Sometime this century, after 4 billion years, some of Earth's regulatory systems will pass from control through evolution by natural selection, to control by human intelligence. Will humanity rise to the challenge? This landmark essay by Tim Flannery is about sustainability, our search for it in the twenty-first century, and the impact it might have on the environmental threats that confront us today. Flannery discusses in detail three potential solutions to the most pressing of the sustainability challenges: climate change. He argues that Australia has a special responsibility when it comes to climate change, and that our prime minister could be a critical player on the global stage in Copenhagen in December 2009 - but only if we take swift and effective action and make sharp cuts in emissions. Brilliant and terrifying, _Now or Never_ is a call to arms by Australia's leading thinker and writer on the natural world. "Throughout the latter part of 2007 and into 2008, I found it increasingly hard to read the scientific findings on climate change without despairing ... I think that there is now a better than even chance that, despite our best efforts, in the coming two or three decades Earth's climate system will pass the point of no return." —Tim Flannery, _Now Or Never_