AFP: Australian Prime Minister Julia Gillard Thursday welcomed surprise backing from BHP Billiton, the world’s biggest mining company, for a carbon tax to ease pollution. Gillard, whose fragile coalition includes the environment-focused Greens party, said the comments from BHP chief executive Marius Kloppers chimed with government plans. “I welcome the statements today from Mr Kloppers,” Gillard said. “Obviously many members of the business community, Mr Kloppers included, …