King tides are back and what they’re telling us

King tides return this weekend and with them a reminder of rising sea levels.

“As sea level rises, the king tides will get higher and the potential damage that extreme high tides cause will be greater,” said Annie Kohut Frankel, grants and education manager at the California Coastal Commission. “Soon the places we love so much—the beaches, trails and coastal communities will be underwater or flooded at least twice a year.”

When the earth, the moon and the sun all align in a straight line, there are higher tides due to the combined gravitational pulls of the moon and the sun. The moon orbits the earth in an ellipse, and so does the earth around the sun. Ellipses are not quite round, tending to be more oval-shaped, causing varying distances from the center to the diameter.

Twice a year, when the earth is closest to the sun, while the moon is also closest to the earth, we get the highest high tides and also the lowest low tides. These are called king tides.

King tides are often 1 to 2 feet higher than average tides. But global warming, extreme weather and rising sea levels have recently led to a greater public concern about king tides.

Higher temperatures, extreme weather conditions and ice melting will all contribute to higher and higher tides in the following decades. “The king tides give us a very visceral way to understand what the future may look like,” Frankel said.

She is part of the California King Tides project, an initiative by the California Coastal Commission aimed at raising awareness about king tides and their future implications. Residents of coastal California come together during king tide days to not only experience the magnitude of these tides in real time but to capture these tides on their cameras.

The pictures are collected by the King Tides project, which creates a record of changes to the coast and estuaries through a visual map. “It is an opportunity to encourage people to start thinking about climate change and what we can do to reduce the amount of sea level rise that we see,” said Frankel.

In the past decade, there has been an increased attention to king tides by local communities across California. Field trips, trail walks, beach events and even marsh painting sessions have become popular methods for people to engage, learn and experience the king tides.

Several local organizations have come together under the California King Tides project. One of them is The Exploratorium, a popular San Francisco museum of science, arts and human perception that informs the public about physics, biology and, more recently, climate change and rising sea levels.

People are increasingly becoming aware of climate change and rising sea levels, said Emma Greenbaum, project director for climate and landscapes at the Exploratorium. “There’s a lot of vulnerability to people’s homes and businesses from rising sea levels around the Bay Area,” she said. “This is causing people to get involved and be a part of making decisions that will shape their lives in the coming decades.”

The Exploratorium stands on Piers 15 and 17 on San Francisco’s waterfront, providing a unique location for public engagement and education on rising sea levels. Just last month during the last king tides, 100 students from San Francisco Unified School District came together at the Exploratorium to learn about rising sea levels due to climate change.

“Climate change is causing more storm surges that might coincide with king tides, and the flooding could be much worse, much sooner,” Greenbaum said. Although the drastic effects of sea level rise on king tides is still a distant event, Greenbaum noted the need to plan early: “We cannot put this on the back burner; we need to plan the adaptations now rather than later, when it will be too little, too late.”

There are scientists, however, who believe differently.

“The word ‘king’ designates something really big and powerful, which I think is confusing,” said Gary Griggs, distinguished professor of Earth and Planetary Sciences at UC Santa Cruz. “People expect something like a tsunami, but king tides are just a few inches higher than a normal high tide.”

An expert on coastal erosion and sea-level rise, Griggs spoke about the predicted tide gauge of the Friday-to-Sunday king tides—6.7 feet on Friday, 6.9 feet on Saturday and 6.8 feet on Sunday. “These are as high as they get, except if it’s an El Niño year, but they are not that impressive.”

However, he elaborated on the future of ocean tides, based on two categories of sea level rise: short-term and long-term. Short-term sea level rise is caused by extreme weather events, which, when coinciding with king tides, cause major flooding due to higher tides and larger waves. Griggs mentioned the floods on Westcliff on Jan. 5 that wiped out trails and washed down to Capitola and Del Mar.

“The tides around Monterey on that day were about a foot higher than predicted,” he said.

In case of long-term sea level rise, the effects will not be apparent until 2050, he said. “The sea level may rise by a foot, and then by 2100, things become uncertain because a lot of it will depend on how much the planet has heated by that point due to greenhouse gases.”

In the long run, Griggs firmly believes there is nothing we can do to hold back the ocean. “There isn’t a seawall big enough that can hold back an ocean.”

He offered “managed retreat” as a more realistic solution, to pull back communities near the coast more inland. It is a difficult solution, however, as people rarely want to uproot their homes, work and lives because of a threat that’s roughly 30 years off.

But he emphasized the need to act now rather than later. “King tides are not a real problem, but high tides in the future are going to be a real problem,” he urged, “For each community, we need to figure out how we are going to respond, rather than react at the last minute.”

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