PARIS — Negotiators at climate change talks here are working to produce a realistic plan to limit global warming to no more than 2 degrees Celsius (3.6 degrees Fahrenheit) from pre-industrial levels, but many scientists say that may still be too warm to avert climate catastrophes.More than 100 mostly developing countries at the Paris conference that runs through Dec. 11 have called for the official goal to be shifted toward a rise of only 1.5 degrees Celsius. (Climate negotiators use Celsius temperatures).
