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

November 14, 2016 | 2:08 pm
Erika Spanger-Siegfried
Director of Strategic Climate Analytics

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.


The nearly-full moon on Sunday, Nov. 13, 2016. Credit: NASA/Bill Ingalls.

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.


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. Credit: Charleston Waterkeeper

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

Evidence of that march continues—it was just announced today that 2016 is expected to be the hottest year on record, topping 2015, which topped 2014, which topped 2010…

Even as fear and deep uncertainty occupy those working for climate solutions, people from around the world are gathered in Marrakech to advance the Paris Climate Agreement—the hard-won plan that is our last best hope for securing a recognizable future climate.

Because time and tide wait for no man—no, not even him—and the clock is winding down.


International negotiations push forward in Marrakech, Morocco. Credit: UNclimatechange.

Both the supermoon and the flooding are worth trying to see. As we often do, my family and I will be watching the moonrise tonight—somehow, always miraculous. And I’ll be touring the Boston waterfront at high tide on Wednesday.

See the moon and tides

  • Check here for moonrise times.
  • Check here for tide times and here for predicted tide heights.
  • Check here for flood warnings.
  • And if you get out there, record and share your flood images here.

You can also learn more about our reaction to the presidential election and take action today to defend climate science and clean energy solutions.


Accelerated erosion along the Gold Coast of Queensland, Australia, courtesy of king tides. Credit: CSIRO.