The impact of global warming could be twice as severe as the worst situation feared 【C1】______ the United Nations' scientists, the world's largest climate-mod- cling experiment has shown. Average temperatures could 【C2】______ by 11℃ to reach highs that would change the 【C3】______ of the globe, researchers who have run 60 000 computer simulations (模拟) of 【C4】______ change said yesterday. The conclusions suggest that 【C5】______ by the UN's Intergovernmental Panel on Climate Change (IPCC) 【C6】______ be much too conservative. In the worst case, the world would 【C7】______ heat up by almost double the 【C8】______ increase imagined by the Panel. The IPCC's latest report predicted that temperatures will rise by 【C9】______ 1.4℃ and 5.8℃ by 2100. A 【C10】______ 11℃ warmer than it is today would be unrecognizable: 【C11】______ records show that the 【C12】______ has been hotter than it is today for about 80 percent of its history, there is no evidence 【C13】______ it has ever been more than about 7℃ warmer. Although it would take hundreds of years for the full 【C14】______ to be felt, the polar ice caps eventually would 【C15】______ completely, causing sea levels to rise by 70 m. to 100 m. Coastal and 【C16】______ cities such as London and New York would be submerged. As the 11℃ 【C17】______ is a global average, temperatures would be expected to climb even 【C18】______ in some regions. David Stain forth, of the University of Oxford, the study's chief scientist said: 'When I start to look at these figures, I get very 【C19】______ about them. An 11- degree warmer world would be a dramatically 【C20】______ world. What shall we do now?' 【C1】