Sea-level rise from climate change could exceed the high-end projections, scientists warn By Jeff Berardelli Sea levels could rise even more rapidly Of the many threats from climate change, sea-level rise will most certainly be among the most impactful, making hundreds of thousands of square miles of coastline uninhabitable and potentially displacing over 100 million people worldwide by the end of the century. This threat is a top concern for national security experts because forced migration poses significant risks to international security and stability. The magnitude of this threat depends heavily on how much the oceans rise in the coming decades. But because of the complex dynamics of massive ice sheets in Greenland and Antarctica, exact estimates remain elusive, ranging from just over a foot to several feet above current levels. That disparity is the difference between tens of millions of people forced from their homes or a much more unmanageable hundreds of millions displaced.