There's huge uncertainty over the numbers that will migrate to other countries as a result of climate change.Associated Press

Assumptions that up to a billion people will permanently migrate from poor to rich countries to escape the effects of climate change are "alarmist" and false, a meeting of population and climate experts in London heard yesterday.

Cecilia Tacoli, a migration researcher at the Institute for Environment and Development (IIED), a not-for-profit research body based in London, called on policy-makers to change their view of migration. It is not so much a "problematic consequence of climate change" that needs to be prevented, she said, as one of the solutions for adaptation to climate change.

The meeting, which continues today, is organized by the United Nations Population Fund and the IIED. Intergovernmental bodies such as the International Organization for Migration (IOM) and representatives from the UN Framework Convention on Climate Change (UNFCCC) are also attending.

The aim is to agree how to deal with the humanitarian outcomes of climate change, including migration. The meeting also aims to boost discussions of the issue higher up political agendas, in an attempt to get them included in the negotiations on climate change in Copenhagen, Denmark, in December.

Unquestioned orthodoxy?

Tacoli warned the meeting against frequently cited estimates of the number of people who will migrate because of climate change, which range from 200 million to 1 billion people by 2050.

In a paper Tacoli presented to the meeting, to be published later this year in the journal Environment and Urbanization, she says it is "surprising" that these figures have "become an unquestioned orthodoxy, especially amongst natural scientists concerned with climate change". She told Nature News that the figures are "based on assumptions that are simplistic, if not outright dodgy", and add to the alarmist view of migration that is rife among policy-makers.

For example, The Economics of Climate Change, the 2006 review commissioned by the UK government from Nicholas Stern, a former chief economist at the World Bank, quoted the most frequently cited estimate of 200 million environmental refugees by 2050.

Tacoli says this figure is an estimate of the number of people at risk — those living in areas most likely to be affected by climate change — rather than the number of those who will move as a result.

Policy-makers have a "negative perception of migration", Tacoli believes. They see migration as a problem because they think it will be permanent, and that the majority of movement will be from rural areas in poor countries to urban areas in rich ones.

Poor people are unlikely to have the financial resources needed to migrate long-distances to international destinations, the study says.

The evidence also shows that temporary migration is far more common than permanent moves, with people predominantly moving from one rural area to another within national borders, Tacoli says. For example, a 1999 census in Vietnam mentioned in her study found that 37% of migration was between rural areas, compared with 26% between urban centres and 27% in rural-to-urban movement.

There may be large scale migrations, Tacoli says, but just not in the "ways and numbers predicted": a lack of reliable data and the interplay of other factors, such as poverty, currently make it difficult to produce reliable figures.

She says a "radical change in thinking" about migration is needed to view it as part of the solution in adapting to climate change. "Those people who cannot use it as part of the solution will be at a disadvantage," she says.

Unheeded warning

Norman Myers, an expert in the environment and sustainability at the University of Oxford, originally came up with the 200 million estimate. He told Nature News, it is "difficult to demonstrate definitively" that the numbers of people who will migrate will fall in the 200 million to 1 billion range. His estimates were based on anecdotal evidence on migration from all over the world, including Africa, Central America and India.

But he said that climate change presents an "unprecedented challenge" for migration and that the available evidence suggests numbers of people forced to move as a result will fall within the range.

Despite warnings from the Intergovernmental Panel on Climate Change in its first report in 1990 that "the gravest effects of climate change may be those on human migration", the UNFCCC and its Kyoto Protocol are silent on the issue. The issue also received very little attention in the discussions on Kyoto's successor until the Inter-Agency Standing Committee, a forum bringing together UN agencies and other non-governmental organizations working on humanitarian issues, raised it at the climate change summit in Poznań, Poland, in December last year.

On 30 April, in a move unprecedented in its 17-year history, the committee issued a joint statement to Yvo de Boer, the executive secretary of the UNFCCC, calling for the humanitarian implications of climate change, including migration, "to be acknowledged and addressed in the successor agreement to the Kyoto Protocol".

Philippe Boncour, head of the International Dialogue on Migration division at the IOM, says the IOM has made some progress lobbying countries — he would not say which — to encourage them to include a statement on humanitarian issues, including migration, to be included in the text of the climate change deal to be negotiated at Copenhagen.

He told Nature News that here is a "great need" for additional research into environmental migration. "The only thing we have to go on is small-scale case studies," he says. "We need to upgrade this to regional and country level."