Reuters: An environmental group on Wednesday asked U.S. Secretary of State Hillary Clinton to deny permits for pipelines that would bring oil from Canada’s oil sands to the United States. ForestEthics said production from Canadian oil sands, also known as tar sands, generates up to five times more greenhouse gas emissions than conventional oil. It said this conflicts with President Obama’s pledge to tackle global warming. “Oil from the tar sands is one of the world’s dirtiest,” the …