From the BBC World Service: The U.N. has warned that it's no longer enough to refer to global warming — we are now in an era of global boiling. The warning comes as Europe and swathes of the U.S. are experiencing prolonged periods of extreme heat. France recently became the first country in the world to ban some short-haul internal flights between cities which take less than two and a half hours to travel between by train. But the jury’s still on how effective the ban is.