Macro Business: China and the US, the worlds two largest carbon polluters, have both ratified the Paris climate change agreement in a big boost to efforts to bring the UN accord into force. The joint move on Saturday highlighted the determination of both presidents not to let differences over territorial claims in the South China Sea, economic disputes and cyber espionage stand in the way of progress in other areas. It also came just hours before Mr Obama met Mr Xi on the last trip of his presidency to Asia....