CAST your mind back two years and you’ll recall that the government and opposition were in another, albeit very different, debate over carbon policy. Back then, Kevin Rudd was prime minister, Malcolm Turnbull was opposition leader, and the balance of power in the Senate was split across the ideological spectrum. The debate was about what would be “in” and what would be “out” of the Carbon Pollution Reduction Scheme, who would be compensated and by how much, and what the targets and caps would be. There were party-room spats and leadership spills and vitriolic slanging matches in the Senate…