Australian Broadcasting Corporation: TONY JONES, PRESENTER: On the eve of his Australian tour, the renowned US environmentalist Bill McKibben is urging Australians to do the math. That's the catchphrase of his US roadshow and media campaign highlighting what he describes as the terrifying consequences of CO2 emissions. Mr McKibben puts a figure on how much more CO2 can go into the atmosphere to avoid catastrophic climate change. It's one-fifth of the remaining fossil fuel reserves in the world. But how can Australians do the math when...