A large slab of ice is breaking off an Antarctic glacier

A more probable (but still fairly unlikely) scenario is that this could destabilise the ice shelf over a longer timescale (maybe decades). Removing ice from the front would let the ice behind accelerate, stretch and thin, which makes it more vulnerable to calving again, and so forth.

The most likely outcome though is that there's no significant change to the ice shelf, except maybe the flow of the ice speeds up a bit, which is interesting glaciologically, but probably not something the rest of the world will get excited about.

Obviously, any and all of this could change as the climate continues to warm. If we start to see significant levels of surface melt ponding across the shelf, then we can worry.

Potentially a very long time, although it will likely break into smaller pieces first. A lot of icebergs get caught in the Antarctic Coastal Current, and just drift around the edge of Antarctica, not melting very much at all. Over time, most of them break free and drift north into warmer waters and melt, but others stick around. Iceberg B-9, which calved in 1987, still has a few chunks sitting around.

> * Is ocean ice this large called an iceberg?

Yes. You'll sometimes see the bigger bergs described as "ice islands", but that's just a subcategory of iceberg.

> * Does is get an official name, like IIS Wilmington (international ice station, capital of Deleware)?

It'll get a numeric designation, A-nn, where A indicates which quadrant of Antarctica it originated from (in this case 0-90W) and nn is a sequential number, probably in the high sixties depending on whether any other large bergs calve first. Then, as it breaks up, the resulting bergs will get letters added to the name, A-nnA, A-nnB, etc.

> * Have large ice sheets in the past forced/caused changes in human behavior, such as altering shipping lanes, in the same way planes fly around a storm?

In 2005, B-15A blocked the entrance to McMurdo Sound, where the main US and New Zealand Antarctic bases are located, and they were unable to get cargo ships in for a few weeks. And of course, ships are redirected around icebergs in the open ocean all the time.

(pedantic Blue Hen here.)

Not human in this example, but they can be devastating to penguin populations:

https://www.theguardian.com/world/2016/feb/13/150000-penguin...

If you mean more broadly how can we help prevent the loss of ice from Antarctica, then I'm not a climate policy expert, but https://350.org/ is a good place to start.

Of course, that shelf is also having some crack problems: https://www.theguardian.com/world/2016/dec/07/british-antarc...

This is all much further south than cruise ships normally go though.

Also, remember, you're only seeing the top 10% or so of the berg. There can be interesting shapes below the waterline, caused by preferential melting.

As for the glaciers feeding the shelf, that's an interesting question. Floating ice on its own provides very little resistance to their flow, but the mouth of the ice shelf is narrower than the back, so the converging flow has a resistive effect, like squeezing toothpaste out of a tube. If a gap is made in the ice blocking the mouth, then there should be some speedup of the glaciers. It all depends on exactly where the rift goes next, and on the exact balance of stresses in the shelf, which there's some uncertainty about.

I'm not an ecologist though, so I'm hazy on the details.

Then, once you had it back into position, you'd need to apply your "glue" to the whole crack surface, which is around 40 square kilometers, a little smaller than Manhattan Island. Also, the majority of that crack surface is hundreds of meters deep in sub-zero waters in one of the most inaccessible places on the planet.

Then, once you've done that, the same forces which caused this bit to calve off would cause a new bit to calve a year or two later.

Sea ice doesn't contribute to sea level rise when it rises; continental ice sheets and grounded ice shelves do. There are three great ice sheets: West Antarctica (~2.2 million km³), Greenland (~2.8 million km³) and East Antarctica (~20 million km³). By contrast, the largest ice shelf, Ross Ice Shelf, is only ~0.1-0.2 million km³. I don't know how much of that is grounded and thus capable of inducing sea level rise on loss. By comparison, the piece that's breaking off is only 1700 km³ or so.

Our knowledge of the exact state of these ice sheets and shelves has a lot of holes in them, but it's clear that the East Antarctic Ice Sheet is gaining in mass, West Antarctic Ice Sheet about stable to slightly negative, and Greenland is shedding at a fast clip of a few hundred km³/year. The ice shelves, particularly in West Antarctica, do seem to generally be in retreat.

At current rates of loss, the melting of the ice sheets provide only a very modest rate of sea level rise--maybe 0.5mm/yr. By comparison, in, say, Norfolk, the isostatic rebound from the loss of the Laurentide Ice Sheet contributes about 1.5mm/yr in sea level rise. The fear is that there could be some kind of tipping point that causes the ice sheets to very suddenly and dramatically collapse (à la Larsen B), but we don't have much evidence to suggest that this is likely to happen.

Source: Put some ice cubes in water. Observe that they float.

  ≈ (0.2 to 0.3) × mass of a Handy size cargo ship ( 28000 to 40000 lg tn )
  ≈ (0.3 to 0.5) × mass of a Small Handy size cargo ship ( 20000 to 28000 lg tn )
  ≈ 0.83 × daily mass of trash produced in New York City (≈ 1.2×10^7 kg )

EDIT:

For the ice slab in question, W|A gives following comparisons:

  ≈ ( 0.25 ≈ 1/4 ) × total area of Wales (≈ 8023 mi^2 )
  ≈ 1.7 × total area of Rhode Island ( 1212 mi^2 )
  ≈ 3 × area of forest flattened by the asteroid explosion over Tunguska in 1908 (≈ 2000 km^2 )

I don't deny that many progressives are less open minded than they think. But better challenge them things like anti-GMO / pro-organics ideas that don't really have much base in real science.

Unlike in the climate field, you'll find that actually lots of people who research GM / food safety will not agree with the alarmist headlines of GMO or "processed foods".

The climate deniers are the ones like the Catholic Church