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Comment by gnatman | Hacker News Reader

I just went looking for a map to see how different coastlines would look with a 200m sea level rise. It's, unsurprisingly, significant!!

https://www.floodmap.net/

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Surprisingly if you put it to 20 meters the effect globally seem insignificant. Although 80% of my own country would be flooded, so that's not great.

I guess you mean the shape of the countries doesn't change much? iirc the majority of Earth's population lives on coastlines, most major cities will be inundated

They'll have a _long_ time to migrate though, no?

The rise in sea level is something of a misnomer, because the real damage comes in storm surges. Even a 1cm rise increases the amount of water that can pushed inland by *checks notes* a whole helluva lot. So while manhattan isn't going to be put underwater even after a whole foot of sea level rise (predicted by 2100), the storms it has to survive will be much worse.

People won't move just from a little water in the roads (just look at Miami), I think even in the year 2099 you'll have a hard time getting new yorkers to move to ohio, but once a storm comes through and destroys their housing they will have to find somewhere else to live.

Housing is super expensive for people now. All of that coastal infrastructure will need to be rebuilt.

But housing isn't expensive because it's hard to build. It's expensive because building it isn't allowed. If it all had to be rebuilt, that would be much cheaper than trying to build it under existing conditions.

Yeah, I was looking at this and thinking "At 20m, basically the entire Eastern and Southern Seaboard of the US is gone."

Not at all. Those living along the shore have flood insurance which will continue to pay for restoration of the coastline.

Insurance isn't an endless bucket of money, and it's also going to adapt. Eventually you just won't be able to get insurance for properties in areas like that. Just look at the floods in New Orleans or the current flooding along the east coast of Australia, I doubt there's enough money to make all those affected whole again.

I think insurance may be the main driver for when people actually decide to move. People are pretty resilient, but if you can't get a home loan because you can't get insurance, people won't keep living there.

I live in NJ. As I understand it, the state gov - via taxpayers, obviously - subsidizes property insurance at the shore (as NJ calls the beach).

That generosity isn't endless.

These communities are wealthy and influential. Places like Buffalo will go bankrupt keeping places like NYC above water.

The big problem, as a sister comment pointed out, is that, for various reasons, a lot of people live close to the coast line. And a lot of people having to move was historically never really a good for peace, plus we loose a lot of agriculturally valuable land in the process.

Transportation by water is like 50 times cheaper than by land and it has been like that for at least the last 2000 years. So most people live either along the coast or along rivers.

At 20 meters, the Bay Area, the Central Valley, Los Angeles, and parts of Orange county are significantly impacted.

Well if California goes, we might as well all pack up, civilisation is over.

Okay. So what do you think will happen when a significant chunk of the United States economic power is under water?

From https://earthobservatory.nasa.gov/images/148494/anticipating...

> In its 2019 report, the IPCC projected (chart above) 0.6 to 1.1 meters (1 to 3 feet) of global sea level rise by 2100 (or about 15 millimeters per year) if greenhouse gas emissions remain at high rates (RCP8.5). By 2300, seas could stand as much as 5 meters higher under the worst-case scenario.

I guess thy will migrate the datacenters before 2300.

I suspect it will look like Amsterdam, or Venice, or any number of cities that figured out how to cope with existing at or below sea level.

Well, billions of poor people without iPhones will be displaced or flooded. But actually on reflection, that's irrelevant compared to, dunno, having to build sea walls in Los Angeles and ruining the beach.

When I imagine the value of beach houses in Orange County dropping due to sea level rise, it fills me with such sadness.

Mostly knowledge workers. Remote work already reducing potential impact.

On a global scale, sure, but as you pointed out for some spots it wouldn't be good. Both Miami and New York (to a lesser extent) would be having a bad time.

And as Lex Luthor pointed out in Superman1, there may be profit to be had. So honestly, two sides to that coin, amirite?

Certainly significant but that also happens on a massive time scale - the best estimates have us up 0.7 meters in 2100.

https://www.noaa.gov/news-release/us-coastline-to-see-up-to-...

Unfortunately, that's just linear extrapolation from current rates.

Ice sheet collapse can be extremely nonlinear, accelerating rapidly. https://www.nature.com/articles/s41467-018-05003-z.pdf?origi... Or watch any of Eric Rignot's presentations in youtube. The term is Marine Ice Sheet Instability.

This video in my opinion gives a fun demonstration of it https://www.youtube.com/watch?v=jLdaAKIkpKA

Miscommunicating sea level rise risk is a big problem.

False, the long term NOAA models are far more complex than simple extrapolation (though that is of course a part of any forecast) and they certainly aren’t linear. Feel free to read up on them yourself:

https://oceanservice.noaa.gov/hazards/sealevelrise/sealevelr...

> Global mean sea level, or the average height of the ocean surface, has risen 6 - 8 inches (15 - 20 centimeters) since 1920. In the continental U.S., relative sea level has risen about 10 - 12 inches (25 - 30 centimeters) over the same period. Observational data from tide gauges and satellites also show that sea level rise, both globally and along the continental U.S., is accelerating, with more than a third of that rise having occurred in the past two and a half decades (see NOAA and NASA portals for altimeter-based global rates and NOAA for local tide gauge rates).

So, 30% of the normal one foot per century (somewhat less worldwide) happened in the last 25% of the time. That’s not a big acceleration, that’s measurement error.

And yet this report says the rate of rise will nearly triple over the next thirty years. This is simply not plausible.

Generally, the report reduced the predictions. Also, they eliminated the 2.5 meter (!) scenario.

Thanks, I was wrong. The report is good reading.

But you must have seen something I didn’t. See my comment nearby.

This map is weird. I put 20m sea rise and it shows Caspian Sea expanding, roughly doubling its size. But the thing is: Caspian Sea isn't a sea at all, it's a lake (named "sea" only because of its size), not connected to oceans in any way - why would its level rise at all?

Also, it is nice to see that my family home is safe until about 350 meters rise (although it would be located on a small island in that case)

It's possible it's the algorithm has a bug for stuff like this, but I did notice that with, for example, 40m sea rise it shows a connection from the Black Sea to the Caspian Sea.

Interesting that even at a ridiculous, unprecedented 500m sea level rise, there are still substantial areas of dry land. It would be a radically different world, and a smaller one for us land based animals, but it doesn’t seem outlandish that civilization could persist.

It's difficult to imagine the extent and depth of suffering that humans will endure during the transition.

The Netherlands didn't endure much suffering. In fact, quite the opposite.

The highest point in the Netherlands is 322 meters (https://en.wikipedia.org/wiki/Vaalserberg), so even the mighty Dutch might have a problem with a 500m rise in sea level.

I think they're referring to the increasing intensity of severe weather.

Not only that, but also the massive loss of land that is currently dense urban area, and the massive loss of land in general. There will have to be huge reconfigurations of where people live and what people's livelihoods are. I am not optimistic that such changes can be managed among several billion humans without war, famine, etc.

Seems par for the course of human history no?

Dry land is just one aspect of climatic stability. Tolerable and predictable weather patterns is another. Fertile regions, a critical consequence of that. The question isn't whether some will survive, the question is: Who, why them, and at what cost? Furthermore, it's best to avoid population bottleneck scenarios in general, isn't it?

So, sure; we can relax at least our fears for a Kevin Costner "waterworld."

Maybe "stability" isn't the best factor for human progress? I'm not saying "therefore, let's maximize chaos!" -- just pointing out that /stability/ in today's world is more likely to lead to "business as usual."

I know Hollywood movies like to focus on dystopian scenarios wherein the Onepercenters always end up the sole benefactors of significant changes (especially due to worsening climate/pollution)...but is that really so? I envision that they in particular would want stability -- especially political -- far more than the average person. The reason why especially such persons historically preferred western nations, for example, was precisely due to greater stability, and not because of tax laws, for example.

Perhaps it was "stability" that contributed to scientific stagnation in some cultures?

Lastly, another term for "stability" is steady state. Remember what cell bio teaches regarding steady state vs equilibrium.

If you're suggesting that what human civilization needs, in order to elevate us to a more global maximum (by your favorite rubric, whatsoever), is climate catastrophe, I think you could serve yourself well by looking into generational trauma and PTSD.

It's the culling of vulnerable populations that will limit our biodiversity and development towards ultimate catastrophe resilience. We've seen enough homogenization of architecture and institutions already to seriously endanger our tenure on the planet.

It's strange to me that you view "western nations" as possessing "greater stability" than the Persian, Indian, Chinese, and Ottoman empires and, likewise, strange that you think "the Onepercenters" "historically preferred" strong, stable social structures and not, specifically, a differential between their holdings and a marginal region to exploit.

Some people like to romanticize the opportunities available for underdogs in times of crisis but, for example, the aftermath of Hurricane Katrina is an easy counter-example. Vulnerability isn't strength. A "rising tide" doesn't lift all boats.

Ours is a hugely abstract and almost criminally vague level of discourse, however. I can't think of any meaningful consensus at which you and I might arrive. I just hope you can grow to recognize that survival of the fittest has no foresight, and no memory. Too cheaply do we cull the only locally unfit. Leaving climate change to do its worst in the hopes that it might topple "business as usual" sounds like a great way to preserve the most ruthless actors.

And large changes would take at least decades or centuries. It seems outlandish that civilization wouldn't persist just because coastal settlements move their center of mass over time.

Not to mention 500 meters will likely take a thousand years or more. Where will society be a thousand years from now? Changing the climate might be as easy as using the terrain editor in Sim City.

something like only 10 meters is necessary to depopulate large part of Florida (due to loss land and freshwater aquifers) and turn part of central California into a salt marsh and start reducing the USA's most productive farmland.

Good to keep in mind that best estimates right now have sea level rising by less than 0.7 meters through 2100. 10 meters may happen some day but it will be a very slow process.

https://www.noaa.gov/news-release/us-coastline-to-see-up-to-...

Ecological estimates have been shown to wildly conservative.

Who ten years ago had in their ecologic prediction bingo card that we'd have rampant wildfires globally and 118 degree ground temps in the Arctic Circle by 2020?

If you have better sources than the NOAA estimates then by all means provide them, all I see is an unsourced claim and an anecdote

was always curious about how below sea level works there, how much sea rise does it take before death valley becomes the new dead sea?

That is a flaw with this site, it seems to "fill in" Death Valley even with no change in sea level. The best way to read the map is to look at what new blue areas are connected to oceans, rivers, and seas. If they aren't, then it's unlikely they will be flooded as illustrated in the map at that new sea level. Death Valley, to go with that, is still detached from any oceans or rivers until almost a 600 m sea level rise.

Right on, thanks for the answer.

What a great tool for generating fictional maps.

Solves the question of who gets Ukraine..

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