Reuters: The following factbox compares goals for curbs on greenhouse gas emissions by major nations ahead of U.N. climate negotiations in Bonn, Germany, from March 29-April 8. China, the United States, the European Union, Russia and India are top world emitters. Targets they set will go a long way to decide the ambition of a new U.N. deal to fight global warming due to be agreed in Copenhagen in December. Rich nations’ plans cluster around cuts of roughly 15 percent below current …