Using data from tide gauges, satellites and computer modelling, the authors were able to project sea level rise with greater certainty out to 2050 than they had been able to before, and extended their projections into the future. The two main causes of rising tides are directly related to the continued burning of fossil fuels: seas rise as ice caps and glaciers melt and because ocean water expands as it warms. .

“If we reduce emissions, you start eliminating some of these very rapid, high-impact processes at sea level,” said Ben Hamlington, one of the report’s authors and a scientist at NASA’s Jet Propulsion Laboratory in Southern California. “There are still a lot of uncertainties about the melting of the ice caps. They could really play a big part in those high-end scenarios here in California.

What Hamlington says is important about this update is that the tide gauge observations almost reflect intermediate levels of sea level rise of nearly 10 inches on the west coast by 2050. This suggests that projections of intermediate sea level rise, rather than the highest, might be more accurate for California. But after mid-century, he says, “the range of uncertainty explodes.”

Because real-time tide gauge observations closely track climate patterns, Mark Merrifield, director of the Center for Climate Change Impacts and Adaptation at the Scripps Institution, says it’s critical to act quickly on climate change.

“If we assume the worst-case scenario…we’re going to be facing a sea level rise problem here that will far exceed what we’ve faced in the past,” he said. “There is literally no end in sight if we continue on the same trajectory.”

The predictions for 2050 are slightly lower than those of a few years ago, and that’s because the science has improved. However, the researchers note that it all depends on carbon dioxide emissions and local factors such as subsidence, storm surges, waves and groundwater levels.

“In some cases it will actually flood and flood low areas,” Merrifield said. “Places that have been built on reclaimed land and water tables that rise with sea levels are areas that are going to be particularly vulnerable over time.”

‘Where was God?’

Low-lying communities around the edge of San Francisco Bay, like East Palo Alto on the peninsula, are already vulnerable to damaging flooding from rain, high tides and contaminated groundwater.

East Palo Alto is in a federally designated flood zone. According to projections, in a decade, up to two-thirds of the land within the city limits could be regularly flooded. By mid-century, these areas could be frequently underwater during high tides. Flooding of this magnitude would stress major flex points throughout the Bay Area, such as Highway 101 and the Dumbarton Bridge. This would overwhelm many residents already struggling with inequalities like homelessness, unemployment or poverty.

“If you were to know 100 families in East Palo Alto, maybe 50 out of 100 are already right at this point where the savings are so low that … a flood … could be that tipping point,” said Derek Ouyang, manager. program manager and speaker at the Stanford Future Bay Initiative, which works with community leaders in the city.

For some in East Palo Alto, flooding and climate change threaten their homes for the second time. Climate refugees from the Pacific Islands have already fled rising seas, to face similar threats in a new country several thousand miles away. Appollonia Gray ‘Uhilamoelangi from Samoa, known as Mama Dee in her community of East Palo Alto, founded ‘Anamatangi Polynesian Voices as a bridge between the city and its Polynesian people.

“The last two floods here, the question is, where was God?” she says. “Don’t get me wrong, I believe in prayers. But I’ve been through so many disasters.

East Palo Alto residents — and commuters crossing the Dumbarton Bridge — will be protected, in part, once a new high levee is built, separating part of town from a nearby creek that connects to the bay.

Creating flood protection for existing communities like East Palo Alto is critical as the new federal report found that moderate flooding, which already occurs during high tides or storms, will likely occur 10 times more often. by mid-century than today.

“We are not prepared”

As sea level rise predictions have become more definitive through 2050, Zack Wasserman, chairman of the San Francisco Bay Area Commission for Conservation and Development, or BCDC, says the predictions do not confirm what the agency already knows: a slow catastrophe is brewing.

“The difference in potential damage between 7 feet and 10 feet [past the year 2100] has some significance, but today we are not prepared for either,” he said of the more extreme weather patterns.

Wasserman says the slight, short-term adjustment gives BCDC a bit more time to prepare and involve more agencies, cities and counties in a Bay Area-wide plan.

“This report just demonstrates the need for us to continue our efforts and, to some extent, accelerate our efforts,” he said.

Jessica Fain, the agency’s planning director, says she’s glad the projections extend to 2150. This allows her team to plan even farther into the future, which is vital as the agency The state is spearheading a regional sea-level rise adaptation plan, called Bay Adapt.

“That’s 70 years from now, the lifespan of a person who was born today,” she said. “So having those more distant numbers to think about is really valuable.”

Plan with confidence

California sea level planners are taking the new update seriously. Kelsey Ducklow, coastal resilience coordinator at the California Coastal Commission, says it will likely take a year to incorporate recent federal data into state climate plans.

“Having more confidence in the impacts of sea level rise over the next 30 years gives more confidence in the actions we can take,” Ducklow said of safer levels of sea level rise. of the sea planned by 2050.

But she admits that all of the projects in play in California — highways, homes, buildings — have lifespans beyond 2050, and that’s why planning for the most extreme projections after mid-century is essential.

Susheel Adusumilli of the Scripps Institution is collecting data to rework the state’s 2018 sea level rise guidelines. He says rising tides could be worse for parts of California, such as Foster City in San Mateo County, where he says the land is sinking.

He also says California’s update, coming in 2023, must detail how Black, Middle Eastern, Latino Asian communities will suffer economically from rising tides.

“California is a wealthy state, and if California adapts to rising sea levels in an equitable manner…it will be heard around the world,” he said.

An aggressive approach

Sea level rise planners in San Mateo County are preparing the entire coastline – from East Palo Alto to Brisbane – for an additional 10 feet of water above today’s high tide .

This level of protection goes well beyond the new federal forecast.

“It’s an aggressive number, so in this century we’re not going to see an overshoot if we pick that number,” OneShoreline’s Materman said.

To protect the hundreds of thousands of people, tech giants and infrastructure in San Mateo County that sustain the entire Bay Area, Materman says choosing not to be conservative when planning for rising tides is a no-brainer. .

“Forty years from now, I don’t want people looking back at our agency and saying, ‘Oh, you trusted a report from 2022, which underestimated what the damage would be. So now we have to go in and elevate everything,” he said. “That’s not our point.