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Question about sea levels and ice melting.


blackhole123
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I repeat my message. There is no realistic chance that the vast bulk of the ice in Antarctica will melt any time in the next 100 years. Probably not any time in the next 1000. There is ice melt in the Antarctic Peninsular. However, that small part of the total appears to behave in terms of ice melt as if it were a part of a different country. The peninsular is a relatively tiny part of the whole, and supports a tiny part of the total ice mass.

 

For this message — prediction — to carry any weight at all it must be grounded in some science, which, by definition means a model of some sort. Why is your prediction better? Or, put another way, why is your model better than everyone else's?

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Swansont

I have read a lot of material on global warming ideas. I have NEVER read any credible, grounded in science, account suggesting any sizeable fraction of the main, on land, ice mass of Antarctica will melt within 100 years. Everything I have read, that predicts melting, relates to the fringe of the continent, and especially the Antarctic Peninsular. The vast bulk of the land ice mass in Antarctica is not in danger of melting any time soon.

 

Even Greenland, which is more at risk than Antarctica, will not melt, except at the fringes, for a long time to come.

http://www.climateark.org/shared/reader/welcome.aspx?linkid=78559

 

I quote :

 

"It said that the entire Greenland ice sheet would melt over a period of thousands of years, if temperatures remained around 2 degrees centigrade (3.6 Fahrenheit) or more above the levels predating wholesale industrialization in the developed world."

 

In other words, any risk of more than fringe ice melting is long term, rather than short term. Short term meaning within 200 years. I think humanity can do a hell of a lot in 200 years!

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I have NEVER read any credible, grounded in science, account suggesting any sizeable fraction of the main, on land, ice mass of Antarctica will melt within 100 years.

 

I've never seen a live platypus, either. Doesn't mean such a thing doesn't exist.

 

This cannot possibly be this hard to find a reference for, especially with Google Scholar and Google Books.

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Mokele

I think you missed the point. The reason I have never seen such a report is that no such report exists. Climate scientists, even the disaster-mongers, do not believe that the vast bulk of ice in Antarctica is going to melt any time in the next few hundred years.

 

Predicting ice melt around the fringes of the continent is one thing. Predicting the many kilometres thick ice in the centre at minus 50 C will melt. Well, if you believe that, how about the Loch Ness Monster??

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The reason I have never seen such a report is that no such report exists.

Have even read any of the posts that I personally made to this thread? What is wrong with you, man?

 

Climate scientists, even the disaster-mongers, do not believe that the vast bulk of ice in Antarctica is going to melt any time in the next few hundred years.

You must have missed it the last four times I said it, but, yes... they do. I even shared why this is so and also how they explain it.

 

 

Predicting ice melt around the fringes of the continent is one thing. Predicting the many kilometres thick ice in the centre at minus 50 C will melt. Well, if you believe that, how about the Loch Ness Monster??

 

Appeal to incredulity.

Appeal to ridicule.

Ignoring the data which proves your claim false.

 

This is why people get so annoyed and frustrated with you, Lance. Closing your eyes and plugging your ears is not evidence to rebut the issue that the ice sheet is going away very quickly, despite its vastness and the relatively limited temperature increase. Case closed. Good bye.

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iNow

I have NEVER seen a proper scientific report predicting the melting of the entire Antarctic ice mass in the next 200 years. If you have such a thing, feel free to post it. Sure, lots of predictions of ice melt round the fringes, but the entire ice mass?? Uh uh!

 

Swansont said, and I agree, that the Antarctic ice mass is sufficient to cause a 60 metre sea level rise if it all melted. Even James Hansen does not predict anything like that within 200 years. The maximum IPCC prediction is 1 metre by 2100AD.

 

So, iNow, either you misunderstand what I am saying, or you have a serious lack of understanding of the subject.

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Swansont

I have read a lot of material on global warming ideas. I have NEVER read any credible, grounded in science, account suggesting any sizeable fraction of the main, on land, ice mass of Antarctica will melt within 100 years. Everything I have read, that predicts melting, relates to the fringe of the continent, and especially the Antarctic Peninsular. The vast bulk of the land ice mass in Antarctica is not in danger of melting any time soon.

 

Even Greenland, which is more at risk than Antarctica, will not melt, except at the fringes, for a long time to come.

http://www.climateark.org/shared/reader/welcome.aspx?linkid=78559

 

I quote :

 

"It said that the entire Greenland ice sheet would melt over a period of thousands of years, if temperatures remained around 2 degrees centigrade (3.6 Fahrenheit) or more above the levels predating wholesale industrialization in the developed world."

 

Thanks for including the link. This is why we insist on references, though:

 

You have quoted the statement that is being superseded by new evidence. The article's whole point is that the melting is happening faster than what you have quoted.

 

The lead-in of the article is this:

New research shows that man-made climate change could cause the Greenland ice sheet to break up in hundreds, rather than thousands, of years, the chair of a United Nations panel of scientists said on Monday.

 

In other words, any risk of more than fringe ice melting is long term, rather than short term. Short term meaning within 200 years. I think humanity can do a hell of a lot in 200 years!

 

I don't know what that last sentence is supposed to imply — predictions from models assume certain conditions. If you change the conditions, the prediction no longer applies, without affecting the validity of the model.

 

Why would humans have to do anything in 200 years if the models are unreliable and there's really no problem?

 

I don't see how this article supports your contention that Antarctica has no realistic chance of melting in the next ~thousand years.

Care to try again?

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iNow

I have NEVER seen a proper scientific report predicting the melting of the entire Antarctic ice mass in the next 200 years. If you have such a thing, feel free to post it. Sure, lots of predictions of ice melt round the fringes, but the entire ice mass?? Uh uh!

Well, you've repeated your appeal to incredulity (just b/c you haven't seen them doesn't mean they don't exist). You've been informed of this repeatedly, and further, MY OWN REFERENCES IN THIS THREAD PROVE YOU WRONG. I'm not sure what else I need to do or say to get you to accept this point.

 

Further, you've now added strawman to your list of logical argumentative fallacies, as "the entire ice mass" was not anything I referenced.

 

 

Either way, I DO have other resources to support my claim, and I ask that you be a man, step up, and admit that you were mistaken... or, at the VERY LEAST, stop repeating claims which have already been proven false.

 

 

http://efdl.cims.nyu.edu/publications/refereed/jclimate_nonlinear_warm_08.pdf

We have determined that the response of ice shelf basal melting to ocean warming follows a quadratic relation. This occurs because the melt rate is primarily governed by the transfer of heat through the oceanic boundary layer beneath the ice shelf, which is influenced by changes in both oceanic temperature and velocity. As the ocean warms offshore of an ice shelf, both of these quantities increase linearly, leading to a quadratic increase overall. Examination of a range of model configurations shows that altering topography changes the magnitude of the melt rate.

 

<...>

 

The quadratic melt rate dependence should be of interest to scientists concerned about the long-term effects of global warming on Antarctic climate stability as a whole. First, it implies that for a given topography, ice shelves melted by warm waters are more sensitive to temperature changes. Second, if a steady warming of waters offshore of an ice shelf were to take place, then our results imply that melting of the ice shelf base would increase at an accelerating rate. Whether this leads to thinning or collapse of the ice shelf will also depend upon glaciological and meteorological processes, but the fact that the melting increase accelerates requires that some other process counteracts melting in an above-linear fashion to stabilize the ice shelf and, therefore, the ice sheet feeding it.

 

Which is precisely what I've been arguing...

 

Also, this:

 

http://www.ggy.bris.ac.uk/personal/StephenPrice/images/images/documents/Price+_JGlac_54no184_2008.pdf

Recent observations of increased discharge through fast-flowing outlet glaciers and ice streams motivate questions concerning the inland migration of regions of fast flow, which could increase drawdown of the ice-sheet interior.

 

 

http://www.springerlink.com/content/t1265r6548477378/fulltext.pdf

Another complication is that ice sheets do not grow and decay simply and linearly with global average temperature. During Heinrich events, the Laurentide ice sheet surged into the ocean in response to no evident climate forcing at all. Once an ice sheet forms, its high albedo tends to stabilize it, perpetuating its own existence. However, this effect did not save the Eemian world from 4–5 m of sea level rise in a world only about 1°C warmer than preanthropogenic, nor is it evident at any other time in the past from Fig. 3. In spite of the potential complications, the figure shows a clear correlation between global temperature and sea level in the geologic past.

 

The forecast for the coming century is for only 0.2–0.5 m under business-as-usual (A1B scenario), in spite of a temperature change of 3°C (Solomon et al. 2007). The sea level response to global temperature is one hundred times smaller than the covariaton in the past. The contrast between the past and the forecast for the future is the implicit assumption in the forecast that it takes longer than a century to melt a major ice sheet.

 

There are reasons to believe that real ice sheets might be able to collapse more quickly than our models are able to account for, as they did during Meltwater Pulse 1A 19 kyr ago (Clark et al. 2004) or during the Heinrich events (Clark et al. 2004), neither of which are well simulated by models. Ice sheets are also demonstrating tricks today which models don’t predict in advance, such as accelerating flow (Zwally et al. 2002) and seismic rumbling (Ekstrom et al. 2006) following the seasonal cycle in Greenland. Ice shelves such as the Larsen B on the Antarctic peninsula collapse catastrophically, and the ice streams that flow into them accelerate (Bamber et al. 2007). Recognizing the insufficiency of current ice sheet models to simulate these phenomena, IPCC excluded what they call “dynamical changes in ice sheet flow” from their sea level rise forecast.

 

 

At this point, I'm more than comfortable claiming that my point has been amply supported, and yours proven false.

 

 

So, iNow, either you misunderstand what I am saying, or you have a serious lack of understanding of the subject.

Uh huh... :rolleyes:

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I think you missed the point. The reason I have never seen such a report is that no such report exists. Climate scientists, even the disaster-mongers, do not believe that the vast bulk of ice in Antarctica is going to melt any time in the next few hundred years.

 

No, actually, you missed the point - you should be able to find a reference saying "This will not happen for the following reasons". If it's fairly basic, you might have to go digging in the literature fairly deeply, but there should be some mention somewhere explaining it.

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iNow said :

 

"At this point, I'm more than comfortable claiming that my point has been amply supported, and yours proven false."

 

The reason you can say that is because we have not been arguing the same point. Or, as I said before, you misunderstood what I was saying. If you go back over the last few posts you will note that I was talking about the whole Antarctic ice field, which covers the entire continent.

 

I stated that there was no way this was likely to melt within the next 200 years, and probably not within 1000, which is true. I admit that the 1000 year time span is more problematic. However, we are talking about an incredible mass of ice, at a very low temperature - average minus 50 C. To melt it all would require an increase in temperature over Antarctica of more than 50 C, and a very substantial amount of time for all that ice to melt.

 

Antarctica's average ice thickness is 2,100 metres (7,000 feet). This is not gonna melt in a hurry!

http://www.antarcticconnection.com/antarctic/weather/snow-ice.shtml

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I stated that there was no way this was likely to melt within the next 200 years, and probably not within 1000, which is true.

You do know, right, that repetition alone does not add any validity to an already invalid point?

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However, we are talking about an incredible mass of ice, at a very low temperature - average minus 50 C. To melt it all would require an increase in temperature over Antarctica of more than 50 C, and a very substantial amount of time for all that ice to melt.

 

Why? Does the current Antarctic ice only disappear because it is exposed to above-freezing air temperatures, and for extended periods of time?

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Swansont

You know better.

Currently much of the sea ice disappears each summer due to the warming of the ocean. You are well aware that land ice is quite different. The ice at the fringe of Antarctica, close to the sea, such as that covering the Antarctic Pensinular, can melt for a host of reasons.

 

However, that is not what I have been talking about. I have been talking about the ice that covers the bulk of Antarctica - the continent. It is 14 million square kilometres 98% covered with ice to an average depth of over 2 kms. http://en.wikipedia.org/wiki/Antarctica The vast bulk of Antarctica is more than 100 km and up to 1200 km from the ocean, making warm seas of limite dimpact in melting ice. After all, Antarctica is bigger than Europe.

 

So Swansont, how about being honest and admitting there is no likelihood of total ice melting in Antarctica any time within the next 200 years? After all, honesty is a prime scientific virtue.

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how about being honest and admitting there is no likelihood of total ice melting in Antarctica any time within the next 200 years?

 

None? That's flat-out wrong.

 

Antarctica is *not* cold just because of where it is - 30 million years ago, it was in the same spot give or take a few degrees, and it had temperate forests and no permanent ice caps.

 

Antarctica is mostly cold due to the structure of ocean currents, the same currents that explain why the UK is so unseasonably warm for its latitude. If the currents are disrupted by climate change (either directly, or via disruptions of other currents), Antarctica *could* warm quite quickly. How quickly? I don't know, but I'm sure someone, somewhere has run a simulation.

 

The point is, look to the past - climate can change, and change fast, even without major forcing events such as extensive volcanism or asteroid impact.

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Mokele, please....

 

No red herrings, please. What are the odds of a meteor that will melt Antarctica in the next 200 years? And there is no 'normal' process able to melt all of Antarctica's ice within 200 years.

 

Actually, this debate is getting really weird. The catastrophist view is heading way out into never never land. There is absolutely no credible science to suggest that ALL the ice in Antarctica is likely to melt within 200 years. Even 1000 years would be a major stretch.

 

How about you guys get your heads out of disaster fairy land and get back into the real world like the rest of us, and admit that real science does NOT suggest all the ice in Antarctica melting within 200 years?

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Swansont

You know better.

Currently much of the sea ice disappears each summer due to the warming of the ocean. You are well aware that land ice is quite different. The ice at the fringe of Antarctica, close to the sea, such as that covering the Antarctic Pensinular, can melt for a host of reasons.

 

However, that is not what I have been talking about. I have been talking about the ice that covers the bulk of Antarctica - the continent. It is 14 million square kilometres 98% covered with ice to an average depth of over 2 kms. http://en.wikipedia.org/wiki/Antarctica The vast bulk of Antarctica is more than 100 km and up to 1200 km from the ocean, making warm seas of limite dimpact in melting ice. After all, Antarctica is bigger than Europe.

 

So Swansont, how about being honest and admitting there is no likelihood of total ice melting in Antarctica any time within the next 200 years? After all, honesty is a prime scientific virtue.

 

 

I can't help but notice you didn't answer the question I asked.

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Swansont

That was because it did not need answering, and was irrelevent to the main point. Ice melts for a number of reasons, but the ice we see melting right now is doing so for reasons that have nothing to do with any hypothetical ice melt within the continent.

 

For example ; melting due to contact with warmer ocean water cannot affect ice that is many kilometres inland. Ice sliding into the ocean is not a factor for most of Antarctica.

 

The point I am making, and which you, Swansont, for some weird reason, see fit to deny, is that the vast bulk of the ice covering the continent of Antarctica is in no danger of melting within 200 years, and probably not for a much longer period. I am a bit disappointed, actually. I expected better of Swansont. iNow, of course, has a history of stubbornly clinging to arguments that have been proven wrong, but Swansont should be more faithful to good science. Why is he not?

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Swansont

That was because it did not need answering, and was irrelevent to the main point. Ice melts for a number of reasons, but the ice we see melting right now is doing so for reasons that have nothing to do with any hypothetical ice melt within the continent.

The references I shared in this thread directly rebut this claim. There is nothing hypothetical about it.

 

 

For example ; melting due to contact with warmer ocean water cannot affect ice that is many kilometres inland. Ice sliding into the ocean is not a factor for most of Antarctica.

False, as demonstrated by the references I shared.

 

 

iNow, of course, has a history of stubbornly clinging to arguments that have been proven wrong...

Pots calling kettles black. I take great offense by your comment, Lance. They are out of line, and plainly false.

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SL, this whole cluster**** of a thread is due to you dragging something totally unrelated into a thread started to answer a very simple question. Furthermore, *nobody* asserted that the entirety of the polar ice caps would melt any time soon until *you* brought it up (without any reference for who's making this claim) in post #21.

 

That's the problem - from that point on, the whole thread devolved into your strawman and us trying to figure out what the hell you're gibbering about.

 

Thread closed.

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