AAP: The Greens have warned that Australia must adopt a price on carbon or face greater costs as more countries introduce tariffs linked to pollution and climate change. Greens senator Christine Milne says it is inevitable that countries that do take action on climate change will look to pass on the cost by imposing tariffs on polluting industries. The comments come after Trade Minister Craig Emerson on Sunday said carbon tariffs were simply “old protectionism” and that Australia …