Earth, The Blue Marble, courtesy NASA
COP 21 is, perhaps, the most important international effort in history. It concluded with an agreement by 196 nations to limit CO2 emissions to hold global temperature rise to 1.5 degrees Centigrade or 3.3 degrees Fahrenheit (NPR).
The only way to do this is to phase out fossil fuels, quickly, and replace them with efficient use of sustainable energy systems, i.e., solar, wind, geothermal, hydro, and insulation.