A Note: Global Warming Threads

Discussion in 'Earth Science' started by Tristan, Aug 27, 2004.

  1. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    You have it backwards. The warming of the deep ocean, as now, will accelerate the release of CH4, as most of it in ocean is now cold and stable:
     
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Andre:Your graph in post 918 does NOT tell what is happening to the VOLUME of arctic sea ice, only the area of ocean it covers. As I recall, the average thickness is now less than half what it was in graph's 1980 thru 2000 averages. I.e. more than half the arctic ocean ice has melted!

    Yes the waves break up the now (fall or Oct thru November) often less than meter thick ice so it does spread out more. Essentially your post 918 graph, but with more recent data and with a little more honesty is also here: http://nsidc.org/cryosphere/sotc/sea_ice.html and reproduced below.
    I.e. "honest" as it notes that if only 15% (or more) is ice covered that fraction of the Arctic Ocean is counted as "ice covered." If waves have broken up 100% ice cover to be only 50% ice cover then that would double the "ice coverage." It is the ice volume (or average thickness) that is much more useful indicator of what is happening.

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    Note right graph ends in 2010 and the sharply falling red ICEsat curve was already then below 1 meter (less than 0.5 meter average ice thickness now?) Also left graph is 6 to 10 years old so shows much thicker fall ice. Even if we neglect the self acceleration of ice melting as albedo changes from ~0.9 to ~0.3 or less, absorbing three or more times more solar hearing, just simple linear extension of this melting rate will have Arctic Ocean essentially "ice free" on 1 November 2019 or sooner.
    The left graph's black and reddish data - "sub" (submarine's sonar looking up thru the floating ice above it) is very accurate and shows the ice has half melted!

    The ice does not need to be all gone for there to be a more economically shipping path to China, etc. from Europe. In fact a few moths ago the first ever non-ice breaker cargo ship set sail for China thru the Arctic Ocean! Next end of summer with even less thick ice more will. I think Prof. Peter Wadham's prediction* in your post 920 is likely to be demonstrated before 2020:I.e. an essentially ice Arctic Ocean as fall starts.

    * "In the end it will all just melt away quite suddenly."
    Yes that is what will happen when wave energy is being dissipated in 20 to 30 cm thick, one year old or "new ice" sheet ice is still covering large part of the Arctic Ocean in late summer.
     
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  5. Trippy ALEA IACTA EST Staff Member

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    Say what? Here's what exchemist said:

    Here's what you said for context:


    If you're talking about the Nobel prize acceptance speech Al Gore made in 2007, what he actually said was:
    Which would make it 2014 (2007 + 7 = 2014) not 2013.

    What Maslowski actually said was that the Arctic could be ice free in autum by 2011 - 2016 (or 2016 +/- 3 years), for example, see Maslowski's slide show here
    Here is what he has to say as of 2012. But he repeatedly emphasizes the large unceartainties in the models.
     
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  7. Andre Registered Senior Member

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    889
    With a little more honesty, this graph comes from your source:

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    With even a bit more honesty we should include the main reason for Arctic sea ice decline: wind (again same source)

    Then if we even add more honesty, we might include antarctic sea ice cover. (but note the wind again)

    For an honest historical anectdote

     
  8. iceaura Valued Senior Member

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    That is exactly what I said, with the additional information that the rate of heat transfer to the deep ocean so far appears to be too slow to touch off a methane catastrophe.

    Take another look at your graph - they are not warming faster, but absorbing heat faster, a much different matter. The actual temperature change at the bottom is what frees the methane, not the heat content of the whole volume. The rate of heat transfer observed so far, even though faster than expected, is not fast enough to raise the temperature fast enough to touch off the methane bomb.

    There are serious worries, of course - warm currents sinking to the bottom due to salt concentration, that kind of thing - but so far no methane catastrophe seems at all likely.

    Complete bullshit, as always from you: an irrelevant graph and some technical sounding verbiage you either don't understand or are using deliberately to confuse the naive.

    The decline in Arctic ice cover is a trend over several decades now, has been measured in extent and volume and mass and age, and it correlates with the air and ocean temperatures rather than the wind over those decades. And no one with a scientific bent, or otherwise capable of reading graphs and stats, can have failed to see that in the data available for a long time now.
     
  9. Andre Registered Senior Member

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    889
    Please, be so kind to tell that to Nghiem et al...

    ...and maybe also to Rigor et al as explained here

     
  10. arfa brane call me arf Valued Senior Member

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    From the Rigor et al ScienceDaily item:
    Note that the first sentence in no way supports any contention that AGW is a hoax.
    And that the last sentence is a conjecture, not a prediction.

    Straw man, much?
     
  11. iceaura Valued Senior Member

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    They're not here, and your use of their research to bullshit here is not their fault.

    Or to quote the man, from your link: "The Arctic Oscillation has been in a primarily moderate to high phase during the last decade or more, and the only way to reproduce this tendency in the oscillation using a numerical climate model is if you include the observed increase in greenhouse gases in the model."

    That is, the winds you refer to are products of the warming trend rather than alternatives to it.

    That, in addition to the fact that the ice loss trend has persisted through decades of various wind regimes (see the graph in your first link, despite its very dubious fifth order regression) , provides explanation for your posting of a graph of the last two years of ice only, and similar nonsense. You aren't making an argument from evidence, but attempting to present evidence in such a way that it creates an illusion of supporting your claims.
     
  12. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Andre: Yes I agree the wind (and the waves it makes) is very strong factor in determination of the melting rate of Arctic ice. Said so here:
    In addition to the three fold increase in solar absorption wind's waves spreading broken ice sheet adds / brings warmer water in contact with much greater extent of floating "ice edges," the breaking itself adds energy to the ice. I.e. to break any solid, you must do work on it - add energy to it.

    Fundamentally because your are creating an increase in total surface area, and thus the "surface energy" held by the solid is increased.** The fact, your references noted, that the wind can blow ice pieces out into the non-arctic oceans to quickly melt them, when the direction of the wind is that way. is of course very important reason why the total volume of ice decrease more in some years than in other years, but EVERY YEAR, the several times faster temperature rise in the Arctic (than globally) due to GW is melting ice.

    ** But in practice the breaking also sets up sound and other waves in both new pieces and these waves "die out" giving their energy to the solid too. Just "flexing" a solid adds energy to it also - easy to show: take any wire you can bend and repeatedly bend it until it gets too hot to hold in your bare hands. Waves are very important indirect form of solar heating melting ice.
     
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  13. Andre Registered Senior Member

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    889
    However, when GW is a global signal, what then is making the Antarctic ice grow a bit more, on the average, every year?

    The ice volume of the Arctic has been erratic throughout the millenia, it was also likely greatly reduced around 9000 years ago, causing Siberian tree lines to reach the Arctic oceans (McDonald et al 2000). So as it happened before, without greenhouse effects, what makes it so sure that this time it must be the greenhouse. How about a interaction of the Arctic Oscillation and the North Atlantic Oscilation, combined with other effects?
     
  14. iceaura Valued Senior Member

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    There are several mechanisms by which a global warming trend can cause an expansion of Antarctic sea ice extent - from higher rates of glacial flow into the ocean, to increased snowfall from moisture laden (warmer) air, to effects on boundary currents in the ocean and boundary windflow patterns in the atmosphere. Do you consider them all invalid, and if so why?

    Why do you think more northerly tree lines would be "caused" by, or even correlated with, a reduction of Arctic sea ice such as we are experiencing?
     
  15. Trippy ALEA IACTA EST Staff Member

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    10,890
    It's been widely predicted since the '80s (I'll track down some papers for you when I have the time if you want) that:

    1. Because of the Antacrtic circumpolar current, the Antarctic experiences a degree of thermal insulation and isolation from the rest of the world.
    2. Because of this effect the warming in the Antarctic is predicted to lag behind the warming in the Arctic.
    3. It was predicted in the '80s or '90s that because of the increased moisture content in the air would lead to increased precipitation in the Antartic resulting in no change in, or net growth of the antarctic ice sheet.
    4. A corrollary of #3 is that because of the conservation of mass this has the net effect of reducing or eliminating sea level rise for a period of time.
    5. The only way #3 can be true is if some or all of the icesheet experiences some degree of acceleration of the transport of its ice from the interior to the ocean.
    6. A corrollary of #6 is an increased amount of iceberg calving feeding the growth of sea ice, which would tend to be enhanced by #1 and #3.
     
  16. Andre Registered Senior Member

    Messages:
    889
    Mac Donald et al 2000, from the abstract

    Moreover, there are more studies indicating quite a bit of variation in Arctic (ice/sea surface temperature, AO, NAO) dynamics during the Holocene, like for instance Darby et al 2001, Darby et al 2012, Kim et al 2004,Olsen et al 2012.

    This would beg the question why current variability in Arctic ice dynamics is necesarily attributed to anthropogenic causes.
     
    Last edited: Nov 8, 2013
  17. Andre Registered Senior Member

    Messages:
    889
    As you can see from the previous, I show my sources for scrutiny. Has something to do with due dilligence. Not everybody does.

    Oh and 'THEY're HERE' sends her regards.
     
  18. Trippy ALEA IACTA EST Staff Member

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    10,890
    As do I ordinarily, however, I don't always have the time to trackdown the orginal papers for any one of a number of reasons. For example, the post you are replying to was made from my work place on my personal mobile device. Tracking down papers at work isn't always an option. I always try and get back to a thread where I have made such a promise, however, I'm absent minded, have a disabled wife, two children, and work fulltime. Sometimes things get forgotten.

    Of course, you could have looked into the claims for yourself - nothing stopping you from doing that.

    Cool. Say hi back to her for me.
     
  19. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    I'm not 100% sure it is, especially as I tend to be skeptic bout many claims, but the rate of floating Arctic ice mass melting (more than half melted in the last decade, I think.) does seem to be too fast for any other explanation.

    I have many times posted that it is the un-precedented* RATE of CO2 release and the never before observed by man, bubbling up of CH4 in dense (sub sonar killing) Arctic Ocean bubble clouds that concerns me that we may be making a possible great disaster for mankind (and other warm blooded animals that cool by evaporation as being in a wet-bulb environment of only 35C will kill you in less than an hour and due to increased ocean evaporation, the amount of rain and average air humidity is increasing now.) The fact that increasing atmospheric concentrations of CH4, increase the half life of CH4 in the air and CH4 is at least 10 times better IR absorber than CO2 is sort of scary too.** - If present rates of CH4 continue, even neglecting their self- accelerations, then in a few decades at most, CH4 will be a more important GHG than CO2.

    * Except perhaps during large volcanic eruptions.

    ** Currently the CO2 concentration, in ppm, is ~ 400 and that of CH4 averages ~1.816 (data sources and more discussion in post 909). So there is 400 / 1.816 = 220 times less CH4 concentration than CO2 in the air, and CH4 absorption is still in a linear absorption-function concentration range. If the CH4 concentration were to increase by a factor of only 1.85/0.51 = 3.627 to an average concentration of 6.59 ppm then it would be as important as CO2 is now and still in the linear function range. CH4 is the real GHG threat, not CO2, that all focus on.

    That is why I think it is imperative that man switches away from petroleum ASAP as burning it seems to be a very likely cause for rapid rise in both CO2 and CH4 atmospheric concentrations. How to easily*** do this is well known: Demonstrated in Brazil for more than 3 decades to be both practical and even more economical than using gasoline as car fuel on a per mile driven basis!

    The volume of alcohol fuel needed to fuel all the world's cars, even if cellulosic alcohol does not prove to be economically competitive with that produced from sugar cane, can be produced with only about 2% of the earth's arable land growing sugar cane. (Or less than 1% of Earth's "agricultural land.") The advances of modern agriculture can increase the yield per acre, compared to the primitive means used in large areas, by at least 20% so while switching to sugar cane based alcohol, there could be also at least a 10% increase in the production of food and fiber.

    *** Only trivial modifications to the current factories producing liquid fuel IC engine cars are required to switch to alcohol fuel. The cost of switching factories to that production would be at least 10 times less than switching to factories producing battery powered cars and even converting almost all existing gasoline car to alcohol fuel is a small: <3% of their cost, why not do this, to be safe?

    PS - Want to know why more economical than gasoline alcohol fuel is not already the norm? Answer: Vested interest "big oil" lies: Say that switching to alcohol would destroy the rain forests. Big oil also diverts public attention from the facts they don't like by promoting alternate fuels like hydrogen that can never compete economically with their gasoline. Go ahead, Sucker, fill up with gasoline and pay higher taxes so Big Oil can get its "depletion allowances," and other subsides you pay them as well as paying more at the pump than you need to!
     
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  20. Trippy ALEA IACTA EST Staff Member

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    True to my word - I assume by your response you want to see papers (It's been six months since I looked at this one last):

    From 1988, and predicts cooling poleward of the circumpolar current.
    Interhemispheric Asymmetry in the Transient Response of a Coupled Ocean-Atmosphere model to a CO2 Forcing: Bryan, Manabe & Spelman 1988
    Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise: Davis et al, 2005
    IPCC First Asessment: Chapter 9 - Sea Level Rise (1990)
    So even the IPCC predicted in 1990 that the Antarctic Icesheet may grow leading to a reduction in sea level rise. Also note that they cite papers (apparently) predicting this dating back as far as 1977. They also note that whether the mass change in the antarctic ice sheet leads to a rise or lowering of sea level (in the near future at least anyway) is a result of the complicated interaction between wasting at the periphery and accumulation in the interior. They also go on to discuss the possibility of instability in the west antarctic ice sheet as a seperate topic.
     
  21. Andre Registered Senior Member

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    889
    Thanks, Trippy, much appreciated. I'll study it before responding, maybe tomorrow, I do have a bit of a social life and online/study time is limited. Also Billy is entitled to a long detailed response.

    One thing after glancing over the list, not sure if we compare apples with apples, ie sea ice cover with land based ice sheet accumulation.
     
  22. Trippy ALEA IACTA EST Staff Member

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    10,890
    You may have a valid point, but I find it hard to imagine that the sea ice cover is independent of the predicted increase in precipitation and the predicted cooling poleward of the circumpolar current, hence mentioning it in the first place.

    Alternatively you can consider this paper from 1977 which discusses sea ice formation in relation to Stefan's Law - especially in terms of the deep ocean warming.

    Antarctic sea ice growth and oceanic heat flux: Ian Allison (1977)

    Note equation (1) which states:

    \(h^{2} = \frac{2k}{\rho L} \int^{T}_{0} \theta dt \)

    Where \(h^{2}\) is the thickness of the sea ice and \(\theta\) is the temperature difference between the lower and upper ice surfaces (I believe this is also why warm water freezes faster than cold water). Also worth noting is that the biggest problem the Stefan Law has in predicting the sea ice thickness is that it tends to over estimate it.
     
    Last edited: Nov 9, 2013
  23. iceaura Valued Senior Member

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    24,460
    That's nowhere near sufficient reason - a reduction of Arctic sea ice is a common event in paleontological time; a reduction such as we are experiencing has no precedent - certainly nothing from your link establishes one.

    Tree lines take many hundreds, even thousands, of years to move long distances.

    Sure. It would be a legitimate question, if you could assume your audience was as ignorant as you need them to be. But if you actually do that, as several people have including your linked scientists, you'll find it doesn't account for the ice loss. That's what your link said, remember? I quoted the guy for you.

    In Antarctica, your chosen subject, they are closely linked. Antarctica is a large body of land surrounded by water, quite different from the Arctic Ocean, if you recall.

    You might want to reconsider that. Obviously it is not true in the extremes (or one could design an icemaker of truly astounding capability: supply a very cold cup of water - one on the point of freezing - to a large room full of trays of hot water, and get mega quantities of ice in minutes).
     

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