When Icebergs Melt and Pieces Break Off, Sea Levels Rise?

[Dominik_E]

Sorry to come across as being smart, but as said before, ice breaking free from an ice shelf does not change the sea level in a relevant fashion. Neither does melting of a shelf or of ice bergs. The ice is already floating when it is part of the shelf! The sea level rise has very little to do with ice shelves or ice bergs. Most of it is due to meltwater from ice far inland.

 

[Dominik_E]

As just one reference, take a look at this plot:

https://sealevel.jpl.nasa.gov/files/ostm/cazenave.jpg

Leading contribution is from inland ice. Mountain glaciers being the prime contributor. Neither greenland nor antarctica are actually close to being. And that is including the inland ice there.

 

[The Chairman]

Leading contribution is

No one is denying that, not even Jill. But the vastness of the fresh water ice, in terms of icebergs and shelf ice, has an undeniable impact on water levels as it melts, whether you want to admit it or not. Both are true and the warming of the seas is accelerating the process. You can deny it all you want, but global warming is a reality. A harsh reality. Just because you don't understand it, or appreciate the gravity of the problem, doesn't make it less so. In fact, the science deniers are counting on this.

 

[Dominik_E]

The Chairman, frankly, I would strongly ask to not make unfounded assumptions about myself denying climate change. I have stated in one of my first postings in this thread that

a) Whatever the details, the entire effect is clearly due to anthropogenic greenhouse gas emissions. The melting of mountain glaciers is also a consequence of higher temperatures

b) While the wording is unfortunate from a purely scientific viewpoint, this for sure does not detract from the important message of the talk

For full disclosure, I teach (among others) physics of the atmosphere at university. I am also what people here call a climate activist.

My comment was solely intended to get the underlying science completely right. I have also stated that unfortunate wordings like the one that caused the thread here happen to all of us, myself surely included. It is still worthwhile to get it right in the end.

 

[wedivebc]

It changes by the amount of ice above the water line. It's the same reason why it takes 33ft of saltwater to make an atmosphere and almost 34 ft of fresh water to do the same. Sea ice (same density) barely brakes the surface of the ocean or bay it's found in. The same weight of fresh water has a little less than 3% more volume, so icebergs stick out much higher than sea ice due to Archimedes Principle. Scientist Jill is correct in her statements. Really, do you think all that water just disappears when it melts?

No I dont think it disappears. I think the water is displaced by the volume of the iceberg which in its solid state is less dense that the liquid water floating it and that as it melts the volume shrinks which accounts for the mass above the water line.

 

[The Chairman]

The Chairman, frankly, I would strongly ask to not make unfounded assumptions about myself denying climate change.

Mea culpa... I meant denying that melting fresh water ice had little to no impact at all. I'm not sure how to reword it to say that, so I'll leave this as a clarification. All of it, the big and the little, add up to be a catastrophe in the making.

 

[Dominik_E]

The Chairman, to this I agree of course!

Every ton of CO2 is a problem, and every millimeter of sea level is a problem. In turn, this means that (unlike as with many other problems on Earth), we all can do something to reduce the catastrophe.

Actually, the thing about ice bergs and ice shelves at some future point may become much more relevant. Above a certain point, glaciers will flow much quicker. Glaciers become shelves, ice starts floating. And already at this point it displaces water and thus raises the sea level.

I was honest in saying the "sorry for coming across...". It is a fine line between not alienating people with fine distinctions that most will never care about, and on the other hand loosing accuracy to the point that people will question the entire thing.

 

[The Chairman]

I think the water is displaced by the volume of the iceberg which in its solid state is less dense that the liquid water floating it

Which is compounded by the fact that fresh water is also less dense. So sure, there is "shrinkage" given that water is a bipolar molecule, but that's not the "all" of it. Again, there's a bit less than a 3% difference in volume betwixt fresh and salt water. About 3% of the ice above the waterline will be added to the water level. That's just physics.

 

[Norrm]

The point that was missed by the OP is that global warming is bad .

I didn't miss anything, I am not confirming nor denying the impact of global warming. I was simply focusing on the mistake made by the living legend and the perpetuation of the myth that melting icebergs significantly contribute to flooding.

I think the estimate is something like .03 mm per year. Get back to me in 100 years when the sea levels have risen 1 mm as a result of melting icebergs and let me know how you're doing.

Scientist Jill is correct in her statements.

Only if you consider less than a.03mm of rise in sea levels per year to be a significant cause of global flooding. Certain individuals apparently think that very small number is significant - and I guess it could be depending on exactly what it is they happen to be measuring.

 

[tursiops]

I think the estimate is something like .03 mm per year. Get back to me in 100 years when the sea levels have risen 1 mm as a result of melting icebergs and let me know how you're doing.

LOL! The least you could do is get your math right!