Solar dimming, rapid drop in 3 decades

Discussion in 'Earth Science' started by Jagger, Jan 16, 2005.

  1. marv Just a dumb hillbilly... Registered Senior Member

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    I still suggest that you go back and read up on solar flares and sun spots, Star_One, and their effect on the Earth's atmosphere. The Earth has gone through multiple warming and cooling cycles over millions of years because of solar activity.
     
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  3. Ophiolite Valued Senior Member

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  5. Ophiolite Valued Senior Member

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    Global Dimming: A Review of the Evidence, G Stanhill and S Cohen Agricultural and Forest Meteorology Volume 107 (2001), pages 255-278

    The Cause of Decreased Pan Evaporation Over the Past 50 Years, M Roderick and G Farquhar Science Volume 298 (2002), pages 1410-1411

    Observed Reductions of Surface Solar Radiation at Sites in the US and Worldwide, B Liepert Geophysical Research Letters Volume 29 (2002), pages 1421-1433

    Are these notpeer-reviewed papers?
     
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  7. (Q) Encephaloid Martini Valued Senior Member

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    Are these notpeer-reviewed papers?

    Perhaps, but like I said, they are not readily available.

    What are your opinions of these papers? Can you reproduce here any of the vital information?
     
  8. Ophiolite Valued Senior Member

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    I have not read them. I am simply challenging your surprising claim that there are no peer reviewed papers available.
    You are now inserting the criteria that they should be readily available. Your earlier posts did not stipulate this.

    "Where are the peer-reviewed papers on this subject?"
    "No peer-reviewed papers are available."

    You also state A quick search reveals there is little more than alarmist articles in pop-sci mags and newspapers, and of course a plethora of conspiracy sites.

    Most peer-reviewed papers are not available on the internet, especially without subscription. I am certain these papers are all readily available through any University library.

    If you restrict your search to internet resources you should expect to find little more than alarmist articles in pop-sci mags and newspapers, and of course a plethora of conspiracy sites.
     
  9. Andre Registered Senior Member

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    889
    Back for a few seconds but I'm maxed out this week

    1. The dimming has been known for over a year. Nothing unusual, soot and haze are the likely cause.

    2. http://news.bbc.co.uk/1/hi/sci/tech/4171591.stm
    This is the most scandulous claim ever of chicken little BBC and easily refuted.

    I copy this from a post I made in another forum:

     
    Last edited: Jan 18, 2005
  10. Ophiolite Valued Senior Member

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    9,232
    A hoax is a deliberate attempt to deceive. Where is your evidence for such a serious claim?

    You also fail to note that the researchers described the decline in albedo as 'a hint', or to explain the rather cumbersome methodology, definitely open to question, or that the variation almost lies wholly within the declared error range of the method, or that the decline, if real, is likely linked to the sunspot cycle.
    In short it is hardly much of a refutation. I'm surprised at you Andre.
     
    Last edited: Jan 18, 2005
  11. eburacum45 Valued Senior Member

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    1,297
    That New Scientist article does suggest that there is a more complex relationship between cloud cover an thermal characteristics;
    sure increased albedo reflects more visible light, but a cloudless sky leads to increased heat loss- the two effects work in opposition.

    Just like the apparent phenomena of global warming and global dimming.
    A bit more info here;
    http://www.bbc.co.uk/print/pressoffice/pressreleases/stories/2005/01_january/13/horizon.shtml
    Professor Veerabhadran Ramanathan did the most convincing study, contrasting the dusty mass of air over the North Maldives with the dust free mass over the South Maldives.
    There seems to be a measurable effect caused by particulate pollution on cloud cover;
    but most of the southern hemisphere is free of particulate pollution; as it has a greater proportion of low albedo ocean to high albedo land, more energy will be absorbed by the dust-free Southern hemisphere (which is not affected by global dimming).

    In which case perhaps the global thermal equilibrium will not be affected quite so much by the dust in the northern hemisphere as the BBC programme suggests.
     
  12. (Q) Encephaloid Martini Valued Senior Member

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    I am simply challenging your surprising claim that there are no peer reviewed papers available... Most peer-reviewed papers are not available on the internet...

    That is exactly what this site is for - to make peer-reviewed papers readily available:

    http://arxiv.org/

    If you restrict your search to internet resources you should expect to find little more than alarmist articles in pop-sci mags and newspapers, and of course a plethora of conspiracy sites.

    The difference is that you appeared to accept those sites claims without further ado when you stated:

    This is quite simply the most remarkable item I have read in two decades or more. I am astounded.
     
  13. Andre Registered Senior Member

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    889
    Ophiolite

    I'm even more surprised. No time now.
     
  14. Andre Registered Senior Member

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    More than surprised, I'm shocked

    The authors claim an increase in reflection to justify their claims. I have not seem any reference to albedo change, on the contrary. but there is definite proof of a decline in albedo according to independent sources exactly opposing the claims.

    We could add that another independent test of their hypotheses is to compare the temperature trend of certain urban weather stations under known (proven) polluting conditions with rural weather stations with known clean air. If pollution is reflecting solar energy instead of absorbing it, then the urban pollution stations should have a distinct lower warming trend than the unpolluted rural stations.

    I know the outcome of that test already, and believe me, it would be very dissapointing for the scaremongers
    You bet, I have evidence:
    And so far for global warming to be science, it's dogma, propaganda.

    You surprise me, Ophiolite
     
  15. Ophiolite Valued Senior Member

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    Note the singular absence of Earth Science or Climatology Categories. Inability to locate papers on the internet is a reflection of internet limitations, not the absence of such papers. If they were not available through a University library that would be a different matter.
    Appearances can be deceptive.

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    1. The Guardian article quoted several research studies, over a period of time, by allegedly reputable scientists. They provided references for some of these studies.
    2. I did not look at any of the sites you referred to, and so could neither accept or reject their claims.
    3. My astonishment - which remains - is based on the magnitude of the changes. These are almost an order of magnitude greater than what one would expect for such a variable.
    4. My astonishment - which is still firmly in place, one point later - is based upon the possibillity that this may be accurate. A change of this magnitude has such implications, if true, I cannot fail to be astounded.

    For your part you appear to dismiss it out of hand. Why do you consider it faulty? My mind remains open until I have had an opportunity to review the original papers, or further research is published.
     
  16. Ophiolite Valued Senior Member

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    I have already demonstrated that your quoted paper does not provide definite proof but merely hints at a possibility. I am in no way wedded to the notion of global dimming, but so far this 'refutation', at least, is faulty.
    I wait your detailed response with interest.
     
  17. (Q) Encephaloid Martini Valued Senior Member

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    Note the singular absence of Earth Science or Climatology Categories.

    True, but there are other categories in which those papers are accepted.

    For your part you appear to dismiss it out of hand. Why do you consider it faulty? My mind remains open until I have had an opportunity to review the original papers, or further research is published.

    I too would like to review the original papers, that was my quest.

    I dismiss out of hand the pop-sci articles as they almost always are wrong or misleading.

    It's like reading Hawking or Kaku - pure sensationalism.
     
  18. Ophiolite Valued Senior Member

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    My central point remains that availability of quality science journals has to relate to availability through libraries, and not through the inter-net. I would be amazed if I could access even 5% of the journals I should like to, in my field of interest, without a subscription. So, the fact that neither of us has been able to access any of this work directly is a reflection on our resources, not on the content of the papers.
    Your original objection appeared to be that these claims arose from flaky inter-net sites and since no peer reviewed papers espoused these views they could safely be discarded. (If I misunderstood your intention I apologise.) The peer reviewed journals exist. They can only be discarded if further subsequent research invalidates their conclusions. There is an intermediate condition where we might say, "This is interesting and possible, even plausible, but I have reservations A, B and C. Until these have been dealt with I shall suspend even provisional acceptance of the idea."
    What I am arguing about, in a rather long-winded fashion, is that a casual rejection of the hypothesis is just not warranted.
     
  19. Andre Registered Senior Member

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    889
  20. Ophiolite Valued Senior Member

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    Andre, the link will not open for me. I have tried it multiple times with no success.
     
  21. (Q) Encephaloid Martini Valued Senior Member

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    19,125
    What I am arguing about, in a rather long-winded fashion, is that a casual rejection of the hypothesis is just not warranted.

    Agreed, in a rather short-winded fashion.

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  22. NileQueen Registered Senior Member

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  23. NileQueen Registered Senior Member

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    Andre:

    From this report, albedo took a sharp upturn in the past 3 years.

    Scientists who monitor Earth's reflectance by measuring the moon's earthshine have observed unexpectedly large climate fluctuations during the past two decades. By combining eight years of earthshine data with nearly twenty years of partially overlapping satellite cloud data, they have found a gradual decline in the Earth's reflectance that became sharper in the last part of the 1990's, perhaps associated with the accelerated global warming in recent years. Surprisingly, the declining reflectance reversed completely in the past three years. Such changes, which are not understood, seem to be a natural variability of the Earth's clouds.

    http://www.eurekalert.org/pub_releases/2004-05/njio-uci052104.php

    Are you saying this is flawed? Or not a good indicator of albedo?
     

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