hamburg german chancellor angela merkel say saturday please group 20 members besides unite state agree communique paris climate accord irreversible think clear could reach consensus differences paper clearly state merkel tell reporters end two-day meet say share view british prime minister theresa may say friday think washington could decide return climate agreement merkel sharply condemn describe unbridle brutality exhibit protesters northern city hamburg violent clash injure hundreds police officer merkel say g20 communique make differences u.s. climate clear