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Comment by katabasis | Hacker News Reader

For some context about what impact this could have on major U.S. cities, the NYTimes published an interactive a few years back[1].

I guess if this new model is accurate, the scenarios on that link which are projected for 100-300 years out could instead happen in a few decades. This would result in major areas of Miami, New Orleans, NYC, and Sacramento all going underwater.

Scary stuff.

[1] http://www.nytimes.com/interactive/2012/11/24/opinion/sunday...

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Sacramento?? It is 50 miles inland. If that's right, that's crazy.

Central valley all used to be marshlands/lakes/extensions of the bay. The coastal regions of CA are hills. CA is basically a giant bowl (which flattens out towards the south).

That should be pretty feasible to wall off though.

Elevation of Sacramento is 30 feet....that's lower than the bay bridge.

Right, totally not what one would expect. But based on the geography of California, it's very vulnerable if the water levels were to go up significantly. There would essentially be a second Bay cutting deeper into the state, only it would probably be a toxic mess a few feet deep with acres of asphalt and buildings barely submerged.

In all likelihood, Sacramento and SF bay would be fine because it would be inexpensive to levee.

Florida, OTOH, would be lost.

Is there any reason why, if we had a decade of warning, we wouldn't be able to protect much of this area?

Not just any, but many.

This story is about ~1 metre sea level rise. Greenland's glaciers (if they were to entirely melt) provide ~8 metres, and Antarctica's would provide ~60 metres - so even if you built a wall to protect some / much of this area, you'd have to be planning either subsequent abandonment or a lot more construction work.

But this presupposes that it's feasible from an engineering or financial perspective -- I suspect that in any but a tiny number of cases that it would not be.

In turn it assumes that people would want to live behind a wall that is protecting them from probable death if it collapses, or is intentionally destroyed by the kinds of people who like to kill other people. And these walls would be quite an attractive target.

Would you want to live beneath sea-level if you had the option to live above sea-level?

Then there's groundwater issues (salinity is going to render such earth less habitable).

> "I am not a great believer in man-made climate change. I’m not a great believer. There is certainly a change in weather that goes – if you look, they had global cooling in the 1920s and now they have global warming, although now they don’t know if they have global warming. They call it all sorts of different things; now they’re using “extreme weather” I guess more than any other phrase."

> -- Donald Trump, https://www.washingtonpost.com/blogs/post-partisan/wp/2016/0...

There's a considerable chance that this man will be your next president.

I thought he was great at building walls ;)

We've had several decades of warnings about global warming, yet we've barely done anything about it. Why?

Some people stood to lose money.

This was unacceptable to them. So they got to keep their money, and sacrificed the future of the planet instead.

This is a good 'eli5' answer to the question posed.

What is an alternative hypothesis? The energy companies worked against renewable because it was Good For The Country? Because nothing expensive or hard is worth getting? Because economic ruin was definitely going to happen?

The other answers don't actually address your question. To some extent, yes, because adequately protecting large areas of exposed coast requires building and maintaining many miles of seawalls. This isn't impossible by any means, but economically it's not very feasible to protect, say, Miami from both rising sea levels and the intense hurricanes that are likely to result. It would be much cheaper to just relocate people inland as needed.

Im curious, how does this actually happen?

i.e. is there one catastrophic event where everything is immediately flooded? (Similar to Katrina).

Or is the area just slowly flooded over decades? In which case, no one does anything? (i.e. the Sacramento scenario is hard to fathom in this scenario)

I suppose it would be like Katrina (New Orleans) or Sandy (New York), which of course un-flooded after the storm, but each time it floods, with the base sea level being higher than last time, it gets progressively worse until you just give up spending the money to reclaim the land and protect it from the next storm.

Maybe look into whatever it is they do in the Netherlands. A very large fraction of the entire country is just barely above sea level (or even below it in places).

60% of the population is below sea level, even. It's true that only 25% of the land area is below sea level (and another 25% less than 1 meter above it), but that happens to be the most densely populated area.

For example, if the sea were to spill over onto all below-sea-level land, Amsterdam would be an island, some 15 km off the new coastline. The Port of Rotterdam would still be there (25km offshore), but the rest of the city would disappear.

If you strongly believe this could happen in the next few decades why not buy some property on what will be the new water front?

It'll be underwater (literally and figuratively) 5 years after you buy it...

Also, changes in land values are far more likely to be driven by changes in employment patterns, transportation technology, and weather systems than by sea levels.

Might be a good idea to buy future farmland in the middle of Canadian pine forests.

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