As I argued recently regarding "copyright", language matters. So I was disappointed with the most recent policy study from PERC, entitled Trading Forest Carbon: The Panacea or Pipe Dream to Address Climate Change. The substance of the study isn't necessarily objectionable, but I didn't like the author's use of terms like "greenhouse gases". Calling carbon dioxide (but nothing about methane?) a greenhouse gas concedes the (IMHO unproven) assertion that the current period of climate change is caused by human industrial activity, not by solar activity or other phenomena. As far as I can see, climatology is still a young science and we simply do not yet know the causes for what warming is occurring (and by knowledge I refer to provable statements and falsifiable theories, not pseudo-scientific "models" and political consensus). So why throw around loose terms like "greenhouse gases"? That's just sloppy thinking if you ask me. I expect more from the good folks at PERC.