Nov 14, 2016

King Tides and the “Supermoon”—Time and Tide Wait for No Man

Charleston, SC
USA
by
Erika Spanger-Siegfried
,
Union of Concerned Scientists
In most locations, the highest tides will lag behind the full moon by a day or two. For example, while the supermoon is Monday, November 14, the highest tides in Boston are expected on Wednesday, November 16. Tidal flooding in South Carolina is not expected to peak until Tuesday, though flooding had begun in Charleston, shown here, this past Saturday. Photo: Charleston Waterkeeper
In most locations, the highest tides will lag behind the full moon by a day or two. For example, while the supermoon is Monday, November 14, the highest tides in Boston are expected on Wednesday, November 16. Tidal flooding in South Carolina is not expected to peak until Tuesday, though flooding had begun in Charleston, shown here, this past Saturday. Photo: Charleston Waterkeeper

The laws of physics are unchanged by the US presidential election: the planet is still warming, sea levels are still rising, and the moon is still circling the earth.

Tonight, that lunar orbit offers us a “Supermoon”—a closer and thus apparently larger than usual moon, a spectacle that won’t occur again until late this century.

That close proximity means the moon will exert greater gravitational pull on the oceans and drive “king tides” that reach somewhat higher than normal.

Recent sea level rise ensures that when king tides occur they increasingly cause localized flooding. Indeed, they already are this week, with places like Charleston, SC, recording tidal flooding as early as Saturday.

We can recognize these floods—more frequent, widespread, and extensive with each year—as the now unstoppable march of climate change.