Man-made climate change is 'unequivocal(毋庸置疑的)' and demands urgent action. Yesterday's report from the Intergovernmental Panel on Climate Change underlined the former point,【C1】______discussions at the World Economic Forum in Davos last week demonstrated the growing consensus on the【C2】______. The challenge now is action. The IPCC's warning is serious: temperatures are likely to【C3】______by about 3℃ by 2100, with a【C4】______of 2℃ to 4.5℃. The latter would be close to the difference【C5】______the hast ice age and today. Adaptation is going to be part of the response, not least【C6】______a substantial rise in temperatures is already on the way: the stock of greenhouse gases in the【C7】______now is already 50 percent【C8】______pre-industrial levels. But it is also essential to【C9】______growth in the stock, ideally to【C10】______it below 550 parts per million, which would【C11】______be double the pre-industrial levels. On present trends, the atmosphere is【C12】______to reach such a concentration in just three decades. To【C13】______levels rising further, emissions will need to be reduced【C14】______at least 50 per cent below what Sir Nicholas Stern called 'business as usual' --【C15】______is, the continuation of historic trends--by then. The good news,【C16】______the Stern review of climate change, is that the economic【C17】______of achieving these objectives【C18】______be as little a 1 per cent of global gross product. However, the【C19】______news is that big changes to long-lived investment decisions will be required soon,【C20】______in the power sector. 【C1】