Reuters: Ministers struggled to break deadlock in global climate talks on Tuesday, three days before world leaders are meant to agree a new U.N. pact aimed at averting dangerous climate change. German Chancellor Angela Merkel told reporters in Berlin that she was “a bit nervous” about the lack of progress at the U.N. Climate Conference in Copenhagen. Organisers of the talks said environment ministers would work deep into night on Tuesday to narrow wide differences, saying the bulk of …