People affected will include drought-stricken farmers seeking new arable land or different work in urban areas, and others driven out by the need to find clean water, the Bank said in a report issued four days before the United Nations COP26 climate summit begins in Glasgow.

East Africa's five nations – Kenya, Rwanda, Tanzania, Uganda, and Burundi – have increasingly experienced extreme weather events in recent years. Apart from a worsening drought in a region heavily reliant on agriculture, there was extensive flooding in 2020, while a locust infestation of historic proportions that began in 2019 continues to wreak havoc.

"Without broad, urgent action...as many as 38.5 million people could be internally displaced as a consequence of climate change by 2050," said Hafez Ghanem, World Bank vice president for the region.

Concrete steps to reduce greenhouse gas emissions and fund climate change and adaptation schemes could cut the projected number of displacements, but only by 30%, the bank's report said. The bank has committed to ensuring 35% of its financing over the next five years will go to projects that will help address the threat of climate change, Ghanem said.