SANTA CRUZ – Santa Cruz County waters will likely reach a semiannual high over the weekend, with the arrival of a “King Tide” event.
The National Oceanic and Atmospheric Administration predicts ocean tides will reach a high of about 6.7 feet at Santa Cruz beaches through Sunday.
That peak, however, isn’t much more than a high tide that Santa Cruzans might see on any other given day, said Gary Griggs, who studies sea level rise and coastal erosion. at UC Santa Cruz.
“It looks like an upcoming tsunami, but if you look at the actual magnitude, it’s a few tenths of a foot higher than other tides during the year,” Griggs said.
According to Griggs, viewers could see the difference on gently sloping beaches, such as Main Beach or in the Capitola area. The forces of the royal tide are also pulling these high waters further than usual, revealing otherwise unseen stretches of coastline and rocky nooks.
The royal tide phenomenon, Griggs explained, is largely celestial.
Every day, the world’s ocean waters are influenced by the gravitational pull of the moon and sun as the earth rotates, triggering high and low tides. But when the earth is at its shortest distance from the moon – and these two are at their closest point to the sun – the gravitational waves are amplified.
“When the earth, moon, and sun are all aligned, we get the highest and lowest extremes,” Griggs said.
This alignment only happens a few times a year and triggers King Tide events.
Although wave watchers should exercise caution, the “negative tide” phenomenon associated with the event also means ripe opportunities for tidal pooling.
Try to leave around 4 p.m. Saturday and Sunday, when Santa Cruz waters should be around -1.6 feet. Griggs suggested Natural Bridges as a place to carefully scour the rocks for sea creatures.
The event will be most dramatic in the San Francisco Bay, where the National Weather Service has issued a coastal flood alert. Still, Griggs said onlookers should be cautious, citing several deaths in the Santa Cruz area this year due to people being swept out to sea.
High tides also give scientists a clue about what sea levels might look like more regularly in the face of climate change and rising seas.
“Royal tides give us a glimpse of what higher sea levels would look like in maybe 10 years,” Griggs said, “As scientists, that means we can see this in a day; we don’t have to imagine it.
King Tides will impact the area for the next 3 days and bring some of the highest and lowest tides of the year.
These tides will cause localized flooding in several low-lying areas along SF Bay during high tide mid to late morning each day. https://t.co/TZ4mWUYPEf pic.twitter.com/jC4kQWSZVF
— NWS Bay Area (@NWSBayArea) December 2, 2021
As early as the year 2030, California could see half a foot of sea level rise, according to an August 2020 report by the California Office of the Legislative Analyst. A 2017 report by Griggs and other scientists estimated that if serious mitigation efforts are not undertaken in the San Francisco Bay Area against sea level rise, the region could experience a sea level rise of 1.6 to 3.4 feet by 2100.
Interested residents can also submit photos of what spring tides look like in their neighborhood to an ongoing California Coastal Commission Community Science Project, which aims to visualize future sea level rise. For more information about the project, go to coastal.ca.gov/kingtides.