Planning for climate-related migration - from training likely migrants in new job skills to policies for integrating them into cities where most head - will help determine whether migration can be an adaptive response to climate change or is an unavoidable consequence of it, experts said on Wednesday.
But even with the best plans, some climate impacts - particularly sea-level rise - will produce a degree of "pure and simple displacement" that should be looked at differently from migration, warned Mohamed Mijarul Quayes, Bangladesh's High Commissioner in Britain.
Bangladesh could see between 16 million and 26 million migrants by 2050 within its own borders due to pressures such as worsening floods, storm surges, riverbank erosion and sea-level rise, a study by the UK's University of Sussex Centre for Migration Research suggests. But predicting numbers of climate-related migrants on an international scale is "at best guesswork" experts said, quoting a 2007 Intergovernmental Panel on Climate Change (IPCC) report.
Today the total number of world migrants annually is around 1 billion, with 250 million of those crossing international borders, said Dominic Kniveton, a climate change and migration specialist at the University of Sussex and lead author of the Bangladesh study. Based on that, predictions of anywhere from 140 million to 1 billion environmental "refugees" by 2050 could be high, he told an event at the London-based Overseas Development Institute.
The decision to migrate is often complex, tied up with political, economic and cultural pressures as well as environmental ones. It also depends on a huge range of personal characteristics, such as the potential migrant's age, sex, education, marital status, wealth, ethnicity, religion, and language skills, experts said.
Women, for instance, may be less likely to migrate for a range of reasons, including limited mobility because they care for children or older family members, or ties to their land, including their role in food production, said Veena Rivachandran, a senior research adviser with the Climate and Development Knowledge Network.
Many women cannot choose to migrate, and for those who do go, there can be "huge costs", she said.
Making migration a successful adaptation to climate change pressures - rather than a symptom of failure to address them - will require policy changes such as encouraging skills training in areas likely to produce migrants and expanding government services to help migrants find jobs in international labour markets, Kniveton said.
Incorporating migration into longer-term planning and enabling people to see migration as a potential solution rather than a threat will also help, he said, as will clarifying the legal status of climate migrants, who cannot now be classified as refugees.
LIMITED RESOURCES TO MOVE
Finding financial resources to prepare for migration and assist migrants will be key too, experts said, as will supporting cities - where many migrants end up in slums - to prepare for them. Otherwise migrants may find themselves more exposed to climate risks than at home, the researchers said.
It is already becoming clear that responses to growing climate pressures - including migration - are harder to predict than anticipated. In Burkina Faso, for instance, the University of Sussex found that worsening drought decreases international migration, apparently in part because people have fewer resources to make the trip.
Climate and migration experts warned that the people most at risk from climate-related threats in many places may not be among those migrating, simply because they lack the money to relocate.
In El Salvador, losses of crops and livestock to extreme weather boosted the chances farmers would migrate to the United States, but earthquake losses led to a drop in migration, the study found.
And in Bangladesh, people who faced losing their homes or assets from riverbank erosion were less likely to migrate than average - unless they had a history of migration, in which case they were more likely to move, the study showed.
Much climate-related migration - except forced displacement from disasters and sea-level rise - follows traditional seasonal migration patterns, and remittances sent home by migrants are now a crucial source of income in many communities, often outstripping foreign aid, Kniveton said.
In considering how to deal with climate-related migration, "we should be asking: 'What are the legal questions? What are the moral questions? What are the policy questions?'" noted Alex Randall, coordinator of the Climate Outreach and Information Network (COIN), a UK-based charity focused on climate change communication.