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Hey folks,

I'm one of the scientists on Project MIDAS (the team that made the announcement). Happy to answer questions about this. I've also been keeping a spreadsheet of things roughly the size of the iceberg, for journalistic comparisons: https://twitter.com/mewo2/status/818826891545210881

A few questions:

* How long will it take for "Deleware" to melt?

* Is ocean ice this large called an iceberg?

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

* 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?

> * How long will it take for "Deleware" to melt?

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.

> Iceberg B-9, which calved in 1987, still has a few chunks sitting around.

Thanks for posting, and curious about this. When icebergs subdivide, how is tracking accomplished?

I assume late 80s was recent enough for decent resolution space imagery?

Yeah, once these things are moving, you don't need much resolution to see them - we're talking about objects several kilometers wide, at the very least. Easily visible on even the most primitive satellite imagery. The difficulties would be cloud cover and orbital inclination.

> I assume late 80s was recent enough for decent resolution space imagery?

Landsat (https://en.wikipedia.org/wiki/Landsat_program) was likely the best available imagery back then. In the 80's it looks like they had 60m resolution - I assume that would be big enough to see an iceberg?

I'm not an expert on icebergs but I have used enough satellite imagery to answer... Yes the 60m Landsat imagery would show large icebergs under its ground track.


That bit about McMurdo is interesting. I doesn't surprise me, but I didn't know, that they send and receive thinhs via ships. I always hear about McMurdo as being inaccessible by plane during some chunk of time during the cold season, usually tied to some real world emergency or movie plotline with a sense of urgency.

  Potentially a very long time, ...
Am I the only one who is concerned that a scientist wouldn't immediately comment that this is irrelevant with respect to effect on sea level? Once any body of ice is free-floating, its effect on sea level is immediate and doesn't get worse as it melts.

It's almost like the conventional terminology for bergs (http://www.ccg-gcc.gc.ca/e0010735) might need to be expanded for these monsters. Some of them may as well be floating glaciers.

FYI, Dover's the capital of Delaware.

(pedantic Blue Hen here.)

My bad :). My head said Dover, and my hands wrote biggest city I could remember. Don't tell my 8th grade U.S. History teacher. He'd have an anuerism.

Or your spelling teacher (aneurysm)

Don't tell his spelling coach either!!

Wouldn't your geography teacher be more annoyed than your history teacher, or have I missed the point?

My U.S. History teacher grilled us every week on knowing US states & their capitols. You have to show weekly improvement, and finish the term w/ 100%.

Regarding spelling, I plead not guilty by reason of autocorrect+gorilla-fingers-on-little-screen.

In some schools (like mine) we did a geography segment as part of the history class. So same teacher, primarily teaching history.

Will there be a man made ravine breaking it into northern & souther halves, though?

> Have large ice sheets in the past forced/caused changes in human behavior

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


I have a really stupid question. Here it goes, anyway. Isn't there a way to "glue" these big block of ice back to the main part?

I was going to add a few ideas on how to glue it back, but then I deleted them as it would sound more stupid than it already does.

I think you might need to recalibrate your idea of the scale of this object. The iceberg weighs about a trillion (10^12) tons. For comparison, a Nimitz-class aircraft carrier is about a hundred thousand (10^5) tons. So you're talking about moving an object which weighs about a million times as much as the whole US Navy carrier fleet.

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.

What would be the point? Even if you could somehow freeze it back on, the natural forces that caused it to calve off are going to continue, so all you've done is bought a little time, perhaps not even a full season.

Get 10,000 snow machines to dredge the water and spray snow and water everywhere ;) If people can build islands, why not glaciers?

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Nuclear winter.

I saw some footage on the BBC over the weekend showing the are around the Larsen Ice Shelf and I was stuck by how perfectly sheered many of the ice bergs in the area were. They looked like precision cuts, perfectly flat, they looked like blocks. I have not seen this before. Is there an explanation to this phenomenon of near perfect cleaving?

Also are there implications for the glacier(s) that feed this ice shelf after this part of the shelf breaks off?

Yes, the edges are impressive, aren't they? The ice is floating, almost flat, and has had hundreds of years to reach equilibrium, so there's practically zero vertical shear stress in the ice shelf. As well as that, the ice itself is very laterally homogeneous - there are layers within it, but all the horizontal variability is on scales of kilometers or more. There are no particular faults or planes of weakness within the material. This means that when it breaks under tension, like this, it breaks in a very clean and even way.

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.

Fascinating. Thank you for the detailed response. This is a really iteresting project, its wonderful that you get to work on such things. I will now have to stay updated with the progress. That photo in the article of the plane wing and the fissure extending to the horizon really puts the beauty of the Antarctic in perspective. I would like to make it down there one day. Cheers.

Hi, there seems to be some mixed messages on the implications of this for the rest of the Larsen C shelf. Are we likely to see a collapse of the whole thing in the next few years, Larsen B style?

Probably not. The Larsen B collapse was preceded by widespread surface melting across the shelf, which caused lots of crevasses to fill with water, driving them open, and the whole shelf pretty much shattered under the stress. We don't see that sort of melt on Larsen C - even though it's quite nearby, the climate is a couple of degrees colder.

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.

Thanks for these facts! The article has somewhat of a different spin on it.

Well, there's not a whole lot of factual difference between "Big Thing Could Happen" and "Big Thing Probably Won't Happen", and I know which one I'd lead with if I was an editor. I don't think there's anything in the article which I'd disagree with on a scientific level.

And what if you are wrong about that prediction?

Is there anything living on/around that ice? Will this have any immediate ecological effects if it does start to drift away?

I think there are some microorganisms in the snowpack, but other than that it's a pretty barren place, at least above the water. Below, a lot of sea life congregates around the ice front - there are nutrients that melt out of the ice - and this supports an ecosystem, but that should all just move to the new ice front. The iceberg itself will probably support a small marine ecosystem as it floats away and melts.

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

>I think there are some microorganisms in the snowpack, but other than that it's a pretty barren place, at least above the water.

Just guessing:

There might be tardigrades. They can withstand extremes of hot and cold. First saw them mentioned here on HN some time ago. Amazing creatures. From the Wikipedia article:

Tardigrades are notable for being the most resilient animal: they can survive extreme conditions that would be rapidly fatal to nearly all other known life forms. They can withstand temperature ranges from 1 K (−458 °F; −272 °C) (close to absolute zero) to about 420 K (300 °F; 150 °C),[8] pressures about six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space.[9] They can go without food or water for more than 30 years, drying out to the point where they are 3% or less water, only to rehydrate, forage, and reproduce.[3][10][11][12]


Is this event likely to cause large waves in the area? I ask because I will be taking a cruise next month which stops in the Antarctic sound, and I would like to live.

No, not particularly. It's already floating, so it will just drift away for the most part. Some smaller bits will probably fall off and produce some spectacular waves. By smaller bits, I mean stuff up to a cubic kilometer, so I wouldn't want to be standing next to it when it happens.

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

Just curious if large ice shelves like this ever start to separate and end up refreezing before they actually break. Looking at the diagram in the article leads me to think that this part of the ice shelf is a goner, but I don't actually know that much about the environment in or near Antarctica.

It's unlikely in this case, but it has happened in some other areas. The Brunt Ice Shelf (where the British Halley VI station is located) is largely made of reconstituted icebergs like you describe.

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

So what should we (the people) do about it ?

What is your theory ? What should society as a whole do now in order to stop these processes ?

Nothing! This is a completely natural process - ice builds up over time in the shelf and it has to be lost somehow. The calving of the iceberg is, in itself, not a result of human activity.

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.

I have read that Antarctic ice is overall increasing. Is there a reason to be concerned with loss of ice from Antarctica? https://insideclimatenews.org/news/31052016/why-antarctica-s...

We need to distinguish between sea ice (a ~1m thick layer of frozen seawater), and land ice (up to 3000m thick layer of compacted snow). Sea ice is quick to respond to climate change (because it's so thin), and has a large seasonal component to its extent. Land ice is much slower to respond, and harder to replace once it's gone.

Antarctic sea ice extent has been increasing, largely because of a change in wind patterns. Winds blow ice away from the coast, leading to more open water, which leads to more sea ice formation. Even though Antarctica is getting warmer, it's still much too cold to melt sea ice in most places, so climate warming isn't having a huge direct effect on sea ice.

However, the land ice in the Antarctic is almost certainly decreasing (exact measurements are quite hard), and the trend is definitely towards more ice loss. Ice shelves, although floating, are the outer extremes of this land ice.

This is a good review paper on the subject of the mass balance of land ice: http://www.vliz.be/imisdocs/publications/248038.pdf

Worse, melting land-ice increases sea level, while melting sea ice does not.

If the entire Antarctic ice shelf melted, global sea levels would rise about 60 meters (200 feet).


Though it would take a huge temperature rise for that to happen -- enough that the other climatic effects would probably be as bad or worse than the sea level rise.

Greenland is not nearly so cold, so it's more likely that its ice shelf would melt, which would add about 7 meters (20 feet) to sea level.

The larger problem with melting sea ice, as I understand it, is that the reflectivity of water is much lower than that of ice, so less of the incoming energy from the sun is reflected, accelerating warming.

The antarctic is fundamentally different from the Arctic (it is the Arctic that is the canary in the coalmine for global warming). It is surrounded by >30 degrees of latitude of water, and the Coriolis effect ensures that winds blow without the interference of land around the globe between the roaring forties and screaming sixties. This insulates the antarctic and is the main reason it is colder than the Arctic - there is little heat transfer from warmer latitudes. In contrast, the Arctic is all about heat transfer and global warming simulations show it will warm much faster than the antarctic.

Reference: http://www.livescience.com/40125-climate-change-affecting-ar...

Here's a good reference explaining the data: https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-o...

The article says that this is "likely accelerated by rapid human-caused global warming." Is that actually true? Does a degree or two make such a difference to something so huge?

What that bit is referring to is that the ice shelf has been thinning as a result of climate change. The temperatures on the Antarctic Peninsula have increased by about 3˚C (5˚F) over the past half century or so, which is a huge change to the climate of a region.

I get that the temperature increase is happening, but I don't get how this in turn increases the melting and thinning of ice. According to Wikipedia, summer temperatures in the warmest part of Antarctica still average below 0°C. Can someone explain?

There's a big difference between average temperatures and peak temperatures. On Larsen C, we regularly measure localised temperatures in excess of 10˚C for days at a time. That's enough for some serious melt.

Also, surface melt is only half the story. The base of the ice is in contact with the ocean, which is also warming. Water in contact with ice is (more or less by definition) at the freezing/melting point - if it warms, the ice melts a bit, if it cools, the water freezes. So a change in ocean temperatures can have a big effect on melt rates.

Finally, it's not enough that the shelf be in equilibrium, melt-wise. The ice is constantly thinning, as it stretches and flows under its own weight. There needs to be enough extra mass added (mostly as snow) to compensate for that, if the shelf is to remain a constant thickness.

Thank you! :)

Here's a question: Are you at all comfortable with the realization that a website as bad as Business Insider is carrying your story? Understanding, of course, that the grand majority of the stories on that site are out and out clickbait garbage.

Well, it's a major news story - according to our press office, over a thousand outlets worldwide were carrying the story. So it would be weird if Business Insider didn't cover it. That said, I'm slightly surprised that this is the version of the story linked on HN. Personally, I like the BBC version better: http://www.bbc.co.uk/news/science-environment-38522954

How far could it float away? Any chance of crashing into South America?

Unlikely, it's hard for these things to get close to the coast - remember that the base is several hundred meters below sea level, so it will ground if it gets into even remotely shallow water. More likely it'll break up, and bits will wander off into the South Atlantic and Indian oceans.

There are quite a few inhabited islands spread between south America and southern Africa.

They're mostly old volcanoes some are still active but so pointy there wouldn't be much for a berg to catch on until it was right on top of them.


Thank you for using proper units in your spreadsheet :)

If you want your comparisons to have impact, might I suggest finding a more communicative way to visualize the data.

It had plenty of impact on me just as it is.

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