Business Green: Australian prime minister Julia Gillard refused today to commit to a tax on carbon despite public pressure from BHP Billiton and AGL Energy — two of the biggest carbon-intensive firms in Australia. The prime minister told reporters that the government would assess the options of a recently established climate change committee, but would not make any promises yet. “Obviously many members of the business community, [Marius] Kloppers included, have made statements and have called …