Millions of people will be "trapped" in areas at increasing risk from environmental hazards, such as flooding, around the world, a report into future migration has warned.
And millions will move into places which are more vulnerable to the impacts of environmental changes brought on by global warming and pressure on resources, such as low-lying cities, the study by 300 experts from 30 countries said.
The Foresight report into environmental change and migration over the next 50 years said the focus had previously been on those who would leave areas affected by floods, droughts and extreme weather - often termed 'climate refugees'.
But the experts behind the report said the future would also see people migrating into areas which are more at risk from a range of environmental problems, with 192 million extra people predicted to be living in urban coastal floodplains in Africa and Asia by 2060.
And they warned that millions of people, particularly the poorest, would struggle to move out of areas which were at risk, raising the spectre of humanitarian disasters in the face of severe environmental shocks such as floods.
They also issued a warning against policies which attempted to prevent or constrain migration, which they said could be part of the solution to coping with environmental changes as well as part of the problem.
For example, money sent home from migrants working abroad in 2009 totalled 300 billion US dollars (£190 billion), three times the total overseas development aid provided by governments that year, with cash helping people pay for education, improve their lives and protect themselves against environmental disasters.
Professor Sir John Beddington, the Government's chief scientific adviser, said: "Environmental changes threaten to have a profound impact on communities around the world - particularly in low income countries.
"However, this report finds that the nature of the global challenge goes beyond just focusing on those that might try to move away from areas of risk.
"Millions will migrate into - rather than away from - areas of environmental vulnerability, while an even bigger policy challenge will be the millions who will be 'trapped' in dangerous conditions and unable to move to safety."