[watsisname]

I think the sea level rise aspect of Antarctic Ice Sheet tipping points is the least relevant to our generation and also the least interesting. 

What would it do to the energy balance, or atmospheric and ocean circulation?

[Luis Dias]

Mostly nothing? If anything, sea ice around Antarctica has been going northward, not southward, which in a way is a regional negative feedback on global warming.

[watsisname]

I was speaking of other effects of the long term deglaciation of Antarctica, not current sea ice trends.

[General Battuta]

IANAclimate scientist but it'll reduce Earth's albedo, right? That seems like it could be some nasty positive feedback.

[Beskargam]

Yes. and Less albedo in poles will produce patterns in rainfall change.

Climate change will also produce changes in polar jet streams. Polar ice loss leads to less strength in jet stream, and jet stream begins to assume a more sigmoid appearance.  Acrtic sea ice loss while not important in terms of SLR, is important in terms of salinity and ocean currents.

[Luis Dias]

There are many effects here to take into consideration. On one hand, if land becomes ice-free, the Albedo goes down and that's a positive feedback to take into consideration. But on the other hand, a little warming in the Antarctica has so far created more sea ice area than before:



And unlike the Artic complete meltdown (and its dangerous positive feedback), the sea around Antarctica is getting its albedo higher and higher, creating a negative feedback. This might also help explain why the southern hemisphere has hardly any detectable warming for the past 30 years, unlike the northern hemisphere.

[watsisname]

IANAclimate scientist but it'll reduce Earth's albedo, right? That seems like it could be some nasty positive feedback.

Precisely.  Any exposed landmass and ocean has lower albedo than the ice which was covering it, so the deglaciation of Antarctica would entail a positive albedo feedback.  It is not likely that we would see this feedback take hold in our lifetimes, however, even if the OP content is right in claiming that it is now too late to prevent it.  We may have passed the tipping point but the ice sheets will still probably remain stable for centuries or even millennia.

So, folks, don't worry about sea level rising tens or hundreds of meters any time soon.  The best estimates for sea level rise during this century are ~1 meter, with error bars of course.  About a third of that rise comes from thermal expansion of the oceans as they warm, and rest comes from melting land ice.

[IANA climate scientist either -- I just follow current research and have taken some courses in atmo physics, climate dynamics, and a fair deal of astrophysics carries over as well.]

[watsisname]

@Luis:

Antarctic sea ice extent increases at present for a combination of reasons:
-The continent is well isolated (in a thermodynamic sense) from the rest of the planet, by the southern circumpolar current and wind field
-Glacial melt produces a layer of cold fresh water around the ice shelfs, which is much easier to freeze.

It is not known how long this positive trend will continue, though it is expected to reverse eventually as various thresholds are passed.

[Luis Dias]

Your first reason is incompatible with the assertion that Antarctica is warming. Your second is very near to what I've been told about the subjcet too, although the version that I heard of also included a narrative wherein a warming Antarctica meant a little bit of more evaporation and rain, but in this case, snow, which tends to increase the rate of the formation of ice sheets over the sea.

Nevertheless, the point I was trying to make is that the albedo in the region is increasing in a very large area, and that's at least a bit of a good news.

[Phantom Hoover]

Your first reason is incompatible with the assertion that Antarctica is warming.

No, it's really not. Antarctica warming slowly does not preclude it warming at all.

[Luis Dias]

Yes, that makes sense.

[watsisname]

Your first reason is incompatible with the assertion that Antarctica is warming.

It is warming at a slower rate than its surroundings, which changes the pressure gradient and thus wind field.  This wind can help to push sea ice out to greater distances.

[Mongoose]

From what I understand, the kicker with Antarctica isn't that the sea ice is expanding, but that the land ice sheets are thinning comparatively quickly, and that isn't good news for anyone.

The one issue I really have with this level of doom-and-gloom is that it operates on the assumption that humanity won't be capable of actively counteracting climate change as the decades progress.  I mean at some point, we're going to figure out effective large-scale artificial carbon sinks, or solar reflector systems, or the like.  Will they be massive engineering feats that are, for the foreseeable future, prohibitively expensive?  Of course.  But that doesn't mean they won't happen.

[Luis Dias]

They are not prohibitely expensive. They are actually very very cheap, in comparison with ending co2 emissions. The big problem is that once we start doing that, we are acknowledging we have the control of the earth's climate. I seriously doubt all the big institutions of this world are prepared for this kind of responsibility. Actually, I'm pretty sure they are not, which is why people are ****ing scared of that level of discussion.

[watsisname]

I refuse to stop smoking excessively because I am scared to death of the idea of acknowledging control over the health of my lungs.

[Mobius]

What's the problem? Ice sheets are an exception in the history of Earth, not a rule.

As long as you don't live in Venice, you're fine.

[Grizzly]

The one issue I really have with this level of doom-and-gloom is that it operates on the assumption that humanity won't be capable of actively counteracting climate change as the decades progress.

The problem from that statement is that it assumes that we most certainly will have that ability in the future. Currently we are still developing an understanding of how the climate works in the first place.
Also, I bet a lot of people expected us to have developed hydrogen by now. It's not a good idea to plan your work aroudn technology which does not exist yet.

[Luis Dias]

I refuse to stop smoking excessively because I am scared to death of the idea of acknowledging control over the health of my lungs.

This analogy is as out of the ballpark as an ant is to a titanossaurus. No wait, at least this one is comparing a similar thing like size, whereas what you are referring to isn't. Geoengineering isn't like stop smoking in any conceivable way. A better analogy would be to start to throw some untested aerossols into your lungs until it stops overheating.

But the problems are bigger than this. It implies geopolitics actually coming together to solve this issue, there exists actual trust between countries and institutions even when problems and unforeseen consequences arise, these tools aren't served as weaponry, etc., etc.

Just looking into current geopolitical events, it's ****ing obvious to me we aren't mature enough as a civilization in order to begin a project of controlling such a beast like the climate.

[deathfun]

I'll enjoy my new ocean-front property, but something tells me Vancouver won't

Richmond is going to be screwed...

Vancouver's mostly fine. Richmond's ****ed.

I wonder who owns Antarctica, and who gets to move there once it melts.

...Oh you beat me to it

Wait, just how many people live here from HLP

[watsisname]

I refuse to stop smoking excessively because I am scared to death of the idea of acknowledging control over the health of my lungs.

This analogy is as out of the ballpark as an ant is to a titanossaurus. No wait, at least this one is comparing a similar thing like size, whereas what you are referring to isn't. Geoengineering isn't like stop smoking in any conceivable way. A better analogy would be to start to throw some untested aerossols into your lungs until it stops overheating.

But the problems are bigger than this. It implies geopolitics actually coming together to solve this issue, there exists actual trust between countries and institutions even when problems and unforeseen consequences arise, these tools aren't served as weaponry, etc., etc.

Just looking into current geopolitical events, it's ****ing obvious to me we aren't mature enough as a civilization in order to begin a project of controlling such a beast like the climate.

The analogy is to show the absurdity of stating 'control' as the conscientious cessation of an activity which was having the effect in question. 

By smoking heavily, one is affecting their lungs.  By stopping, he may perhaps be taking controlling over his behavior (if the smoking was an uncontrolled addiction; our use of fossil fuels might also be said to be an addiction), but he is not suddenly starting to control his health.  He was doing that already by smoking.  By burning fossil fuels and releasing the CO2 into the atmosphere, we are affecting the climate.  It is absurd to say that we suddenly control the climate by choosing to adopt mitigation strategies.

Now if you originally meant to say that you are scared of geo-ingineering (the use of measures to sequester CO2 from the atmosphere, or even more drastically, the application of negative forcings to try to counteract the GHG forcing), then you are in good company because such choices are indeed terrifying, particularly by the law of unintended consequences.  But stating that regulation/reduction of greenhouse gas emissions is scary because this implies acknowledging control of the climate system is really silly.