Climate change soon to cause mass movement, World Bank warns

140m people in three regions expected to migrate before 2050 unless environment is improved

Climate change will result in a massive movement of people inside countries and across borders, creating "hotspots" where tens of millions pour into already crowded slums, according to the World Bank.

More than 140 million people in just three regions of the developing world are likely to migrate within their native countries between now and 2050, the first report on the subject has found.