By Allison Lampert and David Shepardson MONTREAL, WASHINGTON (Reuters) – Changes to a flagship U.N. aviation emissions agreement are closer to being approved after an airline trade group walked back objections on Wednesday, airline and government officials told Reuters. Members of the 193-nation International Civil Aviation Organization (ICAO) are under pressure to reach consensus to curb emissions from global flights at its triennial assembly in Montreal through October 7. Countries plan to change the baseline of the UN aviation agency’s landmark Carbon Offsetting and Reduction Scheme for Int…