As many as one billion people could lose their homes by 2050 because of the devastating impact of global warming, scientists and political leaders will be warned today. They will hear that the steady rise in temperatures across the planet could trigger mass migration on unprecedented levels. Hundreds of millions could be forced to go on the move because of water shortages and crop failures in most of Africa, as well as in central and southern Asia and South America, the conference in London will be told. There could also be an effect on levels of starvation and on food prices as agriculture struggles to cope with growing demand in increasingly arid conditions. Rising sea levels could also cause havoc, with coastal communities in southern Asia, the Far East, the south Pacific islands and the Caribbean seeing their homes submerged. North and west Africans could head towards Europe, while the southern border of the United States could come under renewed pressure from Central America. The conference will hear a warning from the UN High Commissioner for Refugees (UNHCR) that the developed world should start preparing for a huge movement of people caused by climate change. […]