As David Spratt posted at Climate Code Red a giant crack has opened across the full width of the Pine Island Glacier (PIG) ice shelf, spawning a new iceberg about 720 square kilometres in area, roughly eight times the size of Manhattan Island in New York. This is about the best photo I can find:
We’ll get some orientation first and then look at the implications. This image locates the PIG on the continent of Antarctica:
This image from the LiveScience photo gallery outlines the PIG basin:
This basin together with the Thwaites Basin just to the south drains 40% of West Antarctica. These two glaciers alone could lead to sea level rise of half a metre by 2100 according to material cited by Spratt.
This image compares Antarctica with Greenland:
The red patches show the ice sheet thinning from 2003 to 2007.
This image shows the decadal warming from 1957 to 2007 as much greater in West Antarctica than on the giant ice sheet of East Antarctica:
David Spratt cites research and climatologists suggesting that the PIG and Thwaites glaciers may have already tipped. He reckons that Fred Pearce’s prediction made some years ago looks spot on:
Another vulnerable place on the West Antarctic ice sheet is Pine Island Bay, where two large glaciers, Pine Island and Thwaites, drain about 40 per cent of the ice sheet into the sea. The glaciers are responding to rapid melting of their ice shelves and their rate of ﬂ ow has doubled, whilst the rate of mass loss of ice from their catchment has now tripled. NASA glaciologist Eric Rignot has studied the Pine Island glacier, and his work has led climate writer Fred Pearce to conclude that ‘the glacier is primed for runaway destruction’. Pearce also notes the work of Terry Hughes of the University of Maine, who says that the collapse of the Pine Island and Thwaites glaciers — already the biggest causes of global sea-level rises — could destabilise the whole of the West Antarctic ice sheet. Pearce is also swayed by geologist Richard Alley, who says there is ‘a possibility that the West Antarctic ice sheet could collapse and raise sea levels by 6 yards [5.5 metres]’, this century.
As against that a recent study which attempts to come to terms with ice sheet decay suggests sea level rise of 69cm by 2100 with only a 5% chance that it could go beyond 84cm. That was in May this year. In June another study surveyed all the Antarctica ice shelves and found that the ‘basal melt’ the melting from below exceeded glacier flow and iceberg calving above. They found:
the melting underneath all of the ice shelves accounted for 55 percent of all ice-shelf mass loss between 2003 and 2008, which is significantly higher than what anyone had previously thought.
Spratt also cites research by Blancon et al which found that sea levels rose 3 metres in 50 years due to the rapid melting of ice sheets during the Eemiam interglacial 120,000 years ago. I’m cognisant of the fact that much of the bedrock under the Antarctic ice sheet is below sea level, bringing the ice sheet edges in direct contact. This is one image indicating the underlying topography:
Sea level is where blue and green meet. The intervals on the left are 5,000 feet (1,524 metres). Finally from the earlier post on Greenland I’ll repeat the image from James Hansen showing the effect that a 10-year exponential doubling of ice sheet melting can have late in this century:
I’d suggest that we still can’t be at all confident we know what’s going to happen by century’s end. Reality will be less smooth than Hansen’s lines. Chunks falling off the Pine Island Glacier are definitely a worry, but not so much immediately. The second half of this century is likely to see more dramatic action than the first.
60 thoughts on “Pine Island Glacier spawns a giant iceberg”
Whilst stopping increases in emissions of greenhouse gases is a lovely idea – it doesn’t have the chance of a snowball in hell.
We’ve seen this in, for instance, in the shenanegans over ‘carbon price’ in Australian business and politics – and the rest of the world isn’t much better.
The greedy, foolish decision makers everywhere will still be making a quick buck out of hastening destructive climate change even as the rising seawater comes up to their necks. (The good news is that since so many of these short-sighted boofheads live in very expensive waterside properties; their properties will become worthless).
I think we should all concentrate on practical responses to all the adverse changes and thereby avoid catastrophe.
For example, stop pouring good money after bad on the Gold Coast – the place is doomed anyway – and money squandered trying to halt natural processes and outcomes would be better spent right now building infrastructure, such as a re-routed Pacific Highway (for essential transport), 16 or 17 Metres higher than the present sea level. That’s a lot higher than most predictions of sea level rise – but it’s better to do it once and do it right rather than to keep on fiddling and flustering with repairs each time the waves come crashing in.
Politically unpopular? My oath! But it has to be done.
Those who will scream and wail and throw tantrums over such bold and necessary measures have had ample time to do their bit to alleviate the situation – and for decades, they did nothing. Tell them ‘Bad luck – now finish packing and get out of the new seabed before you have to start swimming’.
Consideing the expected rise of the continent without the weight of the ice on it. Does anyone know if we can expect large tsunamis from that direction?
Does this mean that mountain dwellers like myself will have a shorter drive to the beach when the sea level rises? That seems like a big win to me!
Seriously though this piece is just pointless gloom and doom because even if the predictions are accurate (a big ask) there is nothing that can be done about it except adapt if and when it happens.
Finally the fate of the Gold Coast is simply an artifact of the folly of building on the ever changeable sandy coastline as if it is unchangeable even if the seas were never to rise any higher its design and location would put a great deal of that city at risk of being swallowed by the sea.
We are already getting them, flukus. There is recognition that the changing pressures on the globe can prematurally trigger techtonic plate movements. At this stage it is theorised and not necessarily quantitatively proven, and we are talking about movements that would ultimately happen anyway eventually as that is driven by greater forces within the mantel. As I understand it.
flukus: Very unlikely. The rebound after glaciation is limited by the viscosity of the mantle, which is really, really large. Think something along the lines of the pitch drop experiment they’ve got going at U. Queensland, except pitch is about 10^8 Pa s, while the mantle is a whopping 8 to 16 orders of magnitude more viscous, about 10^16 to 10^24 Pa s. So rebound is _very_ slow, occurring over hundreds of thousands of years. North America is still rebounding from the last glaciation.
Here’s a link to the pitch viscosity experiment: https://en.wikipedia.org/wiki/Pitch_drop_experiment
Also, I hate the way we always measure area in Manhattan Islands. I have no idea how big/small that is.
Wolfram Alpha tells me that Manhattan Island has an area of about 6 * 10^7 m^2 while Sydney (the administrative area) has an area of 6 * 10^6 m^2. So one Manhattan Island is about 10 Sydneys.
So in parochial terms, this glacier is 80 times the size of Sydney CBD.
Oops, looks like Wolfram Alpha has some pretty crap sources. Wikipedia tells me that the City of Sydney actually has an area of 2.5 * 10^7 m^2, so that would mean one Manhattan Island is about 3 Cities of Sydney.
So then the iceberg is 24 times the size of Sydney. Still quite large whichever way you dice it.
Goddammit, I can’t multiply this early in the morning. Make that 1 Manhattan Is ~= 2 times Sydney CBD, so iceberg ~= 16 Sydneys.
Sorry for the threadjack Brian. We need some comment editing! 🙂
Jess I have seen this being commented on. It is not about the rebound effect due to ice weight, but about the redistribution of the melt water. A little bit over a very large area it is suggested may be applying sufficient pressure change to cause already stressed areas to shift prematurely. Another influence might be surface ocean density change from relative change in salinity in various parts of the oceans. These might tend to cancel each other out in some areas but compound in others.
No threadjack Jess – it helps us visualise how large it is.
You won’t be closer to the “beach” if the sea level rises. There will be no “beach”. There will be a rather iffy and polluted liminal space where swimming will be for the strong of stomach and small of brain only.
Looks like we’re buggered, to me, Brian.
Graham points out just one aspect of the type of essential actions we need to take in order to avoid catastrophe, however the venal and corrupt idealogues and plutocrats of the “denialosphere” have suceeded thus far in their delaying tactics, with significant global consequences already “dialled in” wrt current CO2 emissions.
While the transition to a zero or low carbon civilisation is essential (in terms of survival), I see no signs that the political class (excepting the Greens) are taking the current challenges seriously. It is of no comfort that as new data accumulates, older predictions have universally proven to be too conservative.
I, for one, appreciate many of the fruits of our civilisation and look forward to its evolution, rather than its destruction in a runaway greenhouse effect.
I have taken the liberty of preparing a graphic depicting the size of the Pine Island glacier as superimposed over a map of Melbourne, centred on the GPO. As you can see, it extends southwest to Altona, northwest to Sunshine, north to Coburg, northeast to Macleod, east to Surrey Hills and southeast to Elwood.
I was of course being factious about the beach .
To those here in panic mode I suggest that you all just let your worry go because there is absolutely NOTHING that you can do that will make a blind bit of difference There is also plenty of reasons to believe that this berg may well just stay precisely where it is for a very long time and that it being “separated” from the glacier that spawned it won’t matter a jot.
BillB: Yes, I was aware of the correlation between earthquakes and ice sheet melt in Scandinavia & Alaska. I read flukus’ question as asking whether the continent would rise under isostatic rebound fast enough to generate a tsunami & just wanted to emphasise what a slow process that was. Maybe it’s my bad comprehension!
There’s been some really cool research come out of NASA’s satellite surveying program looking at the links between de-glaciation and earthquake frequency. I’m not so sure that it’s a straightforward remove ice = more quakes link for Antarctica though. As a contrasting example, the presence of ice in tectonically quiet regions seems to suppress the smaller earthquakes, so when you do get one (under an ice sheet) it tends to be larger to compensate for all the extra energy that would have been removed by the smaller quakes. So it might be that removal of the ice sheet _decreases_ the overall seismic risk in the longer term by allowing faults to blow off steam early.
Obviously this sort of thing depends entirely on how stressed some of these faults are, and Antarctica is like Australia – it’s fairly quiet seismically. It’s quite different to Alaska where you have a subduction zone providing a lot of extra stress where the small changes in load due to glacier melt can have a big effect…
Iain: it will matter because the tongue of the glacier is what provides a lot of resistance to flow further up the glacier. If the ice has broken off it suggests that the flow interior to the glacier will speed up, even if the tongue is just ‘sitting there’.
And what people are really worried about is not just this iceberg per se, but what it is symptomatic of – glacial thinning & warmer ocean temperatures around Antarctica.
There’s plenty that can be done to prevent global warming, Iain.
I have been interested in the issue for many years and I yet to see anything suggested that can be made to work in the real world rather than it being caveat encrusted wishful thinking. So please share with us what can be done and explain how that thing will make the slightest bit of difference,
glaciers flow, its what they do and you essentially can’t stop them
Getting grouchy with Iain is all a bit silly.Why not let Nestles down there to get all that bubbly water!Then they could bottle penguins for tourism!? I suppose you know the mark up on their commercial deal for water elsewhere!?MAKES FOR THINKING BOILING THE JUG FOR WATER FOR A CUP OF HOME BREW BECOMES A MORAL ACT. I AM A POPE IN COMPARISON TO NESTLES. Which makes Brian a Archangel,and even Iain a sort of Russian Orthodox,eh,Brethren!
thanks for some sanity Iain.
Jess @ 6, I too had a problem with Manhattan Island. I did see a comparison with Adelaide, but then couldn’t find it. Even then you need local knowledge about the municipal boundaries. Melbourne doesn’t help me much either.
This article puts it at half Greater London and reckons it’s no big deal. Similar has happened in 2001 and 2007.
RealClimate in 2009 identified PIG as the weak underbelly of the West Antarctic ice sheet.
This article talks about a study that says we have too little data yet to tell what’s going on.
This article says 2.3 metres per degree Celsius, but I don’t see the time frame. It couldn’t be long term (ie thousands of years). That would have to be in the region of 15m per degree.
Sorry about all those posts. I had it all in one, which the software usually allows me as a logged in administrator, but suddenly it will only allow me one link at a time. A major pain!
There was some work done by Schaeffer et al about SLR in the next few centuries. I tend to place significant weight on the paleo evidence which puts equilibrium SLR at around 25 metres for 400ppm of CO2. That’s about up to the Bruce Highway approaching Cairns, Iain.
That doesn’t help in terms of the next 100 years, but it might help people realise that Hansen’s 350ppm in the first instance is not a bad idea.
Adaptation vs mitigation is a completeky false dichotomy.
Obviously a certain amount of warming is ‘locked in’ and emissions are not going to stop tomorrow, or the day after, so we are going to have to adapt as best as possible. But the idea that we can just keep hoing BAU and deal with whatever happens is nonsense. We need to mitigate as strongly as we can.
Then we just have to hope like hell that on between these two we are left with a world that is half decent.
The nonsense is your claim we need to mitigate as strong as we can because if the cost vs the effectiveness of said mitigation efforts don’t add up (IE the cost is very high and the effect is so small as to be unmeasurable) then mitigation efforts are counter productive because they waste resources and effort better spent on adaptation.
As I see it all of the global mitigation efforts either in train or mooted won’t make ANY measurable difference so at best they are empty symbolism.
Why is the dichotomy false?
It looks very reasonable to me.
The dichotomy is false because you can do both and we will need to. Instead we see people like yourself argue or imply “because we will need to adapt therefore we don’t need to mitigate.”
Of course mitigation is subject to a cost-benefit test, within a framework of uncertain estimates of future benefits. Since you do not accept conventionsl science of course your personal estimate of those benefits is low. This is an extreme, minority position – worth considering but with a very low weight in formulating policy. More reasonable estimates suggest that future costs of BAU are sufficiently high to justify strong mitigation (the costs of which are routinely exaggerated.)
Iain: way to miss the point.
BillB: Speak of the devil – Argentina reports a magnitude 7.3 quake on the Antarctic peninsula.
This link has a graph which shows a ‘do nothing’ scenario against various mitigation scenarios.
My criticism would be that the BAU scenario is wildly optimistic to think it will taper in the out centuries. At some point West Antarctica will become a mess. At that point Greenland will also be in trouble. By the time that happens East Antarctica will be bleeding significantly. Meanwhile there's half a metre in ice caps and glaciers and thermal expansion.
We are pushing the system multiple of times harder that has ever happened before. In this context I'm doubtful about any models to get a good handle on what's going to happen in the next blink of geological time.
Further to Helen @ 10, sometime this century beaches everywhere are likely to be in trouble. Here’s a pic of the kind of thing we may see more of (from the Isle of Wight).
It looks very reasonable to you, Iain, because you clearly do not know very much. The intense drive to develop technologies to reduce carbon emissions has gone some of the way to develop the technologies for adaption at the same time.
If the world intentionally suppressed mitigation technologies and waited until the need to adapt became unavoidable it would be far too late to effectively adapt if only because of the economic disruption that would have set in by that time. You cannot develop effective technologies when the means to do so are failing faster than they can be rebuilt.
JWHoward will be remember by history as Australia’s most disasterous economic manager. Not because he was not effective at penny pinching and hoarding, but because he was prepared at the same time to bet the farm at the environmental casino. And then to further compound the mistake by promoting his most ideologically locked lieutenant in an attempt “hold fast” on this disasterous course.
“Save a Penny, Loose a Pound” is the saying. “It is Labour who are the wastrells” comes back the cry,…and there is some measure of truth in that, but as far as the GRAND PLAN is concerned the game was lost by Howard. Labour gave some measure of hope by enacting the Renewable Energy Targets. It is this initiative that has laid the groundwork for both mitigation……and ……adaption.
Adaption requires the ability to survive profound global economic collapse. The assumption that everything will remain on track only we will need to use our air conditioners more and that is ok because we have huge amounts of coal is totally false.
The reality is that we are rapidly approaching the end of affordable oil. there will be a date in the not too distant future when the Saudi’s say “we need the rest of our oil for our own people”. All of the major oil finds are guaged in how many days global oil supply they contain, not decades, certainly not centuries. Economic collapse threatens the one never mentioned resource,….electronic components. The last GFC shutdown chip foundries all over the world and created a global shortage of components sufficient to cause car companies to cut electronic systems from their new vehicles.
It is a fools paradise to imagine that adaption will be a little bit tough but we will get through it. Completely false. The reality is that the cost of adaption is immense, probably even unaffordable if global warming continues on its accelerating track which given that we arrived at 400 ppm sooner than anyone expected is the certain expectation.
The ability to survive financial collapse requires self sufficiency. Go back and look at how that played out in the great depression, but view it in the framework of drought, pestilence and a flabby four fold population.
Further to @ 30, West Antarctica is worth about 5-6m in SLR, Greenland about 7m and east Antarctica about 59m. Thermal expansion I don’t know, but ice-free is in the region of 75m. Remember that 22,000 years ago sea level was about 120m lower when the temp was 5-6C cooler. So 4-5C hotter, which we are likely to see by 2100 or thereabouts under BAU is a certain way to wreck the future when the sea level reaches equilibrium. The cost of doing nothing is truly incalculable.
Try this experiment. Put a cube of ice in a glas and watch it.
Interesting eh? Same thing happens with icebergs. Imagine an iceberg the size of (choose your city) doing that. Tsunami did you say what? There will have to be a new word developed to describe that wave kiddies.
On the contrary I an quite well read and very familiar with the scientific method.
The intense drive to develop technologies to reduce carbon emissions has gone some of the way to develop the technologies for adaptation at the same time.
Please explain just how this is the case
I am not suggesting that anything be “suppressed” only that efforts that will have no effect are pointless and not worth the expense. Further there is no reason to suggest that economic collapse is inevitable if the Green Goddess is not placated with appropriate sacrifice. You seem to think taht really high tech solutions would be necessary when in reality the solutions to environmental change would in fact be rather simple. As an example lets look at the consequences of a rise in sea level. All of the panic merchants assume that this would necessitate building huge earthworks(levvies ect) when the simpler solution would be to just move to higher ground, which is what humanity has done since the year dot.
Ok I get that you are a lefty who does not think much of being economically prudent but sound management of any economy has to rest on the “Macawber principle”, namely you spend slightly less than you earn and your happiness will be assured for the long term, spend consistently more than you earn and all you can expect is misery. The left seem to want to put every thing on the plastic and that is a disaster in waiting and will give the nation no scope to have the resources for anything bad that happens.
The counter aphorism to the one you cite is “look after the cents and the dollars will look after themselves” . On renewable energy, the principle is fine, but the technology is far form being that reliable and the cost of the subsidies seem to hurt those who can least afford it in the form of higher energy bills…
You won’t find anyone more keen than me on personal autonomy and self sufficiency but I don’t see the connection between adaptation and profound “global economic collapse” and please don’t assume that I think that more air-conditioning is any sort of answer.
Well as a confirmed petrol head I had better enjoy my cars while I can Eh? Seriously though simplicity and a lack of electronics in cars would be an advantage in my book and i say that as a bloke who has built his own car.
That is utter bollocks it is the versatility of humanity that has allowed us to thrive and to dominate every aspect of the planet’s biosphere and we will always find a way to continue to make a place for ourselves on this planet. Sadly I think that your problem is that you think that adaptation is something that will only occur directed from above rather than the grass roots.
hard times are well, hard but they are also a great encourager of innovation and new ideas. Its no surprise taht some of our most clever inventions come from times of war.
The world is awash with oil ( google it ). The oil drum died for a reason you know.
Lots and lots and lots of gas too. Price of gas in the US is way below what it was just a few years ago
That is .005 of the ice sheet. Surely there must have been many icebergs of equivalent size break off in the last millennium or so?
Luxxe, that’s lame. Surely you can do better. Have a look at the thinning and warming in the 4th and 5th images in the post and go to what Jess said @ 15. Perhaps I should have spelt out a bit about the mechanics of glacier flow and how they are speeding up. It’s contained in the survey work in this link which also found that 55 percent of all ice-shelf mass loss comes from below where it’s not obvious.
It’s the processes that are the concern and the direction that things seem to be taking. Some respected experts fear the ice sheet is at a threshold where melting may accelerate.
Pappinbarra Fox (and Luxxe), sure, an ice cube melting in a glass of water won’t raise the water level, but you’re forgetting three things.
1. Thermal expansion of the ocean is likely to give us that 1 metre sea level rise by the end of the century.
2. The icecaps on Antarctica and Greenland aren’t in the ocean. Yet. I can’t remember what the estimated effect of that is, but it’s likely to be tens of metres eventually.
3. Once the weight of the ice is off Greenland and Antarctica, isostatic rebound will also have some effect on sea level.
I don’t think you’ve thought this through.
Sure there is plenty of oil, but it has to be oil that can be extracted, on the one hand, and used without destroying the environment on the other. Oil is not stored in the ground in convenient easy to drain to the last drop containers. Most of the easy oil has now been consumed, just as the number of people wanting to enjoy the pleasures of cheap air travel and long commutes to work is rapidly expanding.
Go Google that.
And the US’s cheap gas is coming at the extreme cost man induced earthquakes and polluted essential aquifers.
It seems to me that your primary source of information is Fox news and rehashed glossy extractions from oil company prospectii. Try The Oil Drum archives or Robert Rapier’s R squared Energy Blog for more definitive assessments from oil industry connected professionals.
Oh Iain, Iain, so much wrong in such a small space. Shall we deal with your main errors?
ah the old “scientific method” canard, a subtle dig at climate science adn a completely irrelevant aside. How does being “familiar with the scientific method” qualify you to assess the quality of the science underlying modern climate modeling? Let’s test: do you believe that global warming has “paused” because there has been no statistically significant warming for 15 years?
You do understand this means abandoning New York, don’t you? In an earlier comment you were talking about cost-benefit analyses, now you are hand-waving away the decision to abandon New York. And where exactly are the people of Bangladesh going to move? Also, which “panic merchants” assume huge dykes? Are you aware that it is “huge dykes” that protect New Orleans and Amsterdam now? I guess you can hand-wave that away along with New York and Bangladesh?
You don’t actually know what the effects of sea level rise will be, do you?
more ignorance: national economies have nothing in common with family finances, and this principle holds no meaning for them. Even less meaning in a fiat currency. Do you know what that means?
Will this continue to be true if there is a simultaneous agricultural collapse in North America, the UK and China? Do you understand the strain that water systems are under at the moment, and are you aware of how much crop failure affected the world last year? If we “dominate every aspect of the planet’s biosphere” why is it that a large proportion of children in much of the developing world is stunted? Even if you accept that that stunting arises from inequality in food distribution rather than challenges of food production, do you think the situation will get better or worse if there is a generalized agricultural collapse in several major food producing areas?
Today’s news here in Tokyo told me that hospital admissions due to heat stroke were 2.3 times higher than last year, with 97 people seriously ill and 4 deaths. That was in June, which was less uncharacteristically hot than July (which has been ferocious so far). How exactly do you think we are going to adapt to living at the limits of the human biome? Perhaps you think we should abandon Tokyo as well?
It’s nice to be optimistic, Iain, but you obviously have no idea of the costs that are coming down the pipeline – in our lifetime, not two generations from now – and no idea of the very real challenges in food security, water access, and population movements that will arise. It’s no wonder given this that you are so confident that adaptation will be cheaper than mitigation. But you are wrong. Simply wrong.
You really should get out more. Your chicken little stance is getting a bit old. You say that “Most of the easy oil has now been consumed..” yet exactly the same thing was said about gas in the US. Gas is now as cheap as chips due to new extraction techniques. Oil production is way up as well – in fact it’s up by so much that OPEC is considering cutting production to prevent a big drop in price and the US oil export ban looks likely to be lifted as well.
Exactly why should I read old Oil Drum articles ( actually I used to but… ) when they have been proven to be so comprehensively wrong.
Copper is another example of how badly people underestimate these things.
In 1970 world copper reserves were estimated to be “about 280 million metric tons of copper. Since then, about 400 million metric tons of copper have been produced worldwide, but world copper reserves in 2011 were estimated to be 690 million metric tons of copper, more than double those in 1970, despite the depletion by mining of more than the original estimated reserves.”
Brian @38, if experts and scientists want people onside, then insulting them is not the way to go.
And then, Joe Blow, there is the ready recyclability of oil. You’re a genius.
Luxxe @ 44, I agree. My apologies if what I said was perceived as an insult.
BTW I’m not a scientist and definitely not an expert. Just a bloke trying to nut it all out and share what I read.
A news item on a very large solar PV farm to be built on the Sunshine Coast of Queensland. Apologies for my lack of detail but I wonder if this is such a good idea given cyclone risk, loss of good agricultural land. Proximity to customers and existing grid are in its favour but my preference would be for a bit of national planning on the optimal citing of very large solar farms which is why places like Chinchilla in central inland Queensland make sense.
Maybe something for your next climate clippings Brian?
Hey David Irving – you completely misunderstood my request for an experiment. I said watch it – you didn’t do the experiment did you? Come on fess up. If you had after a while you would have seen the icecube turn over. Imagine an iceberg doing that – happens inevitably with the melting of the ice and the change in centre of balance – creates quite big waves – but a berg the potential size of the one breaking off in the post would create a wave to circle the globe and do a helluva lotta damage I suspect.
Sorry, Pappinbarra Fox, I completely missed your point. Would something that big roll over though? Given the large area and comparatively small depth, I wouldn’t expect it.
Pappinbarra @48: you realise the iceberg is several kilometres on a side and tens of metres deep? The experiment you’re proposing is more like putting a sheet of paper flat on the table then bumping the table.
Yep, icebergs DO turnover but there are other considerations – how deep the water is (iceberg may scrape on bottom etc). Actually it is Nothing like a sheet of paper on a table. Unless the table is fluid and the sheet of paper has 2/3 of its mass submerged in the table. May be possible in your universe Moz, but not mine. The iceberg flips quite dramatically and suddenly due to the shift that occurs in the centre of balance/gravity of the iceberg when it melts – which melting does not happen consistently through the berg. Here is an idea google it – there are videos of past events.
Maybe the berg would have to melt quite a lot before it rolled – but really not an experiment I would like ot see run. Just like I don’t like the experiment we are running now pumping CO2 into the atmosphere.
Pappinbarra Fox: I’m not arguing that icebergs don’t ever flip, just with the geometry of your “big slabs of ice shelf” flip. I think you’re more likely to get a big tsunami from a calving event – find a glacier that’s 1km high when the grounded part reaches the sea, clear the cruft away from the base so you’ve got open sea all the way to the base, then break off a 1km high chunk as wide and long as you can. Calving from a grounded end means you don’t need the 90% of the ice that would otherwise be holding up your floating/falling mass.
Running some quick numbers based on Krakatoa (since tsunami energy is hard to find), 200MT TNT is ~10^17J. If you drop a 5km cube of water 500m you get a similar energy release. So a 1km high slab 250km long and 500m wide should have a somewhat similar effect, if it fell all at the same time… it just seems unlikely to actually happen.
This is why fiddling with CO2 taxes and low-emissions technologies will do nothing (significant).
The world climate will change, it is arrogant to assume we can control it.
As a matter of interest, according to my calculator 27 x 27km will give you 729 square kilometres.
duncanm @ 54.
Yeah but we had opportunities to mitigate its effects – but chose to make money instead. Start swimming.
Graham @56, no we didn’t.
Go have a peek at a world temperature record spanning a few hundred millennia then get back to us.
There’s more risk of (and harm to) us plummeting into an ice age.
but duncamm, aren’t scientists all dickheads because in the 70s they predicted a global ice age?
Scientists are often wrong – that’s what makes science.
Duncanm @ 57>
There have been all sorts of massive climate – and tectonic – shifts over several million years.
There have been all sorts of opportunities, over several decades, to mitigate the effects of the latest one – but we chose to make money instead of planning to mitigate the adverse effects of the latest change in climate. Although I didn’t say anything about controlling climate, it would be, and is, downright stupid to do things or to ignore things that exacerbate such adverse effects. Clear enough now?
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