To understand today's coastal flooding, a UAF scientist will study an ancient one

The last time the sea drowned the coast of western Alaska, it swallowed an entire subcontinent — the Bering Land Bridge, the highway that once carried humans, animals and plants between Asia and North America.

A University of Alaska Fairbanks researcher is about to spend two years reading the record that drowning left behind, and the reason is anything but ancient: the same coast is flooding again, and the past is the closest thing to a forecast.

Beginning Aug. 1 under a $462,771 National Science Foundation grant, postdoctoral researcher Jessica DePaolis will reconstruct how and when the land bridge went under — a story that's largely a mystery, because the evidence now sits beneath the Bering Sea. Her tool is the diatom: microscopic algae, preserved by the billions in seafloor sediment, whose species act as fingerprints of the ancient water they lived in. By matching fossil diatoms to modern ones, she can trace the moment freshwater land gave way to advancing ocean.

That transition — from dry ground more than 20,000 years ago, when the sea stood some 120 meters lower, to open water — is the same kind of shift now threatening the region's coastal communities. Understanding the old flood, the project's stated payoff goes, sharpens the picture of the new one.