The United Nations headquarters in New York is where the annual gathering of world leaders known as the UN General Assembly will get underway later today.The agenda facing them is long and complex, ranging from nuclear non-proliferation to peacekeeping and development. President Barack Obama makes his debut, giving his first address to the assembly which will set the tone for his diplomacy over the next few years. But how much substance is likely to result? Yesterday’s special UN conference on climate change was full of warnings from UN Secretary General Ban ki-Moon but a consensus to pave the way for a gas-curbing new deal at December’s Copenhagen summit is still missing. China, one of the world’s biggest polluters along with the US, promised to lead from the front and cut its greenhouse gases by a notable margin but no figures or deadlines were attached to the words. As a video illustrating the dangers of global warming was shown to the politicians, the reality remains that CO2 emissions have reduced this year mainly due to a major drop in manufacturing and economic activity. Dealing with the reality of the recession will be a subject brought up by twenty leaders of government later this week at the G20 meeting in Pittsburgh.