Comment by dukoid | Hacker News Reader

Comment by dukoid | Hacker News Reader

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TLDR:

The calving of the 1.1 trillon ton ice berg (2x amount of water used in the US each year) marks the end of a decades long splintering, first seen by satellites in the 1960s.

1. What's next? It will drift north along the coast of the Antarctic Peninsula, then northeast into the south Atlantic Ocean. Likely no threat to ships navigating the area. Can take months to splinter apart.

2. Is this climate change? Calving is a natural process and Antarctica is not breaking apart, but climate change can't be ruled out.

3. What does it mean for Antarctica? Not much on its own, but could be a signal that other major changes are on the way. Paying attention to the Thwaites Glacier, which could raise sea levels 10 feet if it collapses.

4. Will it make the oceans rise? barely (0.1 mm)

5. Politics: The calving was barely noticed on Capitol Hill, which is distracted by a bitter health care debate, federal budget bills, and the controversy surrounding President Trump and Russia.

P.S.: Read the full article -- it's worth it and has interesting illustrations showing the scale of the event.

>"2. Is this climate change? Calving is a natural process and Antarctica is not breaking apart, but climate change can't be ruled out."

"Climate change" doesn't make specific enough predictions about this type of stuff to ever be ruled out, people could just keep coming up with ideas about X indefinitely:

  Climate Change -> X -> Larsen C rift

A more accurate way to put it is that, up until now, all proposed ideas for X have been ruled out (I am basing this all on the comments from the MIDAS team about the ice thickening, etc).

At the same time I find it totally implausible that there is zero link between this event (or anything else that happens on earth) and the climate. So "no link" should be taken as shorthand "any influence due to climate change is a negligible factor".

Also, it is clear to me from reading the news and comments about this event that many people really, really want this to be linked to climate change. It is to the point that cognitive dissonance ensues when it is pointed out the experts are in disagreement with them. That is unhealthy.

>> Also, it is clear to me from reading the news and comments about this event that many people really, really want this to be linked to climate change. It is to the point that cognitive dissonance ensues when it is pointed out the experts are in disagreement with them. That is unhealthy.

I think it's healthy. The people who experience cognitive dissonance are so personally invested in their belief that they are no longer able to see things objectively. That's not a good place to be in any case.

Go through my comment history for this topic, you will find some of the most bizarre reasons proposed for why the MIDAS team was being quoted as saying this is probably natural and not anything ominous.

Just go through this thread. Almost every poster knows there is some ominous global warming stuff going on here, despite being told otherwise by the experts and being totally ignorant on the topic.

> Climate Change -> X -> Larsen C rift

I think if you compare historical rates of iceberg calving to current rates of iceberg calving, you should be able to find some significant quantifiable difference.

Although ultimately the important thing is the influence on flow rates of land-based ice.

>"I think if you compare historical rates of iceberg calving to current rates of iceberg calving, you should be able to find some significant quantifiable difference."

So? The rates could increase/decrease for many reasons. If all your X mechanism predicts is that the rate should change (or only slightly better, increase/decrease) it isn't going to be distinguishable from any other reason.

Edit:

It really sounds like you are making the usual NHST error of thinking a significant difference means your theory is true.

Of course there's a link between this event and the climate. Clearly. If Antarctica weren't cold, there would be no ice shelf to begin with.

The salient point is that this specific event would have seemingly happened with or without our currently-changing climate. As the iceberg that the shelf extends from flows out toward the ocean, the shelf grows until it reaches a point where forces acting on the floating mass of ice induce part of it to calve away from the rest of the shelf.

> "Climate change" doesn't make specific enough predictions about this type...

Actually it does. In a warming world more frequent calving events are expectable. This part of Antarctica shows quite some positive temperature anomalies. So, asking whether Larsen C would be still intact today without Climate Change the answer is certainly yes.

As I said a month ago when this coverage started, it is very strange how there are so many people (in the media and internet posters) who are so sure about that, when the actual people studying it claim otherwise: https://news.ycombinator.com/item?id=14577296

>“Although this is a natural event, and we’re not aware of any link to human-induced climate change, this puts the ice shelf in a very vulnerable position. This is the furthest back that the ice front has been in recorded history. We’re going to be watching very carefully for signs that the rest of the shelf is becoming unstable.” http://www.projectmidas.org/blog/calving/

>'Andrew Shepherd, professor of Earth Observation at the University of Leeds, agreed. “Everyone loves a good iceberg, and this one is a corker,” he said. “But despite keeping us waiting for so long, I’m pretty sure that Antarctica won’t be shedding a tear when it’s gone because the continent loses plenty of its ice this way each year, and so it’s really just business as usual!”https://www.theguardian.com/world/2017/jul/12/giant-antarcti...

>"And while climate change is accepted to have played a role in the wholesale disintegration of the Larsen A and Larsen B ice shelves, Luckman emphasised that there is no evidence that the calving of the giant iceberg is linked to such processes." https://www.theguardian.com/world/2017/jul/12/giant-antarcti...

Look, I did not answer the irrelevant question whether Larsen C calved because of Climate Change. Attributing single events in remote areas is hard. That's why I answered a different question, the key words are 'today' and 'more frequently', please read the comment carefully again.

>"So, asking whether Larsen C would be still intact today without Climate Change the answer is certainly yes."

> Calving is a natural process and Antarctica is not breaking apart, but climate change can't be ruled out.

This is science's inherent weakness in the public eye: the pundits on both sides will make conclusive statements based on little data; the scientists, with all the data we have, only speak in chances, odds, and percentages.

It's not their fault, it's the correct way to speak. But both sides will spin this to suit their agenda, for better or worse, and continue to muddy the waters.

  Will it make the oceans rise? barely (0.1 mm)

Where do they get that? The melting of already-floating icebergs has zero net effect on sea lever or (liquid) water volume. It would take a huge amount of added water to make even a .1mm effect worldwide.

The article explains that an iceberg of this size would add 3 mm to sea levels if it had not already been floating in the ocean. I'm curious, too, about the 0.1 mm.

EDIT: Apparently the 0.1 mm change is due to the difference in salinity. https://phys.org/news/2005-08-ice-sea.html

Could be thermostatic sea level rise: the water will spread to warmer parts of the ocean and expand.

Thermal expansion is the primary source of sea level rise in general, isn't it?

Melting of an ice cube in a glass of water doesn't change the water level. It was in the highschool physics cirriculum where I'm from.

This won't hold true when melting a _freshwater_ ice in _salty_ water, but I too doubt the change will be anywhere near 0.1mm

It is the melting of the ice on above the water surface minus the difference in volume of the ice below the surface and the water it would become. Someone else mentioned that if the entire iceberg were melted it would cover California with 4.5in of water. If you divide that by the ratio of the ocean area to the area of California you get 0.13mm. I'm not sure how much is above the water vs below the surface but it seems like a reasonable thing for them to estimate.

Just enough of it is above the surface to account for the change of volume when it melts. Or equivalently, it displaces its own weight in water.

Hmm. I see what you are saying. So they probably did do the calculation I referenced but I agree it is probably faulty. However, there is some rise from melting: https://www.newscientist.com/article/dn18841-melting-iceberg...

Thank you. You actually make me want to read it

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