How Soon Will the Seas Rise?
59 comments
·October 20, 2025skybrian
I think this can be summarized as “nobody knows but it might be very bad.” Mathematical models containing large uncertainties aren’t a crystal ball. They will likely be revised again.
You shouldn’t dismiss disaster scenarios since preparation for tail risks is important. But maybe don’t focus on them exclusively, either? It’s possible to keep multiple scenarios in mind, rather than focusing on one exclusively.
In California, there are wildfires, earthquakes, droughts, and (in some places) flooding to worry about, and this partly plays out via scarce and expensive property insurance.
nemo44x
> The model suggested that ice from Antarctica alone — before any additions from Greenland, mountain glaciers or thermal expansion — could raise the seas by more than a meter by 2100.
> In a 2021 update that incorporated additional factors into the simulations, DeConto and colleagues revised that estimate sharply downward, projecting less than 40 centimeters of sea-level rise by the century’s end under high-emission scenarios.
In essence, they have no idea.
Windchaser
I'd think that "between 0.5 and 1 meters" is an idea. Like, we aren't worried about sea level dropping, and we aren't worried about +10m by 2100. This is still useful info, even if there's some uncertainty remaining.
dingnuts
I like how you changed "less than .4 meters" into "between .5 and 1"
That was some smooth propagandizing you just did, I wonder if anybody else noticed. Between less than .4 (0) and 1 (1) is a much bigger window than the one you invented wholesale in your reply.
I think the grandparent might be right, and your willingness to bend the statistics when they are literally on the same page as your comment, along with others like you doing the same thing for decades, is the reason your side is losing and continues to lose the public's trust.
If the problem is really so obvious and so serious you should not feel it necessary to exaggerate. So quit it.
EddieRingle
They're citing another section of the article rather than the cherry picked quotes they were responding to.
throwway120385
But they know that it is coming and we need to plan for it. 40 centimeters is still half a meter. If you filled my office with half a meter of water it would be between my butt and my ankle where I'm sitting. There are a lot of berms that couldn't withstand king tides 40 centimeters higher, especially with storm swell factored in. A lot of seaside infrastructure where I live needs to be relocated even with a lower estimate.
constantcrying
Obviously you get downvoted for this here, but you are absolutely correct.
Climate science is one of the most speculative fields of science, which for political reasons is rarely admitted towards the general public. The climate in 100 years is incredibly uncertain.
The general story of rising sea levels due to increased temperatures due to increased carbon in the atmosphere is of course very plausible. But it is just one of large number of effects at play and one of many ways the climate is changing. (Which isn't to say that the sum of these effects can not have server negative consequences)
Science communication around climate change has always been built around the obvious falsehood that climate models make good predictions, especially when it comes to long term trends. Instead of honestly communicating the actual state of science, which is that while specific predictions are hard, negative consequences of human intervention in the earths atmosphere likely will have sever negative consequences if they aren't mitigated, science communication has focused in on stories about "in X years Y will happen". When Y inevitably did not happen that was (and it is hard to blame people for this) taken es evidence that no negative consequences can be expected.
Edit: It is pretty surprising how anti science the crowd here is. These are just basic truths about he state of the science. Accurate climate models do not exist, if you disagree I suppose you should read a bit into the literature.
margalabargala
This is completely wrong and I'm frankly not sure how you came to this conclusion from the parent comment's data.
The uncertainty is "we do not know whether the amount of sea level rise due to human GHG emissions will be closer to 40cm, or closer to 100cm 75 years from now".
Science communication regarding this has generally always expressed uncertainty. Right wing entertainment masquerading as news frequently portrays it otherwise, but that's easy to do when unencumbered by a connection to reality.
Don't confuse what is most profitable to say, with what is most correct to say.
constantcrying
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pureagave
The models are always wrong. It's virtually impossible to model something with an impossible amount of unknown inputs. Even accurately measuring the Earth over time is a joke. Unfortunately the models are presented in pop science and mainstream culture as accurate or something that we should use to create public policy.
user____name
What should we base public policy on instead?
dboreham
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constantcrying
Lying about science is not helpful. The key driver behind climate change denial is science communication misrepresenting climate science. All climate science models are incredibly uncertain and making concrete predictions based on them has and will continue to make scientists look like idiots.
rolph
rising sea level, is only one symptom of whats happening.
https://climatecosmos.com/climate-news/why-the-tropics-could...
it seems there will be big problems in the 50-75 year span.
jncfhnb
I’m gonna guess that sea level rise will end up being one of the lesser problems introduced by climate change
jacquesm
A very large fraction of humanity lives in zones that will end up being flooded, this is already happening in some parts of the world.
For instance, Vanatu:
https://climateknowledgeportal.worldbank.org/sites/default/f...
There is nuisance flooding, which is definitely up already in many parts of the world, and then there is the kind of flooding that essentially makes it impossible to live in certain places. My own country (NL) has been working since a bad flood in 1953 to raise the various flood protection systems to account for rarer events and the mechanisms put in place have already been triggered several times. Right now they're working on raising the whole protection level another meter (three feet), and if necessary they'll do more than that but there are some complicating factors. At some point the rivers won't empty any more and you end up with either reverse flow or internal flooding simply because that river water has nowhere to go to.
ManBeardPc
It will be a big one for people living near the coast. Basically all port infrastructure will need to be moved. Of course there a things like extreme heat waves, cold snaps, lack of rain or floods that will make a lot of land unlivable too. Lack of food will be another thing. But land being under water is not a lesser thing at all, as it makes the land unavailable.
deedree
I'm not so sure, ground water will turn salty and make large swaths of land unlivable and river mouths will change stream upwards so all dike infrastructure as it is now will be unusable.
simmerup
As long as you don't live on an island or have coastal property...
michaelbuckbee
I think the point was more that even if you're on a coast a lot of other problems are more likely to impact you first: higher energy and more frequent hurricanes, insurance, costs, etc.
jghn
It's not as a-vs-b as this. Rising sea levels will increase the damage of those more frequent hurricanes long before one's house falls into the sea. And that increases insurance costs, and so on. The whole thing is a single system with a giant feedback loop.
jncfhnb
I suspect most islanders and coastal property dwellers will be wrecked by volatile weather first
lawlessone
There's a sweet spot where i will eventually have coastal property.
AnimalMuppet
Temporarily...
Muromec
nerviosly coughs in Dutch
riffruff24
I wonder if the dutch have a plan to evacuate the whole country in say, a year time, in case walling the seas no longer feasible?
Not in an emergency scenario but more like "it doesn't make sense to stay here anymore".
quickthrowman
Or say, a country bordering Bangladesh. Sea rise of 1 meter would inundate 10% of Bangladesh, a country of 170M in 150,000 sq miles. I suspect a refugee crisis in Bangladesh would end in genocide…
Noaidi
Do you know the populations of the world that will be displaces, and the amount of real esate that will be affected by this?
Sea rise is not just about flooding, but it affects sewers and infrastructure well before affecting properties.
gmuslera
You need to have extreme weather into account. Global sea rise is a slow process, it won't happen overnight, and even with an accelerated, but not catastrophic, melting of some of the fragile glaciers in Antarctica it will take years.
Extreme weather, in the other hand can affect big areas for extended amount of time, right now. In 2022 a third of Pakistan ended flooded, in 2024 there were big floods in parts of Europe and South America. Droughts, extended forest fires, tornadoes and similar has been changing in area patterns and strength in the last years. And things may get extremer in the coming years
jeffbee
Something like 2 billion people rely on glacier melt for their fresh water supply and these supplies will end abruptly before catastrophic sea level rise.
okokwhatever
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FrustratedMonky
It can be measured.
The whole argument that "just because the sun rises today, does not mean it will rise tomorrow", line of reasoning is pedantic at best.
phendrenad2
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jghn
"see pockets of high heat and pockets of deep freezes" does not at all contradict a statement that overall global temperature is rising. In fact, one would expect that an overall rise in temperature would lead to local pockets of colder temperatures.
rolph
the rise in temperature makes a more turbulent atmosphere, this disrupts familiar atmospheric distribution of thermal energy, we already have unusual atmospheric stalls and vortexes, along with changes in oceanic circulation.
bilsbie
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titzer
Despite this comment being an ignorant throwaway, the irony is that markets can sometimes force the price of scarce natural resources up, which attracts investments because the goods are becoming scarce. In the short term, it could cause a spike in coastal property prices that would cause superficial analyses to conclude that there is no problem whatsoever, further fueling an exploitative short term bubble.
What will definitely be affected is insurance prices. Those are a better gauge of what the actuaries think is going to happen. We are already seeing that in Florida today and on the eastern seaboard, as insurance prices have skyrocketed. Some places are not even insurable.
ltbarcly3
I think you might have overlooked the point they were making.
Whether or not the market price is properly pricing in future risk is irrelevant. What OP is implying is that activists are engaged in cognitive dissonance, similar to what you commonly find in religious people. They say they 'believe' in something but you would not find any evidence of that 'belief' revealed in their behavior.
For example: believing that the world will end tomorrow, posting to social media that the world is going to end tomorrow, and then checking your work email at 8pm.
Yes, you can probably make a just-so story where they are buying beachfront property based on a belief they can unload it, or they will die, before it becomes worthless due to being underwater or destroyed by storms. I think the point stands however, and it underlines the importance of looking at revealed beliefs rather than simply stated beliefs.
(To be clear, the point depends on climate activists actually buying beachfront property, which I doubt is very common at all, so I don't actually think it's a good argument at all. However your response still misses the point.)
jghn
I believe that world ocean level will be catastrophic by 2100. I do not plan on living until anywhere near 2100. In fact, 2050 would be pushing it. If I wanted to have a nice seaside house *now*, why is that cognitive dissonance? Sure, it is likely that I'd have to give it up in 15-20 years, but I might not make it that long myself.
stetrain
But if someone has and enjoys beachfront property, that might actually be a motivation for wanting to protect it, and thus be an activist. That relationship is not so clearly hypocritical.
Noaidi
I wonder how many activists own ocean front properties? Not of course counting wealthy people who are concerned about climate change but are not activists.
But you should start worrying now. As someone who has been exposed to the environment all over the United States the change is here. And farmers are already adapting to it, they just do not believe it is caused from humans.
https://www.scientificamerican.com/article/what-do-farmers-t...
spicyusername
What?
This is one of those comments that evokes an emotional response, but is devoid of actual content.
Is there some sinister plot involving activist beachgoers!?
What kind of data would anyone even have on whether or not climate change activists own oceanfront property and what percentage they own?
What would it even matter?
If anything, one would imagine that oceanfront property owners would in fact care more about the effects of climate change because they are most impacted, lol.
d_silin
"Depending on future emissions, the IPCC now projects an average sea-level rise of half a meter to 1 meter by 2100"
somerandomdude2
Not how soon will the seas rise, but in which direction are they trending? The world is not static - it's dynamic, always changing. Long before human civilization, the environment was getting warmer, then cooler, then warmer, etc.
Instead of freaking out about it, work to understand how we as a civilization can make it through the changes. Attempting to hold the environment stable is like plugging dikes with your finger.
simonh
I don’t think anyone here is advocating for freaking out about it, and I do not see any suggestion we should that you’re replying to.
Also, it’s pretty clear from the IPCC report that holding the environment stable isn’t an option. At this point about 0.5m minimum sea level rise this century is probably locked in. However a 1m rise might not be.
So yes, the issue is that either way policy planning needs to be considered in the long term.
OkayPhysicist
Humans are causing a change to the environment drastically faster than any normal ebb and flow. In the same way that you can get from 0-60 either by pushing on the gas pedal, or being hit by a train, rates of change matter a lot.
cindyllm
[dead]
One thing that a lot of people seem to miss is that we talk about sea-level rise so much in relation to climate change because it's one of the things we can at least reasonably predict (even if the how much and when is hard). But the impacts of climate change increasing become hard to model as the world falls out of predictable patterns.
A great example of just how extreme things can get was the last major climate change event ~10,000-20,000 years ago (which will likely be minuscule in comparison to what we're going through now in the geological sense once this plays out).
The Channeled Scablands of Eastern Washington[0] have a very distinctive geology. For many years it was believed that these features were carved out slowly over hundreds of thousands of years. It turns out they we created in hours, around 15,000 years ago (humans were already living in WA at that time). They were created by the Missoula floods. There used to be a glacial lake over what is now Missoula Montana which would have current day Missoula under 1,000 feet of water. The glacial damns holding back this lake started to break down resulting in frequent floods the scale of which it's hard to fathom. The peak flow is estimated to have been 6.5 cubic miles per hour (for context, the peak flow observed over Horseshoe falls was 0.0055 cubic miles per hour, the Amazon river flows at an average of 0.18 cubic miles per hour)
Imagine driving East on 1-90 from Seattle towards Spokane, then as you get through the Cascades you suddenly see a 200 foot wall of water racing towards you across the horizon.
That event was in the past and it still took us a long time to piece together what actually happened. As we head into states of climate never witnessed by humans, it's genuinely hard to predict what might happen other than "this probably won't be good". Humans have made a lot of progress in the last 10,000 years, but it's no coincidence that the last 10,000 years have been some of the most stable in the Earth's climate history.
0. https://en.wikipedia.org/wiki/Channeled_Scablands