German Chancellor Angela Merkel is seeking to build momentum within the European Union (EU) about moving toward adopting a goal for zeroing out greenhouse gas emissions by the middle of the century. Under the Paris climate deal, Germany set itself the goal of reducing carbon dioxide output by 80% by 2050 compared with 1990 levels. Targeting net-zero emissions by the middle of the century would imply tighter limits than already is planning. Photograph: Bloomberg