LONDON, May 14 (Reuters) - Global warming will create at least one billion refugees by 2050 as water shortages and crop failures force people to leave their homes, sparking local wars over access to resources, a leading aid agency said on Monday.
In its report "Human tide: The real migration crisis", Christian Aid said that as the developed world was responsible for most of the climate-changing pollution, it should bear the brunt of the cost of helping those worst hit by it -- the poor.
"We believe that forced migration is now the most urgent threat facing poor people in the developing world," said lead author John Davison.
Scientists predict that average temperatures will rise by between 1.8 and 3.0 degrees Celsius this century because of greenhouse gas emissions, mainly from burning fossil fuels, causing floods and famines and putting million of lives at risk.
The Intergovernmental Panel on Climate Change says that by 2080 up to 3.2 billion people -- one third of the planet's population -- will be short of water, up to 600 million will be short of food and up to 7 million will face coastal flooding.
"We estimate that, unless strong preventative action is taken, between now and 2050 climate change will push the number of displaced people globally to at least one billion," the Christian Aid report said.
Security experts fear that the tidal wave of forced migration will not only fuel existing conflicts but create new ones in some of the poorest and most deprived parts of the world, those least equipped to deal with them, it said.
"A world of many more Darfurs is the increasingly likely nightmare scenario," the report said, citing the conflict in the western Sudan where the United Nations says at least 200,000 people have been killed and 2 million forced out of their homes.
While many climate refugees would cross national borders -- becoming an international problem -- many millions more would be unable to leave their countries and would remain largely invisible to outsiders, it said.
"These internally displaced persons, or IDPs, have no rights under international law and no official voice," the report said. "Their living conditions are likely to be desperate and in many cases their lives will be in danger."
Christian Aid said Colombia was second only to Sudan in the number of IDPs. Many displaced Colombians had been forced to flee by civil war but their number was now being swelled by those evicted from land destined for huge palm oil plantations.
People in Myanmar are also being displaced to make way for palm oil plantations and dams, it said.
Palm oil is in increasing demand to make biofuel as a substitute for petrol in the battle against global warming.
In Mali, Christian Aid said that farmers were already having to leave their land to find work because erratic rains and falling crop yields were making their lives untenable.
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