What does 1.5C mean in a warming world?
(World News Science)

In a word - politics. The idea of two degrees as the safe threshold for warming evolved over a number of years from the first recorded mention by economist William Nordhaus in 1975. By the mid 1990s, European ministers were signing up to the two-degree limit, and by 2010 it was official UN policy. Governments agreed in Cancun to `hold the increase in global average temperatures below two degrees`. However, small island states and low-lying countries were very unhappy with this perspective, because they believed it meant their territories would be inundated with sea water as higher temperatures caused more ice to melt and the seas to expand. They commissioned research which showed that...