Accra, Apr 22 Climate change in Africa could leave 250 million more people short of water by 2020, spurring conflicts and threatening stability on the world's poorest continent, the 2007 Nobel Peace Prize winner said on Tuesday. Rajendra K Pachauri, chairman of the United Nations panel of climate experts who shared the prize with former US Vice-President Al Gore last year, said the responsibility lay with wealthy developed nations to curb their carbon emissions.