"Reasons for concern" (about climate change) in the United States

Article 2 of the United Nations Framework Convention on Climate Change commits its parties to stabilizing greenhouse gas concentrations in the atmosphere at a level that "would prevent dangerous anthropogenic interference with the climate system." Authors of the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2001a, b) offered some insight into what negotiators might consider dangerous by highlighting five "reasons for concern" (RFC's) and tracking concern against changes in global mean temperature; they illustrated their assessments in the now iconic "burning embers" diagram. The Fourth Assessment Report reaffirmed the value of plotting RFC's against temperature change (IPCC 2007a, b), and Smith et al. (2009) produced an unpated embers visualization for the globe. This paper applies the same assessment and communication strategies to calibrate the comparable RFC's for the United States. It adds "National Security Concern" as a sixth RFC because many now see changes in the intensity and/or frequency of extreme events around the world as "risk enhancers" that deserve attention at the highest levels of the US policy and research communities. The US embers portrayed here suggest that: (1) US policy-makers will not discover anything really "dangerous" over the near to medium term if they consider only economic impacts that are aggregated across the entire country but that (2) they could easily uncover "dangerous anthropogenic interference with the climate system" by focusing their attention on changes in the intensities, frequencies, and regional distributions of extreme weather events driven by climate change.