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MELTING GLACIERS
#21
Richard111,

Hi. You have done some calculations to come up with an estimated 334 quadrillion joules, or 334 billion MJ, of heat necessary for the isothermal melting of 1 cubic km of glacial ice that begins at a uniform temperature of 0.0°C.

One of your premises is that 334,000 joules are necessary for 1 kg of ice at the said temperature. And you have stated that ice is 1/1.1 times or .9090909 times as dense as water, so that the amount of ice to be melted per cubic km of water that is required is 1.1 cubic km.

1g of liquid water takes up 1 cubic cm. Thus, with your density conversion factor, 1 cubic cm of glacial ice has mass of .9090909 g.

The number of cubic cm in a cubic km is 100,000 * 100,000 * 100,000 = 1 million billion, or 1 quadrillion, cubic cm. 1 quadrillion cm^3 * .9091g/cm^3 = 909.0909 trillion grams or 909.0909 billion kg.

A cubic km of glacial ice, according your density assumption, contains 909.0909 billion kg.

(909.0909 billion kg / cubic km of ice) * (.334 MJ/kg) = 303.6364 billion MJ / cubic km of ice.

So you're off by a little bit on the megajoules-per-cubic-km-of-ice calculation.

You then have to figure out the volume of the ice-equivalent of the amount of water you need. The needed water, per your assumptions, is 361,132.4 cubic km. This corresponds to a volume of 361,132.4 * 1.1 = 397,245.64 cubic km of glacial ice.

397,245.64 cubic km * 303.6364 billion MJ / cubic km = 120.6182 quadrillion MJ in total. That is what you reported.

So even though you had the wrong intermediate figure, you ended up with the right final answer for MJ. Apparently, the way you calculated is not exactly as you reported.

But it's still interesting findings!

RTF
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#22
RTF, thanks for the maths check. I will check it again. May have been cavalier with my decimal points. The ice melt energy requirement figure I took from Pat Tyson's site. Have posted the links elsewhere, probably in Layman Struggles.

Anyway, I realise my thesis is pie in the sky as I make the ridiculous assumption there is a 1 metre high wall around the global oceans! I haven't a clue how much water is required to cover the world's lowlands. Also I ignore the isostatic effects of mass tranfer from the land to the oceans. Again I haven't a clue what this will do to the final global sea level.

The reason I attempted to work out some figures is to squelch discussions of "rising sea levels". I state something like: "Do you realise it needs something in the order of ONE HUNDRED THOUSAND CUBIC MILES OF ICE (loud voice) to raise sea levels just one metre?" If they still insist I offer to do the math with them. Big Grin

Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#23
(01-15-2011, 02:06 AM)Richard111 Wrote: RTF, thanks for the maths check. I will check it again. May have been cavalier with my decimal points.

Richard, my pleasure. It's good work! Really good stuff.

I did a back-of-the-envelope calculation a few years ago, and came up with the estimate that, at the rate of 6 mm/year increase in sea level, it would take at least 1,400 years for my house at elevation of 36 feet to become oceanfront property.

For those who were mathematically inclined, when I showed them some of the numbers, they were suitably impressed, and I think the realization of the time scale we were looking at had a positive effect in terms of educating them.

RTF
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#24
RTF, I stand by my calculations as shown above, there are no hidden calculations.

From your explanation you seem to imply that energy required is proportional to VOLUME.

I am working on the assumption energy required is proportional to MASS.

Am I missing something?
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#25
(01-20-2011, 04:18 AM)Richard111 Wrote: RTF, I stand by my calculations as shown above, there are no hidden calculations.

From your explanation you seem to imply that energy required is proportional to VOLUME.

I am working on the assumption energy required is proportional to MASS.

Am I missing something?

The part I was offering a correction to was:

"334,000,000,000,000,000 joules to melt 1 cubic kilometre."

Your mistake was that you were quoting joules for the mass that would be contained by a cubic km of water. The correct number should have been for a cubic km of glacial ice, which, given your assumptions, is what I calculated.

I wasn't saying something was hidden. And you did get the right final answer for total joules, which means you correctly calculated the total mass of the ice needed. The only thing was that when I read it, it was apparent that the means of getting to the number of total joules was not correctly reported. You cannot get to your final answer directly using "334 quadrillion joules / cubic km of water".

Again, an excellent thought experiment, and I thank you.

RTF
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#26
Okay. I think I see what you mean. Just my laymans way of thinking. I equated 1.1 cubic kilometers of ice melt results in 1 cubic kilometer of water thus TOTAL WATER was all I needed. I tend to look for the simplest way to solve a problem. Smile
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#27
(01-22-2011, 06:59 AM)Richard111 Wrote: Okay. I think I see what you mean. Just my laymans way of thinking. I equated 1.1 cubic kilometers of ice melt results in 1 cubic kilometer of water thus TOTAL WATER was all I needed. I tend to look for the simplest way to solve a problem. Smile

That's actually not really a bad way of looking at it for this problem. As I'm remembering now, the main source of confusion for me was before the 334 number. Based on how you got there, it wasn't clear to me that the number really _was_ for water. Obviously if it were for ice, it would be wrong. My best guess at the time was that you had gotten a number for ice, but mistakenly thought it was for water.

So I had to go back to the start and do all the calculations myself, to confirm whether it was ice. When I found out it wasn't, I figured, "Well I already got this far, might as well finish it with the ice number." Smile

RTF
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#28
Out on the internet one Dr Marco Tedesco seems to be a major driving force, with the help of the WWF, for claims of dramatic ice melt from Greenland. I found some numbers to work with:

Greenland Ice Melt In 2010 More Than Double Average Of Previous Three Decades

Quote:“Based on computer models, Dr Tedesco estimated that runoff in 2010 was 530 gigatonnes, or billions of tonnes, compared to an average of 274 gigatonnes for the period 1958-2009, and 285 gigatonnes for 1979-2009.”
simple arithmatic ---
. . . . - 2010 = 1 year . .@ 539/y = . 539 gigatonnes (10^9 = 1,000,000,000)
1958 - 1979 = 21 years @ 274/y = 5,754 gigatonnes
1979 - 2009 = 30 years @ 285/y = 8,550 gigatonnes
----------------------------------------------------
grand total. . . . . . . . . . . . . . . . . 14,843 gigatonnes of water

Amount of water need for 1 metre sea level rise = 361,132.4 gigatonnes

Therefore sea level must have risen by 41 millimetres over that 31 year period and is completely lost in the ~3mm/y recorded sea level rise.

But then again, this is all computer model clap-trap. Rolleyes
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#29
Quote:But then again, this is all computer model clap-trap.
... absolutely!

Question: What variable is used to drive the ice model of Greenland? The chances are it is the worthless gridded temperature reconstructions from CRU, GISS, etc. They bare little resemblance to reality.
"Correlation is NOT Causation"
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#30
(01-29-2011, 03:56 PM)Questioning_Climate Wrote:
Quote:But then again, this is all computer model clap-trap.
... absolutely!

Question: What variable is used to drive the ice model of Greenland? The chances are it is the worthless gridded temperature reconstructions from CRU, GISS, etc. They bare little resemblance to reality.


Leonard Weinstein shows how the topography of the Greenland Ice Cap and the atmospheric temperatures at altitude make it impossible to melt the Greenland Ice Cap except at the lower elevations:

The Truth About Arctic and Greenland Ice

http://noconsensus.wordpress.com/2009/05...nland-ice/
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#31
(01-29-2011, 03:56 PM)Questioning_Climate Wrote:
Quote:But then again, this is all computer model clap-trap.
... absolutely!

Question: What variable is used to drive the ice model of Greenland? The chances are it is the worthless gridded temperature reconstructions from CRU, GISS, etc. They bare little resemblance to reality.

AND, the difference between actual surface temperature and near surface air (gridded) temperature.
Which also bares little resemblance to reality ON THE GROUND.

Has anyone mentioned the latent heat of change of state?
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
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