[HN Gopher] Sea level much higher than assumed in most coastal h...
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       Sea level much higher than assumed in most coastal hazard
       assessments
        
       Author : jacquesm
       Score  : 95 points
       Date   : 2026-03-04 16:24 UTC (6 hours ago)
        
 (HTM) web link (www.nature.com)
 (TXT) w3m dump (www.nature.com)
        
       | bikenaga wrote:
       | [flagged]
        
         | buildsjets wrote:
         | The only thing you ever post is AI summaries of articles. Why?
        
           | Schiendelman wrote:
           | I assume that's a bot that helps us not have to click on
           | articles for basic information. Personally, I find it quite
           | useful. I'd love to have that built into HN.
        
             | solid_fuel wrote:
             | I think every browser has an AI summary feature now, if you
             | find reading and engaging with information just too
             | difficult and challenging.
        
         | MisterTea wrote:
         | We are more than capable of reading thanks.
        
       | sebmellen wrote:
       | The saddest part of global turmoil around AI, Iran war, etc. is
       | how dramatically climate change has disappeared from the 'global
       | conversation'. This is not something we can afford to ignore for
       | much longer.
        
         | jatari wrote:
         | Climate hasn't been a real topic of discussion since the Obama
         | administration.
        
           | jonahrd wrote:
           | I disagree, Greta Thunberg's whole thing started in 2018,
           | leading to larger and larger climate protests and action
           | globally...
           | 
           | ..until about 2020, with COVID/russia-ukraine/Oct 7/trumps
           | re-election following and burying it below tons of other news
           | cycles.
        
           | crystal_revenge wrote:
           | And the Obama administration really just talked about it. It
           | was under his administration that the US shale oil extraction
           | really started heating up.
           | 
           | The problem is the only solution to climate change is keeping
           | oil in the ground. There are other things that can be done to
           | make a zero emissions transition less painful, but oil (and
           | all other fossil fuels) need to start staying in the ground.
           | 
           | During the Obama administration is when we started to see a
           | dramatic _increase_ in US oil production [0]. The US hegemony
           | is oil powered and founded on the petro-dollar. There 's no
           | way US policy can be aligned with anything remotely
           | resembling a path towards a sustainable energy environment.
           | 
           | 0. https://www.eia.gov/dnav/pet/hist/leafhandler.ashx?n=pet&s
           | =m...
        
           | michaelteter wrote:
           | Fox News and Trump still routinely say it's a hoax. And their
           | devotees repeat that line in one breath, and in the next
           | breath say, "wow, we just set a new high temp record in
           | January!"
        
           | tencentshill wrote:
           | No, it just got boring. There have been massive renewable
           | buildouts since then, as a direct consequence of those
           | policies. No matter how much trump hates it, the economic
           | scales have already tipped.
        
             | spwa4 wrote:
             | The point is that renewable buildouts don't help. ONLY
             | permanently preventing exports in oil producing countries
             | helps. Not temporary reductions. Stopping exports entirely
             | before the oil is dug up. Everything else might be nice in
             | it's own right, but doesn't change the global warming
             | calculation much at all.
             | 
             | Which effectively means that renewable deployment in the
             | west might still be a good idea, but not because it
             | supposedly slows or stops global warming.
        
         | pocksuppet wrote:
         | We've been getting progressively more dog-eat-dog short-term
         | since Reagan.
        
           | dingnuts wrote:
           | Close, but it's actually Nixon and the end of Bretton Woods
        
           | andai wrote:
           | Isn't that artificially imposed survival fear the natural
           | consequence of fractional reserve banking?
        
         | giraffe_lady wrote:
         | I don't think climate change is being ignored: AI, war
         | profiteering, ICE, detention centers, destruction of the
         | international system, global fascism _are_ their answer to
         | climate change.
         | 
         | It's not to prevent it, or to mitigate its damages, it's for
         | the people who disproportionately caused it, and have already
         | benefitted from it, to finalize their control over the
         | resources they want. Some of those resources are some of us.
        
           | georgemcbay wrote:
           | And they aren't even really bothering to hide it anymore.
           | 
           | A lot of Trump's seemingly odd obsessions like taking over
           | Greenland and Canada are less odd (but still very unsettling)
           | when you accept that the global power elite have already
           | accepted that run-away climate change is inevitable and the
           | only open questions are who is going to profit from it and
           | how.
        
             | spankalee wrote:
             | This is it exactly. Russia and Canada are in the best
             | position to possibly "benefit" from global warming.
             | 
             | The US has Alaska, but if it wants more newly arable land
             | in the future, the only options seem to be Greenland and
             | Canada, the two places which Trump just so happens to be
             | obsessed with annexing.
        
           | surgical_fire wrote:
           | You don't have to worry about the future if you ensure there
           | is no future.
        
           | axus wrote:
           | Disagree, the motives are the same with or without climate
           | change. We're still at the slow part of the curve. Knowing
           | what's coming doesn't change their behavior.
        
           | beedeebeedee wrote:
           | There are also some people in power who believe climate
           | change is related to the end of times and eagerly welcome it
           | to hasten their idea of 'Armageddon'
        
           | Herring wrote:
           | You're giving them too much credit. They're just blindly
           | seeking profit.
           | 
           | Humans are not that good at planning longer than 6 months to
           | 5 years out. The brain is legacy hardware, optimized for the
           | Pleistocene epoch. Reward circuitry (Striatum) often
           | overpowers logical simulation (Cortex).
        
             | sebmellen wrote:
             | The other thing is, we can't stop. Someone always will
             | outcompete you if you try to pause.
        
         | maest wrote:
         | The US has been taking steps in the wrong direction wrt climate
         | change and they will undoubtedly be judged to jave been on the
         | wrong side of history on this one.
         | 
         | In the near term, however, Americans will blame everything
         | except man-made pollution for the fallout from climate change.
        
           | sebmellen wrote:
           | Regardless of the politics of the day, where is the long-
           | term, popular will (or capacity) for a "green/electric"
           | revolution in the US? We are massively dependent on fossil
           | fuels, and our quality of life is too.
           | 
           | At the same time, we don't have China's industrial capacity
           | or their stomach for massive state-driven subsidies. I don't
           | see how you escape peak oil otherwise.
        
             | Retric wrote:
             | Oil is just one aspect of climate change, coal was far more
             | important because there's plenty of coal to case extrem
             | harm.
             | 
             | The vast majority of new electricity generation installed
             | in the US over the last 15 years has been wind and solar.
             | That naturally results in fossil fuels being fazed out when
             | existing power plants age and thus need to be replaced. 70%
             | of US electricity came from fossil fuels in 2010, that
             | dropped to 60% by 2020. More significantly it mostly
             | swapped to natural gas which emits far less CO2/KWh than
             | coal.
             | 
             | We could go faster but the tail end of the curve represents
             | a small fraction of the CO2 vs the peak. Even natural gas
             | is facing severe pressure from ultra cheap battery backed
             | solar. More importantly natural gas power plants don't last
             | nearly as long so will get fazed out much faster.
             | 
             | EV's are also about more than tailpipe emissions, making
             | and transporting gasoline is quite harmful before it ends
             | up in a gas tank.
        
             | shimman wrote:
             | Your comment ignores how much corporate welfare the US
             | already provides. Maybe the better question to ask is why
             | the US government cares so much about making such a small
             | amount of people more rich at the expense of not only the
             | living population but future generations as well.
             | 
             | We absolutely have the capacity, it's just being given to
             | already wealthy families to ensure their wealth is
             | contained to themselves rather than the country.
        
             | danaris wrote:
             | I mean, to some extent, you're not wrong, but if a Democrat
             | were in office right now, we wouldn't be actively fighting
             | the rising tide of solar power.
             | 
             | At present, the _bare economics_ of it, without any
             | subsidies, put solar as _the_ most cost-effective new power
             | capacity to add.
             | 
             | Last year--2025, the first year of Trump's second term--
             | something like 90% of _all new generating capacity_ in the
             | US was solar. Even _with_ his active antipathy toward it.
             | 
             | There no longer needs to be a massive movement willing to
             | pay more for energy just to get it decarbonized. All we
             | need is for the fossil fuel industry and the people in its
             | pay to _get out of the way_.
        
               | mullingitover wrote:
               | > At present, the bare economics of it, without any
               | subsidies, put solar as the most cost-effective new power
               | capacity to add.
               | 
               | Not just more cost-effective for new power.
               | 
               | The _operating expenses_ for a given coal plant are
               | greater than the buildout cost for the equivalent
               | solar+battery plant.
               | 
               | It no longer makes financial sense for coal plants to
               | continue existing in almost all cases. This isn't some
               | environmentalism thing, it's strictly hard math. Fossil
               | energy is no longer viable without taxpayers keeping it
               | on life support.
        
             | mmooss wrote:
             | IIRC, polls show most Americans support action on climate
             | change. When it's politicized, then they oppose it.
        
           | 0xffff2 wrote:
           | I say this as an American... I can't help but feel that the
           | US will be judged to have been on the wrong side of history
           | in virtually every topic for which there are sides in the
           | last decade if not longer. For reasons I don't understand, we
           | seem to be actively and aggressively working to destroy our
           | country and as many global institutions as we can.
        
             | datsci_est_2015 wrote:
             | > For reasons I don't understand
             | 
             | History is full of examples, but maybe not explanations, of
             | the type of behavior coming out of the current
             | administration in the US. They're not particularly special,
             | or extraordinary, by any measure. They've simply made the
             | decision to hit the "defect" button over and over again
             | like a teenage boy discovering porn for the first time.
             | 
             | And since the adults that preceded them were reasonable and
             | responsible, they built up plenty of rules and norms,
             | creating many opportunities to now hit "defect".
        
               | mmooss wrote:
               | Could you give us some of these examples?
        
               | datsci_est_2015 wrote:
               | People spend entire careers doing these types of
               | analyses, so my off-the-cuff comment will always be
               | amateurish in comparison. But here goes anyway, some
               | examples of blunders that come from a place of arrogance,
               | or being overeager to hit the "defect" button:
               | - Various Roman emperors overextending and destroying
               | what their predecessors slowly built       - Indigenous
               | peoples (especially the Americas) allying with colonial
               | forces to defeat other indigenous enemies (won the
               | battle, lost the war)       - Brexit       - Perhaps the
               | most documented regime of all time, 1930s and 40s
               | Germany. Specific event? The eastern offensive
               | 
               | Edit:                 - Royal lineages have plenty of
               | examples, like Louis XVI
        
             | mmooss wrote:
             | Here's an hypothesis: A fundamental model of politics is
             | similar to the model of innovation in markets: The status
             | quo power and the challenger or disrupter power.
             | 
             | The status quo's power rests on its institutions,
             | stability, and the fact that it is the social norm -
             | generally humans are tied to social norms and attack
             | anything that violates them. The challenger, to succeed,
             | needs to disrupt the institutions, stability, and norms,
             | and one tactic is to just constantly attack them,
             | regardless of the consequences, as a means to the end of
             | taking down the status quo and gaining power.
        
           | crystal_revenge wrote:
           | > wrong side of history on this one.
           | 
           | There's not much _history_ left. What we 're seeing right now
           | is people getting ready to win the end game of civilization.
           | The oligarchs are well aware of the myriad existential
           | threats to our civilization (and species) and are playing the
           | game to make sure they're the last person alive living in
           | comfort.
           | 
           | History will increasingly be told by powerful, oligarchical,
           | modern warlords.
        
         | crystal_revenge wrote:
         | Reducing the severity of climate change (we've already signed
         | up for potentially civilization destroying consequences, even
         | if we could go zero emissions today), requires keeping proven
         | reserves in the ground. No amount of "green" energy will impact
         | our future if it doesn't mean we start using _less_ fossil
         | fuels (globally) than today.
         | 
         | Darkly, a disastrous global nuclear war that sends us back in
         | time 500 years would be the most effective and most probable
         | way of achieving this.
        
           | spongebobstoes wrote:
           | what if we could capture carbon at a significant rate? I know
           | that we can't right now, it's a hypothetical
        
             | KellyCriterion wrote:
             | yes, I guess with fusion this would be possible?
        
             | bgnn wrote:
             | It's not only carbon. There are a multitude of gasses which
             | cause greenhouse effect.
        
         | noncoml wrote:
         | Not because of AI or Iran war. It's because we, in the US,
         | voted for it to disappear.
        
       | metalman wrote:
       | Watch your warming oceans expand in real time here
       | 
       | https://nsidc.org/sea-ice-today
       | 
       | above shows what may be the earliest ever peak sea ice
       | 
       | and
       | 
       | https://www.ospo.noaa.gov/products/ocean/sst/contour/
       | 
       | and the one above is absolutly terrifying , or should be to
       | wanabe hegemnons thinking that the naritive, is thiers.
        
         | lazyasciiart wrote:
         | Can you explain what background knowledge I need to be
         | terrified looking at the second one?
        
           | metalman wrote:
           | it is a tool that shows daily snap shots of the SST to use it
           | you need to have a good grasp on geography/oceanography, and
           | then spen a bit of time each day looking at it, and cross
           | corelating with things like hurricanes, to see the trace
           | spiral of cooler water that a giant storm will imprint into
           | the oceans surface, or this year, the very significant
           | chanhes in the worlds major hot and cold currents, and size
           | of the spill over from the south wester pacific into the
           | atlantic.
        
         | bvdw wrote:
         | The first link contains a banner that perfectly illustrates the
         | tragic moment we're in: "Due to non-renewed funding, several
         | Sea Ice Today tools and services are now suspended or reduced."
        
         | sebmellen wrote:
         | So we are more than 1 million square kilometers lower than our
         | record minimum year of 2012. Holy shit.
         | 
         | https://nsidc.org/sea-ice-today/sea-ice-tools/charctic-inter...
        
       | measurablefunc wrote:
       | In almost every fictional story1 dealing w/ near future outcomes
       | every author just assumes that Miami & New York are under water.
       | 
       | 1https://en.wikipedia.org/wiki/The_Ministry_for_the_Future
        
       | pjmlp wrote:
       | We just started another war with unforeseen consequences to the
       | planet, while destroying all resources to feed the AI monster,
       | forget about all those paper straws.
        
       | mmooss wrote:
       | > ... 90% of the hazard assessments assume coastal sea levels
       | based on geoid models, rather than using actual sea-level
       | measurements.
       | 
       | > A geoid is an equipotential surface model that approximates MSL
       | based on gravity and the rotation of Earth. As geoid quality
       | depends on gravity observations, uncertainties in global geoid
       | models can range up to several metres in regions that suffer from
       | gravitational data paucity ..., predominantly located in the
       | Global South. Moreover, actual sea-surface height is not just
       | determined by the gravity and rotation of Earth, but also by, for
       | example, ocean currents and large-scale circulation, winds,
       | tides, seawater temperature and salinity. As a result, time-
       | average sea-surface height can deviate strongly (up to several
       | metres) from a geoid, and its difference is the so-called mean
       | dynamic topography (MDT).
       | 
       | I don't quite grasp how those flaws in geoid models lead to an
       | overall significant underestimation of sea-level. Shouldn't all
       | those average out?
       | 
       | > uncertainties in global geoid models
       | 
       | Why would those tend toward underestimation?
       | 
       | > sea-surface height is not just determined by the gravity and
       | rotation of Earth, but also by, for example, ocean currents and
       | large-scale circulation, winds, tides, seawater temperature and
       | salinity.
       | 
       | Other than temperature and maybe salinity, those factors move
       | water in a closed system: increasing water one place reduces it
       | in another (?).
       | 
       | > time-average sea-surface height can deviate strongly
       | 
       | Why would average deviation by positive and not zero or negative?
        
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