Fifty million "environmental refugees" will flood into the global north by 2020 - fleeing food shortages sparked by climate change, experts warned at a major science conference that ended here Monday.

"In 2020, the UN has projected that we will have 50 million environmental refugees," University of California, Los Angeles professor Cristina Tirado said at the annual meeting of the American Association for the Advancement of Science (AAAS).

"When people are not living in sustainable conditions, they migrate," she continued, outlining with the other speakers how climate change is impacting both food security and food safety, or the amount of food available and the healthfulness of that food.

Southern Europe is already seeing a sharp increase in what has long been a slow but steady flow of migrants from Africa, many of whom risk their lives to cross the Strait of Gibraltar into Spain from Morocco or sail in makeshift vessels to Italy from Libya and Tunisia. [ YAHOO NEWS ]