Guardian: The aviation industry will tomorrow make a dramatic pledge to slash carbon dioxide emissions in half by 2050 in a move that will force up air fares and spark a green technology race among aircraft manufacturers. The British Airways chief executive, Willie Walsh, will unveil an agreement between airlines, airports and aircraft companies to cut emissions to 50% below 2005 levels by 2050. In a bid to seize the initiative from environmental groups clamouring for higher taxes on the …