Things to know about the A68 iceberg
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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.
"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
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.
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.
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.
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.
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.
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.
>“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...
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)
EDIT: Apparently the 0.1 mm change is due to the difference in salinity. https://phys.org/news/2005-08-ice-sea.html
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
We deal with this frequently in medicine. There are lots of questions that the non-expert doesn't know how to ask, or asks clumsily. When patients ask "doctor: does this medication have any risks?" The literal answer is "yes; dozens of side effects are possible, ranging from mild to life-threatening".
But that answer is so accurate that it's useless. What almost all patients really want is "help me understand the most common side effects, and tell me what to watch out for regrading rare-but-serious side effects".
With respect to global warming, we don't really care whether this event can be tied back to antropegenic climate change in a linear way. What we really are asking is "should we be taking climate change seriously?". And the answer is an emphatic "hell yes".
This is an opportunity for people to focus on climate issues. I worry that HN will think I'm a paternalist jerk, but scientists shouldn't get bogged down in the literal answer to the literal question in this case.
My best answer would be "climate change is real, accelerating (meaning getting worse every day we continue to consume more fossil fuels), and the biggest threat we have to face as a species".
https://www.theguardian.com/environment/2017/may/05/could-to...
I could certainly be wrong though. I couldn't find much info googling.
The Gulf countries offer desalinated water at city scale, but it's not cheap enough for irrigation.
Naively, the energy cost of towing should go as the 2/3 power of the mass of the iceberg, whereas the energy cost of desalination is linear. So bigger is better!
Of course, it's a million times bigger than the biggest iceberg ever towed, so I guess there is some technical risk. But where's your can-do attitude?
"The calving of icebergs is a natural process. ... as news of the calving spread, many researchers were careful to note that they were not chalking it up to global warming."
The falling of trees is a natural process but when they fall in a storm we don't often say to not chalk it up to the storm.
When a tree falls, the rain that loosened the soil around the roots, the wind that pushed upon the end of the trunk-lever, and the beetle that damaged the bark such that the tree became less flexible are all responsible.
When it comes to icebergs calving from glaciers, warming is a contributing factor, but so is a snowfall upon the glacier further up the slope. Ice above pushes ice below away from the support of land, and like many crystalline minerals, water-ice has far less strength under tension than it has under compression.
I wonder what age these shelves were and what a sustainable rate of such events would be. Without seeing such information I dont trust general statements on the events meaning.
As another massive iceshelf breaks off - it really looks like an event which we could connect with more for these environmentally crucial times.
These shelves move fairly rapidly, and will calve with or without global warming. The Ross Ice Shelf, for example, moves northwards at about 1 km/year.
If we are with the consensus on climate change, there is very little doubt this event is affected by it. It occurred in most warmed area of this map:
http://www.realclimate.org/wp-content/uploads/ODonnell1.png
From here:
http://www.realclimate.org/index.php/archives/2010/12/a-brie...
I dont see any sense in excluding these quite rare events from the confidence of climate change, unless we are not confident in climate change.
The grandparent says that the ice shelf moves into the ocean at about 1km/yr.
This specific calving has been going on in stages since at least the 1960's.
Within the order of magnitudes of estimation, that lines up entirely with natural process that has been going on at roughly the same rate since the 60's. Climate change hasn't had a measurable effect so far, based on this limited data point.
I think the scientist's quoted cautious skepticism is entirely appropriate.
The maps show the very location of these events, raised by several degrees C since 1950. The rate of this event is quite certainly strongly affected by local temperature, which is known to be elevated due to global warming. So the event has quite certainly been strongly affected by global warming.
I can conclude this very confidently because global warming is already a given for me. Only when we doubt global warming has raised the temperature of the location of these calving events does it make any sense to say, "this could be happening naturally"
However fast this could happen naturally - it is happening faster due to global warming.
Some have said that even all the CO2 we can produce won't be enough to stop the natural cycle. I wonder if it will actually speed it up a little bit. Something triggers the end of the inter-glacial and clearly we are not there yet. Therefore, I conclude that the planet was never at the steady state the climate alarmists pretend it was before humans interfered.
"Some have said" -- Stop. Just stop.
If you can't cite, you aren't worth debating.
As a casual earth science enthusiast, I believe this means that the melt-water will stay proximal, and will encourage accelerated freezing on the coast, somewhat "repairing" the damage.
When it breaks up/drifts away, the coast will be subject to normal freezing patterns from the briny water.
An iceberg the size of Delaware is now in motion. If it follows the path of previous icebergs from the Larsen Ice Shelf, it will drift north along the coast of the Antarctic Peninsula before heading northeast into the south Atlantic Ocean, according to NASA.
Action is required at this point, regardless of transnational economic inertia.
What does it take to root out scientific provocateurs, and shut them up?
> The calving of icebergs is a natural process. While climate change is affecting Antarctica in a variety of ways, this week's event does not signal that the region is entering a new state. That is happening in the Arctic, which has already been dramatically reshaped by human-caused global warming, according to National Oceanic and Atmospheric Administration researchers. Scientists do not believe Antarctica is in a precipitous state of warming right now. Yesterday, as news of the calving spread, many researchers were careful to note that they were not chalking it up to global warming.
Climate change is an important issue to be sure, but this seems unrelated.