, for example.  We still have a few unresolved issues with that particular force (really), but I don’t see anyone grabbing onto those tiny knowledge gaps to suggest that we shouldn’t pay any attention to it and exiting through a second-floor window is perfectly acceptable.  This slider shows you one representation of the literature, a literature that represents a clear plurality view in favor of ACC (though given many of the “neutral” papers are reporting on work done because the authors accept the fundamental premise of ACC, suggesting a significant majority in this camp).  Enough with the irrational doubt – let’s focus on the real challenges (better understanding the mechanisms of change, the total human contribution to observed change, and the likely resilience of ecology and society in the face of the challenges that now loom . . .