Guardian: A Greenpeace ship protesting against deep sea drilling by a British oil firm in the Arctic has been confronted by a Danish warship, and its captain threatened with arrest. The Danish navy has warned Greenpeace that the Esperanza will be boarded by armed personnel if it breaches a 500-metre exclusion zone around two wells drilled off Greenland by the Edinburgh-based oil firm Cairn Energy. The confrontation came as scores of climate protesters targeted Cairn Energy’s headquarters …