German Chancellor Angela Merkel on Thursday urged the world's top industrial countries to agree on fighting global warming at a summit next month _ but conceded that she did not know if they would succeed on finding a way forward. «The leading industrial countries must move ahead on this question, otherwise we will not be able to fight climate change,» Merkel said as she spoke to parliament about plans for the Group of Eight summit in Heiligendamm, on Germany's Baltic Sea coast, June 6-8. With German holding both the G-8 and European Union presidencies, Merkel has made climate change a priority, The Associated Press reported.