For some context on size, the calving event in this video is about 7 cubic kilometers. The Larsen C berg will be about 1000 cubic kilometers. On the other hand, this berg is overturning, so the calving is, to put it mildly, quite energetic (equivalent to a couple of hundred kilotons of TNT). The Larsen C berg will just drift away in a much less dramatic fashion.
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
* 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?
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
Yeah, that's sort of deliberate. Because the consonant system is so much more developed than the vowels, it's easier for them to do more of the heavy lifting, even if that is a bit unusual in natural language terms. I could probably stand to tweak the probabilities a bit though.
There are quite a lot of existing word generators that allow you to describe words in different ways (declaratively according to phonotactic rules vs. procedurally and so forth), and at different levels of detail depending on the user's level of linguistic knowledge.
A fairly popular one which recently had a major update is Lexifer by William Annis (http://lingweenie.org/conlang/lexifer.html), which allows specifying some fairly sophisticated statistical distributions.
My own entry into the space is Logopoeist (https://github.com/conlang-software-dev/Logopoeist). I did a comparative review of every known word generator at the time last November, but unfortunately I haven't gotten around to publishing it yet.
I can't believe I'm doing this, but I think I'm going to defend Mercator here.
The Mercator projection was indeed originally designed for compass navigation, but the reason it's still used for web mapping is slightly different. The Mercator projection is conformal. What this means is that angles (and hence in some sense shapes) are preserved locally. When we zoom in on a small section of the Mercator projection, we get a reasonably accurate representation of the actual shape of features. This is generally not true for most more fashionable projections, which will stretch and skew things, so they don't always look great when zoomed.
In general with map projections, you have to make a compromise between global properties and local properties. Choosing Mercator means going full-on for local quality, at the expense of the global map being quite distorted. This makes it great for zoomable web maps, because most of the time the global map is just used to find the area you're actually looking for.
Now, you could argue that for a living-room wall, you want something that looks good globally. If it was my wall, I'd agree with you. However, this guy seems to be really interested in local detail. He worries about his four-point fonts becoming blurry, and about having as many small villages marked on the map as possible. If he's interested in that kind of detail, then I think he probably cares far more about local properties than the kind of global properties that would bother me or you.
If I understand correctly, Mercator is the only conformal projection where north is always up, no matter where you zoom in. That makes it nice for online maps. If you relax the "north is up" requirement, there's tons of conformal projections that look nice: http://www.progonos.com/furuti/MapProj/Normal/ProjConf/projC...
I like the "classic Guyou" projection you linked to as well.
But referring back to the OP, notice the grid of books and curios along the entire neighboring wall, and the grid-like pattern of the wood flooring underneath. The Mercator projection seems of a piece with this grid theme in the room.
According to your linked image, one advantage of classic Guyou projection to the writer of the article is that it seems to contain a straight, uninterrupted vertical path through only ocean. He stated that he wanted maximize ocean in his panel cut, but I think he still had to cut through a bit of Africa.
"classic Guyou"... the sizes and shapes of the landmasses are surprisingly realistic
I don't think so at all. Australia is fairly balanced east/west in real life, but on that projection it looks like it's got an eastern tumour. Africa looks like it's got a western tumour. Spain looks like it's the size of the Arabian Peninsula. The British Isles (300k sq km) are the same size as India (3M sq km). It looks horribly distorted compared to a map on a globe.
>The Mercator projection was indeed originally designed for compass navigation, but the reason it's still used for web mapping is slightly different. The Mercator projection is conformal.
Just speculating here, but it's also a big rectangle that is easy on the eyes. Non-rectangular online maps would fit awkwardly in websites. As for Gall-Peters, that map is just irredeemably ugly to me, and I'm ignorant of other rectangular projections that could compete with Mercator.
Yes, absolutely! The Mercator projection isn't the only conformal projection, but it is the only one for which north-south maps to the vertical axis, and east-west to the horizontal axis. That means that it maps the whole world onto a rectangle, which works well both for computers and interior decorating.
As for other rectangular projections, the most common is the equirectangular (or plate carrée), which simply maps (longitude, latitude) to (x, y). This is a pretty common representation for gridded global data.
Gall-Peters is also a conformation projection that maps north-south maps to the vertical axis, and east-west to the horizontal axis. As to online maps one major advantage is the X-Y scale does not get nearly as messed up at multiple zoom levels.
However, online maps alter the projection as you zoom so this is not much of an issue.
Gall-Peters is definitely not conformal. It preserves area, but greatly distorts angles, apart from at the two standard parallels of 45 degrees north and south. This results in the shapes of land masses getting very squished towards the poles (and to a lesser extent, the equator). For an example, look at the shape of Greenland, which appears twice as wide (east-west) as it is tall (north-south), when in reality it's the other way around.
I'm also not aware of any of the main online maps changing projection as you zoom. It seems like that would be more pain than it's worth.
A Mercator projection (ed: is a Conformal map, but) it also greatly distorts both angles and shapes as you approach the poles. The trivial example is to walk a square mile (N,W,S,E) you would expect the opposite sides to be at 45deg angle, but on Mercator the sides get stretched so a square in the real world can have a 10+:1 or even 100:1 side lengths on a Mercator map.
The property they both preserve is points north, south, east, or west of them on a globe are also north, south, east, or west of them in the projection. (Plenty of rectangular projections don't have this property ex: http://geographer-at-large.blogspot.com/2011/08/fun-with-map...)
The issue is interior angels of a triangle on a sphere don't add up to 180 degrees so you literally can't preserve all angles on a projection.
PS: If you actually walk exactly 1 mile north, 1 mile west, 1 mile south, then 1 mile east you don't necessarily end up on exactly the same place on a globe. (It does work if you start half a mile below the equator.)
> as many small villages marked on the map as possible
Based on this image: http://www.dominik-schwarz.net/potpourri/worldmap/images/DSC... the entire continent of Africa looks only slightly larger than Greenland (when in fact it's about 14 times larger), and substantially smaller than Russia (when it is actually ~1.7 times larger).
Greenland has a population of ~60,000. Africa has a population of ~1.1billion.
I think Africa would have more small villages than Greenland (and Northern Russia) combined, yet is afforded less space.
I always think of '^' and '<' as being arrows pointing at the relevant dependencies, i.e "that list of things up ^ there" or "that thing on the far left <". It can also help to think of '<' as being like a stdin redirect, so a simple rule might look like "myprog < $<".
Pure liquid water does indeed freeze at 0C, but the water in Europa's oceans is unlikely to be pure. The presence of salts can significantly depress the freezing point of water; ocean water on Earth freezes at about -2C or so. With just sodium chloride alone, it's possible to knock that down to about -20C. Europa's oceans are known to contain magnesium chloride (http://www.jpl.nasa.gov/news/news.php?release=2013-082), and probably have other chlorides as well. It's definitely possible, indeed likely, that the temperatures involved are sub-zero, but I agree that -50C sounds unlikely. I'm not sure what the actual lower bound would be though, given the largely unknown chemistry of the water.
The data source is the voting records since 1998. It's run through a parametric Bayesian MCMC model. The input data and the code for last year's model, which is pretty similar, are on GitHub: https://github.com/mewo2/eurovision
Countries only vote in the semifinal in which they qualify (except the automatic qualifiers, who are assigned a semifinal to vote in). There probably is a systematic difference between the semifinals and the finals though.
Yesterday before the show I made a bet with a return of 2.0 that a participant of Semi 2 will win the contest (I think it will be Sweden, but wanted to hedge it somewhat). So it is nice that your calculations predict high chances for Sweden, Malta, Norway and Estonia. ;)
Comparing the MCMC calculations and book maker odds are interesting. For example you rank Turkey (which I think is the better song) higher than Azerbaijan, but in the odds it is dramatically different. A return of 3.0 when Turkey comes ahead. Hmhmhm.
Be somewhat wary of the predictions for the countries which have automatically qualified - they're based on much less information than the other countries. The reason that Turkey is ranked above Azerbaijan is that the model has absolutely no information about the quality of Azerbaijan's song. Turkey, on the other hand, made it through a semifinal, so their song can't be completely abysmal. That said, Turkey do have a pretty strong structural advantage in terms of incoming vote patterns. Out of the 10,000 simulations, Turkey beat Azerbaijan about 75% of the time.
Also, this should go without saying, but this is not financial advice, please don't blame me if you lose money betting on the predictions of this model, etc.
I am not a big gambler. But I wonder if these sort of calculations could be better in forecasting than prediction markets like intrade.com.
Very interesting work on the Eurovision at least! There are so many potential variables. Age, gender, BPM of the song, changes in the performance, political stuff. For example I don't expect any points for Azerbaijan from Germany, because the media reported very critically on the undemocratic regime. But don't know how this will play out in the rest of Europe. Are you American? This song contest and its history must be pretty strange for outsiders.
I'm Irish, so I'm fairly familiar with the contest's history. I do live in the USA now though.
I am a bit skeptical about how effective politically motivated boycotts can be in Eurovision. The problem is that it's not possible to cast a vote against a country, so the only way a boycott can work is if it convinces a lot of people who were otherwise going to vote to abstain. That said, there has been quite a lot of coverage in at least the Western European media which has been very critical of Azerbaijan, so we'll see. It's also just possible that nobody will like their song - I'm not sure how we'd tell which had happened.
Israel's numbers are actually fairly middle-of-the-road. They don't have any habitual points donors (except maybe France), but they've only failed to qualify three times (four if you include last night). They made the top ten in both 2005 and 2008, and they won in 1998.
I think you may just have a different opinion of what makes a good song than the voters of Europe.
