The global aviation industry has agreed to cut its net carbon emissions to half 2005 levels by 2050 under a plan to be set out on Tuesday by British Airways chief, Willie Walsh. Mr Walsh, who will outline the initiative at Tuesday’s United Nations forum on climate change in New York, said it was the “best option for the planet” and should be taken up at the December Copenhagen summit, where world leaders are due to come up with a new accord on limiting greenhouse gas emissions to replace the 1997 Kyoto agreement