According to a World Bank Group report released Monday, climate change could force more than 200 million people to move from their homes by the year 2050.

“They will migrate from areas with lower water availability and crop productivity and from areas affected by sea-level rise and storm surges,” the authors of the report said in the report’s abstract.

According to the report, climate migration “hotspots” could form as soon as 2030. Under the most pessimistic scenario, up to 216 million people could be forced to move within their own country due to climate change.

“This is our humanitarian reality right now and we are concerned this is going to be even worse, where vulnerability is more acute,” International Red Cross Red Crescent Climate Centre Director Prof. Maarten van Aalst said.

Sub-Saharan Africa is the most vulnerable region. It could see up to 86 million people move within national borders due to climate change. North Africa, however, is predicted to have the largest proportion of climate migrants, with roughly 9 percent of its population moving.

“The report also finds that rapid and concerted action to reduce global emissions, and support green, inclusive, and resilient development, could significantly reduce the scale of internal climate migration,” the authors wrote. However, in the most climate-friendly scenario the world could still see 44 million people being forced to move due to climate change.

Among the actions recommended were achieving “net zero emissions by mid-century to have a chance at limiting global warming to 1.5° degrees Celsius” and investing in development that is “in line with the Paris Agreement.”

Many scientists say the world is no longer on track to the worst-case scenario for emissions. However, van Aalst said many impacts are now occurring faster than previously expected, “including the extremes we are already experiencing, as well as potential implications for migration and displacement.”

The report didn’t look at the short-term impacts of climate change outside of people being forced to move. This includes the effects of extreme weather events. It also didn’t look at climate migration across borders.

“Globally we know that three out of four people that move stay within countries,” said Dr. Kanta Kumari Rigaud, a lead environmental specialist at the World Bank and co-author of the report.