Earth Protect Blog

Sea level is rising around the world, but in many places on the U.S. East Coast, it's rising considerably faster than elsewhere. An oceanographer studying this phenomenon explains.

A team of U.S. Geological Survey scientists recently discovered that the sea level along the East Coast of the United States, particularly a 600-mile stretch from Cape Hatteras, N.C., to Boston, has risen at an annual rate three to four times faster than the global average since 1990.

When the global sea level rose by 2 inches, Norfolk, Va., saw a rise of 4.8 inches, Philadelphia answered with 3.7 inches, and New York City 2.8 inches, according to the study, which was published in the journal Nature Climate Change. Peter Howd, an oceanographer and co-author of the study for the U.S. Geological Survey, helped illuminate just why the East Coast is in the wrong place at the wrong time. It's complicated, but the short version is: The Gulf Stream might be slowing down.

Early European explorers didn't cut straight across the Atlantic Ocean in their quest for the New World because it was impossible, for the same reasons that flight paths destined for the United States from Europe are northward and curvilinear. The Earth's spin and temperature gradients cause the winds that travel over the Northern Atlantic Ocean to move in a clockwise pattern, dragging the waters below along a similar pathway.

Because of the Earth's rotation and friction in the water column, Howd says, water on the ocean's surface is transported approximately 90 degrees to the right of the direction the wind is blowing. This rerouting of the water toward the center of the ocean basin is called Ekman transport. If the wind is blowing to the north alongside the East Coast, for example, the water transport will be to the east. For winds blowing westward from North America to Europe, the water will move to the south. For winds blowing south along the European coastline to Africa, the water moves west, and so on.

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