The main thing that needs be made clear is that the Antarctic is not fundamentally floating ice. It is glacial ice that is supported, at least in a central area, by land mass. When pieces of antarctic ice break off into the ocean, they raise sea level. This is not true of arctic ice, which is floating ice. But it is true of Greenland’s glaciers and other land mass supported ice.
Alarmist or not, if all the ice of antarctica were to melt, it would raise sea level by about 60 meters. Combined with other ice that would likely be melted by then also, like Greenland ice, and expansion, the ultimate total potential for sea level rise is 80 meters. Lack of permanent ice was the norm in the previous history of earth, and there was a correspondingly higher sea level also. We live in a peculiar era, which has served us well but we are hastily disposing of. Actually if we could have moderated global heating correctly, we could have simply prevented a otherwise forthcoming ice age. But that hope is distant now. From this point, there may not be any more ice ages going forwards. More immediately, on the order of a few thousand years or less, the ultimate sea level rise will make most of human establishment worthless, as a large proportion of human habitation and essential physical plant are less than 80 meters above current sea level, including structures which support essential trade. OK so this won’t happen tomorrow, but what will be happening tomorrow, and every day afterwards long into the future, is a halting rise, coupled with increased storms and surges which will chip away at what we have bit by bit, and moreso each coming year.
We’re only saved if you want to call it that by the time which would be required to melt all of the ice, which is often guesstimated on the order of 1000’s of years. But it seems every day we find this or that bit of glacial ice is melting faster than expected. Water flowing under the ice or in cracks can accelerate the process. So how long this is actually going to take is a deep unknown. It might well take less than 1000 years.
Global heating is also a millenial process by which I mean that even if we quit burning fossil fuels today (and that would still be too late, as by now a crippling 2C or so of rise is already baked in) it will take a millenia or so merely to reach the new equilibrium created by the higher level of CO2 we have created.
I’m sorry that most world politics doesn’t want to deal with this, but mine does. I work to make my own activities carbon neutral, and try to push society in general in this direction as much as I can. I always try to think of the very long term, and not just the next 50 years.
The reason politics can’t deal with this is that it is controlled by money, and there’s still a lot of money which could be made by more fossil fuels, and a lot of rich people are expecting return on their civilization destroying investments.
This is the ultimate test of “democratic” capitalism, and it will almost certainly fail to deliver a good outcome.
And sea level rise is only one small part of this outcome.