Rising Waters Threaten China’s Rising Cities | Hacker News Reader

Rising Waters Threaten China’s Rising Cities

nytimes.com

57 pointshourislate33 comments

China has a huge flat coastal river delta that's heavily populated. The US has that only at New Orleans, which is a much smaller city and has high ground nearby.

The US comes out fairly well on rising sea levels. Except for Florida. Florida has so much low-lying coast that it's hopeless. The US west coast is mountainous enough that high ground isn't far inland, and only short sections of the coast at SF and LA are vulnerable. The coastal cities of the east coast have reasonably short coastlines, enough money to build sea walls, and compact river mouths.

Have you ever noticed that the Sacramento river delta, while way inland, is actually quite near sea level?

True, but the problem with the Sacramento delta is keeping the fresh water flow high enough to keep salt water from going upstream, not getting rid of the river water. If sea levels rise, the delta becomes a salt flat and the fresh water is diverted to the California Water Project. See Peripheral Canal.[1] Maybe build a dam at Vallejo and stop salt water incursion from going further upstream.

[1] https://en.wikipedia.org/wiki/Peripheral_Canal

I don't understand the relevance of nearby high ground. Assuming you can't build levees, doesn't the cost of losing a city come primarily from losing the buildings (which must be rebuilt), not the transport cost of moving items inside the building to a new location? In other words, if your house is in the path of a tornado, learning that there is a nearby patch of land guaranteed not to be hit is not useful.

The difference is that the sea level rise happens over decades, and the city will gradually move inland and upward as its (newly) beachfront property recedes. China's river delta cities can't.

Venice. Air, Sub and Boat-traffic.

It's not clear to me that this is less costly than moving across the country. You'd have to look carefully at the network effects, but from an infrastructure perspective you still end up building a whole new city.

In other words: what's the advantage of building San Diego II a few dozen miles from San Diego, even slowly, rather than just expanding Denver by moving people there.

(Note that I agree it's better than building a new city in the middle of nowhere; the question is whether the network benefits of San Diego II can be mimicked by Denver. In this sense, I agree that countries with cities that are almost all on the coast would benefit from having high ground nearby their doomed coastal cities.)

In the case of New Orleans, some of that high ground is within the city itself. If flooding eventually becomes frequent enough that the federal government decides to relocate flood insurance claimants and stop funding the Army Corps of Engineers' improvements to the levees, then the city can retreat to its pre-1930 borders. Most of those areas did not flood in Katrina and could get by with a much smaller flood protection system that might be justified by the city's economic productivity.

Except for Florida. Florida has so much low-lying coast that it's hopeless

The New Yorker has an excellent article on precisely this topic: http://www.newyorker.com/magazine/2015/12/21/the-siege-of-mi... . There will be a weird sort of shadenfreud (or, more likely, whatever term is most appropriate for seeing someone's arguments utterly proven wrong) when FL floods, given the politicians FL has been electing.

The coastal areas of FL are blue, sadly.

Well... yeah. Miami isn't going to be around for all that much longer either. Large parts of the world are going to be inundated, flooded, or actually drowned. To be fair though, the fine distinction between "frequent flooding destroys everything," "Literally underwater all of the time," and "It's a salty swamp here now," might be lost on former residents.

Some places will be able to adapt, because they have money and the right geological conditions, but plenty of others (Miami) would require... well... I can't even imagine.

Hmm, what if someone could accurately predict what the shoreline would look like and then buy a whole swatch of cheap properties that will eventually be on the waterfront? A la Superman, where Lex tries to split the San Andreas fault...

If we could predict the changes, then we wouldn't be debating climate change.

Discount rates and property taxes make it relatively infeasible to buy that land and turn a risk-adjusted profit - especially since the margin for error is so slim (a few hundred horizontal feet one way, your properties are a 100% loss, a few hundred feet the other way, you lose much of the waterfront premium). Compared to investing in a stock index at 5%+, the idea is nowhere near worthwhile; you need to find land which would at least double or triple in value just to try to profit at 10-20 years out, and even more if you are planning 20+ or taking into account the carrying costs & risk.

To be honest, I think it is fairly unpredictable what will happen with stock values if there is strong global warming. And if government breaks down having anything might not be worth much unless you have an army to defend it.

In the long run, equities have always outperformed real estate, regardless of climate or weather events: companies and peoples can move, pieces of land cannot. And 'Mad Max' scenarios are currently not projected to happen anytime remotely soon if ever.

To be fair, 'Mad Max' isn't something you project, it's an overly optimistic post-script to a total nuclear exchange. It may be that pressure from climate change and poor coping mechanisms on an international scale could lead to said nuclear exchange, although I certainly hope not.

You'd have to not only predict the time-frame and the shoreline, you'd have to have a lot of faith in the economy and governments that will exist when that starts to go down in a serious way.

Ocean levels will continue to rise for centuries. I don't think the timescales quite make sense from an investment perspective.

Right - nobody is going to want that ocean front property in 100 years knowing they'll be underwater themselves in the next 25.

Property values are still climbing in Miami because the market seems to think that the city will be bailed out by some colossally-expensive engineering project to fix the problem on the taxpayer's dime. Nobody knows what that is yet- the usual levees and canals won't work because Florida is a limestone sponge and the water just comes up through the ground if you try to dam it- but they assume there'll be something.

Depressingly, the market is probably right. Abandoning Miami would mean admitting that global warming is real, and that's just not going to happen. Besides, "retreat" isn't in our vocabulary! `Murica!

I don't think that saving Miama is really possible, it's facing too much from too many sides. I think the biggest issue is that people love living there, and they'll believe it's over after it's over.

Of course, the first people to get the message will be those with some money and education, and their exist will tank that market. As for admitting anything, they'll just switch over to "It's not man-made!". There is no limit to the human capacity for self-delusion.

> I don't think that saving Miami is really possible, it's facing too much from too many sides.

I don't think it is either, but that doesn't mean we're not going to spend hundreds of billions of dollars trying.

Oh I see, yes I agree completely. We're going to exhaust resources in last-minute desperation, waste it in war and conflict, and then in the end maybe try to geoengineer out way out, which is one hell of a gamble if it's even plausible.

Property values are going up in Miami because it's 50 years away problem in a 5-10 year world. Everyone is buying and selling and hoping they won't be the person left holding soggy property. The city is already planning for the floods. New construction has to shops and parking on the ground floor. 2nd and 3rd floor has to be planned to be street accessible. That means when the street is eventually filled in the 2nd floor becomes the ground floor.

Now where they will get all that material to fill in the street is a good question.

Until recently I wouldn't have disagreed with a word of your post, but now... I think 50 years is probably optimistic. It seems more like 30 or so where Miami is concerned, and that means that the inevitability of it all should actually start to emerge (at least for some) in 10-15 years.

The rest of what you're saying I'm totally on board with, but I think the answer is: denial is like a crappy superpower.

The article makes the claim ("In the Pearl River Delta, breakneck development is colliding with the effects of climate change.") that climate change is having a major impact, but all of the items they listed (outside of a sea rise) are caused by human development.

Climate change seems like an innocent bystander in this one.

Isn't the solution simple here - to build levees or damming the river? I know levees are expensive but given how critical this area is to China's development, the cost is justified. I mean, entire New Orleans region is below sea level and is supported by levees.

That's what they have been doing in Netherlands for decades. Half of Netherlands is less than one meter above sea level. A significant portion is below sea level already.

I haven't yet read this article but is this really that much of a threat to these cities? It really does seem like the solution to build levies/walls is obvious and straight forward. Am I missing something about the complexity of this problem?

I'd imagine the scale/length could be quite expensive for some of these areas. But it hardly seems like an unattainable infrastructure building project. Especially considering all of the talk about billions of dollars in potential damages to cities... This is exactly why we pay taxes.

The problem probably isn't the situation 364.8 days per year, but what happens that one time every few years when weather (typhoons) and maybe even the tides align to create conditions much worse than average for just a few hours. See New Orleans... the worst part is that because it's so rare most people (and media) will rant against the "waste of taxpayer money". You have to build very expensive infrastructure that's almost never needed, that goes against human nature it seems to me.

The East and Gulf coasts of the US are hit with tropical storms and hurricanes each year. A rise in sea-level means more intense flooding and destruction when storms land in these regions.

The problem is no one wants to pay for expensive stopgaps or solutions at the moment.

Damming the river makes it worse. Water flow from the river has to go somewhere. As sea levels rise, the river expands. The Mississippi creates floods of this type well upstream from New Orleans.

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