[HN Gopher] Why is sea level rise worse in some places?
___________________________________________________________________
Why is sea level rise worse in some places?
Author : rbanffy
Score : 117 points
Date : 2023-04-11 12:45 UTC (10 hours ago)
(HTM) web link (nautil.us)
(TXT) w3m dump (nautil.us)
| akeck wrote:
| The affect of sea level rise on the Bay of Fundy is going to
| be... interesting.
| mdjasper wrote:
| I just looked up The Bay of Fundy on Google maps, having not
| heard of it before. I'm interested, can you explain what about
| this particular bay will make it interesting?
| ridgeguy wrote:
| Highest tidal range on the planet.
|
| https://en.wikipedia.org/wiki/Bay_of_Fundy
| Kon-Peki wrote:
| There's even a waterfall that reverses direction based on
| the tides!
| timbit42 wrote:
| Reversing Falls:
| https://en.wikipedia.org/wiki/Reversing_Falls
|
| Also mentioned by Tom Scott:
| https://www.youtube.com/watch?v=nCrTsWtPVIY
| akeck wrote:
| Yes. I've seen its tides in person. It's almost unreal.
| Boats go from sitting on their sides on dry land to
| floating in 3+m of water and back every tidal cycle.
| roelschroeven wrote:
| At first I was thinking that that doesn't sound all that
| unusual; here near Antwerp, Belgium we also have tides
| high enough that small boats can go from sitting dry to
| floating clear. But then I looked it up and it turns out
| that the tidal range in the Bay of Fundy is about 16
| metres (52 feet)! That really is a lot, and much more
| than the about 5.5 metres we have here.
| PeterWhittaker wrote:
| Yes, and it is always COLD. (Newly engaged I took my
| fiancee to a beach west of Saint John and decided to go for
| a swim. I mean, I should have known better, I grew up
| there. It was a shallow slope, so by the time it was deep
| enough to dive in, I couldn't feel my ankles. It was a
| short swim. It's not like I was going to wimp out and turn
| back in front of my sweetie. Ah, the pride of youth.)
|
| Re the tides: when Charles ame Diana visited NB in 1983,
| they disembarked at high tide in the Saint John harbour.
| The gangplank was at about 45 degrees, slopes down to the
| dock. A few hours later, it was 45 degrees down to the
| royal yacht. Some of the sailors, many of whom had long
| experience, having served in the falklands, among other
| places, had never seen anything like it.
| BoxOfRain wrote:
| Interestingly there can be similarly large tides in the
| UK, the Severn Estuary has a range of around 50' too.
| timbit42 wrote:
| Tom Scott at the Bay of Fundy:
| https://www.youtube.com/watch?v=nCrTsWtPVIY
| jdontillman wrote:
| (Largest tides on the planet. The bay acts as a kind of
| resonant organ pipe amplifying the tides on the Atlantic
| Ocean.)
|
| Hey; if they can handle 52ft tides, they can handle anything.
| stochtastic wrote:
| This article only briefly touches on what I think is the most
| interesting aspect of sea level rise: gravitational adjustment.
| Even though I never worked seriously on sea level research, it
| was by far my favorite course in graduate school. For anyone who
| would like to learn more, I highly recommend listening to Jerry
| Mitrovica expound on the subject [1]. I guarantee that you will
| learn a few things that will stick with you.
|
| In my experience, the first order adjustment effects are not
| widely known even among physical oceanographers. I remember
| describing it to a preeminent expert on El Nino, and him being
| incredulous that local sea level fall near the source of
| meltwater could be the first-order effect beyond accounting for
| rebound. "The first-order response is a Kelvin wave -- you've
| surely been misinformed."
|
| [1] - One example lecture:
| https://www.youtube.com/watch?v=s_rGksRoG9A
|
| [2] - Another, shorter summary talk
| https://www.youtube.com/watch?v=yj7JIxU9Af4
| donatj wrote:
| > If we look at the global picture, there are two major reasons
| why sea levels are rising. One is that the ocean is warming, and
| it needs more space and expands.
|
| My understanding is that water expands quite a bit less in the
| range between 32degF and 212degF than it does when it freezes.
|
| It seems like floating ice melting and decreasing in volume 9% is
| notably more significant than the volume increase from a couple
| degree temperature increase. There also certainly way more liquid
| water than solid to contend with.
|
| I'd be curious to know the effect of melting ice decreasing the
| volume versus the temperature rising increasing the volume.
| stochtastic wrote:
| Archimedes would like a word. There are some small effects due
| mostly to salinity differences, but sea ice isn't a major
| contributor because it is already floating and thus displacing
| an equivalent volume of water:
|
| https://en.wikipedia.org/wiki/Sea_level_rise#cite_ref-113
| hinkley wrote:
| Sea ice also reflects light. Remove the ice and the water
| beneath heats up.
|
| That's part of the runaway effect we are freaked out about.
| wanderinghogan wrote:
| It's wild how locally variable the sea level surface is. I worked
| on a study that incorporated local sea levels into a bath-tub
| style sea level rise model that that also incorporated storm
| surge using ADCIRC modeling, and we tried to account for local
| land subsidence and uplift rates... anyways.
|
| If you look at the "NOAA Tides and Currents" data, and go to
| Maryland, and click two points across the Chesapeake bay from
| each other. Go to More Data > Datum, you can see just across a 20
| mile stretch of bay, Bishops Head MD MHHW (Mean Higher High
| Water, when there are two daily high tides, this is the elevation
| of the higher of the two) is 2.06 Feet over the vertical datum,
| while 20 miles away at Solomons Island MD it's a half foot lower,
| 1.48 Ft.
| balderdash wrote:
| On a smaller body of water is that mostly wind?
| [deleted]
| BigCryo wrote:
| Because overall it has not risen at all?
| consumer451 wrote:
| Last I looked at the data, sea levels in Key West had risen by
| around one foot in the last hundred years.
| thombat wrote:
| For that to be true there would be plenty of places where it's
| falling. Are there?
| flavius29663 wrote:
| there absolutely are, a google away
| https://tidesandcurrents.noaa.gov/sltrends/
|
| But they are generally rising, just not more than compared
| with pre-industrial era.
| ohdearno wrote:
| I mean, "plenty" isn't really true based on that link.
|
| A best you could say "a few, in areas that are losing
| glaciers, which is expected due to basic physics"
| ohdearno wrote:
| It's risen ~97mm since 1993. The rate of increase in that rise
| has been increasing steadily since ~1993. The consistency of
| our data has also been much better since then (previously it
| was only the highly noisy coastal tide gauge data).
|
| Fun fact: the slowest its been in the last century was when we
| did a crap-ton of dam projects in the 50s-70s, still rose, but
| very little.
| rcme wrote:
| There are other factors, too. I remember reading about sea level
| change as a result of Greenland's ice melting. The sea level
| around Greenland is actually predicted to go down. One reason is
| that the ice is pushing the land down, and that effect will
| reverse as the ice melts. The other surprising reason is that the
| ice is massive enough to have a noticeable gravitational effect
| on the surrounding water.
|
| https://www.theguardian.com/environment/ng-interactive/2018/...
| tannhaeuser wrote:
| That's exactly what TFA is explaining.
| tonmoy wrote:
| This is literally two of the three things the article talks
| about.
| ohdearno wrote:
| Yeah, and that's good locally, but _globally_ we see a rise
| overall.
| HPsquared wrote:
| Seems we are missing "Land level rise" and "Land level fall".
| Those will be more patchy and local than sea level.
| joseph_grobbles wrote:
| [dead]
| Cthulhu_ wrote:
| Fun random factoid, big parts of Europe are still slowly rising
| because the weight of ice compressed a lot of it.
|
| On the other side, a lot of land is sinking because the soil is
| drying out due to years of droughts and water mismanagement
| (farmers like to keep the water table lower. I live in NL where
| we have the water management infrastructure to tweak the water
| table)
| arethuza wrote:
| Post glacial rebound:
|
| https://en.wikipedia.org/wiki/Post-glacial_rebound
| GrumpyNl wrote:
| When the soil is drying out, it will start to float. Im from
| Boskoop in NL, we have that problem with peat soil (veen
| grond). This is also irreversible, when peat soil gets dried
| it will not become wet again.
| ceejayoz wrote:
| > On the other side, a lot of land is sinking because the
| soil is drying out due to years of droughts and water
| mismanagement...
|
| Shockingly fast, too, in some spots.
|
| https://www.nytimes.com/2021/05/25/us/corcoran-california-
| si...
|
| "Over the past 14 years, the town has sunk as much as 11.5
| feet in some places..."
| morkalork wrote:
| Same thing happened in Vermont with some of the evidence for
| it being whale skeletons found in fields hundreds of miles
| from the ocean: https://en.wikipedia.org/wiki/Charlotte_whale
| justsocrateasin wrote:
| Seeing a lot of people talk about how the density of water is
| going to change with a temperature change. I don't really think
| that's true. Liquid water density is pretty darn inelastic and
| almost fully incompressible. It's one of the reasons hydraulics
| works. Ice on the other hand has a pretty different density.
|
| Water density table - https://www.usgs.gov/special-topics/water-
| science-school/sci...
|
| If the temperature of the ocean changed by 10degF that would
| result in a .1% change in overall volume. Obviously that does
| make a difference because the ocean is so big, but it's a lot
| less consequential than ice, which is above the water, melting
| into the water and ice.
| kybernetikos wrote:
| But if the ice is floating, it should displace the same volume
| of water that it will melt into.
| nemo44x wrote:
| It's amazing how many people don't understand this. It
| displaces the same amount of water whether it is frozen and
| floating or melted. Easily tested by filling a glass with
| water and adding an ice cube and then drawing a line at the
| water level and letting the ice melt. The water level will be
| the same.
|
| Of course, if the ice is on land and melting into the ocean,
| that's different.
| somenameforme wrote:
| Kind of a nitpick but glaciers are made of less dense fresh
| water compared to the salt water of the ocean. So melting
| glaciers will _slightly_ increase sea levels.
| SapporoChris wrote:
| Oh hey, what about the difference in density between fresh
| water and salt water?
|
| https://nsidc.org/news-analyses/news-stories/melting-
| floatin...
| WeylandYutani wrote:
| The Netherlands is also sinking so you get a double whammy.
| spacetime_cmplx wrote:
| I have two related questions:
|
| 1. Global temperature is rising. Any water that used to be above
| 4degC (or the equivalent for salt water) now takes more volume.
| But what about water that's below 4degC? Wouldn't that water
| compress? What portion of the ocean is colder than 4degC? I'd
| imagine all of the Arctic zone and near Antarctica is, which is
| an awful lot of water to offset the tropical water. An even more
| nuanced perspective would be to look at the actual temperature
| distribution and use it to weight the dV/dT of water at different
| temperatures.
|
| 2. Global temperature is rising. Ice is melting into water. This
| is new mass entering the ocean. Why can't the sea bed, which is
| under more pressure due to extra mass, expand? The sea bed isn't
| a steel utensil, it's sand and rocks. And it's constantly
| shifting. And it's composition is different in different regions.
|
| Has anyone done a detailed computer simulation of the whole
| earth's geology under rising temperatures? There might be
| feedback loops that might amplify or negate some effects so it's
| quite important to account for all variables. And obviously
| there's a lot of variables to account for.
|
| (It's sometimes scary how little we know about our own planet.
| I'm not talking about the things in my comment because I'm sure
| it's just my ignorance.)
| Timon3 wrote:
| > 1. Global temperature is rising. Any water that used to be
| above 4degC (or the equivalent for salt water) now takes more
| volume. But what about water that's below 4degC? Wouldn't that
| water compress?
|
| It might marginally, but the amount of water compressed will be
| a lot smaller than the amount of water "uncompressed", both due
| to the larger range of temperatures above 4degC (below is only
| a bit, and then ice) and due to the fact that the densest water
| is at the bottom, meaning that it's easier for everything else
| to heat up.
|
| > 2. Global temperature is rising. Ice is melting into water.
| This is new mass entering the ocean. Why can't the sea bed,
| which is under more pressure due to extra mass, expand?
|
| Expand _where_? It can 't just rise since there is gravity, and
| the pressure above increases with more water. It can't go down
| because there is already other stuff there.
| spacetime_cmplx wrote:
| >Expand where?
|
| Think of the ocean bed as a trampoline. Obviously much more
| rigid, but that's the image in my head.
|
| >It can't go down because there is already other stuff there.
|
| Why not? Rocks and sand can be compressed with sufficient
| pressure.
| friend_and_foe wrote:
| In regard to that last point, I hadn't thought of it but
| there is something called post-glacial rebound, it would make
| sense that the increased weight on the seabed would _deform_
| it, and potentially even cause bulging of land without ocean
| on top, potentially negating the sea level rise effect to
| varying degrees worldwide.
| slackfan wrote:
| Reminder that Ice takes up more volume than water.
| spacetime_cmplx wrote:
| I know, did I say otherwise anywhere?
| marcosdumay wrote:
| > Wouldn't that water compress?
|
| You say it because of the extra volume on top of it?
|
| If that's the case, not because of heating. The volume
| increases, the water still weights the same.
| spacetime_cmplx wrote:
| No, water is most dense at 4degC. If you take water at 2degC
| and increase its temperature by a degree, it will _compress_,
| not expand. But if you take water at 10degC and heat it by a
| degree it will expand. My question is what percentage of the
| expansion is offset by the compression.
|
| (Note that the 4degC number is only for pure water.)
|
| > water still weights the same
|
| Weight has nothing to do with my first point. It's the
| increase in volume that spills into land.
| adgjlsfhk1 wrote:
| the key point is that there is very little water below 4
| Celsius because it would rise into warmer water and heat up.
| jdontillman wrote:
| The NOAA Sea Level Trends data and visualizations are
| fascinating:
|
| https://tidesandcurrents.noaa.gov/sltrends/
|
| Sea levels have been monitored for over 100 years... because of
| commerce.
|
| East coast US seems to be going up about 3mm/year, or a foot per
| century. That's on top of 7 foot tides.
|
| West coast US is very steady, barely moving at all.
|
| The sea level is dropping in Alaska by 10mm/year. Dropping in
| Scandinavia also.
|
| Some cities show rising sea levels, but really the cities are
| sinking due to collapsing aquifers; New Orleans and Bangkok. And
| measurements made on river deltas are always going to be wild due
| to silt and all.
|
| Most notably, I can't find an example in the NOAA data of the
| rate of sea level rise increasing due to industrialization.
| Anybody?
| arethuza wrote:
| Isn't that _relative_ sea level changes in places like
| Scandinavia - the sea isn 't dropping, the land is rising?
|
| https://en.wikipedia.org/wiki/Relative_sea_level
| BurningFrog wrote:
| Yeah, the sea must be "level" in some sense across the
| planet.
|
| Don't know if local variations in gravity may have a
| measurable impact?
| beerandt wrote:
| The absolute value of gravity _is_ (to oversimplify) the
| sea-level datum for current generation datums, like the
| delayed NGS (nominal year) 2022 datums.
|
| They've (NGS) been flying absolute gravity measurement
| equipment in planes with precision GPS and lidar since
| ~2005 as part of the GRAV-D program.
|
| Additionally, slight 'variations' (ie deviations from the
| expected circular/elliptical) in the orbits of GPS
| satellites can be used to infer slight variations in the
| gravity below.
|
| Separately, the military likely has had all of this
| measured and modeled for decades as part of ballistic
| missile targeting, but remains mostly classified at useful
| resolutions.
|
| The transitions from NGVD27 to NAVD88 to the work-in-
| progress 22 datum is exactly because the idea of a simple
| "universal" sea-level doesn't exist in the manor you would
| expect it to.
|
| But even with the GRAV-D based datums, the actual observed
| water levels will occur at slightly different datum heights
| in different locations, for various geophysical reasons.
| CorrectHorseBat wrote:
| The melting of glaciers themselves can have an impact on
| gravity, causing water levels to drop around them.
| https://www.theguardian.com/environment/ng-
| interactive/2018/...
| cwillu wrote:
| PDF of gravitational correction factors by geographical
| region for use in theoretical weighscale calibration (vs
| calibrating with actual test weights): https://hardyinst.cu
| sthelp.com/app/answers/detail/a_id/1588/...
| [deleted]
| jdontillman wrote:
| Exactly.
|
| Because the sensors are mounted on that very land.
|
| So tectonic movement will certainly have an effect. And you
| can see remnants of earthquakes in some of the data.
| AnimalMuppet wrote:
| In Scandinavia, isn't it glacial rebound rather than
| tectonic?
| bell-cot wrote:
| > 3. (geology) Of, relating to, or caused by large-scale
| movements of the Earth's (or a similar planet's)
| lithosphere
|
| - https://en.wiktionary.org/wiki/tectonic
| LeifCarrotson wrote:
| I expect the parent is referring to human-caused melting
| of glaciers as the root cause of that tectonic movement,
| rather than the expected natural motion of the tectonic
| plates.
| Scarblac wrote:
| It's the glaciers melting at the end of the last Ice Age
| that Scandinavia is still rising from.
|
| https://en.wikipedia.org/wiki/Last_Glacial_Period#Weichse
| lia...
|
| > As a result of melting ice, the land has continued to
| rise yearly in Scandinavia, mostly in northern Sweden and
| Finland, where the land is rising at a rate of as much as
| 8-9 mm per year, or 1 m in 100 years. This is important
| for archaeologists, since a site that was coastal in the
| Nordic Stone Age now is inland and can be dated by its
| relative distance from the present shore.
| mc32 wrote:
| I think the arctic region is affected by glacial rebound: the
| ground slowly recovers from past glacial compression.
|
| Subsidence is a thing in Silicon Valley. San Jose has sunk some
| feet since the aquifer was drawn, fist for agriculture and now
| urbanization.
| twawaaay wrote:
| There is only one reason the sea can rise currently due to
| weather and that is glaciers getting melted.
|
| Another reason (but not due to weather) is that when land
| somewhere goes up, it will displace water everywhere else. And
| so, for example, if the land is still recovering from the ice
| age we should see ocean levels going up everywhere except for
| the pieces of land that are recovering from the weight of the
| glacier that is no longer there.
|
| Mind that Arctic is not causing sea level rise. Any ice that is
| floating on water will not cause any water level change when it
| melts. (I know this is somewhat unintuitive but it comes
| directly from Archimedes principle)
|
| So we are talking basically Antarctic ice and Greenland because
| these are by far the largest bodies of frozen water that are
| supported by land rather than floating on the ocean.
|
| I think it should be pretty easy to observe how much of that
| water melted or slipped into the sea.
|
| I also think that currently, coastal erosion is mostly caused
| by changing weather patterns. Basically this comes down to wind
| blowing in different directions, speed and variety and these
| changing patterns mean coasts are eroding in different places
| than before.
| locopati wrote:
| Also, warming oceans causes expansion which causes sea level
| rise.
|
| https://www.jpl.nasa.gov/edu/learn/project/how-warming-
| water....
| twawaaay wrote:
| Not true.
|
| First of all, most of the temperature rise only happening
| close to the surface with average surface temperature rise
| being only about 1.5F or 1C since 1901.
|
| This article says deep ocean water is projected to warm up
| by only 0.2C during next 50 years:
| https://www.openaccessgovernment.org/deep-ocean-warming-
| subt...
|
| Furthermore, at around 4C which is what deep ocean water is
| close to (everything below 200m is essentially 4C), thermal
| expansion is almost nil. For colder water thermal expansion
| is actually negative.
|
| 4C is when water is at its densest. It is not an accident
| that all oceans are 4C, because 4C water sinks to the
| bottom and anything colder or hotter than 4C floats up.
| This remarkable property of water is what causes even
| shallow water to be fantastically stable in temperature --
| a lake that has more than couple tens of meters in depth is
| likely to be 4C at the bottom throughout the year whether
| it is frosty winter or hot summer above it, unless some
| kind of powerful event is able to mix the water in the
| lake.
|
| Now, the small temperature differences will definitely have
| outsize effects on water circulation, ocean currents, life
| and weather. But I doubt they will cause meaningful sea
| rise unless somebody can calculate otherwise?
| mcguire wrote:
| The average ocean surface temperature is about 20degC and
| the thermal expansion coefficient is 0.000207/degC
| (https://www.engineeringtoolbox.com/water-density-
| specific-we...). If I have my google-fu and math right,
| that's about 1cm/deg for a 50m deep water column.
|
| Thermal expansion of surface water is not negligible.
| Tuna-Fish wrote:
| > But I doubt they will cause meaningful sea rise unless
| somebody can calculate otherwise?
|
| Plenty of people have, in fact, calculated otherwise.
|
| Roughly half of the current, ongoing sea level rise is
| from expansion of water. The effect is small, but there
| is a lot of water that is expanding.
| [deleted]
| jdontillman wrote:
| Fascinating; thanks.
|
| Question: How does the salinity and pressure of deep sea
| water affect that 4C point?
| Retric wrote:
| That's mostly accurate, but the nuances are significant
| and lead to different conclusions. For example the
| hypolimnion may be much warmer than 4C in lakes in warmer
| areas. More importantly tropical ocean water is above 4C
| down to roughly 2km and not only is that depth expected
| to increase, but also the depth of warm water as you go
| north. https://en.wikipedia.org/wiki/Thermocline
|
| The important thing to remember is even a 1 part in 1,000
| decrease in density * 2km of depth = 2m of expansion.
| Ballpark estimates aren't enough you really need fairly
| detailed simulations to get any significant accuracy.
| Actually doing such simulations shows meaningful sea
| level rise from thermal expansion at ~0.07 inches per
| year or roughly half the current rate of increase. This
| might not sound like much, but consider that volume of
| sand you need to replace to maintain beaches etc etc.
| kergonath wrote:
| > That's mostly accurate
|
| No, that is mostly inaccurate. Thermal expansion is
| small, but there is an awful lot of water. As you point
| out yourself, thermal expansion contributes about half
| the sea level rise. Oceans absorb energy just like the
| atmosphere does and this effect has been known for quite
| a while (e.g. https://www.nature.com/articles/330127a0 ).
| atlantic wrote:
| Not necessarily. The density of water peaks around 4oC. So
| as oceans warm between 0o and 4o, they actually contract in
| volume.
| twawaaay wrote:
| Except water in oceans is _at_ 4C (at least almost
| everything deeper than ca 200m). And in the vicinity of
| 4C the thermal expansion is very negligible. This graph
| should explain why:
| https://images.app.goo.gl/FXzvTkPvE9dYxoUA7
| withinboredom wrote:
| Umm. I'm pretty sure if water that exists above the water
| line is melted into the water line, the overall water line
| will rise. You can directly observe this in a glass of ice
| that starts with no liquid water will melt into a glass of
| liquid water.
| brilee wrote:
| This is untrue.
|
| Ice is about 91% the density of water. If you have water at
| 0 height, and you put in water equivalent to +1 unit of
| height. If it's in liquid form, obviously height goes up by
| +1. If it's in ice form, there is +1.09 height worth of ice
| (because it expands when it freezes), but it only displaces
| water up to +1 unit of height in order to support its
| weight through buoyancy. The overall change in height is +1
| unit regardless of whether it's liquid or ice
| nrclark wrote:
| I could be wrong about this (it's been awhile since I took
| chemistry), but I think the ice has to be floating for the
| Archimedes principle to apply.
|
| You can fill a glass of ice-water right up to the brim, and
| it won't spill over as the ice melts. But only if the ice
| is floating in the water. It's because the ice's mass
| pushes down on the liquid water, displacing a fixed amount
| relative to the weight of the ice.
| withinboredom wrote:
| Ah. I missed the "floating" part. That makes sense.
| trompetenaccoun wrote:
| No, it's not just due to weather (you probably mean climate
| anyway). For example, ice melting in one place, say
| Antarctica, will affect sea levels elsewhere on the planet
| because of weaker gravitational forces where the ice used to
| be. Geoscience is complex and measuring changes on such a
| global scale is not "pretty easy", even if it's only sea
| level changes. It's nothing like a bathtub or elementary
| school physics.
|
| Not to rant but this is one of those threads again. The
| majority of comments contain misinformation.
| margalabargala wrote:
| > East coast US seems to be going up about 3mm/year, or a foot
| per century. That's on top of 7 foot tides.
|
| That's the average rise it you average all data going back to
| the 1950s.
|
| Unfortunately, looking back to the 50s is only really useful if
| interested in how much sea levels have already risen. Otherwise
| it presents an unrealistically optimistic view, as the rate has
| accelerated since.
|
| Per the article, the east coast (North Carolina) is currently
| experiencing an increase of about a third of an inch per year,
| which is an increase of one foot per 36 years, or close to a
| meter per century.
|
| If current trends continue, this will accelerate, not
| decelerate.
| jessewmc wrote:
| Your unit mixtures hurt my brain
| revelio wrote:
| [flagged]
| detrites wrote:
| I'm old enough to remember we were all _" science"_ supposed
| to be _entirely underwater_ by now. Yet here we are quibbling
| about millimetres? First it was "the coming ice age", then
| "global warming", now its "climate change".
|
| What's next? The "millimetre sea-level imbalance
| catastrophe"?
|
| I'm over it. I've lost my respect for climate science, and
| the field _has done that to itself_. It needs to take full
| responsibility for its repeating cycle of "alarmism ->
| failed prediction -> u-turn" that caused me to.
| ohdearno wrote:
| > I'm old enough to remember we were all "science" supposed
| to be entirely underwater by now.
|
| The _science_ never really said that. Bad PopSci reporting
| did. The science said that was a worst case _possibility_.
| Kind of "if we do the worst things possible as much as
| possible, then this is the worst case scenario".
|
| Then you read hacks--and paid disinformation spreaders,
| which we have documentation of various oil companies in
| particular doing I might add--reporting that as if it was a
| sure thing. Because clickbait isn't a new concept.
|
| Also - we actually DID change what we did. We did things
| like ban CFCs, etc. It made a significant difference to
| models! Hooray us for doing the bare minimum.
|
| We're not quibbling over millimeters, not unless you're
| completely misunderstanding or misrepresenting the topic
| anyhow. We're pointing out the _rate of change is
| increasing_ and we haven 't even seen the worst case
| effects yet (like CO2 release from the oceans, Greenland
| melting, etc).
|
| The global temperature is going up, rapidly, and we're at
| the point were these effects are already starting to be
| seen. That's... a tipping point.
| revelio wrote:
| Unfortunately, if we take what prestigious climatologists
| have said as "the science" then you're wrong. They have
| in fact said exactly that. Here's just two examples, of
| many.
|
| James Hansen is perhaps the most famous climatologist, he
| worked at NASA and testified to Congress about global
| warming at the end of the 1980s. Back then he was telling
| people that by ~2010 highways in New York would be
| underwater, there'd be tape on the windows due to high
| winds and that crime would have increased due to the
| heat.
|
| https://web.archive.org/web/20110202162233/https://www.sa
| lon...
|
| Not that it might happen, or there was a worst case
| possibility that it would happen. That it would
| definitely happen.
|
| None of that occurred (and in fact crime in New York went
| down a lot) but he didn't learn anything. Here he is in
| 2008. "Hansen, echoing work by other scientists, said
| that in five to 10 years the Arctic will be free of ice
| in the summer".
|
| https://news.google.com/newspapers?nid=1988&dat=20080624&
| id=...
|
| It's now 35 years after his first prediction and 15 years
| after his second. New York isn't under water and the
| Arctic isn't ice free in the summer.
|
| When people claim that scientists never get it wrong,
| that when people remember bad predictions it actually
| never happened and if it did it was all the journalist's
| fault, then they are making the problem worse because it
| teaches scientists that they can be wrong without
| consequence, that people will side with them over the
| journalists who in most cases were directly quoting what
| they had said.
| ohdearno wrote:
| If you don't know the difference between "the science"
| and "one scientists statement" then... well, you don't
| know what science is, sorry.
|
| That said, you did _exactly_ what I described originally:
| took bad reporting of statements and presented them as
| factual. Thanks for demonstrating it so well.
|
| Firstly, his 1980s testimony talked about worst case
| scenarios. That was one of them. As I said previously.
| His 1988 speech and report to congress says _no such
| thing_ about New York, neither does your linked article.
| What it says is that, in conversation with another
| person, he discussed that as a possible outcome (or
| perhaps a likely one, if we didn 't change course
| somewhat... which we did). 3rd hand reporting of his
| words without ANY context. But you took it as fact and
| repeated it as such.
|
| Secondly, that newspaper article doesn't quote him for
| your statement about the arctic sea ice, it simply
| alludes to it being something he said. With no quote and
| context we can't know what he actually was talking about,
| just how the journalist took it and decided to summarize
| it. Again, see the previous post for where I talked about
| this.
|
| However, it is worth noting that, since satellites first
| began monitoring the Arctic in 1979, the average area
| covered by sea ice has shrunk by at least 40%. The past
| 15 years have seen the 15 lowest summer sea ice minimums
| on record. It's entirely likely he was, again, talking
| about worst case (or simply just bad) scenarios. It's
| also possible he was talking about point-of-no-return
| (which some believe we may have reached with arctic ice,
| as it's almost all 'young' ice now).
|
| We can't know, it's not reported. What we _do_ know
| thought is that what you said is false.
|
| Again, thanks for _perfectly_ demonstrating my point. I
| urge you to actually look into the sources rather than
| reading PopSci reporting. It will help you to not make
| these mistakes again.
| revelio wrote:
| _> > perhaps a likely one, if we didn't change course
| somewhat... which we did_
|
| We didn't. CO2 has continuously risen and the rise
| accelerated with time. Hansen's predictions should
| therefore have absolutely come true if he was right, but
| they didn't. Or do you think the graph of CO2 I showed
| you in the other post is misleading as well?
|
| W.R.T. the quotes, now you're getting really desperate.
| Sure, sure, those poor innocent scientists keep getting
| ascribed word-for-word predictions they never made and
| they're all just too polite to complain about having
| words put in their mouth like that. Come on, wake up! He
| wasn't being misquoted. Here he is in another 2008
| article _written by himself_ in which he makes exactly
| the same prediction:
|
| https://www.theguardian.com/environment/2008/jun/23/clima
| tec...
|
| _" As a result, without any additional greenhouse gases,
| the Arctic soon will be ice-free in the summer."_
|
| Lots more CO2 was added, 15 years passed, the Arctic is
| not ice free. Nor are ice levels falling. Here's the data
| from Hanen's own former employer showing that summer ice
| sea levels stabilized around 2010, which should not have
| been possible according to these people:
|
| https://climate.nasa.gov/vital-signs/arctic-sea-ice/
| autoexec wrote:
| It's pretty telling that all you've linked to are news
| stories with zero direct quotes about underwater highways
| or an "ice free arctic" and very little context to the
| alleged claims.
|
| The point being made, that many people have been largely
| misinformed about the science and what it predicts by
| media that misrepresented those things, still stands. The
| good news though is that even if James Hansen did run
| around telling everyone wild theories (and some argue
| that many of his predictions have held up remarkably well
| https://www.theguardian.com/environment/climate-
| consensus-97...) we don't have to depend on anyone's
| comments to the press, there is actual research being
| reviewed, modeled, and reassessed constantly that just
| doesn't get the attention alarmist news stories or
| interviews by authors trying to cash in on climate fear
| will generate.
|
| That isn't to say that scientists don't get things wrong.
| Some scientists are just plain bad at their job, some
| scientists get paid to falsify data and bury results
| unfavorable to the person signing their paychecks, and
| some just make mistakes, and those are all things we
| should be working to minimize, but I'd be shocked if our
| best understanding of the impacts of our changing climate
| hadn't changed several times over the last 35 years.
|
| Scientists getting things wrong isn't some gotcha that
| proves science is broken, it shows that science is
| working. Getting things wrongs is just one step of the
| process. All science does is provide the tools to give us
| the best understanding of something we can get with the
| information we have at the time. The more we learn, the
| more data we have, the more our understanding will change
| and evolve. People don't like uncertainty and some might
| wish science was all about dictating indisputable truths
| that cannot be wrong or questioned, but that's never been
| what science does or what it's for.
| revelio wrote:
| _> > Scientists getting things wrong isn't some gotcha
| that proves science is broken, it shows that science is
| working._
|
| See this is the attitude that causes people to give up in
| disgust:
|
| If scientists make correct predictions, that's science
| working!
|
| If scientists make wrong predictions, that's also science
| working!
|
| Literally no matter what they do or what happens, they
| cannot lose.
|
| _> > People don't like uncertainty_
|
| People are fine with scientific understanding being
| uncertain. They are not fine with being told by
| scientists that The Science is so certain it's
| undisputable, that the only people who disagree are paid
| to do so, that the world should undergo massive changes
| on the back of this 100% certain science and then when
| their predictions are all invalidated it's "hey, being
| wrong is all just part of the process, if you don't
| understand that you don't understand science!".
|
| If scientists make a confident prediction and then turn
| out to have been woefully misjudging their own
| competence, it is correct and right that their
| reputations are trashed and they should get defunded. But
| that doesn't happen. Instead we get the Believe Science
| brigade who insist that all those bad predictions never
| happened, if they did happen it wasn't a problem and
| anyone saying otherwise needs to be suppressed.
|
| And BTW both quotes come with literally an entire article
| of context, and Hansen wrote a whole article for the
| Guardian in which he makes the same predictions about
| Arctic ice. So please don't try to claim he never said
| these things. He's on record as doing so, many times in
| many contexts.
| revelio wrote:
| Yeah. A great example of the corruption problem is the
| story of Tuvalu. Here's a research paper from 2018 that
| looked at the size of the islands using radar data:
|
| https://www.nature.com/articles/s41467-018-02954-1
|
| It starts by saying:
|
| _" Sea-level rise and climatic change threaten the
| existence of atoll nations. Inundation and erosion are
| expected to render islands uninhabitable over the next
| century, forcing human migration"_
|
| but then just two sentences later:
|
| _" Results highlight a net increase in land area in Tuvalu
| of 73.5 ha (2.9%) [in the past 40 years], despite sea-level
| rise, and land area increase in eight of nine atolls"_
|
| Tuvalu got bigger! It goes on to explain that Tuvalu has
| grown due to other factors that were not previously
| considered. Yet the field is so corrupt that a paper
| literally reporting that Pacific islands are getting bigger
| has to start by repeating the claim that those very same
| islands will be "inundated" and "rendered uninhabitable".
| It goes on to argue that maybe the biggest problems the
| islands face is not climate change per se but rather "the
| historic imprint of colonial agendas and entrenched land
| tenure systems".
|
| That was in 2018. It had no effect on the narrative
| whatsoever. In 2019 the Guardian wrote a huge story telling
| its readers that Tuvalu is going to be drowned by climate
| change and how angry they are at Donald Trump because in
| future they'll have to evacuate their homes:
|
| https://www.theguardian.com/global-
| development/2019/may/16/o...
|
| _"Tuvalu is sinking" is the local catch-all phrase for the
| effects of climate change on this tiny island archipelago
| on the frontline of global warming._
|
| The entire story is misinformation, but you'd never know
| that if you didn't double check these things and the
| Guardian not only never will but actively tells its readers
| that people who do double check are evil.
| Sakos wrote:
| I've lost my respect for people like you who'd rather deny
| the very real effect climate change is having and will have
| on hundreds of millions of people.
| magicalist wrote:
| > _Careful man! You 're on the verge of becoming a climate
| denier with research like that! Sea level rise is indeed not
| due to CO2 or industrialization. Here's a graph of what's
| claimed to be long term sea levels:_
|
| > https://commons.wikimedia.org/wiki/File:Post-
| Glacial_Sea_Lev...
|
| Not super helpful to post a graph where the era we're talking
| about is like 7 pixels wide using a line of about the same
| thickness.
| revelio wrote:
| It shows that the claim that sea level rise is caused by
| CO2 isn't correct, which is relevant.
| ohdearno wrote:
| It shows nothing of the sort. It shows that melting
| glacial ice causes rising sea levels. That is all it
| shows. We know that.
|
| Guess what (eventually) causes glacial ice to melt? CO2.
| revelio wrote:
| Here's a graph of sea level rise since 1900 plotted
| against CO2:
|
| https://dailysceptic.org/wp-
| content/uploads/2022/09/image-56...
|
| No correlation.
| ohdearno wrote:
| You... really have no idea how to read that graph, do
| you? Or what a lagging indicator is, I'm guessing.
|
| The fact is - we can see the rate of change of the sea
| levels start changing in the mid-90s, though the graph
| you're using compresses the Y-axis to minimize how
| obvious that is (deliberately, I'd say, given the
| source).
|
| Which, given its a lagging indicator of the result of
| rising CO2, makes sense it would happen after.
|
| So, even accounting for the dishonesty of the
| presentation (and make no mistake, it's VERY dishonest)
| it actually demonstrates the exact opposite of what you
| claim.
| revelio wrote:
| The graph shows clearly that sea level rise did not
| change at that location, and thus cannot demonstrate the
| exact opposite of what I claim. The Y axis isn't
| particularly compressed and changing it wouldn't reveal
| anything, as should be clear from looking at it. But feel
| free to replot that gauge with a different Y axis and
| show us the results if you like.
|
| Your belief that sea level rise accelerated in the 90s
| comes from splicing of two divergent datasets. Up until
| the 90s sea levels were tracked with tide gauges which
| say ~1.5mm a year on average although it varies depending
| on measurement point. At the start of the 90s TOPEX-1
| started tracking sea levels from space, but the rate of
| rise measured by satellites was 2x the rate as measured
| from the ground. Rather than resolve this disagreement
| they simply cut to the satellite data from the tide gauge
| data and pronounced the discontinuity an "acceleration".
| amelius wrote:
| What I wonder about is: rising wrt. what? Did they take into
| the account the possibly vertical movement of tectonic plates?
| revelio wrote:
| They do take that into account. They calculate that the ocean
| floor is sinking but then ADD that displacement to their
| reported measurement of "sea level", which is backwards. When
| the ocean floor sinks sea level goes down, but they report it
| as going up instead, using this justification:
|
| https://sealevel.colorado.edu/index.php/presentation/what-
| gl...
|
| _currently some land surfaces are rising and some ocean
| bottoms are falling relative to the center of the Earth (the
| center of the reference frame of the satellite altimeter).
|
| since the ocean basins are getting larger due to GIA, this
| will reduce by a very small amount the relative sea level
| rise that is seen along the coasts.
|
| We apply a correction for GIA because we want our sea level
| time series to reflect purely oceanographic phenomena. In
| essence, we would like our GMSL time series to be a proxy for
| ocean water volume changes. This is what is needed for
| comparisons to global climate models, for example_
|
| This is nonsense, of course. Volume isn't measured in
| millimeters, that's a measurement of distance. GMSL when
| talking about satellites is defined as the average distance
| of the surface of the ocean from the center of the Earth, and
| the reason people care about it is because if it gets too
| high then things we care about end up flooded. Changing the
| definition of GMSL half way through from sea level to sea
| depth is the kind of slippyness that pervades this space.
| WillPostForFood wrote:
| We shouldn't be calling subsidence sea level rise. They are two
| distinct, measurable, phenomena that happen to have the same
| impact.
| sp332 wrote:
| I don't think it was possible to measure them separately
| until we had good satellite data from the last two decades.
| If we're extending trends back to the beginning of the
| industrial revolution, they're going to be mixed.
| revelio wrote:
| Satellite data isn't that good unfortunately. Tide gauges
| say 1.5mm/year of rise, satellites say 3mm/yr, and they
| estimate satellite error to be +/- 0.5mm year, so the error
| bars are a significant fraction of the size of the overall
| change.
|
| Also that assumes the scientists are completely accurate
| and don't make any mistakes. As recently as 5 years ago
| they discovered that the measured rise for almost all of
| the 90s was wrong and revised it by 3mm/year +- 1.7mm/year
| - the error was the same amount as the imputed level of
| rise!
|
| This is no knock on the scientists, because measuring the
| height of a moving ocean from orbit to a level of accuracy
| that lets you see mm level changes is inevitably going to
| be very hard. But we should bear in mind that they're
| heavily biased towards wanting to believe the data is
| accurate. Their decade long inability to get the
| measurements correct didn't seem to have any impact on
| their confidence that they're currently getting it right,
| and why would it? Those who seize the data, seize the day.
| stochtastic wrote:
| > Also that assumes the scientists are completely
| accurate and don't make any mistakes. As recently as 5
| years ago they discovered that the measured rise for
| almost all of the 90s was wrong and revised it by
| 3mm/year +- 1.7mm/year - the error was the same amount as
| the imputed level of rise!
|
| Citation for this? There are always improvements to our
| understanding of past data, but you seem to be implying
| that the uncertainty exceeds the signal. That's simply
| not the case [1].
|
| [1] -- https://www.ipcc.ch/report/ar6/wg1/downloads/repor
| t/IPCC_AR6... pp.1291-1292
| revelio wrote:
| Ablain, "Uncertainty in Satellite estimate of Global Mean
| Sea Level changes, trend and acceleration", p4
|
| _They have shown that there was a drift in the GMSL
| record over the period 1993-1998. This drift is caused by
| an erroneous on-board calibration correction on TOPEX
| altimeter side-A (noted TOPEX-A). TOPEX-A was operated
| from launch in October 1992 to the end of January 1999.
| Then TOPEX side-B altimeter (noted TOPEX-B) took over in
| February 1999 (Beckley et al., 2017). The impact on the
| GMSL changes is -1.0 mm /yr between January 1993 and July
| 1995, 120 and +3.0 mm/yr between August 1995 and February
| 1999, with an uncertainty of +-1.7 mm/yr (within a 90%CL,
| (Ablain, 2017))._
| stochtastic wrote:
| Figure 1 from that paper didn't convince you that it was
| a minor issue? Their correction is about 7% of the
| 1993-2018 signal, and it resolves the discrepancy with
| respect to other estimates, including non-satellite ones.
| Nobody relies on estimates from a single satellite alone.
|
| https://essd.copernicus.org/articles/11/1189/2019/essd-11
| -11...
| revelio wrote:
| _> > Nobody relies on estimates from a single satellite
| alone._
|
| Yes they did. From the paper I just cited:
|
| _The six main groups that provide satellite-altimetry-
| based GMSL estimates (AVISO /CNES, SL_cci/ESA, University
| of Colorado, CSIRO, NASA/GSFC, NOAA) use 1 Hz altimetry
| measurements from the T/P, Jason-1, Jason-2 and Jason-3
| missions from 1993 to 2018 (1993-2015 for SL_cci/ESA).
| The differences among the GMSL estimates from several
| groups arise from data editing, from differences in the
| geophysical corrections and from differences in the used
| method to spatially average individual measurements
| during the orbital cycles_
|
| The apparently independent time series are actually
| computed from the same raw data sources, as there isn't
| an abundance of redundant satellites measuring sea level.
|
| But isn't this goalpost shifting? At first you said I was
| wrong that uncertainty has been the same size as the
| measurements in the past, citing the IPCC as proof which
| of course doesn't mention any of this, saying only that
| they have high confidence in these numbers (the IPCC is
| not trustworthy). Then it became that the error isn't big
| enough for you, and nobody relied on a single satellite.
| Now I show that they did indeed rely on a single
| satellite.
|
| The core issue here remains the same: how do they know
| they're getting it right now? A calibration error so
| large it invalidated their entire time-series lasted for
| the entire lifetime of the TOPEX-1 mission, and it then
| took 20 years for the problem to actually be detected and
| corrected for. They've only been measuring sea level with
| satellites for 30 years, and the discrepancy between tide
| gauges and satellites has never been properly reconciled
| even though they theoretically measure the same thing.
| stochtastic wrote:
| The thread is at max depth, so I'll reply here:
|
| As you quoted from the paper:
|
| > The six main groups that provide satellite-altimetry-
| based GMSL estimates ...
|
| 1) You're restricting your attention to groups producing
| satellite-derived estimates.
|
| 2) Several of those groups, e.g. CSIRO, are using data
| assimilation to combine satellite estimates with gauges
| [1].
|
| 3) There are multiple satellites, often overlapping in
| time, often of totally different design/orbit/etc... [2]
|
| 4) Up to the most recent IPCC report (AR6), assessments
| were based on tide gauges alone [3]. For many of the
| reasons that you bring up. Hence "Nobody relies on
| estimates from a single satellite alone." Reconstruction
| of historical sea level is a huge scientific discipline
| and you would benefit from doing some more reading before
| beating a dead horse. The estimated uncertainty is large
| for a reason, but it does not encapsulate any scenarios
| where the observed change has been insignificant. If you
| think otherwise, I'd be happy to take your money for 2100
| options on coastal real estate in about 90% of the
| world's coastline.
|
| [1] -- https://research.csiro.au/slrwavescoast/sea-
| level/measuremen... and https://link.springer.com/article
| /10.1007/s10712-011-9119-1
|
| [2] -- https://research.csiro.au/slrwavescoast/sea-
| level/measuremen...
|
| [3] -- https://www.ipcc.ch/report/ar6/wg1/downloads/repor
| t/IPCC_AR6... p.1287
| timcavel wrote:
| [dead]
| martinpw wrote:
| > Most notably, I can't find an example in the NOAA data of the
| rate of sea level rise increasing due to industrialization.
| Anybody?
|
| You can look at the graph on the NOAA site here and see the
| acceleration visually: https://www.climate.gov/news-
| features/understanding-climate/...
|
| The notes to the left of the table say 1.4mm/yr for much of
| 20th Century to 3.6mm/yr now.
|
| There is also evidence of acceleration of sea level rise just
| from satellite data, 0.08mm/y^2:
|
| https://www.sciencedaily.com/releases/2018/02/180212150739.h...
| Trumpi wrote:
| Back in 2006, our expectations were set when An Inconveient
| Truth contemplated what would happen if sea levels rose by
| six meters (in our lifetime). 3.6mm a year seems a bit meh in
| that context.
| TaylorAlexander wrote:
| Something I see a lot is people looking at worst case
| predictions as if they were presented as the most likely
| predictions. A lot of the IPCC reports say things like "if
| we continue to increase emissions, this will happen" (a
| worst case scenario) and also "if we make moderate
| improvements, this will happen" (a slightly better
| scenario). Then people who don't want to talk about climate
| change mitigation will highlight the worst case scenario
| and say "see they were wrong and hysterical!" even when the
| moderate prediction, which they will ignore, ended up being
| essentially totally accurate.
| Trumpi wrote:
| Well, I'll go a step further and say that 3.6mm/yr is not
| evidence of a crisis.
| adgjlsfhk1 wrote:
| that's not a problem in the decade timeline but it is
| problematic over a century or two. it's especially
| problematic since it's accelerating and has a couple
| decades of inertia. the CO2 we release today will raise
| sea levels for the next 50 years or so.
| luckylion wrote:
| Are the Qattara Depression project and similar proposals too
| small in impact or more expensive than building better flood
| management, or why aren't we doing those?
| BurningFrog wrote:
| Making Qattara a bay of the Mediterranean would be great as a
| way to bring life and human habitation to the desert.
|
| It's incredibly expensive though.
|
| Scott Alexander estimated it would "reverse one year worth of
| global-warming induced sea-level rise" here:
| https://slatestarcodex.com/2016/04/15/links-416-they-cant-li...
| thombat wrote:
| Much too small. Using Wikipedia's figures: volume of Qattara
| Depression = 1,213 cubic kilometres, volume of Greenland ice
| sheet = 2,850,000 cubic kilometres. And the project is only
| useful as a long-term power source if the contents evaporate
| leaving space for renewed inflow, i.e. it only sequesters a
| fraction of its volume.
| [deleted]
| irrational wrote:
| > One is that the ocean is warming, and it needs more space and
| expands.
|
| That doesn't sound right. I think it is common knowledge that
| water expands as it freezes (hence, burst pipes), not when it
| warms up.
| nomel wrote:
| No expert, but here's what I found, because I was curious too.
|
| Ice in water doesn't change the waters height. If you put an
| ice cube in a cup, the water will be the same height after the
| ice has melted [1], since the "excess" is lifted out of the
| water. For some numbers, in 2020, it looks like total sea ice
| peaked at 18,785 km3, with the oceans volume being 130,000,000,
| so 0.014% [2].
|
| The thermal expansion of water, as liquid form, is going to be
| much more important [3].
|
| Related, every time I try to look into climate numbers, I get
| the sense that there's a gap between grade school explanations
| and research papers. There's not much between. Asking ChatGPT
| just reinforces this view. It treats me like a kid, or wraps
| unsolicited disclaimers/summaries around everything.
|
| 1. https://physics.stackexchange.com/questions/110645/why-
| does-...
|
| 2. https://arctic.noaa.gov/Report-Card/Report-
| Card-2020/ArtMID/...
|
| 3 https://physics.stackexchange.com/questions/506759/how-
| much-...
| justsocrateasin wrote:
| Water density is almost fully inelastic w/rt temperature. At
| 60degF the density is 0.99907 g/cm^3, at 100degF the density is
| 0.99318 g/cm^3. I think that's something like a .5-1% change in
| density. Pipes bursting is purely because of the drastic
| density change from ice crystallization.
|
| https://www.usgs.gov/special-topics/water-science-school/sci...
| mcguire wrote:
| The thermal expansion coefficient of water:
| https://www.engineeringtoolbox.com/water-density-specific-we...
| kybernetikos wrote:
| Water is at its most dense around 4 degrees C. As the
| temperature increases from there it gets less dense.
| giraffe_lady wrote:
| That's just a quirk of ice, that it's lower density than water.
| Liquid water still does what most (all?) liquids do wrt
| temperature changes.
| realworldperson wrote:
| [dead]
| lapama wrote:
| Because in the long term the world does not act like a glass of
| water: there are currents and gravity.
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