State projections for how high the ocean could rise this century have as much as doubled, giving new urgency to efforts to plan for mitigation efforts, San Francisco planning officials said this week.
Sea level rise projections from the state Ocean Protection Council were increased earlier this year from a maximum of 66 inches to as high as 122 inches by 2100. That projection includes both sea level rise, which will account for 11 to 24 inches by 2050, and coastal erosion and shoreline flooding.
Planning Department Director John Rahaim said at a Planning Commission hearing Thursday that certain areas of The City will likely see “routine flooding” by 2030.
“Some of the numbers… are in big ranges and there’s this tendency to think of sea level rise as so far in the future that it’s hard to get people’s attention,” Rahaim said. “There are things that are happening in the short term that we really have to start thinking about. It’s not something we can put off to the next generation.”
The commission was briefed Thursday on the progress of efforts to curb the impacts of inundated shorelines since the publication of the 2016 Sea Level Rise Action Plan, which directed city agencies to assess the impacts of sea level rise on San Francisco.
One component of the action plan is an ongoing assessment to measure and describe the impacts of sea level rise and “future coastal flooding on public infrastructure and private land use across San Francisco, according to planning documents. It will also assess the consequences that sea level rise and coastal flooding will have for people, the economy, and the environment.
“We have been working with our public infrastructure agencies to really understand, ‘What does this mean for MUNI? What does this mean for our Public Utilities Commission, for our parks?” Maggie Wenger, an adaption planner with the department. “And then what does it mean if those systems face impacts, for the people who live here, work here and come to visit.”
Preliminary findings suggest that between 17 and 84 miles of streets, 242 to 704 acres of open space, 335 acres to 1,203 acres of public land and 2 to 20 schools will be affected by flooding between 2030 and 2100.
The assessment found that roughly 6 percent of land area along San Francisco’s coastal areas is vulnerable to sea level rise.
“Not all areas in this zone are equally vulnerable,” said Wenger, adding that some are likely to see flooding impacts “in the next decades, others in the next century.”
While some areas may require minor interventions, others are more vulnerable due to aging architecture or the location of vital city infrastructure.
“When you look at Fisherman’s wharf, North Beach, you have historic resources there they are more sensitive because of construction type, maybe less adaptive because you are constrained in what you can do,” said Wenger. “We also have city serving infrastructure that is located along the shoreline— The Muni Kirkland Yard, as we go further south there’s other major infrastructure.”
The full report is expected to be finalized in mid 2019, and the information will be used in agency and city capital planning, neighborhood planning efforts such as the Islais Creek Southeast Mobility Adaptation Strategy grant, and for citywide policy development, according to Planning Department Spokesperson Gina Simi.
“I feel better knowing that even though some of these numbers doubled, that we are on top of it doubling,” said Commissioner Joel Koppel. “I think we have to take it a step further and have plans for if [the numbers] triples or quadruples, just to be safe.”
Along with the assessment, The City is currently rolling out a its Port Seawall Earthquake Safety program and has adopted the Islais Creek Southeast/Southeast Mobility Adaptation strategy which focuses on design solutions to strengthening the area and improving the resilience of transportation assets.
A more than $400 million bond proposal to repair San Francisco’s seawall will go before San Francisco voters in November.