In 1990, the Intergovernmental Panel on Climate Change (IPCC) noted that the greatest single impact of climate change could be on human migration—with millions of people displaced by shoreline erosion, coastal flooding and agricultural disruption. Since then various analysts have tried to put numbers on future flows of climate migrants (sometimes called “climate refugees”)—the most widely repeated prediction being 200 million by 2050. But repetition does not make the figure any more accurate. While the scientific argument for climate change is increasingly confident, the consequences of climate change for human population distribution are unclear and unpredictable. With so many other social, economic and environmental factors at work establishing a linear, causative relationship between anthropogenic climate change and migration has, to date, been difficult.
URL : http://www.iom.cz/files/Migration_and_Climate_Change_-_IOM_Migration_Research_Series_No_31.pdf