Rising sea destroys homes, erases beaches in California | Hacker News Reader

Rising sea destroys homes, erases beaches in California

reuters.com

42 pointsgeox34 comments

Coastal erosion =/= sea level rise.

This is textbook expected behavior on a high energy deep water coast (eg cliffs, not mangroves)

Ya, I don't want to minimize the problem of sea levels rising, but the recent storms had massive swells (I believe partially because of the El Nino year). The sand on most of these beaches is not natural, it's pumped up to the shore to encourage tourism. It is normal for it to wash away during big swell, and not necessarily an indication of the sea level rising.

You could argue that the extreme El Nino this year is due to global warming, which is obviously related, but it's not quite the same as just rising sea levels.

It's annoying for coastal areas, and a problem for beach houses, but California isn't really that vulnerable to rising sea levels. The Pacific Coast is mountainous and the ground slopes upward in short distances.

Here's the US topo map.[1] Look at vulnerable spots, such as Malibu and Oceanside. Three blocks inland you're 20 feet above sea level. Almost all problems are on the ocean side of the Pacific Coast Highway, which was a marginal place to build anyway.

Cliff edge erosion is an ongoing problem. That's why CALTRANS gave up on Devil's Slide as a road route and built the Tom Lantos Tunnels further inland. Small changes in sea level don't affect hundred-foot cliffs that much, though.

The places that really suffer from rising sea level are river deltas, sitting on deposited sand just barely above sea level. In the US, New Orleans has the worst problem. New York City has problems, and they're building coast defenses against storms. China's coastal cities are mostly on river deltas with really flat terrain. That's why China has to build ports way off shore, reached by miles of bridges, to get to deep water.

[1] https://en-us.topographic-map.com/map-9t5k57/Venice-Beach/?c...

Isn’t the Bay Area quite vulnerable? I’m thinking they’re going to have to build a dam with locks in front of the golden gate

The problem with that is that there are rivers and streams emptying into the bay. All of that water has to make it to the sea somehow.

The Netherlands has solved that problem

No way. The Golden Gate is really deep.

The Bay Bridge channel is so shallow it has to be dredged. There was a 1946 plan to fill it in.[1] There were Corps of Engineers plans for a lot of filling, but they didn't go that far. I have a copy of their 1960-2020 plan for the Bay Area.[2] Their vision was to make the SF bay area a major industrial city, building on the facilities built for WWII. Aluminum smelter in Sausalito. Steel mills at Tiberon. Five freeways up the Peninsula (101, 280, 35, 1, and one on stilts in the bay.) Another Bay Bridge. Maybe a SF-Alcatraz-Angel Island-Tiberon link. It would have been like Pittsburgh.

[1] https://www.sfgate.com/local/article/second-bay-bridge-plans...

[2] https://archive.org/details/futuredevelopmen00unit

This plan also resulted in a real-world scale model of the bay: https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_B...

The topographic map says, the Bay Area is just around the first bay, there's a whole second bay opening up behind it (Sacramento area valley) which could flood with enough sea level rise.

I'm used to people assuming California = LA + Bay area, but it's the first time I see someone arguing that they don't count…

CA already floods at high tide so I think another 10 ft is really gonna mess stuff up. There are so many rivers that empty at sea level and a lot of roads that cross over low points that will need reworking.

The Bay Area is one big river delta, going inland to Sacramento.

It's not the Pacific coast communities you have to worry about like Half Moon Bay or Santa Cruz. They have a beach, and then cliffs, and then the actual city is like 50-100 feet above sea level.

It's the bayside communities. Foster City. Redwood Shore. The Embarcadero. SFO. Port of Oakland. Highway 101.

All of these are pretty critical parts of Bay Area infrastructure, and gone with as little as a 1.6' sea level rise + 20yr storm.

https://www.kqed.org/science/1973624/maps-see-which-bay-area...

Foster City has a pretty hefty levee [1]. Palo Alto is building a "horizontal levee" [2]. Looks like Redwood Shores will be raising theirs [3].

This work has to be done for good reason, but looks like they're on it?

[1] https://fostercitylevee.org/ [2] https://www.sfchronicle.com/climate/article/palo-alto-sea-le... [3] https://www.smdailyjournal.com/news/local/new-200m-levee-upg...

It's striking how much preparedness the SF bay area does. After the 1989 earthquake, all of the following were done:

- All freeway pylon supports were beefed up. They were already on the heavy side, but huge metal supports were built around them. You can still see those.

- The SF bay bridge eastern span was entirely replaced with a new bridge.

- The western span, the suspension bridges, was made more flexible. The roadway was jacked up and stainless steel slide plates were inserted to allow the roadway to slide relative to the towers if necessary.

- The Golden Gate Bridge had been strengthened a few decades previous, after the Tacoma Narrows bridge disaster.

- Most, but not all, unreinforced masonry buildings in SF have been strengthened or demolished.

- The backup water system (three hilltop tanks and an entirely separate plumbing system) for fire protection has been beefed up. In 1989, there were some water main breaks and nobody up at the tank to close the valves, and the Twin Peaks reservoir drained out.

- Three new fire boats. (There were zero in 1989, and that was a problem.)

The SF Embarcadero seems completely unprotected, and the bay front buildings get a bit wet at peak tides if there is any sort of storm surge lately. It seems to me that even another foot could be quite problematic.

Earlier this year the road was flooded as bay water went the wrong way through the storm drains…

This is a pretty cool map. I'm at 20' above sea level. That should be good enough right?

I just dodged being stuck on the Outer Banks or evacuating for a hurricane which has now closed Hwy 12 based on which week the family agreed on for the annual beach vacation:

https://www.outerbanksnews.org/post/n-c-highway-12-damaged-c...

(and they have an on-going beach replenishment effort as well)

Im pretty sure _don't look up_ was supposed to be a scathing indictment of climate change deniers, but it makes me wonder how many people living in low low-lying areas of the seacoast claim to believe that climate change is real and happening and vote for everyone else to change their lives but ignore the water lapping at their doorstep

[Insert HbomberguyShoutingAtBenShapiro.gif here]

https://www.youtube.com/watch?v=0-w-pdqwiBw

I would think the dominating factors in Oregon and California are their uplifted soft geologies. The orogenies that lifted the West have resulted in an elevated, cliff-bounded sandy coastline along the Pacific that has been aggressively eroding for a lot longer than humans have been there.

right, except that humans have fixed the high tide lines over whole geolographical areas and done massive work to redirect almost all of the rivers and streams to agriculture, industry and domestic uses, and stopping most of the sand from reaching the ocean, plus sand mining for building is so extensive that there now shortages, meaning that the main surface sources are gone. those fixed high tide lines are also the collateral for trillions of dollars in loans and investments, and given the tripple wammy described in the article, things could get out of hand in a whole new way.

The Seattle Times ran an article maybe last year that measurements of sea level at Seattle had increased 8 inches over the last century.

The flaw in that is what is the reference frame? The tectonic plate Seattle is sitting on is going down under the cascade mountains.

And beaches have been eroding for millions of years.

If you're talking about this article[0], you'll have to argue with NOAA[1] as that's the source that The Seattle Times used to determine that the "high tide in Elliot Bay has risen 10 inches since 1899".

Since you didn't provide a link to your referred article, I have no idea if the Times blamed any particular cause or not. In the article I've referenced, there were several causes for the flooding in the South Park neighborhood.

[0] https://www.seattletimes.com/seattle-news/climate-lab/4-thin...

[1] https://tidesandcurrents.noaa.gov/sltrends/sltrends_station....

That still leaves open the question of what is the reference point, when the land also rises and falls. Plate tectonics wasn't even a theory in 1900.

Geod-Ellipsiod separation dynamics both mean globally and on a plate by plate basis accounting for creep is a thing. As is epoch based modelling and forward and backward projection.

So measurements from harbour posts can be reconciled to WGS84 despite a bit of Californian bounce.

It also almost washed out the San Clemente track. Which re-opened in 3 days despite having waves crash over it.

tbh maybe it's good and changes something quicker and on the long term that rich people experience it firsthand before the Maldives or Bangladesh

(probably nothing just me being optimistic but the rich always have a get out of jail card, like X more properties)

Gonna be interesting when that Kelvin wave overlaps with king tide…

The city of Santa Barbara painted a line through the town 25 years ago saying if we don’t stop global warming, the town will be under water to that line in 25 years…

No they didn't, that was merely a proposal.

If they had drawn the proposed line, it would still be the same distance from the coast today. So its presence would be a detriment to global warming proponents.

> global warming proponents.

The only global warming proponents are the people insisting that we should keep pouring CO2 in the atmosphere.

And if a frog had wings, it wouldn't bump its ass when it hops. But frogs don't have wings, and the line wasn't drawn.

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