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Comment by rconti | Hacker News Reader

When I was shopping for a house in the Bay Area 3 years ago, my agent asked me if I was willing to consider Redwood Shores (which is built on fill and very close to the bay). One reason among several for saying "no" was the proximity to sea level.

I'm not worried that the next tsunami will swamp it, or that it will be (physically) underwater in my lifetime, or that nothing will be done to prevent slow rise from swamping the land.

I'm just simply unwilling to make a 30 year commitment to today's value, when I don't know what we'll know in 30 years. It's an absolute certainty that we'll know more in 10 years than we know now. When will that property become un-sellable? When will the value start being impacted? I'd guess sooner rather than later, and if that isn't until 2040, that's still way too soon for comfort -- particularly if I'm trying to retire then.

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Wide areas near there built on the former marshes/landfill can be quite musky during hot months as well depending upon prevailing winds, it's not obvious that is a problem unless one lives in an apartment nearby in the right weather conditions beforehand - many of the apartments don't have central air or heat.

I had the same thoughts when buying a house last year. We really like Alameda island - great neighborhood, houses, and shops. But we eliminated it from consideration because it's just a few feet above a king tide, and that buffer is shrinking. AFAIK, there's no abatement plan for the island yet, and while it may not be underwater in the next 30 years, the property values there will decline on the worry that it's only getting worse, and king tides will start flooding more and more of the island and its infrastructure.

And then there's the insurance issue- as insurance rates go up, the home value has to decline as well. Didn't seem like a good long-term investment, or even short term, as more and more people start considering these issues like I did.

The prices will drop way before they're under water.

We ended up buying a house in the hills - 900ft. up. I wonder if in 10 years folks in Alameda will start migrating our way.

The unique risks in the hills are fires and mudslides.

Yes. Those threats are real, but can be mitigated. Sea level rise, for now, can not.

Moved from the coast to a cold place more than 5k ft above sea level 18 years ago, specifically thinking about sea level rise and warming trends.

However...wildfires.

Oddly, sea level will probably go down this far north. Earth is spinning, drawing water to the equator. More mass, more gravity pulling water to the equator, along with less mass at the poles to offset.

But, yeah, I don't think I'd buy anything by the water either.

edit

So, I'm wrong, Northern California isn't far enough north. it's a real effect. You're all underestimating the mass of 100,000 cubic miles of ice.

[1] http://science.sciencemag.org/content/323/5915/753

[2] http://www.nature.com/nature/journal/v409/n6823/abs/4091026a... reply

> Oddly, sea level will probably go down this far north. Earth is spinning, drawing water to the equator. More mass, more gravity pulling water to the equator, along with less mass at the poles to offset.

Can you provide a reference or show some workings which demonstrate that statement to be true? I've not heard this before, and it's not obvious that it should be true.

Here's one.

http://harvardmagazine.com/2010/05/gravity-of-glacial-melt

Wikipedia eqitorial bulge has some info as well.

I'm unconvinced. I don't see anything in the harvardmagazine article that suggests sea level fall in Northern California. The wikipedia page explains that equatorial bulge has been decreasing. I'd expect ice-melt to add mass along the equator and further slow rotation which should further reduce equatorial bulge. I'm not saying you are wrong its just that your references don't explain your contention in a way that I can make sense of.

I'm wrong. edited the main comment with more references.

California isn't an area where sea level will go down, ironically it will go down near Greenland and Antarctica due to less gravity from ice sheets. There are some nice maps towards the bottom of this article:

http://onlinelibrary.wiley.com/doi/10.1029/2012GL053000/full

Since Florida is near the equator, facing the same ocean as Greenland, and has subsiding land, it will likely experience more effects of sea level rise.

Jerry Mitrovica is a Harvard geophysicist who's at the forefront of variations in sea level rise.

http://nautil.us/issue/33/attraction/why-our-intuition-about...

More mass? From where? I don't think the mass of polar ice caps significantly pulls water toward the poles. Water follows gravity, which points approximately toward the center of the earth everywhere, with very minor deviations for the centrifuge effects of rotation.

Your intuition is incorrect, the impact of ice sheets on local sea level due to gravitational attraction is significant (tens of feet). http://sealevelstudy.org/sea-change-science/whats-in-a-numbe...

I think, and I'm not convinced here, that they're considering the distribution of mass to be the key factor not total mass as that is (as far as we're concerned here) fixed. Again, just speculating.

Uhh... Is this true? Doesn't seem right to me...

There is a small effect in that direction - the earth's spin makes the sea level a few feet higher at the equator than it would be if the earth were not rotating.

But the bit you quoted implies something more of a runaway effect. I'm pretty sure that won't happen - there's not enough mass in water compared to the total mass of the earth. In fact, I'm pretty sure that adding more water to the oceans will raise sea levels even at the poles, despite the rotation of the earth.

It's pretty easy to calculate the acceleration due to rotation at the equator. It's a = omega^2 x R, where omega is (2 pi) / (24 * 60 * 60) seconds = 7.27e-5 / seconds, and R is the radius of the earth = 6.371e6 meters. The acceleration due to rotation is then a = 0.0337 m/s^2. Compare with 9.8 m/s^2 for gravity. That's 0.3% of gravitational acceleration. That's... not very much.

Can you explain in more detail how melting ice would cause sea level fall in Northern California? Are you saying this would happen because of changes to the speed of rotation? Change of pole location? A change to earth's shape?

I'm not sure that your reasoning makes sense.

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