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jimmydasaint

Don't Icebergs Displace Their Own Mass? [Answered: YES]

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Swansont

According to

http://www.ifremer.fr/ifrtp/pages/API%202007-2008/API/125.pdf

obtaining an accurate mass balance of water/ice movement and the contribution to sea level rise is very difficult. They suggest that current sea level rise is 60% due to thermal expansion. The residue is melting ice. However, how much of that melting ice is from various different sources is hard to determine. Their estimate is 0.9 mm per year from melting mountain glaciers and ice melt from Antarctica and Greenland.

 

An earlier article I read in New Scientist suggested that most of the non thermal expansion was mountain glaciers. However, it looks as though the estimates are little better than educated guesses.

 

This applies to your other reference on Greenland ice melt. There is so much error factor in the estimates of amount of water melting compared to snow precipitating that I cannot take any estimate too seriously.

 

The big objection I have is to those who talk of severe ice melt in West Antarctica, without actually explaining that West Antarctica is just the peninsular and its base, which is a tiny fraction of the whole of Antarctica. I regard that kind of statement as political chicanery - essentially a more subtle form of misdirection - otherwise known as a lie.

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Specific amounts to the milliliter and error factors aside, we know that the ice melt contributes to the volume of water in the ocean, and that the melting is happening faster now. Regardless of your specific variables on amount, it's increasing, and studies by the experts align well with each other on these points, and all attribute the change to a warming globe.

 

 

http://www.giss.nasa.gov/research/briefs/gornitz_09/

Over the past few thousand years, the rate of sea level rise remained fairly low, probably not exceeding a few tenths of a millimeter per year.

 

Twentieth century sea level trends, however, are substantially higher than those of the last few thousand years. The current phase of accelerated sea level rise appears to have begun in the mid/late 19th century to early 20th century, based on coastal sediments from a number of localities. Twentieth century global sea level, as determined from tide gauges in coastal harbors, has been increasing by 1.7-1.8 mm/yr, apparently related to the recent climatic warming trend. Most of this rise comes from warming of the world's oceans and melting of mountain glaciers, which have receded dramatically in many places especially during the last few decades. Since 1993, an even higher sea level trend of about 2.8 mm/yr has been measured from the TOPEX/POSEIDON satellite altimeter. Analysis of longer tide-gauge records (1870-2004) also suggests a possible late 20th century acceleration in global sea level.

 

Recent observations of Greenland and the West Antarctic Ice Sheet raise concerns for the future. Satellites detect a thinning of parts of the Greenland Ice Sheet at lower elevations, and glaciers are disgorging ice into the ocean more rapidly, adding 0.23 to 0.57 mm/yr to the sea within the last decade. The West Antarctic Ice Sheet is also showing some signs of thinning. Either ice sheet, if melted completely, contains enough ice to raise sea level by 5-7 m. A global temperature rise of 2-5°C might destabilize Greenland irreversibly. Such a temperature rise lies within the range of several future climate projections for the 21st century.

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iNow

 

The reference you just posted shows the same piece of lying hypocrasy.

 

"The West Antarctic Ice Sheet is also showing some signs of thinning." .

 

The West Antarctic Ice Sheet is, in fact, a very tiny fraction of all the ice in Antarctica, and represents just that on the Antarctic Peninsular. Using the term "West Antarctic" makes it sound much more ominous than it really is, and implies half of Antarctica is affected instead of a rather small fraction. Why do so called reputable scientists have to be so bloody deceptive?

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Your post doesn't even warrant a response. I'll again remove myself from this thread. :doh:

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iNow

 

The reference you just posted shows the same piece of lying hypocrasy.

 

"The West Antarctic Ice Sheet is also showing some signs of thinning." .

 

The West Antarctic Ice Sheet is, in fact, a very tiny fraction of all the ice in Antarctica, and represents just that on the Antarctic Peninsular. Using the term "West Antarctic" makes it sound much more ominous than it really is, and implies half of Antarctica is affected instead of a rather small fraction. Why do so called reputable scientists have to be so bloody deceptive?

 

The WAIS contains 200 million km^3 of ice, which is 10,000 times more than the annual Greenland melt. IOW, if completely melted, would raise the sea level at least 5m.

http://en.wikipedia.org/wiki/West_Antarctic_Ice_Sheet

 

Which part is the lie, i.e. what is factually incorrect in iNow's reference? And where is the hypocrisy?

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swansont

Did I not make myself clear?

It is the use of the misleading term 'West Antarctica' when they mean the relatively tiny part of Antarctica that is the Antarctic Peninsular.

 

If I said that eastern USA was subtropical, when I meant the Florida Peninsular, people would think I was talking about everything east of the prairies.

 

To say 'West Antarctica' leads to the misconception that people are describing half of the entire continent. While those 'in the know' will appreciate what is meant, those documents are read by an awful lot of other people - as witness the fact that we are discussing them now. How many people who are not part of the clique would realise that 'West Antarctica' refers to only a tiny part of the entire continent?

 

The use of the term 'West Antarctic' instead of the more sensible and more scientifically accurate term 'Antarctic Peninsular' is obviously very misleading.

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but it is not just the peninsula. it is everything west of the transantarctic mountains. now, it doesn't matter what it is called (it could be called stinky pete's chili house for all it matters) all that matters is that it has roughly the same amount of ice as the greenland sheet and is in danger of collapsing.

 

so, are you going to keep argueing about what it is called or are you going to discuss what it actually means that we have a large volume of melting ice?

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swansont

Did I not make myself clear?

It is the use of the misleading term 'West Antarctica' when they mean the relatively tiny part of Antarctica that is the Antarctic Peninsular.

 

Blame the cartographers, then. That's what it's called, and has been for a while. It's the western part of Antarctica.

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The name is a symptom of something much larger, and that is the politicisation of global warming. As many have pointed out on this and similar threads, there is a very right wing political movement that denies global warming. The deniers are, of course, quite wrong.

 

What the same people tend to deny, though, is that there is a similar and opposite political movement that exaggerates global warming. Dr. Patrick Michaels, in his sceptical book The Satanic Gases, suggests that this movement is driven by scientists, bureaucrats, and politicians who are capitalising on AGW.

 

Climate scientists who once would have been tucked away in obscure corners screaming for research funds that never come, are now seen as massively important world savers, and receive very large sums of research funding. If you do not think this is a corrupting influence, you are naive. Bureaucrats who have jobs at IPCC and similar organisations will fight for thir jobs and privileged positions, and politicians like Al Gore who have hung their hat on the AGW pole will never accept anything that might reduce their power and influence.

 

AGW is real. Warming is real and human driven. However, many other aspects of this story are of much greater doubt. How catastrophic is it likely to be? How much time does humanity have to adapt? How accurate are predictions? It is to the benefit of climate scientists, bureaucrats and politicians to put the worst interpretation up.

 

You only have to look at Dr. Stephen Schneider, who admitted deliberate exaggerations for publicity. Or Dr. James Hansen with his 5 metre sea level rise prediction before 2100. The use of the term Western Antarctica instead of the more accurate term Antarctic Peninsular is a symptom of the whole movement towards global warming exaggeration.

 

While the global warming denialists are probably more wrong than the global warming exaggerators, they are both wrong, and should both be opposed in the interests of proper scientific accuracy.

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However, many other aspects of this story are of much greater doubt. How catastrophic is it likely to be? How much time does humanity have to adapt? How accurate are predictions? It is to the benefit of climate scientists, bureaucrats and politicians to put the worst interpretation up.

 

You only have to look at Dr. Stephen Schneider, who admitted deliberate exaggerations for publicity. Or Dr. James Hansen with his 5 metre sea level rise prediction before 2100.

You've been already corrected on this point repeatedly. :doh:

 

 

http://www.scienceforums.net/forum/showthread.php?p=431539#post431539

And this is your error. If sea level rises were to double each decade, you would indeed get a 5-meter increase in in sea levels (1+2+4+8+16+32+64+128+256) in 9 decades. But Hansen didn't say this would happen. He said "let us say" it would happen. It's a math word problem, no more. An example of geometric growth, and as such it is 100% correct: add those numbers and you get 511 cm.

 

<...>

 

His betting his professional analysis and interpretation that the nonlinear form of the positive feedbacks will result in a greater-than-linear rate of sea level increase. And you respond by calling it a pseudo-religion.

 

And to argue that it won't increase faster than linearly because it hasn't in the past misses his point in spectacular fashion. I don't recall reading a scientific argument from you as to why this would not happen, only that you assume it will continue linearly. Conversely, Hansen outlines why the feedbacks are nonlinear, what the positive- and negative-feedback terms are and what could happen under his described set of circumstances

 

 

 

And again, previously in that same thread ~200 posts earlier:

 

http://www.scienceforums.net/forum/showpost.php?p=422791&postcount=238

In my opinion,
if
[/b'] the world warms by 2 °C to 3 °C, such massive sea level rise is inevitable, and a substantial fraction of the rise would occur within a century. Business-as-usual global warming would almost surely send the planet beyond a tipping point, guaranteeing a disastrous degree of sea level rise."

 

(emphasis added)

 

Note the conditional. This is not a prediction of what
will
happen, it's what
could
happen
if certain conditions are met
. The fact that it has happened before means such conditions have existed and are thus achievable. I agree with the Cap'n. Your incredulity is not credible. Further, your use of this as an argument against warming models is incorrect.

 

 

 

 

At least learn from the mistakes you make, and move on once you've been corrected. For the love of Thor, man... :doh:

Edited by iNow

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oh for fsm's sakeskeptic the western antartic ice sheet has been called such LONG before global warming was discovered. get off the damn name and talk about 2 million cubic kilometers of melting ice.

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iNow

 

Hansen expressed an opinion that was unjustified. He did not deny that it was an opinion, but he clearly stated that he believed it would come true. As an example of the kind of exaggerated stance on AGW, it is valid. Hansen is one who is prepared to make statements of pure opinion and pretend it is scientific. This is politics at its worst. Science should be above that sort of thing.

 

I accept that global warming is real and human generated. However, there are extreme views, and those get a lot of publicity. An extreme view that is not supported by the science should not be expressed by scientists. Sadly, scientists are just as prone to political silliness as anyone else.

 

insane alien.

The references I was talking about were not referring to the western antarctic ice sheet. They were talking about Western Antarctica, which implies half the continent. That is misleading.

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iNow

 

Hansen expressed an opinion that was unjustified.

His opinion was "if temps continue to rise, so will sea levels." There is nothing unjustified here, with the exception of your strange desire to spin this into something it's not.

 

 

He did not deny that it was an opinion

Of course, he didn't! The first three words of his sentence were, "In my opinion." :doh:

 

 

but he clearly stated that he believed it would come true.

No, look again. He said, "If temps keep rising, then sea levels would rise." You have a very serious problem in your perceptions if you're reading more into it than that.

 

 

As an example of the kind of exaggerated stance on AGW, it is valid.

No, it's not. The only thing exaggerated here is your response to (as swansont called it) a math word problem.

 

 

Hansen is one who is prepared to make statements of pure opinion and pretend it is scientific.

So, now you assert that he was pretending it was scientific? He did no such thing, and if you claim he was, then you're either lying or fantastically ignorant (then again, these aren't mutually exclusive I suppose).

 

 

However, there are extreme views, and those get a lot of publicity.

Yes, there are extreme views.

 

 

An extreme view that is not supported by the science should not be expressed by scientists.

Why not? They are first humans, and they are first part of humanity. If the science about which they are experts lends to concerns about our collective futures, then there is nothing wrong with them raising the alert and trying to motivate action.

 

You are the one who is exaggerating, Lance, and everyone here knows it except you.

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iNow

 

I have read the Hansen statements in three separate articles - two via email which were posted on this forum, and one in paper copy of New Scientist. What I said was true, and your denial does not change that. Hansen stated a 5 metre sea level rise as a definite belief - not just a vague opinion.

 

iNow,

What I said about politicisation of global warming ideas is also true. Claim and counter-claim. The fact that you appear to be one of the extremists and don't like being identified as such does not make what I am saying incorrect. The fact that several hundred professional climate scientists also state what I have said simply backs up my statement. And yes, we have already named many of them, so lets not do that yet again.

 

Global warming has a certain amount of strong empirical data, and a lot of extrapolation and opinion. I am not arguing against the data, and neither are the sceptical climate scientists. We point out, however, where people go beyond data into areas without good evidence. And politics and self interest is behind a lot of these expeditions.

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I denied nothing, Lance. I shared the exact quote, and demonstrated how silly you were for interpreting it the way you did.

 

I love how instead of addressing my challenges directly you simply label me as "one of the extremists" and assert that I "don't like being identified as such." I'm again done with your silliness. You seem to live in your own little reality, one which I'm no longer interested in visiting.

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Ridiculous argument aside, icebergs do displace their own mass in water, but it's not just floating icebergs which are melting. There is also ice which is on land, and ice which is otherwise locked out of the ocean system.

 

The OP has been answered and I am now closing this thread.

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