Esme Stallard and Mark PoyntingBBC News Climate and ScienceJames Wakibia/Getty ImagesGlobal talks to develop a landmark treaty to end plastic pollution have once again failed.The UN negotiations, the sixth round of talks in just under three years, were due to end on Thursday but countries continued to negotiate into the night in the hopes of breaking a deadlock.There remained a split between a group of about 100 nations calling for curbs on production of plastic, and oil states pushing for a focus on recycling.Speaking in the early hours, Cuban...