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As rising oceans threaten NYC, study documents another risk: The city is sinking
- ars 3y agoThis was discussed before - this is a fake study. They did math and modeling, but neglected to actually measure anything. And they could have, long term GPS is accurate enough to do that.
- User23 3y agoAlso aren’t most landmasses in the northern hemisphere still rising due to the weight of the glaciers being gone?
- Gravityloss 3y agoIt's not so clear cut. In the South Baltic, Northern Germany is sinking while in the Gulf of Bothnia up north, ground is rising a lot because it's balancing or something. Or some parts of British Isles are rising while others are sinking. According to this, New York City looks to be relatively neutral: https://en.wikipedia.org/wiki/Post-glacial_rebound https://en.wikipedia.org/wiki/Post-glacial_rebound
- SoftTalker 3y agoThe crust of the earth is floating on liquid rock. It's constantly moving, rising, sinking.
- George83728 3y ago> The crust of the earth is floating on liquid rock. This is a common misconception. Molten magma under the crust only exists in a few places, the crust by and large rests on the mantle, which is solid. The mantle is extremely thick, but below it eventually is the outer core, which is liquid.
- SoftTalker 3y agoOK liquid was the wrong word. Maybe ductile? The point is the mantle moves under the crust, and this drives plate tectonics. The crust of the earth is constantly shifting, rising, falling. Subduction and all the geological processes that formed the arrangement of the land masses as we know them are still happening.
- User23 3y agoI think plastic is the term used in geology, but it’s been a long time since my undergrad. Ductile as I recall refers more to the ability to draw a material into wire.
- xyst 3y ago? > We show maps of observed deformation from InSAR and GPS data that demonstrate an average 1–2 mm/year subsidence rate across New York City (Figure 5), which is consistent with values calculated for post-glacial subsidence across much of the U.S. northeast coast These articles are referencing this study published earlier this month: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF003465 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF00... I’ll have to read it in depth later but seems the researchers modeled the “subsidence” and compared it with GPS data spanning at least a decade.
- ars 3y agoRead the other comments in the thread, and the last time this was posted. "which is consistent with values calculated for post-glacial subsidence across much of the U.S. northeast coast" Or in other words the entire east coast is moving, and the weight of the buildings in NY add nothing?
- woodruffw 3y agoI wish they'd actually link to the study. Most of NYC's skyscapers are in Manhattan, and are built in the areas where the Manhattan schist[1] is closest to the surface. The Bronx's geology is similar. Brooklyn and Queens don't benefit from the same geology, and have always had flooding problems. Those flooding problems are going to get worse with sea rise, but neither borough has the same density of skyrises that Manhattan does. It's not clear without the study whether they accounted for that. [1]: https://www.nycgovparks.org/parks/j-hood-wright-park/highlights/12369 https://www.nycgovparks.org/parks/j-hood-wright-park/highlig...
- xyst 3y agoCheck it out for yourself: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF003465 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF00...
- saalweachter 3y agoMy understanding is that Long Island (Brooklyn and Queens are the westernmost top of Long Island, for those not familiar with the local geography) is the remnants of the mountaintops of the Hudson Valley, that got scraped off during the last Ice Age and pushed into the ocean by the glaciers. Which means the whole island is essentially built on landfill.
- Animats 3y agoOh, that article again. Even the article says "In New York City, buildings that exert the most downward pressure are skyscrapers, but most of these are anchored to bedrock (e.g., Barr et al., 2011). Hard rock elastic compression occurs instantaneously after a load is applied, meaning we do not expect to see ongoing subsidence under some of the largest loads unless the bedrock is heavily fractured." Parts of the outer boroughs are on fill, and they seem to be taking data that includes those areas and extrapolating it to the whole city. There are cities and buildings in far worse shape. Venice, discussed yesterday, is about 400 meters above bedrock. SF's Millennium Tower was built on pilings that didn't go down to bedrock, and it is settling. It's places with shallow-slope river deltas that have the worst problems, because the ground is often sand and silt carried by the river and bedrock is a long way down. In the US, that's only New Orleans. Hong Kong, though...[1] China has several major river delta cities. Also, their map label for "Manhattan" is in New Jersey. [1] https://www.mdpi.com/2072-4292/10/11/1738/htm https://www.mdpi.com/2072-4292/10/11/1738/htm
- xyst 3y agoFWIW: this appears to be the referenced study in these news articles. I found this study from The Guardian: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF003465 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF00...
- bitxbitxbitcoin 3y agoIs it inaccurate to say that anywhere that is either adding weight above or reducing groundwater capacity below is sinking?
- walterbell 3y agoPrevious discussion, https://news.ycombinator.com/item?id=35983475 https://news.ycombinator.com/item?id=35983475 1-2 millimetres a year, or three quarters of an inch per decade, or two thirds of a foot per century.. This is a non-problem for Manhattan, which has bedrock not that far down across the entire island.. This is all based on the authors' estimations, not actual measurements or observations..
- bobthepanda 3y agoAll buildings subside, because we can’t inject concrete and rebar down into the earth’s core. So long as they do so evenly (so not like the Tower of Pisa) it’s not a massive problem. For alarming rates of ground subsidence, Mexico City subsides at 50cm a year and Jakarta at 25cm a year, due to excessive groundwater extraction.
- yownie 3y agojust watching this headline rattle around the internet the last week or so has been hilarious.
- jvandonsel 3y agoNo problem! The sinking of the city will counteract the rising of the ocean. Oh, wait...