The devastating effects of climate change and conflicts fought over ever-scarcer resources such as water could cause a surge in migration that experts fear the world is totally unprepared for.

At least one billion people will be forced from their homes between now and 2050 by such forces, the international charity group Christian Aid predicted in a recent report.

This forecast is backed up by a new report by the British consultancy Maplecroft, that says developing countries in Asia and Africa face the biggest risks from global warming in the next 30 years.

Poverty and large low-lying coastal regions prone to flooding and cyclones make Bangladesh the most exposed country, while India comes in second, and is vulnerable because of pressures from a rising population of 1.1 billion.