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Post by gdfernan on Mar 10, 2009 21:00:32 GMT
My understanding regarding the most catastrophic aspect of global warming that is used to frighten the public is the melting of the Greenland glaciers which will raise sea level by 6m, and inundate low lying coastal areas, wipe out island nations like the Maldives etc. Now the main left-wing newspaper in the UK, The Guardian, whose readers are referred to as Guardianistas (derisively) have published this article www.guardian.co.uk/environment/2009/mar/10/greenland-ice-sheet-climate-changeIt refers to a study on the melting of the Greenland glaciers and has this to say. ".....It would take an average global temperature rise of 6C to push Greenland into irreversible melting, the new study found. Previous estimates, including those in the recent reports from the Intergovernmental Panel on Climate Change, said the critical threshold was about 3C – which many climate scientists expect to be reached in the coming decades." "....An ice sheet about half the size is known to have persisted there during the Eemian period, about 125,000 years ago, when temperatures were about 5C higher than today." "...Bamber (the researcher) said previous studies (which gore and others used to prophesy catastrophic sea level rise) used a very simple model to mimic how the Greenland ice will melt as temperatures rise." Of course, he then goes on to add the AGW orthodoxy statement. ".."I'm not saying that if you have a temperature rise of 2C then you're not going to lose mass from Greenland, because you are. You warm the planet, ice melts," he added." Note: Italics mineSo, since the most catastrophic temp increase from GW is around 3.5C, and the Greenland glaciers will not melt at those levels, lets just prepare to enjoy the warmer climate.
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Post by socold on Mar 10, 2009 21:13:33 GMT
3C is not the maximum amount. It's the expected amount by a certain time. Even the commonly cited IPCC projections underestimate the total warming, because the IPCC projections only go up to 2100.
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Post by gettingchilly on Mar 10, 2009 22:12:52 GMT
Even the commonly cited IPCC projections underestimate the total warming,
Ha Ha... Ha ha... Ha Ha... Ha Ha...
Simpsons movie all over.
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Post by crakar24 on Mar 11, 2009 4:48:07 GMT
3C is not the maximum amount. It's the expected amount by a certain time. Even the commonly cited IPCC projections underestimate the total warming, because the IPCC projections only go up to 2100. When i was a child we used to go to the circus, there we would see an old gypsy woman and for a small fee she would project/predict your future. Of course none of this ever came true but the old woman was never held accountable because we all knew she was full of crap and was just trying to make a living, we did it just for fun. Socold, In regards to the IPCC can you please list all projections/predictions the IPCC has got right? And for the ones they have got wrong do you think they should be held accountable? Or are they just like that old gypsy woman? Take your time with the lists OK.
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Post by crakar24 on Mar 11, 2009 5:01:03 GMT
3C is not the maximum amount. It's the expected amount by a certain time. Even the commonly cited IPCC projections underestimate the total warming, because the IPCC projections only go up to 2100. Forget the list Socold Here is a cut and paste from a story which makes your claims completely absurd, oh and the IPCC's aswell. "On the current, linear observed trend, CO2 concentration in 2100 will be just 575ppmv (IPCC central estimate 836 ppmv), requiring the IPCC’s central projection of temperature increase to 2100 to be halved from 3.9 to a harmless 1.9 C°. The IPCC’s prediction of Co2 increase is greatly exaggerated, chiefly because the IPCC cannot add up the global “carbon budget” to within a factor of two. According to its metric, CO2 emissions at their current record levels ought to be adding some 4.1 ppmv/year to the atmosphere, yet the actual increase is only 2 ppmv/year. Ever since CO2 concentration has been measured by modern methods, the increase in concentration has run below half the expected rate. Nevertheless, the IPCC tries implausibly to claim 90% certainty that more than half of the warming of the past half-century is anthropogenic. It was the political representatives, not the scientists, who reached this conclusion by show of hands – An intriguing instance of the argumentum ad populum, an Aristotelian fallacy that has no place in serious thought. Science is not a democracy. There is compelling evidence that much of the warming of the past half-century was caused by an exceptional increase in solar activity. During the 70 years 1645-1715, the Maunder Minimum, the Sun was less active than in 10,000 years. Then solar activity inexorably increased for almost 300 years until, during the 70 years 1925-1995, peaking in 1960, the Solar Grand Maximum, the Sun was at least as active as at any time in the previous 11,400 years (Solanki et al., 2005). Hathaway et al. (2004) illustrate this solar increase by reference to the 11-year cycles of sunspot numbers"
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Post by donmartin on Mar 11, 2009 5:46:11 GMT
I believe the bronze age was warmer than current times. And glaciers do not melt - except at their base - otherwise, they evaporate. I think glaciers, unlike sea ice, which accounts for 95% of ice on Earth, are comprised of approximately 50% air on average throughout density. And were sea ice to melt, the ocean levels would probably decrease, given that the specific gravity of ice is less than water. Facing these kinds of facts, the politicos now speak of climate change; not global warming. Something like a hedge fund.
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Post by kiwistonewall on Mar 11, 2009 6:17:56 GMT
I believe the bronze age was warmer than current times. And glaciers do not melt - except at their base - otherwise, they evaporate. I think glaciers, unlike sea ice, which accounts for 95% of ice on Earth, are comprised of approximately 50% air on average throughout density. And were sea ice to melt, the ocean levels would probably decrease, given that the specific gravity of ice is less than water. Facing these kinds of facts, the politicos now speak of climate change; not global warming. Something like a hedge fund. Don, anything floating in water displaces its own mass of water- so floating sea ice melting neither rises nor lowers sea water levels. Water density is affected by with salinity and temperature. The main causes of rises in sea levels are warmer waters (increases volume) and low pressure areas - the water level will rise in an area of lower air pressure - the typical "storm surge' when the sea level rises into an area of very low pressure. "And glaciers do not melt" isn't correct. Glaciers will indeed melt - depending on the surrounding conditions - in NZ we have several Glaciers that descend below the snow line into warmer regions. Ice has a lower melting point under pressure, so pressure points will often liquefy and the freeze again when the pressure is reduced. Sublimation (ice->vapour) requires a lot more energy, generally happens with a dry warm wind. In very cold, dry regions (say the deserts of Antarctica) sublimation may be an important process - but not in moist warm New Zealand. Can't speak for other Glaciers, as I have only stood on good old Kiwi ones (before we had all the health & safety concerns from mother governments) cheers
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Post by donmartin on Mar 11, 2009 16:39:33 GMT
Kiwi, when the volume of water increases, does the water then cool? So how is the point of equilibrium determined?
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Post by steve on Mar 11, 2009 18:06:51 GMT
Of course, he then goes on to add the AGW orthodoxy statement. ".."I'm not saying that if you have a temperature rise of 2C then you're not going to lose mass from Greenland, because you are. You warm the planet, ice melts," he added." Note: Italics mineSo, since the most catastrophic temp increase from GW is around 3.5C, and the Greenland glaciers will not melt at those levels, lets just prepare to enjoy the warmer climate. So you are happy to believe this researcher, but only up to the point where he says that warmer temperatures *will* lead to loss of ice and sea-level rise?! Obviously it is good news if Greenland is more stable than other studies have previously indicated. That the story is widely aired is also proof that the scientific process continues to work well. But this is just one more study. And it is another study that doesn't take into account the difficult to assess issue of ice dynamics. So it's a little early to start being relaxed about taking chances with your coastal living descendents (assuming you give a toss about them, that is).
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Post by woodstove on Mar 11, 2009 19:11:58 GMT
Of course, he then goes on to add the AGW orthodoxy statement. ".."I'm not saying that if you have a temperature rise of 2C then you're not going to lose mass from Greenland, because you are. You warm the planet, ice melts," he added." Note: Italics mineSo, since the most catastrophic temp increase from GW is around 3.5C, and the Greenland glaciers will not melt at those levels, lets just prepare to enjoy the warmer climate. So you are happy to believe this researcher, but only up to the point where he says that warmer temperatures *will* lead to loss of ice and sea-level rise?! Obviously it is good news if Greenland is more stable than other studies have previously indicated. That the story is widely aired is also proof that the scientific process continues to work well. But this is just one more study. And it is another study that doesn't take into account the difficult to assess issue of ice dynamics. So it's a little early to start being relaxed about taking chances with your coastal living descendents (assuming you give a toss about them, that is). So, let me get this straight. Sea level has risen and fallen hundreds of feet during humanity's brief tenure on Earth, and so far (even absent modern technology) we have adapted successfully to these changes. And now, with all the technology at our disposal, and the overwhelming likelihood that sea level is not rising in any menacing fashion anyway (as Morner has measured), people are going to be drowned or some such? Are you serious?
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Post by Belushi TD on Mar 11, 2009 19:50:32 GMT
Don -
When a constant mass of water cools, it looses volume, to a point. That point is almost exactly 4.0 degrees C. After that, the mass of water expands, which is why ice floats. Dihydrogen monoxide is one of an EXCEEDINGLY FEW (I can't think of any others, off the top of my head that do, feel free to correct me if I'm missing one) substances that the solid phase weighs less per unit volume than the liquid phase.
As far as glaciers being 50% air, that's wildly wrong. If that were true, then glacially sourced icerbergs would have something like 50 % of their mass above the surface . Since they have about the same amount above the surface (11% or so) as sea ice, its patently absurd to make that claim.
I will grant that the snow on top of a glacier has a lot of air in it, and the first couple seasons also have a high air content, but the vast majority of the mass of a glacier has little to no air in it.
Belushi TD
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Post by ron on Mar 12, 2009 4:17:05 GMT
eeeeek
Volume would not necessarily be that much higher for ice with a ton of trapped air as the gas would become highly compressed...
I don't know one way or another, but I think your assumption is probably off.
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Post by nautonnier on Mar 12, 2009 12:00:59 GMT
Well there has to be a fair amount of air in ice or the sampling of the ice cores would be a pointless exercise. The main issue was that the gases in the air diffuse out of the bubbles into the surrounding ice at different and sometimes surprisingly fast rates (well centimeters in thousands of years ) and that this diffusion means that some of the proxy measures could be quite inaccurate.
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Post by donmartin on Mar 12, 2009 20:14:10 GMT
I have this strange feeling that "melting" all the ice in the world might not change sea levels very much, if at all. According to Kiwi, if the sea ice melted and evaporated, the sea level would not change. he sea ice displaces its mass in the water.
So I suppose the next question is whether the people who measure potential sea level rise from "melting" of land ice (the remaining 5%) take into account the ice/water volume difference and the amount of air trapped in the land ice. In other words, obviously, you cannot simply take a given volume of ice and convert it to water of the same volume. Is there an average ratio of land ice to water content for any given volume? Is the Ross Ice Shelf sea ice or land ice?
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