(CNN) Tens of millions of people in some of the world's poorest areas could be displaced by climate change in just a few decades, the World Bank has warned in a report.

The report , "Groundswell -- Preparing for Internal Climate Migration," suggests that more than 143 million people across South Asia, Sub-Saharan Africa and Latin America are at risk of the effects of "slow-onset" climate change.

Droughts, crop failure, and rising seas could force millions to move to other places within their countries to areas that are potentially unprepared for an influx of extra people, the report said.

The report suggests that this type of migration will rise until 2050, then "accelerate unless there are significant cuts in greenhouse gas emissions and robust development action."

The numbers include 86 million potential migrants in Sub-Saharan Africa, 40 million in South Asia and a further 17 million in Latin America -- three regions which represent 55% of the developing world's population.

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