San Franciscans love the ocean and the bay, despite the fact that they’re both implacable enemies, stealthily creeping in inch-by-inch to render great swaths of the city uninhabitable in a 100 years. It’s a complicated relationship.
The city today released a 100-page report on sea level rise, with an eye toward future planning for best and worst case scenarios. In the 20th century, the sea level around San Francisco rose about eight inches; by the end of this century, it will probably rise at least 36 inches, the first six of those just by 2030.
There is also potential for an even more drastic rise of up to 66 inches by the time the year 2100 rolls around. And you may remember last year’s apocalyptic projections by a NASA’s climatologist telling us to prep for a rise of 120 inches in the next 50 years, although the city has evidently opted not to work off of those numbers, possibly because it’s hard to do city planning when you’re paralyzed with dread.
(If your nerves can handle it, check out this fascinating but terrifying interactive map, where you can crank up the sea levels and watch big chunks of the Bay Area disappear. Poor Alameda!)
Rising water levels are already bedeviling us with periodic flooding, shoreline erosion, and salt water damage to our water systems, the report notes. So-called "nuisance flooding" would start to become a weekly or even daily occurrence in the future if we neglect to plan for it now. A 66-inch sea rise could affect 1,160 San Francisco buildings, inflicting $55 billion in damage.
Then, of course, there’s the dangers of a 100-year flood, the kind of huge and violent storms that, as the name implies, come along about once every hundred years. (See also: 200-year storms, 500-year storms, etc.) Factor in a storm like that and you’re looking at a $77 billion bill for 2,606 flood-damaged buildings. Ouch.
The potentially good news is that there are all sorts of plans to soften the blow, broken down into three categories: accommodation (which is when we basically just put up with occasional flooding, waterproofing things in low-lying areas as best we can); protection (where we build levies, flood walls, and other barriers to keep the waves back), and retreat (which is, well, when we just leave and let the ocean "reclaim" certain spots).
"For an urban area like San Francisco, retreat is expected along less developed shorelines (e.g., southern reaches of Ocean Beach) or when other options have been exhausted," the report says.
People are floating (if you’ll pardon the phrase) all sorts of potentially ingenious suggestions, from "living levies" along Ocean Beach, to constructed marshlands of eel grass and floating islands off of India Basin (wetlands are a great natural barrier to flood, sucking up water like a sponge), to "self-rising flood walls" of the type used in New York City and Houston, which are buoyed up by the water itself during flood times.
The mayor’s office vows to have a final plan in place by the end of 2018, which will mean wrangling with a huge number of agencies, three different committees, and one "interdepartmental working group." You can read the full report here. In the meantime, enjoy your bay views, and try to ignore that sinking feeling.
- Sea Level Rise Action Plan [City County San Francisco]
- Sea Level Projections Give Us Sinking Feeling [San Francisco Magazine]
- Surging Seas Risk Map [Climate Central]
- How Much Time Until Tides Flood Us? [SF Weekly]
- When Will Your Property Be Underwater? [SF Weekly]