Seventeen years after the first United Nations climate treaty was signed in Rio the world is coming together again in Copenhagen to evolve its international response to a higher and more decisive level. No other gathering of governments on an environmental agreement has attracted more public attention. Billions of people around the globe will be waiting, and watching, to see what heads of state and ministers from over 190 nations finally decide. The UN climate change convention meeting has brought the world together in a way perhaps not witnessed since World War II and it has brought the UN together too. Ban Ki-Moon, the UN Secretary-General has worked tirelessly to make a new, scientifically credible agreement a defining moment in human affairs. He has realized from the start that climate change represents the most extraordinary threat and disruption to security, development and human well-being. But he has also understood that it presents an inordinate opportunity to catalyse a low-carbon, resource-efficient Green Economy, able — if swiftly and comprehensively addressed — to meet the needs and aspirations of 6 billion people, rising to 9 billion by 2050.