Sea level rise projection raised

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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.

Now, a new paper published in the past week warns that if global warming continues at the current pace — reaching high-end warming projections for 2100 — then sea-level rise will probably surpass those projections. Since the late 1800s, sea level has risen an average of about 10 inches globally, but the amount varies from region to region. Last century the largest contributor to the rise of the oceans was thermal expansion; simply put, warmer water expands. But now the melting of ice sheets, mainly from Greenland and Antarctica, constitutes a greater proportion, and that fraction will only grow.