EcoWatch: In the wake of the COP 21 UN climate summit in Paris, a number of important questions still remain unanswered. Take for example the commitment reached by the 197 participating nations to limit warming below the dangerous level of 2C relative to pre-industrial time (neglecting for the time being the aspirational goal of a substantially lower 1.5C limit acknowledged in recognition of the danger posed to low-lying island nations). The question immediately arises: How much time do we have until we...