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Earth

Sea Levels Rose Faster Than Expected Last Year. Blame Global Warming - But What Happens Next? (cnn.com) 134

Though global sea levels "varied little" for the 2,000 years before the 20th century, CNN reports that sea levels then "started rising and have not stopped since — and the pace is accelerating."

And sea level rise "was unexpectedly high last year, according to a recent NASA analysis of satellite data." More concerning, however, is the longer-term trend. The rate of annual sea level rise has more than doubled over the past 30 years, resulting in the global sea level increasing 4 inches since 1993. "It's like we're putting our foot on the gas pedal," said Benjamin Hamlington, a research scientist in the Sea Level and Ice Group at NASA's Jet Propulsion Laboratory. While other climate signals fluctuate, global sea level has a "persistent rise," he told CNN.

It spells trouble for the future. Scientists have a good idea how much average sea level will rise by 2050 — around 6 inches globally, and as much as 10 to 12 inches in the US. Past 2050, however, things get very fuzzy. "We have such a huge range of uncertainty," said Dirk Notz, head of sea ice at the University of Hamburg. "The numbers are just getting higher and higher and higher very quickly." The world could easily see an extra 3 feet of sea level rise by 2100, he told CNN; it could also take hundreds of years to reach that level. Scientists simply don't know enough yet to project what will happen.

What scientists are crystal clear about is the reason for the rise: human-caused global warming. Oceans absorb roughly 90% of the excess heat primarily produced by burning fossil fuels, and as water heats up it expands. Heat in the oceans and atmosphere is also driving melting of the Greenland and Antarctic ice sheets, which together hold enough fresh water to raise global sea levels by around 213 feet. Melting ice sheets have driven roughly two-thirds of longer-term sea level rise, although last year — the planet's hottest on record — the two factors flipped, making ocean warming the main driver. [SciTechDaily reports that between 2021 and 2023 the Antarctica ice sheet actually showed an overall increase in mass which exerted a negative contribution to sea level rise.]

It's likely that an increase of about 3 feet is already locked in, Notz said, because "we have pushed the system too hard." The big question is, how quickly will it happen? Ice sheets are the biggest uncertainty, as it's not clear how fast they'll react as the world heats up — whether they'll melt steadily or reach a tipping point and rapidly collapse... [I]t's still unclear how processes may unfold over the next decades and centuries. Antarctica is "the elephant in the room," he said. Alarming changes are unfolding on this vast icy continent, which holds enough water to raise levels by 190 feet.

Notz describes the ice sheet as an "awakening giant:" It takes a long time to wake up but once awake, "it's very, very difficult to put it back to sleep."

The article notes that U.S. coastlines "are tracking above global average and toward the upper end of climate model projections, NASA's Hamlington said." (The state of Louisiana has one of the highest rates of land loss in the world, with some places experiencing nearly 4x the global rate of relative sea level rise.) But it's not just a problem for America.

"Over the next three decades, islands such as Tuvalu, Kiribati and Fiji will experience at least 6 inches of sea level rise even if the world reduces planet-heating pollution, according to NASA.... "Entire villages in Fiji have been formally relocated," said Fijian activist George Nacewa, from climate group 350.org, "the incoming tides are flooding our roads and inundating our crops." However, if the pace accelerates rapidly, "it will be very, very difficult to adapt to, because things unfold too quickly," he said.
"Humans still have control over how fast sea level rises over the next decades and centuries by cutting emissions, Notz noted."

Thanks to long-time Slashdot reader RoccamOccam for sharing the news.

Sea Levels Rose Faster Than Expected Last Year. Blame Global Warming - But What Happens Next?

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  • Not really news; we've known for a long time that the sea level is rising, and that global warming is contributing to this. The interesting thing about this article is that it does acknowledge the uncertainty in estimates, something that's often missing from science popularizations.

    This is a long-term effect. Don't expect New York to be underwater in the next decade, or the one after.

    • If the news doesn't garner a fix the first time, and it gets worse, then it will repeatedly becomes worthy news as the situation gets worse and worse.

    • Re:Not news (Score:5, Insightful)

      by Sique ( 173459 ) on Saturday May 10, 2025 @06:11PM (#65367421) Homepage
      Yes and no. The news is that the real results measured right now are at the upper level of the estimates, which means that reality is worse than the science popularizations have suggested so far - and they were already called alarmist, when in fact, they were understating the problem.
      • They understate the problem since 30 - 40 years, because they did not want to be called "alarmists".

        Every predictions with the wide error gabs in recent decades: met the upper edges of what was sold as "error bar". And that in all regards: weather changes, peak temperatures, droughts, sea level rise.

        And and deniers pretend nothing bad is happening, just because 50% to 60% of all Taifuns/Hurricans never make landfall, or "only hit Philippines", and people declare it "as normal over there".

        When was it ... No

      • worse than the science popularizations have suggested so far - and they were already called alarmist, when in fact, they were understating the problem.

        What are you talking about, the alarmists are saying the oceans will boil [youtube.com], not that the results will be in the upper level of estimates.

      • by gweihir ( 88907 )

        Indeed. That is the problem with the denying morons only looking at the best-case projections or even denying them: Things can reach the worst case and, worse, since these are projections, they can get _worse_ than the projected worse-cases.

    • acknowledge the uncertainty in estimates
      It is always acknowledged to the amount that is known.

      However: you do not know the unknown. E.g. an iceberg crashes into the ocean from Greenland or Antarctica. It happens. But you do not know when. So ... what is there to acknowledge?

      It is not like someone opened a valve and the amount of water coming through it is known or can be calculated perfectly.

  • by TheMiddleRoad ( 1153113 ) on Saturday May 10, 2025 @04:56PM (#65367253)

    Several condo buildings have had to be abandoned and knocked down in Hawaii. They're ocean front properties, and higher tides inundated the bottom floors. They're complexes that did just fine for many decades.

    Ocean rise is going to accelerate as more CO2 and methane enter the atmosphere as thawing permafrost reveals ancient biomass, and as more heat gets absorbed from ocean revealed by melted ice.

    We are so fucked.

    • by ras ( 84108 )

      We are so fucked.

      Who is this "we"? I just sold my house and build one 40m above the surrounding flood plain. The old one was on the river. Beautiful place, tranquil water views, several meters above to 100 year flood level. But floods have grown noticeably more frequent and higher in the 20 years I owned the place. The writing was on the wall, so I decide it was time to move on. Despite the new house needing far more $ coverage, the insurance is around 1/2.

      I for one there are still people out there wh

    • by AmiMoJo ( 196126 )

      Don't worry, they can just sell that property and move inland.

      https://www.youtube.com/watch?... [youtube.com]

    • by gweihir ( 88907 )

      We are so fucked.

      Indeed. But it will get worse, as still nothing effective is being done.

  • We should nuke the Ocean if it tries to invade!
  • Take a look at real sea level rise at https://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?id=8724580
    Now take a look at the historical sea level rise at https://en.wikipedia.org/wiki/Past_sea_level and note the Post Glacial sea level rise, sea levels are rising but slowly and consistently over the last 2000 years.

    Does sea level and CO2 concentration in the atmosphere correlate? Check out https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide and sc

    • by XXongo ( 3986865 )

      Take a look at real sea level rise at https://tidesandcurrents.noaa.... [noaa.gov] Now take a look at the historical sea level rise at https://en.wikipedia.org/wiki/... [wikipedia.org] and note the Post Glacial sea level rise, sea levels are rising but slowly and consistently over the last 2000 years.

      OK, I did what you asked. Click on the Post Glacial sea level rise graph in that wikipedia article and you see it in more detail: https://en.wikipedia.org/wiki/... [wikipedia.org]
      Contradicting what you stated, the graph shows no sea level rise over the past 2000 years (although it doesn't have enough detail to show the most recent 30 years discussed in the article.)

    • Heating a planet is understandably hard. The temperature and effects of global warming that we are seeing today are the result of CO2 levels that were reached 75-100 years ago. Trying to warm a planet by adding greenhouse gases in the way that we are works, but the lag time on seeing effects is over many decades so it is not the most responsive way to heat a planet. So yes, averages for some effects over the long term do not seem too out of whack to us, but changes are coming. Another perspective: Sinc
      • The temperature and effects of global warming that we are seeing today are the result of CO2 levels that were reached 75-100 years ago.

        You have that entirely wrong. From a recent study [ametsoc.org], "In this paper, we aim to elucidate the mechanisms operating on time scales of hours to years to better understand the response of key climate quantities such as energy fluxes, temperature, and precipitation after a sudden increase in either carbon dioxide (CO2), black carbon (BC), or sulfate (SO4) aerosols. The results are based on idealized simulations from six global climate models. We find that the effect of changing ocean temperatures kicks in after a

        • The mass of the entire atmosphere is 1/5 the mass of just the ice of Antarctica. The atmosphere's long term average temperature is much more the result of heat exchange than it is the small changes in heat retention caused by instantaneous increased greenhouse gases. This is just basic physics and you are misinterpreting that paper you cite. The 75-100 years is because while we are trying to heat up this small mass, all of these other masses that it was once in equilibrium with are holding the temperatu
          • Again you're comparing apples to oranges. Here's is what you said in your original post:

            The temperature and effects of global warming that we are seeing today are the result of CO2 levels that were reached 75-100 years ago.

            That statement is entirely false. The temperature effects we're seeing today are primarily the result of greenhouse gas emissions in the last few decades, not ones from a century ago. If we had stopped emitting greenhouse gasses 75 years ago, the planet would be much cooler today.

            A completely different question is how long it takes to come to equilibrium. This article [mit.edu] gives a good discussion of that:

            In 2020, Sokolov was part of a team that studied a variety of scenarios in which CO2 emissions stop entirely in the near future. In most of the models used in their simulations, average global temperature stops rising after a couple of decades, but stays above the historical average for many centuries. A few models showed continued warming for decades or even centuries after the end of CO2 emissions, but they were in the minority.

            The reason temper

      • Sea level rise is happening, but it is one of least of the impacts of global warming that I worry about ... but then again I am over 100 miles from the ocean.

        If you were the only person around, that attitude would make sense, but lots of the people who live near the ocean or near a river near the ocean (which is actually a very significant percentage of us) are going to have to move. That's going to affect everyone, not just them/us. I live in Humboldt County, CA. Some whole communities here are threatened, like Ferndale, which is already pretty swampy. This area is also at risk of the land dropping significantly [lostcoastoutpost.com] due to the specific type of fault we have located

  • Trump/DOGE de-fund NOAA and w/o any data there won't be any problems -- like he hoped during COVID,

    "If we stop testing right now, we'd have very few cases, if any," Trump asserted.

    Google trump covid stop testing fewer cases [google.com]

    Science!

  • OK. you win (Score:4, Insightful)

    by OrangeTide ( 124937 ) on Saturday May 10, 2025 @11:55PM (#65367885) Homepage Journal

    You've trigger the libs. Go ahead and take a victory lap. Maybe take a nap.
    The rest of the adults are going to try and clean up this fucking mess.

  • What was sea level doing 2001 years ago? (And why is that data being ignored?)
    • by q_e_t ( 5104099 )
      In what way do you think it's being ignored?
      • by armada ( 553343 )
        Any time a timeframe of data is used to make a point you need to ask yourself "why did they pick the particular start date?" In the vast majority of cases it is because the data before the start date destroys the point they want to make. See for yourself and follow the claim to it's source and try to get the full picture.
        • by q_e_t ( 5104099 )

          In the vast majority of cases it is because the data before the start date destroys the point they want to make.

          That's not typically the case for climate scientists (maybe it's possible to find a handful of examples). If you have contrary evidence, for "the vast majority of cases", please provide it.

          See for yourself and follow the claim to it's source and try to get the full picture.

          It's an area of science I've been interested in for decades. I've even played around with some of the models. I know climate scientists. It's why I know that your characterisation above is incorrect.

          In terms of the paper, they had to stop somewhere. Since the model doesn't work well prior to 1000, then 0 seems to be a p

  • Plan ahead and buy a couple hundred yards away from ocean......wait long enough and be on the ocean !

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