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Sea Level Rise Pt. 3

Re: Sea Level Rise Pt. 3

Unread postby mousepad » Sun 06 Jun 2021, 08:46:03

Newfie wrote:
It is a bit like getting older. We don’t see much change year over year; 23 to 24 is no big deal. Yet we know with certainty that 50 years latter the picture will be different.


Yes. I fully agree with you. It would be a nightmare for a 24 year old to wake up one day the find himself to be 50 years old overnight. But growing 50 year old over decades is no nightmare. It's slow enough to be able to adapt.

That's why I ask the question.
How does this nightmare of 2050 look like? And I'm not asking to deny, I'm asking to know. Are we talking famine, war and pestilence? Or are we talking a few more billion $$ that need to be spent to fight some more forest fires?
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Re: Sea Level Rise Pt. 3

Unread postby Plantagenet » Sun 06 Jun 2021, 12:34:56

mousepad wrote:
Plantagenet wrote:Surely you can understand the implications of coastal areas being submerged by rising sea level???....... If not, then please let me know and I will explain further.
Cheers!


mousepad wrote:No, I cannot understand.


No problem. I'm here to help.

mousepad wrote: I fail to see the "nightmare" in it. I've been visiting the beaches of los angeles and san diego a few times in the last 20 years. The beach is as big as it always has been.


Yes, I was recently down in San Diego and went to the Hotel Del Coronado and watched the sun set from their beach bar. A very pleasant experience indeed. However, try to imagine the same scene if the level of the ocean was 3m higher.....thats 10 feet higher in English units. That means the surface of the ocean would be 10 feet higher then it is now. A sea level that high would put the entire beach deep under water. Indeed, the waves would be sloshing right into the lobby of the Hotel Del. That means the beach bar and hotel would be destroyed and abandoned. In fact, all of Cornonado Island would have to be abandoned. And the same would hold true for billions of dollars of property at low elevations around the coast all over the world.

Do you get it now?

Image
Here's what New York city would look like with an 8 foot sea level rise. CHEERS!

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Re: Sea Level Rise Pt. 3

Unread postby mousepad » Sun 06 Jun 2021, 14:40:40

Plantagenet wrote: That means the surface of the ocean would be 10 feet higher then it is now. And the same would hold true for billions of dollars of property at low elevations around the coast all over the world.

Do you get it now?


I'm sorry to say, but I don't get the "nightmare" part of it.
According to the nasa page
https://climate.nasa.gov/vital-signs/sea-level/

The sea level rises 3.3mm/year. I assume the rate is increasing so let's round it up to 5mm/year. Agree?

To get to your 3m rise it would take 3000mm/(5mm/yr) = 600 years.

Here is a page describing life expectancy of real-estate. It refers to houses built in switzerland. Switzerland is a country where houses are built of a higher quality than the wooden shacks in the US. Yet the life expectancy of a house in switzerland is at most 100 years.
https://www.swisslife.com/en/home/hub/w ... 00%20years.
Maybe during your stay at the Corona in san diego you had a chance to knock against the walls? You noticed that the hotel is a glorified shack built of 2x4s. It has a life expectancy of maybe 50 years.

I would think there's ample of time instead of remodeling/rebuilding/refurbishing the hotel, to simply abandoning it to build a new one inland. Will there be a loss? Certainly, but hardly a nightmare.

So, please, I ask again. How is this nightmare of global warming look like? Maybe you have a vastly different opinion of what a nightmare is, but the disappearance of the Corona in San diego over the next 600 years is hardly one I will lose sleep over.
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Re: Sea Level Rise Pt. 3

Unread postby Plantagenet » Sun 06 Jun 2021, 18:24:51

mousepad wrote:I'm sorry to say, but I don't get the "nightmare" part of it.


Thats because you don't understand math.

mousepad wrote:According to the nasa page
https://climate.nasa.gov/vital-signs/sea-level/

The sea level rises 3.3mm/year. I assume the rate is increasing so let's round it up to 5mm/year. Agree?


As I said----You don't understand math.

The observed increase in the rate of sea level rise isn't limited to a maximum of 5.0 mm/yr. I don't know why you made up that number, but it has nothing to do with reality.

The observations and the GCM models both show that increases in the rate of sea level rise are EXPONENTIAL....i.e. the planet is steadily getting warmer and the rate of sea level rise is steadily increasing.

There is no magical limit on the rate of sea level rise at 5 mm/yr as you assume. Because you make this phony assumption the math in your calculation wildly underestimates the amount of sea level rise we are likely to see over the next 600 years.

And thats just assuming that things pretty much go on as they have been.

But we already know that just isn't true.

Some of the largest glaciers on earth in Antarctica are dynamically unstable, so if they retreat enough they will become detached from their grounding line and then will begin to retreat much more rapidly, resulting in even more and more rapid sea level rise. We are very close to the Thwaites glacier reaching a tipping point that will result in extremely rapid ice retreat, adding to the ongoing exponential increase in the rate of sea level rise we've been seeing since the late 19th century.

Image
Global warming causes the retreat of glaciers, putting more water into the oceans and causing sea level to rise. The rate of sea level is increasing EXPONENTIALLY.

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Re: Sea Level Rise Pt. 3

Unread postby vtsnowedin » Sun 06 Jun 2021, 19:50:59

When you do the math for an "exponential" equation you have to know the time period for the increase. Is it doubling every six months or every ten years? Makes a big difference don't you think?.
To just shout that sea level is rising exponentially sounds scary but proves nothing.
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Re: Sea Level Rise Pt. 3

Unread postby mousepad » Sun 06 Jun 2021, 20:05:21

Plantagenet wrote:As I said----You don't understand math.

The observed increase in the rate of sea level rise isn't limited to a maximum of 5.0 mm/yr.

No kidding.

I don't know why you made up that number, but it has nothing to do with reality.

I made the number up because for the purpose of discussion it's "good enough". That's called engineering. It's practical.

The observations and the GCM models both show that increases in the rate of sea level rise are EXPONENTIAL....i.e. the planet is steadily getting warmer and the rate of sea level rise is steadily increasing.

No kidding. Let's take a look at the nasa page again. The data spans 25 years, roughly. (Yes Plant, I made that number up. The data range spans 28 years, but 25 years is good enough for the purpose of this discussion. That's called engineering.)

You will notice that the scale in the Y axis is linear as well as in the X axis. You will also notice that there's practically no visible exponential behavior of the curve. But I'm sure there is, but it's not much. It's so little it's hard to say. That's why I simply increased the yearly increase of 3.3mm to 5mm. To accommodate the exponential behavior. It's called engineering. You approximate. For the purpose of this discussion it's good enough. Even if it's wrong by a factor of 2, it's still good enough.

I was under the impression that you were a scientist and understood things.

Because you make this phony assumption the math in your calculation wildly underestimates the amount of sea level rise we are likely to see over the next 600 years.

Ok thank you. I'm glad we finally make progress. Can you show me how this sea-level-rise curve looks like then?
By what year do you expect the sea to have risen by 3 m? Can you do that without petty insults?

Some of the largest glaciers on earth in Antarctica are dynamically unstable, so if they retreat enough they will become detached from their grounding line and then will begin to retreat much more rapidly, resulting in even more and more rapid sea level rise.

Yes, I know all this. I read tons of text explaining retreating glaciers, sink holes in greenland, methan discharges in sibiria etc etc. I refer you back to the original question. What are the consequences? After several post we have established that the coronado hotel in san diego is under water in LESS than 600 years. Awesome progress! Can you do better?

We are very close to the Thwaites glacier reaching a tipping point

No kidding.
What is "very close". Is that geological close? like in "we're very close to the yellowstone vulcano erutping in the next 10k years?"

So can you try again? How does the world look like in 2050? And what about it is the "nightmare" the original poster referred to?
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Re: Sea Level Rise Pt. 3

Unread postby Plantagenet » Sun 06 Jun 2021, 22:02:13

mousepad wrote:I made the number up because for the purpose of discussion it's "good enough". That's called engineering.


The number you selected is clearly wrong and it leads to an completely unrealistic result. Its definitely not "good enough."

Thats called science.

mousepad wrote:Let's take a look at the nasa page again. The data spans 25 years, roughly. (Yes Plant, I made that number up. The data range spans 28 years, but 25 years is good enough for the purpose of this discussion. That's called engineering.) You will notice that the scale in the Y axis is linear as well as in the X axis. You will also notice that there's practically no visible exponential behavior of the curve. But I'm sure there is, but it's not much. It's so little it's hard to say. That's why I simply increased the yearly increase of 3.3mm to 5mm. To accommodate the exponential behavior. It's called engineering. You approximate. For the purpose of this discussion it's good enough. Even if it's wrong by a factor of 2, it's still good enough.


Its definitely not good enough, even if wrong by a factor of 2.

You can't "accommodate exponential behavior" by just picking a number out of the air. The term exponential means the rate of sea level rise is progressively increasing over time. No single number captures that reality.

AND the NASA page isn't the best place to look at changes in sea level because the time series of sea level data there is so short. I can't imagine why you would just look at 25 years of data from the NASA page. The NASA page only shows data from satellite altimetry which is why the record is so short. We've only had satellites capable of making accurate sea level measurements for about 25 years.

There are much longer records of sea level available from coastal tidal stations. And there are even longer records of sea level that can be derived from studying coastal sediments. It would be better to look at a longer data set rather then just looking at 25 years of data.

mousepad wrote:
I was under the impression that you were a scientist and understood things.


You've go that right. I am a research scientist based at the University of Alaska and one of the things I study is climate change.

Are you a professional engineer? I'm guessing from your references to "engineering" in your posts that perhaps you are involved in engineering yourself. Is that right?

mousepad wrote: Can you show me how this sea-level-rise curve looks like then?


Sure.....check this out:

Image

This curve shows the satellite data that you saw on the NASA site added to the longer tide gauge record that I discussed above.

Please notice that the rate of sea level rise was about 0.6 mm/yr early in the 20th century, and has exponentially increased to the point that sea level is now rising at about 4.4 mm/yr. In other words, the rate of sea level rise has gone up by SEVEN TIMES in a little more than a century. This reality suggests that the estimate that you made above....ie. that sea level would rise from 3 mm/yr to ca. 5 mm/yr and stay at level for the next 600 years....is very unrealistic. For instance, if the rate of sea level rise were to go up again by 7 times over the next 100 years it would rise to over 30 mm/yr....far above the 5 mm/yr you suggested, and even far above your number even if you doubled it. And thats only for roughly 100 years into the future....not for the 600 years you were projecting using the unrealistic 5mm/yr number.

And, just to complicate things even more, as I explained in my post above, we are nearing tipping points for glacier collapse that will accelerate sea level rise even more.

Its pretty exciting to watch as this all happens.

Image

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Re: Sea Level Rise Pt. 3

Unread postby AdamB » Mon 07 Jun 2021, 00:09:03

Plantagenet wrote:
mousepad wrote:
I was under the impression that you were a scientist and understood things.


You've go that right. I am a research scientist based at the University of Alaska and one of the things I study is climate change.


Oh great. So THAT is where researchers who can't be bothered to read their references (All Bolts are being recalled for burning batteries!! oops....that wasn't what the reference says! ) are banished.
StarvingPuutyTat says: I'm so confident in my TOTAL COLLAPSE is IMMINENT prediction that I stake my entire reputation on it. It will happen this year. - Aug 3-2020

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Re: Sea Level Rise Pt. 3

Unread postby mousepad » Mon 07 Jun 2021, 07:45:42

Plantagenet wrote:
mousepad wrote:I made the number up because for the purpose of discussion it's "good enough". That's called engineering.


The number you selected is clearly wrong and it leads to an completely unrealistic result. Its definitely not "good enough."


Ok, let's take a look at your new data.
I superimposed a exponential curve on top of your data.

The formula is
sealevel(year) = ((year-1870)^2.9)/(2.3*10^4)
Unfortunately I don't know how to insert a picture from my computer into the post. If somebody can teach me, I'll add them in.

So when we solve above equation for 3m sea level rise we get the year 2375.
It will take roughly another 350 years to reach 3m of rise.

So my initial assumption of 600 years was wrong but clearly "good enough" for the purpose of this discussion.

With a building life expectancy of 50 years there's ample of time to move the coronada within the next 350 years. Don't you think so?

BTW, it's curious that the exponential curve you provided is actually 3 linear segments. Why is that? Data like that makes me as an engineer "uncomfortable". Are you sure you science types know how to take measurements? If I were you I would go back and take a closer look at the data. Who knows, might lead to another paper and more fame for you?

Its definitely not good enough, even if wrong by a factor of 2.

Yes it was. It turns out the error was less than factor 2.

So, after several posts we solved one mystery. It will take 350 years for the hotel coronada in san diego to be underwater. We conclude this is no nightmare as there is ample of time to abandon, move or otherwise protect the hotel.

We are left with the still unanswered initial question:
1. how do the nightmares of climate change in 2050 look like

What you think? Wanna give it another shot?
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Re: Sea Level Rise Pt. 3

Unread postby Newfie » Mon 07 Jun 2021, 15:24:13

Intergovernmental Panel on Climate Change (IPCC) projected a high end estimate of 60 cm (2 ft) through 2099,[6] but their 2014 report raised the high-end estimate to about 90 cm (3 ft).[7] A number of later studies have concluded that a global sea level rise of 200 to 270 cm (6.6 to 8.9 ft) this century is "physically plausible".[8][2][9] A conservative estimate of the long-term projections is that each Celsius degree of temperature rise triggers a sea level rise of approximately 2.3 meters (4.2 ft/degree Fahrenheit) over a period of two millennia (2,000 years): an example of climate inertia.[1] In February 2021, a paper published in Ocean Science suggested that past projections for global sea level rise by 2100 reported by the IPCC were likely conservative, and that sea levels will rise more than previously expected


Image


https://en.m.wikipedia.org/wiki/Sea_level_rise

Back to the “NIGHTMARE”.

If one were to pick out a single factor of CC and focus on that one item alone, ignoring all the other aspects, the the “nightmare” is merely “plausible” by 2100.

SLR is only one of many CC consequences. These consequences include destabilization of weather patterns, which effect food production. And downstream is climate induced migration, starvation, and civil disruption.

There is no need for this to occur before 2100 to eventually create a “nightmare.” (Nightmare being undefined - I will call it a >20% population decline for clarity) Once the climate forcing is started it takes a long time to come to full effect, so what we do today will inflict the nightmare on future generations. It is sort of backwards from the stock market adage “Past performance is no guarantee of future growth”. This is more like “Past performance guarantees some minimum level of future degrowth.”

Mousepad, did that answer your question?
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Re: Sea Level Rise Pt. 3

Unread postby Plantagenet » Mon 07 Jun 2021, 16:39:40

mousepad wrote:it's curious that the exponential curve you provided is actually 3 linear segments. Why is that? Data like that makes me as an engineer "uncomfortable". Are you sure you science types know how to take measurements?


The real world is an immensely complicated place----much much much larger and much much much more complicated then the simple systems that you engineers typically model and work on---- and contributions to global sea level rise come from many different sources all over the globe. These various sources have different behaviors as the climate warms. This probably mostly accounts for the "jumps" in the rate of sea level rise. For instance, there wasn't much melting in Antarctica until a couple of decades ago, and now Antarctica is a major source of meltwater into the ocean. Think about it....turning on new sources of meltwater as the planet gets warmer and warmer would inevitably lead to jumps in the rate of sea level rise.

Add to that the fact that global warming itself is ratcheting up in an irregular fashion and variability and even jumps in the rate of sea level rise are to be expected.

Please note that NEWFIE in his post just above cites new data and new models that suggest a sea level rise of ca. 2.7 meters or more is "plausible" by the end of the 21st century. This is a substantial increase from prior estimates, and personally I think the actual sea level rise will be even higher because most modeling isn't taking glacial instabilities into account which will greatly accelerate ice flow into the ocean and greatly increase the rate of sea level rise.

mousepad wrote:We are left with the still unanswered initial question:
.... how do the nightmares of climate change in 2050 look like


I'm sorry but your question doesn't make any sense. You wrote: "How do the nightmares of climate change in 2050 look like" but that sentence is gibberish. Perhaps you mean "what do the Nightmares of climate change in 2050 look like?"

Are you trying to say you don't believe in climate change? Or perhaps you don't think there will bad effects from climate change by 2050? What exactly is your question? Again, NEWFIE in his post above does a good job of summarizing some of the negative effects of climate change. Do you disagree with his projections and ideas?

Please clearly say what you are concerned about. THX!

Image
The earth and its atmosphere, geosphere, biosphere, cryosphere and oceans is an immensely complicated place----much much much larger and much much much more complicated then the local mechanical and electrical systems that most engineers typically model and work on

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Re: Sea Level Rise Pt. 3

Unread postby mousepad » Mon 07 Jun 2021, 18:37:59



That's an interesting read. Thank you for posting it. I have to keep a link to that.

Most interesting was also the section about the sea level measurement.
It is amazing that this can even be measured to an accuracy of a few mm. Kudos to the engineers who made it happen. :-)

So if we assume the middle scenario (RCP4.5) to be true, you're saying this will be so disruptive to society in conjunction with all other effects that it will turn out to be a nightmare. And that the change will be so fast that society is not able to react and adapt.
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Re: Sea Level Rise Pt. 3

Unread postby mousepad » Mon 07 Jun 2021, 18:52:25

Plantagenet wrote:The real world is an immensely complicated place----much much much larger and much much much more complicated then the simple systems that you engineers typically model and work on

That is true.


mousepad wrote:We are left with the still unanswered initial question:
.... how do the nightmares of climate change in 2050 look like


I'm sorry but your question doesn't make any sense. You wrote: "How do the nightmares of climate change in 2050 look like" but that sentence is gibberish. Perhaps you mean "what do the Nightmares of climate change in 2050 look like?"

yes, that's what I mean.
Are you trying to say you don't believe in climate change?

Not at all. I try to understand. I have no problem accepting individual effects but I have a hard time grasping the impacts, especially when combined. It is not clear to me how to judge and separate serious consequences from consequences that can easily be mitigated or tolerated.


Again, NEWFIE in his post above does a good job of summarizing some of the negative effects of climate change.

Yes he did. I expected this kind of explanation from the resident climate scientist. But it took Newfie to get the job done. He's probably an engineers. Those guys don't talk bs in circles. They get the job done. :-)

Please clearly say what you are concerned about. THX!

I always do. But you know how it is on this forums. People scan thru a post in a hurry, latch on to some keyword, take the sentence out of context, and throw a petty insult reply back at the OP. I'm glad you're not one of them. 8)
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Re: Sea Level Rise Pt. 3

Unread postby Plantagenet » Mon 07 Jun 2021, 19:13:53

mousepad wrote: you know how it is on this forums. People scan thru a post in a hurry, latch on to some keyword, take the sentence out of context, and throw a petty insult reply back at the OP. I'm glad you're not one of them.


Good chatting with you, mousepad.

You are right....Newfie does an excellent job of getting right to the heart of an issue and addressing it directly and clearly.

Cheers!

PS: Rather then worrying about potential climate impacts in 2050, how about the impacts from climate change we are seeing right now? I'm keeping an eye on the drought and the forest fires in the western US being caused this summer. I used to go to the Shakespeare Festival every summer in Ashland Oregon but for the last several years heavy unhealthy smoke from huge summer forest fires in Oregon and Washington have shut down the festival. One year I went rafting down the Rogue River past forest fires in the mountains around the river.....its an incredible sight to see huge forest fires burning up entire mountain sides as you float by in a little raft. And then we had to to dodge the fires again when we we crossed the Klamath Mountains going back after the raft trip was done. And then the next year they had fires right down near town, and a little town just north of Ashland named Talent was destroyed by fire.

I don't even try to go to Ashland now in the summer. I know there are going to be huge fires in California and Oregon with lots of smoke and everything will be shut down for weeks at a time..

This summer its predicted to be hotter and drier than ever in the American west and that means the forest fires will be bigger than ever, Its a truly remarkable change and its going on right now. And the same thing is going on in the forests of Scandinavia and Siberia and Alaska and Brazil and many other places. As the climate gets hotter and drier, we are seeing more forest fires. And its happenening in forests all over the world.

Image
As the planet warms the ice melts and sea level rises and there are record amounts of forest fires. And its happening right now

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Re: Sea Level Rise Pt. 3

Unread postby Newfie » Mon 07 Jun 2021, 20:41:08

Electrical Engineer; Professional License - since lapsed - retired

I could explain more but it just gets too depressing. Then I don’t get invited out. 8O
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Re: Sea Level Rise Pt. 3

Unread postby dissident » Tue 08 Jun 2021, 14:53:14

The problem with short term climate change is that it does sit in the noise. The signal is sufficiently weak that some denier clown can get away with claiming it is variability. But on multi-decadal timescales, the signal is no longer deniable. We have already seen a substantial shift since 1980. Only politically motivated lunatics pretend we have not seen it.
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Re: Sea Level Rise Pt. 3

Unread postby Plantagenet » Sat 12 Jun 2021, 12:16:46

Here it comes......glacier on Antarctica has sped up by 10% and is dumping huge amounts of ice into ocean.

This glacier is the single largest source of sea level rise on the planet.....

And its going to get worse....

Pine Island Glacier in Antarctica is going to collapse soon

Image

Here comes a rapid foot-and-a-half of sea level rise.....just from one huge glacier......and the show starts in just a few years

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Re: Sea Level Rise Pt. 3

Unread postby dissident » Sat 12 Jun 2021, 18:46:59

If this disintegration continues, “the whole shelf could potentially fall apart in the next few years, which is greatly faster than what we expected,” said Ian Joughin, a glaciologist at the University of Washington’s Applied Physics Laboratory


Now where have I heard that before, that's right the "unexpected" melting rate of the Greenland ice sheet.

It was faster than expected.


this will probably be humanity's epitaph.
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Re: Sea Level Rise Pt. 3

Unread postby Tanada » Thu 17 Jun 2021, 07:57:12

Plantagenet wrote:Here it comes......glacier on Antarctica has sped up by 10% and is dumping huge amounts of ice into ocean.

This glacier is the single largest source of sea level rise on the planet.....

And its going to get worse....

Pine Island Glacier in Antarctica is going to collapse soon

Image

Here comes a rapid foot-and-a-half of sea level rise.....just from one huge glacier......and the show starts in just a few years

Cheers!


This statement right at the end of the article is what drives me batty;
But if ice shelves can shift quickly and decisively, so too can humanity. Healing the ozone hole and taking swift action against climate change will alter the conditions in Antarctica’s atmosphere and oceans and help stabilize the continent’s glaciers.

“The future is still open to change," Davies said — if people do what is needed to change it.


This statement shows 100% lack of understanding of dynamic tipping point behavior. Humanity could just disappear today and thereby stop consuming fossil fuels and it would not do a thing to change the fate of Pine Island Glacier.It has long been known that climate lags anywhere from 20-50 years behind the changes in CO2 and other GHG levels because large complex systems do not change overnight.

The behavior exhibited by Pine Island Glacier 2016-2021 was set in motion by GHG emissions from 1996 or earlier, not what we did in 2016. As far as that goes healing the ozone hole over Antarctica is actually adding to the GHG conditions over Pine Island Glacier because stratospheric ozone is a GHG trapping heat in the atmosphere. That is science, not myself advocating leaving the Ozone problem in place or making it worse, just stating a known scientific fact. Pine Island Glacier is doomed and saying its loss will add 50 cm of sea level rise barely touches on the reality of the situation.

A decade ago Dr. Richard Alley and his team determined that if any of the big West Antarctic sea terminating glaciers move off their underwater sills and become floating ice masses the stability of that whole region falls apart. The reason is basic physics, floating ice can only rise so far above the water line before the sheer forces break it up and lower its ultimate height. This number is around 75 meters or 240 feet. This physics fact is why those huge tabular icebergs like the one that just calved off of Pine Island Glacier look like a flat mesa floating on the sea. The West Antarctic basin is a deep region filled with ice as much as 2000-3500 meters thick. This deep basin is mostly surrounded by mountains and buried peaks that protect the interior ice from the surrounding ocean. In multiple places including Pine Island Glacier the edge of the deep basin forms a submerged ridge known as a sill in oceanography. Think of the sill as being like the lip of a plate.

Here is a science experiment you can do at home to see what this matters. Put a plate in the middle of a kiddie wading pool and pour a bag of ice cubes on it so that they stack high on the plate and surround it on all sides in the pool. Then slowly add water to the pool. Once you have around an inch or 25 mm of water in the pool the edge of the plate buried under the ice is reached. The loose ice cubes that didn't fit on the plate will start floating and moving randomly which will disperse them from around the plate. As you keep adding water it will move under the ice on the plate and the edges of the mound will start eroding, dropping more and more ice cubes into the water where they will disperse just like the earlier loose cubes did. Before long the whole mound becomes unstable and all the ice disperses into floating cubes in the much larger kiddie pool.

That is the behavior the paleoclimate record shows takes place when West Antarctica passes its tipping point. Once the "cork" breaks out of the bottle the effect is basically unstoppable as the mass of ice in the deep basin will start shedding into the opening with a great deal more speed than people intuitively expect. In the plate and pool example the water never gets close to submerging the entire pile of cubes before buoyancy tears the pile apart from edge to center. In West Antarctica when the ice retreats behind the sill the very high pile becomes exposed to the open ocean. Not only does sea water carry vast reservoirs of heat to the contact face of the glacier, the 12 hour tidal cycle creates a buoyancy cycle that stresses the edge of the vast ice sheet with sheer forces up and down without ever stopping. For floating tabular icebergs the tides matter little as the entire berg bobs up and down, but for ice fixed to a large unyielding mass this is not the case. This cycle and the strength of natural ice even very very cold ice the flexing leads to calving in the face meeting the sea. Once it is off the sill the forces erode their way in ward meter by meter until the entire basin is emptied of ice.

Once the process passes the tipping point, which recent reports indicate may be the case, the process will continue until there is no more ice that can be easily destabilized. When the huge Larsen B ice shelf collapsed in 2003 it as the author puts it, took the cork out of the bottle holding back several completely above sea level glacier in the Antarctic Peninsula. Without the ice shelf putting resistance on their movement towards the sea every single exposed glacier accelerated its forward movement thinning each and every one of them in the process and dumping a flurry of icebergs into the sea from where the glaciers crossed the shore line. Pine Island Glacier has its own ice shelf which has been keeping it from moving faster and thinning where it meets the sea. What we are observing now is that shelf eroding strongly, four to six times faster starting in 2017 than it was during the earlier part of the observationa record.

Pine Island Glacier's ice shelf is ripping apart, speeding up key Antarctic glacier

Pine Island Glacier ends in an ice shelf that floats in the Amundsen Sea. These crevasses are near the grounding line, where the glacier makes contact with the Antarctic continent. The photo was taken in January 2010 from the east side of the glacier, looking westward. This ice shelf lost one-fifth of its area from 2017 to 2020, causing the inland glacier to speed up by 12%.

For decades, the ice shelf helping to hold back one of the fastest-moving glaciers in Antarctica has gradually thinned. Analysis of satellite images reveals a more dramatic process in recent years: From 2017 to 2020, large icebergs at the ice shelf's edge broke off, and the glacier sped up.

Since floating ice shelves help to hold back the larger grounded mass of the glacier, the recent speedup due to the weakening edge could shorten the timeline for Pine Island Glacier's eventual collapse into the sea. The study from researchers at the University of Washington and British Antarctic Survey was published June 11 in the open-access journal Science Advances.

"We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected," said lead author Ian Joughin, a glaciologist at the UW Applied Physics Laboratory. "The processes we'd been studying in this region were leading to an irreversible collapse, but at a fairly measured pace. Things could be much more abrupt if we lose the rest of that ice shelf."

Pine Island Glacier contains approximately 180 trillion tons of ice—equivalent to 0.5 meters, or 1.6 feet, of global sea level rise. It is already responsible for much of Antarctica's contribution to sea-level rise, causing about one-sixth of a millimeter of sea level rise each year, or about two-thirds of an inch per century, a rate that's expected to increase. If it and neighboring Thwaites Glacier speed up and flow completely into the ocean, releasing their hold on the larger West Antarctic Ice Sheet, global seas could rise by several feet over the next few centuries.

These glaciers have attracted attention in recent decades as their ice shelves thinned because warmer ocean currents melted the ice's underside. From the 1990s to 2009, Pine Island Glacier's motion toward the sea accelerated from 2.5 kilometers per year to 4 kilometers per year (1.5 miles per year to 2.5 miles per year). The glacier's speed then stabilized for almost a decade.

Results show that what's happened more recently is a different process, Joughin said, related to internal forces on the glacier.

From 2017 to 2020, Pine Island's ice shelf lost one-fifth of its area in a few dramatic breaks that were captured by the Copernicus Sentinel-1 satellites, operated by the European Space Agency on behalf of the European Union. The researchers analyzed images from January 2015 to March 2020 and found that the recent changes on the ice shelf were not caused by processes directly related to ocean melting.


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Re: Sea Level Rise Pt. 3

Unread postby Azothius » Fri 18 Jun 2021, 13:42:54

dissident wrote:
If this disintegration continues, “the whole shelf could potentially fall apart in the next few years, which is greatly faster than what we expected,” said Ian Joughin, a glaciologist at the University of Washington’s Applied Physics Laboratory


Now where have I heard that before, that's right the "unexpected" melting rate of the Greenland ice sheet.

It was faster than expected.


this will probably be humanity's epitaph.



NASA: Earth is trapping 'unprecedented' amount of heat, warming 'faster than expected'
https://www.yahoo.com/news/nasa-earth-t ... 35519.html
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