evidence: Many climate experts believe that outcome is inevitable. Global temperatures will climb higher than 1.5 degrees compared with 150 years ago, they say, though often only in private. [...] The 1.5 C goal "is on life support, and the machines are rattling," said U.N. Secretary-General António Guterres at the opening ceremony of the conference in Sharm el-Sheikh, Egypt, on Monday. "We are getting dangerously close to the point of no return." Yet many scientists privately believe the world has already hit the point of no return. And some say it’s time to make that message public.