The term “king tide” isn't scientific jargon: it's something that's happening this week in San Francisco.
King tides, as they’re colloquially known, are naturally occurring sea-level-rise events that happen twice a year, when the sun and the moon’s gravitational pulls are in alignment—sort of like a lopsided cosmic tug-of-war game, resulting in performance-enhanced tides.
This week, San Francisco is experiencing its very own seasonal king tide event. Water levels will be higher than usual, and there is an increased chance of flooding along the Embarcadero and the city’s shoreline.
As they always do, the city's tides will continue to go up and down, but for the next couple of days, high tide will hover around seven feet. To put that into perspective, summer high tides in San Francisco average about five feet four inches.
While king tides may be standard weather phenomena in the modern era, experts say they can provide a window into what sea levels will soon look like if climate change continues.
She said neighbors shouldn't fear king tides, which “are simply the highest high tides of the year. They're not scary; we know when they're going to happen, and it's not like some kind of Superstorm Sandy situation."
But while they’re not inherently related to climate change, king tides can provide a peek into what a world with higher sea levels may look like.
“What we have today is mild coastal flooding that will become the new normal by as early as mid-century,” said Psaros, noting that king tides—like the ones happening today and tomorrow—can give cities a “great preview” of what sea level rise will look like in the future.
Some scientists predict that between 2060 and 2070, we may experience tides at the same magnitude as king tides on a monthly basis, due to sea-level rise caused by climate change.
Even though scientists and planners are able to forecast and prepare for king tides, the tides’ severity can be exacerbated by other naturally occurring episodes, such as flooding, El Niño, and storms. Dramatic increases in water levels have the potential to cause damage to infrastructure, property, and the coastline.
“King tides like this one aren’t a huge amount over what is normal,” Psaros said, “but when you combine them with storm surges like the one that’s coming in this week, we can see bigger tides.”
The City of San Francisco is hoping to use the king tides to draw locals' attention to the threat of sea level rise.
“Sea level rise demands our action,” said Mayor Lee’s press office, noting that the city has developed a Sea Level Rise Action Plan, and that conversations regarding resiliency against natural and man-made disasters are ongoing.
Future “disasters” aside, Psaros says San Francisco’s current king tide provides a great learning opportunity.
“The good thing about a king tide is that low tide will be about a foot lower than the average," she said, laughing. "Take off work and go tide-pooling or beach-combing."
The next king tide event in San Francisco will be in January. Between now and then, we’ll follow up on how the City of San Francisco is planning to deal with climate change-induced sea level rise, and what it will take to repair the City’s protective seawall.