Climate Central: Say bye, bye, to chemicals that chill your frozen pie. The U.S. is making it clear as ice that it intends to continue moving forward with efforts to clamp down on the use of hydrofluorocarbons, known as HFCs, which are chemicals that helped save the ozone layer but have put the climate in jeopardy. The chemicals were developed for use in fridges, air conditioning systems and other products after ozone-damaging chemicals used for cooling were effectively banned in the 1980s under the Montreal...