The Analysis of Sea Levels.

[mikegarrison]

I think I should make clear here that I did not start this thread. This thread was originally posted in a different thread. Someone posted about a NASA analysis about flooding 18 years from now. I responded to that.

Then the threads were split out. And then, later, the person who made the initial post deleted their post (or asked for it to be deleted). This left it looking like I had started this thread.

The moon has an 18.6 year orbital "wobble". It always has this -- it's not a special event. However, this means that for about 9 years tides are a little lower than normal, and about 9 years tides are higher than normal. We're currently in one of the 9-year higher tide cycles.

The problem, though, is that due to climate change our sea levels have been rising. Due to this, they are warning that in about 18 years from now (in the *next* high-tide cycle) we'll probably see a lot of serious tidal flooding, because of almost 20 more years of sea level rise.

Edited June 27, 2023 by Gargamel
Temp lock, no changes to text

[magnemoe]

7 minutes ago, mikegarrison said:

The moon has an 18.6 year orbital "wobble". It always has this -- it's not a special event. However, this means that for about 9 years tides are a little lower than normal, and about 9 years tides are higher than normal. We're currently in one of the 9-year higher tide cycles.

The problem, though, is that due to climate change our sea levels have been rising. Due to this, they are warning that in about 18 years from now (in the *next* high-tide cycle) we'll probably see a lot of serious tidal flooding, because of almost 20 more years of sea level rise.

Way more so people pump out the ground water and this make the ground sink. This is the problem for Venice and lots of other places. None expected this until it came up. 
Yes climate change is an effect but an minor one compared to dropping the ground meters. 

And obviously the tabloids are an high order of magnitudes more insane than the one demanding money to fix the problem they created. 

[mikegarrison]

2 minutes ago, magnemoe said:

Way more so people pump out the ground water and this make the ground sink. This is the problem for Venice and lots of other places. None expected this until it came up. 
Yes climate change is an effect but an minor one compared to dropping the ground meters. 

You are comparing a local problem with a global one.

Venice is sinking for a combination of reasons. Groundwater pumping is one of them, but also plate tectonics and that sediment is being scoured from the lagoon. In a similar way some other coastal cities are also sinking. Many of them are not build on continental bedrock. They are build on river deltas, swampland, tidal marshes, etc. All of these start to sink as soon as you stop letting them flood with new sediment.

However, Venice has been sinking since it was founded. The rise in sea level is something new.

[kerbiloid]

***

It's time for Holland to build more Holland

https://en.wikipedia.org/wiki/Land_reclamation_in_the_Netherlands

[GoSlash27]

On 7/14/2021 at 7:12 PM, mikegarrison said:

The problem, though, is that due to climate change our sea levels have been rising.

Have they? 

[mikegarrison]

4 hours ago, GoSlash27 said:

Have they? 

Yes.

[GoSlash27]

54 minutes ago, mikegarrison said:

Yes.

And you "know"-know this, or "you've been told"- know this? Because here's the problem: I've been told this as well, but nobody seems to actually have the data to back it up. So far it's all been either a) the same experts who have been making incorrect predictions my entire life and then retiring and buying beachfront property or b) people who are just repeating what they've been told by these same 'experts'. So I go and look at the actual data and I'll be darned if I can see any trend whatsoever outside of the statistical noise floor, let alone one so dire that it will cause any discernable difference 18 years from now.

 Are you privy to some corroborating data I haven't already seen?

Thanks,

-Slashy

 

 

[mikegarrison]

1 hour ago, GoSlash27 said:

And you "know"-know this, or "you've been told"- know this? Because here's the problem: I've been told this as well, but nobody seems to actually have the data to back it up. So far it's all been either a) the same experts who have been making incorrect predictions my entire life and then retiring and buying beachfront property or b) people who are just repeating what they've been told by these same 'experts'. So I go and look at the actual data and I'll be darned if I can see any trend whatsoever outside of the statistical noise floor, let alone one so dire that it will cause any discernable difference 18 years from now.

 Are you privy to some corroborating data I haven't already seen?

There is plenty of data, but I'm not going to bother to argue about it with you, because it's all easily available and yet you somehow claim to not be able to find it. Arguing with people about climate change effects when they have made up their mind that there are none is about as useful as arguing with creationists or flat earthers. Which is to say, not useful at all.

[Rakaydos]

1 hour ago, GoSlash27 said:

And you "know"-know this, or "you've been told"- know this? Because here's the problem: I've been told this as well, but nobody seems to actually have the data to back it up. So far it's all been either a) the same experts who have been making incorrect predictions my entire life and then retiring and buying beachfront property or b) people who are just repeating what they've been told by these same 'experts'. So I go and look at the actual data and I'll be darned if I can see any trend whatsoever outside of the statistical noise floor, let alone one so dire that it will cause any discernable difference 18 years from now.

 Are you privy to some corroborating data I haven't already seen?

Thanks,

-Slashy

 

 

Sea level rise is dependant not in any old melting ice, but melting of ice that isnt already floating in water. The largest of these masses of land bound ice are in greenland and antarctica. If both melt completely, sea levels will have risen 10m, compared to when we first started measuring these ice sheets 50 years ago.

Going back to these ice sheets in the last few years, researchers have found them in the process of melting bit by bit, "rotting" is the term I've seen. it's looking like sea level rise is a more gradual process than initially feared, but there's still the possibility of a sudden surge if a section breaks off one of the sheets and slides into the sea.

[GoSlash27]

1 hour ago, mikegarrison said:

There is plenty of data, but I'm not going to bother to argue about it with you, because it's all easily available and yet you somehow claim to not be able to find it. Arguing with people about climate change effects when they have made up their mind that there are none is about as useful as arguing with creationists or flat earthers. Which is to say, not useful at all.

So I take that as a 'no' then.

Carry on.

Best,

-Slashy

48 minutes ago, Rakaydos said:

Sea level rise is dependant not in any old melting ice, but melting of ice that isnt already floating in water. The largest of these masses of land bound ice are in greenland and antarctica. If both melt completely, sea levels will have risen 10m, compared to when we first started measuring these ice sheets 50 years ago.

Going back to these ice sheets in the last few years, researchers have found them in the process of melting bit by bit, "rotting" is the term I've seen. it's looking like sea level rise is a more gradual process than initially feared, but there's still the possibility of a sudden surge if a section breaks off one of the sheets and slides into the sea.

 Rakaydos,

 Researchers have claimed that they are melting bit by bit, but the data shows that the northern ice sheet is nominal and the antarctic is actually thicker than average.

 "Fears" and "possibilities" are certainly not invalid, but they are also not the same thing as established fact.

Best,

-Slashy 

[Rakaydos]

10 minutes ago, GoSlash27 said:

So I take that as a 'no' then.

Carry on.

Best,

-Slashy

 Rakaydos,

 Researchers have claimed that they are melting bit by bit, but the data shows that the northern ice sheet is nominal and the antarctic is actually thicker than average.

 "Fears" and "possibilities" are certainly not invalid, but they are also not the same thing as established fact.

Best,

-Slashy 

If your measurement is in "thickness" you need to look up the definition of "rotting" again. It's true that the ice sheets are not getting thinner. But they are getting hollower, having less water per volume.

Edited July 16, 2021 by Rakaydos

[GoSlash27]

3 minutes ago, Rakaydos said:

If your measurement is in "thickness" you need to look up the definition of "rotting" again.

"The response of Arctic sea ice to a warming climate includes decreases in extent, lower ice concentration, and reduced ice thickness."

 Extent and thickness are currently nominal for this time of year, and concentration is not tracked because it isn't possible to quantify on a large scale.

 That's the problem with all of this; even when these people have failed to ever make a correct prediction and even when they have been busted committing outright fraud, people still accept them at their word because they are the "experts"... not even pausing to look at the data themselves.

Best,

-Slashy

[James M]

I see no cited sources from anyone.

[Rakaydos]

Just now, GoSlash27 said:

"The response of Arctic sea ice to a warming climate includes decreases in extent, lower ice concentration, and reduced ice thickness."

 Extent and thickness are currently nominal for this time of year, and concentration is not tracked because it isn't possible to quantify on a large scale.

 That's the problem with all of this; even when these people have failed to ever make a correct prediction and even when they have been busted committing outright fraud, people still accept them at their word because they are the "experts"... not even pausing to look at the data themselves.

Best,

-Slashy

Yes, all the early predictions of ice melting assumed it would melt from the sunward side. That was wrong. But they're melting from the inside out, which has the same net effect.

3 minutes ago, James M said:

I see no cited sources from anyone.

How about this: https://climate.nasa.gov/vital-signs/ice-sheets/

Note that it's measuring total mass, not approximation like extent or thickness.

[James M]

9 minutes ago, Rakaydos said:

How about this: https://climate.nasa.gov/vital-signs/ice-sheets/

Note that it's measuring total mass, not approximation like extent or thickness.

See was that so hard ^-^

Post Edit: That's pretty cool data btw  

Edited July 16, 2021 by James M

[kerbiloid]

Afaik, there are several island countries at literally 1 m  above sea level.

I have heard that some of them will get sunk when the sea level raises, but has one actually been flooded? If no, does it mean that the sea level hasn't raised for 1 m?

[Rakaydos]

2 minutes ago, kerbiloid said:

Afaik, there are several island countries at literally 1 m  above sea level.

I have heard that some of them will get sunk when the sea level raises, but has one actually been flooded? If no, does it mean that the sea level hasn't raised for 1 m?

Tides already account for more than +/- 1m from average sea level. Those islands already have to deal with tides, but it's probably gotten worse as (checks source) 425 billion metric tons per year melts and joins the oceans.

[kerbiloid]

1 minute ago, Rakaydos said:

but it's probably gotten worse as (checks source) 425 billion metric tons per year melts and joins the oceans.

But has any of them actually gotten worse?

[Rakaydos]

Edit: Or I can just open the next tab: https://climate.nasa.gov/vital-signs/sea-level/

3.4 milimeters per year. of Sea level rise.

[kerbiloid]

As I can't remember hot news about it.

Just now, Rakaydos said:

3.4 milimeters per year

300 year for 1 m, and if the process won't stop and reverse.

2020 - 300 = 1720

I remember the Netherlands paintings about winter skating...

From XVI or so.

Do these prognoses use a pid regulator model of an oscillation process instead of simple regression?

[Rakaydos]

3 minutes ago, kerbiloid said:

As I can't remember hot news about it.

300 year for 1 m, and if the process won't stop and reverse.

What scientists are really worried about is a catastrophic breackaway of the damaged ice. Because merely melting is only giving millimeters, but significant chunks of the ice sheets would do much more to sea level if they fall in the ocean.

Edited July 16, 2021 by Rakaydos

[OHara]

I think we all rolled our eyes when we saw some of the more extreme 'wobbling moon will causes massive flooding' headlines.  

If they really are referring to the 19-year Metonic cycle, I don't see why the word 'wobble' applies.

In any case, we're planning to extend the port in Galway, and move housing and shops where the old port was, and nearby parts of town already have coastal flooding every few years, so we have to plan for this.

I think the 19-year Metonic cycle causes tides to vary ±2% from their long-term amplitude, so here where the tide swings ±2 meter, high tide will be 20 mm higher than mean local sea level in ten years.

Plus local sea level is rising about 2 mm/year at the minute[*], so high tide will creep up about 2mm ×19 /2 +  20mm = 39 mm over the 9½ years of the rising half Metonic cycle.   So the 19-year cycle really is of similar magnitude to the current linear trend. ([*]We are on a piece of crust still rebounding at 1 mm/year from the previous ice age, so we have a bit less than the global average rise in sea level relative to the land.)

Parts of the city flood when wind from winter storms pushes the water up the bay, giving a storm surge of 1 or 2 metres.  39mm does not sound significant compared to that, until you start thinking in terms of how often you have to sandbag before a storm; 1.95-meter storm surges are more common than 2.0-meter storm surges as those are outliers in the tail of the distribution.

Then there is the worry about the rise accelerating.  The obvious reference here is that archaeology and zoology both suggest that neolithic people and animals walked to Ireland from mainland Europe over a land bridge that is now deeply submerged.  That fits having 10 mm/year rise over the 10 000 years to get out of the last ice age for a 100-meter rise overall.  So depending on how fast ocean warming is in future, people worry about needing to move, not so much here with sloped coastlines, but  there are countries built in river estuaries.

Edited October 12, 2021 by OHara
forgot about the local rebound in crust

[JoeSchmuckatelli]

Just an observation - but when arguing about climate change, assertions that 'if all the continental ice melted' bad thing X will occur seem naive.  As do 'ain't nuthin happenen no way no how' arguments. 

It's literally arguing the extremes when what's needed is reasoned, educated discourse - but the extreme language engages the emotions and shuts down discourse. 

We know that 'the most extreme thing we can think of' is statistically unlikely to occur.  

Similarly, assertions that 'nothing is happening' and 'there is no proof of nutttin' are not only naive, but obstinate. 

The thing we should be asking is whether it makes economic sense to allow industry and convenience to pump ridiculous amounts of pollution into the environment year after year?  Because there will be repercussions, and they will be economic (and etc). 

It's just that when you have one side screaming the sky is falling and the other with its head in the sand saying nope, nope nothing happening - communication is failing and we can't address the real problem. 

So - can we, here, get away from the 'worst case scenario' and 'can't prove nuttin' predictions and arguments? 

Edited July 16, 2021 by JoeSchmuckatelli

[Rakaydos]

7 minutes ago, JoeSchmuckatelli said:

Just an observation - but when arguing about climate change, assertions that 'if all the continental ice melted' bad thing X will occur seem naive. 

It's literally 'if the most extreme thing we can think of happens it will be bad'. 

And yet we know that 'the most extreme thing we can think of' is statistically unlikely to occur. 

Similarly, assertions that 'nothing is happening' and 'there is no proof of nutttin' are not only naive, but obstinate. 

The thing we should be asking is whether it makes economic sense to allow industry and convenience to pump ridiculous amounts of pollution into the environment year after year?  Because there will be repercussions, and they will be economic (and etc). 

It's just that when you have one side screaming the sky is falling and the other with its head in the sand saying nope, nope nothing happening - communication is failing and we can't address the real problem. 

So - can we, here, get away from the 'worst case scenario' predictions? 

I grew up in earthquake country where "devastating thing that probably wont happen soon but we need to prepare for anyway" is a real thing.

[JoeSchmuckatelli]

38 minutes ago, Rakaydos said:

I grew up in earthquake country where "devastating thing that probably wont happen soon but we need to prepare for anyway" is a real thing.

As did I. 

I've also lived in cyclic megadrout region, hurricane land, snow in June at altitude place, and so much rain that trees grow where you don't want them zone. 

My impression of many people arguing about climate change is that they're from the city and read an article once. 

This forum, however, is a bit better read about stuff and not afraid to look at the science.  It's one of the things I like about this place