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Comment by tda | Hacker News Reader

I hope you're right, I expect the world to be in a very different place in a few decades and not for the better. I'm still under 40 so I'm keeping my options open; even though the chances are probably very low, the effect is also pretty extreme making the risk (probability * effect) approximately 0 * inf. I estimate the probability to be somewhat higher than 0, so therefore I believe the risk is significant.

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> I expect the world to be in a very different place in a few decades and not for the better

Given history to date I would say that is a safe assumption when you are living in a time of prosperity, it is the global equivalent of 'this too shall pass'. But even if NL will be hit hard I highly doubt it will be hit hardest or first. We've been vaccinated in a sense in not trusting nature to leave her boundaries where we'd like them to be, the country is more like a machine than a static arrangement.

If we stopped pumping water out you'd be living on the lakeside within a few years, and on the seaside a few years after that.

Indeed we won't be hit hardest or first, but consider this. Just about the entire Randstad is in a single "Dijkring" (Dijkring 14). And because a large part of the Randstad is flooded, if any part of the defense goes, it goes entirely. And as the Randstad is the economic heart of the country, the country will not recover. Also because it can't feasibly be evacuated. So flooding will happen in other places first, but the other places are above sea level and will get dry again. Or a few meters of coastline is lost. Not the Randstad, it will be flooded exactly once and stay flooded completely and forever. Lets just hope it will take a long time before it happens.

I don't think that will happen that quickly. Yes, it is a single dijkring, but also one of the best protected ones. IJsselmeer is right next door giving a very nice way to get rid of a substantial amount of water with a very convenient canal system and the Oranjesluizen to make that happen. That would take care of a surface area the size of the city with 9 meters of so of water standing above it before this would be an issue.

I'm much more skeptical about the delta near Rotterdam/Zeeland and the part where the big rivers enter the country, mostly because of what's on the other side of the border.

https://flamingo.bij12.nl/risicokaart-viewer/app;jsessionid=...

Is a good place to look at, and it more or less confirms exactly what I wrote above.

Yes, there are a few fringe areas that are likely to flood. But as we know that, that is not a problem. These areas are mostly uninhabited, have emergency procedures in place and are somewhat resilient (houses built on artificial mounds). Dealing with the known unknowns is relatively easy. Sometimes these areas flood, but seldom does it cause significant impact (loss of life, significant impact on economy). Taking into account all the known unknowns we have designed and built the greatest sea defense of history designed for 1:10.000 year conditions. And I am very confident this has been done properly (no expense spared).

I believe New Orleans was rebuilt with 1:100 year conditions in mind, and that was after Katrina. Nothing close to 1:10.000.

So are we safe then? A few years ago I would have said yes without a doubt. But now? It's the unknown unknowns I'm afraid of because they are by definition left out of the calculations to get to 1:10.000 year conditions, and we are only just beginning to discover what climate change really means. I'm afraid we "ain't seen nothing yet", and extrapolating from the past just won't cut it.

The only time anything like this came close was a freak storm in 1953 as far as I know - 2000 dead in the Netherlands (also 200 dead in UK). Since then sea defenses have been improved by a huge factor, nothing was left to chance. I just don't see the kind of freak event that can cause this (and why would a freak storm hit the Randstad and not New York / London / San Francisco ?). If you're talking about gradual sea level rise doing this, well the current pace is 3.8 mm rise a year. Even if the rate doubles (is this likely?) we're still under one meter in 100 years. I wouldn't run away to Sweden just yet but hey it's a free country! P.S the sea level rise pace around Netherlands is even lower than the rest of the world currently.

That freak storm did us a huge favor, if not for that the general public would have likely balked at protecting the rest of the country. But 1953 is taught in school here and people in general are quite appreciative of the fact that they have 'dry feet'.

thing is cat 5 hurricanes happen every year (and are thus not freak storms), just not here. In the parts of the world where these happen, people tend not to live below sea level so even poor islands eventually recover after being hit. Extrapolating form the current climate the probability for cat5 hurricane winds in NL is about zero, cause the mechanisms that cause these kinds of storms don't apply here. But as the climate changes, and the seas warm, you might see the general storm patterns change, and you might get into a different regime where such storms are possible. Take hurricane Lorenzo, the easternmost Category 5 Atlantic hurricane on record. What was previously unthinkable just happened last October. If you extrapolate from this trend (more frequent, more eastern hurricanes happening in the Atlantic), I think it looks a lot less unlikely that one of those monster will someday make it to the North Sea.

Same with sea level rise: the currently observed rate of change is very manageable, and even a factor 5 higher can probably be managed. But what if we reach (or have already reached) a tipping point in the climate system that causes rapid acceleration of sea level rise? The existence of these tipping points cannot be derived from historical (say last 1000 years) observations, and therefore one might conclude that they don't exist. I believe such reasoning is known as the black swan logical fallacy. But from my casual observations, we are entering uncharted territory now (greenhouse gas levels, sea temperature, changing weather patters, changing jet stream patterns), so who knows what will happen.

Last point, look at the temperature 40,7 °C reached just last summer. Until 2018 the highest recorded temperature was 38,4 °C (in 1947). Some say this was a huge outlier, I think this is the new normal. I would love to know the probability of this happening taking the weather observations from start of record until 2018, would be surprised it it in the 1:1.000.000 range.

edit: Of course someone did the math (in Dutch) https://www.knmi.nl/over-het-knmi/nieuws/hoe-bijzonder-zijn-...

The British Isles form a big protection block for the country from the worst weather coming form the ocean.

Also, if the sea level rise is caused by ice melting on the North Pole the rises will be countered considerably by the earth's crust rising due to the mass being removed from it.

Sea level rises are scary - and are part of the reason I don't live in Amsterdam / Utrecht / Rotterdam - but that shouldn't be the thing to scare us.

Food shortages and the wars this will fuel will be a problem long before the sea causes the dykes to fail (and my assumption is that said dykes are part of what makes The Netherlands almost impossible to defend).

It's a mixed blessing. They also allow water to pool in the channel because it can't really flow out fast enough. And contrary to what you say the dikes are part of the defenses of the country. The Spanish had an interesting experience to that effect.

None of this seems likely. It's like moving out of San Francisco because an earth quake might happen. Even if a freak hurricane arrives (it shouldn't since the waters aren't tropical, but whatever lets say this somehow changed in the next 50 years), even if, you'd have weeks to evacuate people, so casualties shouldn't be too high. Infrastructure would be damaged yes, but doesn't seem to me like something that devastates the country. The water will eventually be pumped out. And btw what do the once in 10000 years storm defense are preparing for if not just that?

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