How much would the sea level rise if the ice caps totally melted?

[Bohandas]

Googling the question gives me three conflicting figures - 195 feet (NASA), 216 feet (National Geographic), or 230 feet (US Geological Survey).

My family's house is 223 feet above sea level, I'm trying to figure out if a worst case scenario means that we're screwed or if it means that we're rich

[Eldan]

Some of the difference might be how much thermal expansion of the ocean you figure in.

[Anymage]

I'd wager more of the uncertainty is that getting exact figures for how much water is tied up in ice caps is tricky, so there's some estimation at play. Of the three I'm inclined to think that the US geological survey would be the best guess, but it is all guesswork.

However, even if the Nasa figure is right and your property is a leisurely stroll from the beach, I don't think that'll significantly change just how screwed you are from the whole rest of the situation.

[Eldan]

Also estimating the shape of the coast everywhere in the world.

[gbaji]

Does anyone actually believe that all the ice caps on the entire planet will actually melt entirely?

Why not ask "how dark will the sky be if every volcano on the earth erupted?". Or "how hot would it be if the sun expanded by 50%?". Or "how big would the traffic jam be if every car broke down at the same time?". Kinda silly. Doubly so to be worried about where your house may be (presumably in your own lifetime) relative to the current shoreline.

Honestly, if every single ice cap in the world melted, your house's position relative to the shoreline would be one of the least significant effects.

[veti]

Honestly, if every single ice cap in the world melted, your house's position relative to the shoreline would be one of the least significant effects.

Not to the people living in it, it wouldn't.

Don't get me wrong, I don't think it's a very plausible scenario, at least not in the next century or two. Just wanted to point out that "significant" is very much a matter of perspective.

[Eldan]

Does anyone actually believe that all the ice caps on the entire planet will actually melt entirely?

Yes? This has often occured during Earth's history. In fact, Earth has more often had no ice than ice. And if you look at what temperatures were then, and what temperatures are now, we're not far off.

[Chronos]

I think the bigger uncertainty than how much ice there is, is what proportion of that ice is floating. Floating ice, when it melts, won't change the water level, but ice which is currently sitting on top of land will. And nobody really knows exactly where Greenland's real coastline, for instance, actually is.

But yeah, thermal expansion of liquid water is also a big factor, so you'd have to figure how much the overall average temperature would have increased at the point where "all the ice caps have melted".

[Mechalich]

I think the bigger uncertainty than how much ice there is, is what proportion of that ice is floating. Floating ice, when it melts, won't change the water level, but ice which is currently sitting on top of land will. And nobody really knows exactly where Greenland's real coastline, for instance, actually is.

But yeah, thermal expansion of liquid water is also a big factor, so you'd have to figure how much the overall average temperature would have increased at the point where "all the ice caps have melted".

The majority of Earth's land based ice is held in the East Antarctic Ice Sheet. Because of Antarctica's global position and the circumpolar current surrounding it, the amount of warming necessary to completely eliminate that ice is quite extreme. Something like 7.5 C increase is estimated as necessary and even then complete loss would take 1000-10000 years.

[gbaji]

The majority of Earth's land based ice is held in the East Antarctic Ice Sheet. Because of Antarctica's global position and the circumpolar current surrounding it, the amount of warming necessary to completely eliminate that ice is quite extreme. Something like 7.5 C increase is estimated as necessary and even then complete loss would take 1000-10000 years.

Does that count as "far off" or "not far off"?

[Rydiro]

Some of the difference might be how much thermal expansion of the ocean you figure in.

I'm pretty sure those numbers are with thermal expansion. They are too massive to be just the current ice volume.

[Eldan]

Sure, it's just additional factors, which introduce a bit more uncertainty. To explain why the estimates differ.

[Tyndmyr]

Googling the question gives me three conflicting figures - 195 feet (NASA), 216 feet (National Geographic), or 230 feet (US Geological Survey).

My family's house is 223 feet above sea level, I'm trying to figure out if a worst case scenario means that we're screwed or if it means that we're rich

At that altitude, you'd be fine, most likely. All numbers like this are estimates to some degree. We have some measurements of ice depth and what not, but often an average is relied on for a given area, and real numbers can be a shade off.

Does anyone actually believe that all the ice caps on the entire planet will actually melt entirely?

Not in anything like a reasonable timeframe, such that the house would matter. 223 feet is a *ton* of sea level rise. It's just a fun hypothetical. Real loss of this magnitude would take very long timeframes and drastic changes.

But unrealistic hypotheticals remain interesting. I've certainly considered many disaster movies from the perspective of if that happened to me, even where the scenario is something impossible like zombies.

[gbaji]

At that altitude, you'd be fine, most likely. All numbers like this are estimates to some degree. We have some measurements of ice depth and what not, but often an average is relied on for a given area, and real numbers can be a shade off.

It's also worth noting that many sources also just report how much ice from the caps/fields/sheets are "melting". But that's counting water runoff basically, and is only telling half the story (and the more alarming half). There's also regular yearly gains to those ice caps via fresh snow packing on the top/center. Just counting up how much melts and therefore decreases total volume of ice, without including how much snow adds to the volume of ice make things seem more drastic (but also inaccurate if we're actually worried about the "whole thing disappearing"). That's not to say that the ice hadn't decreased in total volume over the last century (it has, quite measurably), but not nearly as much as might be implied by just looking at melt rates.

Not in anything like a reasonable timeframe, such that the house would matter. 223 feet is a *ton* of sea level rise. It's just a fun hypothetical. Real loss of this magnitude would take very long timeframes and drastic changes.

Yup. And any major coastline changes from seal level changes will be gradual enough that they will be almost lost in the normal geological changes over time. Land is not static. It flows. Slowly, but it does. Just ask any geologist friends you have. Homes are removed/destroyed regularly by sea cliff or hillsides collapsing/flowing over time. Homes being removed/destroyed by gradual water level rise is much the same.

The odds of some kind of dramatic/sudden change that causes massive waves of water or something are extremely unlikely. And far more likely (and frequently) to also be caused by land shifts (ie: Tsunami effects) than glacier run off. Humanity somehow manages to adjust ourselves to all of these other natural forces that cause problems for us all the time. So yeah. Water level rise from this is more or less just static in the signal.

But unrealistic hypotheticals remain interesting. I've certainly considered many disaster movies from the perspective of if that happened to me, even where the scenario is something impossible like zombies.

Hah. Ok. I like to do those "what if" stuff to. So totally get it! But then again, I also love watching and laughing at disaster movies too. Yes. I'm looking at you Dante's Peak. Although, I did really like the Stallone one. Um... Daylight I think? Dunno why. It's just kinda neat. Has its silly bits as well though. Honestly think "totally unrealistic action sequences" are a pre-requisite for these kinds of films.

[Mastikator]

There are 24500 million billion kg of ice caps (source: https://climategen.org/blog/how-much...on-antarctica/)

The earth surface is 510 million square kilometers, 71% is ocean, so basically 362 million square kilometers

1kg of ice melts into 1 liter of volume (not perfectly exactly, but close enough a ballpark estimation).

(24500000000000000000 liters) / (362 million km²) = ~67 meters (plus minus a couple of meters for sure)

Edit- You are in the danger zone @Bohandas. 223 feet is 67 meters so you'll be right on the new coastline

[Rockphed]

There are 24500 million billion kg of ice caps (source: https://climategen.org/blog/how-much...on-antarctica/)

The earth surface is 510 million square kilometers, 71% is ocean, so basically 362 million square kilometers

1kg of ice melts into 1 liter of volume (not perfectly exactly, but close enough a ballpark estimation).

(24500000000000000000 liters) / (362 million km²) = ~67 meters (plus minus a couple of meters for sure)

Edit- You are in the danger zone @Bohandas. 223 feet is 67 meters so you'll be right on the new coastline

With numbers that big the differences in volume with temperature start to matter. As do the increase in sea area from rising seas. How quickly it happens also matters since coral atolls can grow upward at about the same speed that sea level is currently rising (so even if we melted all the ice caps over the next 1000 years you would probably still have coral atolls in the pacific where you have them now).

[veti]

(so even if we melted all the ice caps over the next 1000 years you would probably still have coral atolls in the pacific where you have them now).

Doubtful, because coral dies if the sea temperature rises and stays risen. More likely there would be new atolls adorning the newly submerged lands at less tropical latitudes.

[Mastikator]

Doubtful, because coral dies if the sea temperature rises and stays risen. More likely there would be new atolls adorning the newly submerged lands at less tropical latitudes.

Corals need the right amount of light, temperature and acidity. Most likely there won't be corals in a thousand years, or much life in the ocean in general for that matter, what with the ongoing and accelerating biodiversity collapse and all.