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When is Global Warming Significant?

  1. Apr 25, 2005 #1

    Ivan Seeking

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    This number came up regarding the Permian mass extinction

    http://www.bbc.co.uk/science/horizon/2002/dayearthdied.shtml

    I never realized that the threshold was so low.

    http://www.solcomhouse.com/metnoaa.htm

    This also ignores any potential tipping points which could come much sooner.
     
    Last edited: Apr 25, 2005
  2. jcsd
  3. Apr 25, 2005 #2

    matthyaouw

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    I've not read the links yet, but I shall shortly. I just thought I'd add something about this figure. When they state figures like these, they generally refer to a global average, where as a more detailed look may see changes much greater than that in some places than others. It is also averaged over the course of a year, and much greater seasonal variability may occur, with more pronounced temperature change between summer and winter for example. The figure of course does not mention the affects it has on the weather- such a temperature change could have numverous and far reaching knock on effects to atmospheric circulation patterns, leading to drought in some places, and flood in others.

    I'd also venture that its a bit speculative to simply say that a rise of Xdegrees could cause mass extinction. It would be hard to gague the effects without putting a timescale on it, as species would be capable to some degree at least to adapt to climate change if it happened slowly enough
     
    Last edited: Apr 25, 2005
  4. Apr 25, 2005 #3
    Before it will appear significant to the doubters, it will be too late to do anything about it.

    juju
     
  5. Apr 25, 2005 #4

    SOS2008

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    From a PBS program this weekend entitled: "National Geographic's Strange Days on Planet Earth" (The One Degree Factor)
    Even a slight change in temperature is affecting certain species, which in turn effect other species as a part of the food chain.
     
  6. Apr 25, 2005 #5
    I think it's going to end up being like the evolution/creation debate. Half of Florida could be underwater and they'll still be going on about how nothing's conclusive.
     
  7. Apr 26, 2005 #6

    Ivan Seeking

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  8. Apr 27, 2005 #7

    Monique

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    So lets keep the discussion on topic by discussing which criteria need to be met in order to speak of global warming. Some suggestions:

    Are there local geographical areas that are of particular importance; for instance areas that normally have a very stable temperature profile, where a small deviation can be deemed significant.

    Can a defined increase in temperature be used to define global warming, or are the temperatures too variable to draw conclusions.

    Is there a certain time frame over which temperatures need to measured, after which conclusions can be drawn.

    What would be the design of statistical tests to define significant increases in temperature.
     
  9. Apr 28, 2005 #8

    Ivan Seeking

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    Climate Warming and Disease Risks for Terrestrial and Marine Biota

    http://www.conservationmedicine.org/papers/Harvell et al. 2002.pdf
     
  10. Apr 29, 2005 #9
    When is Global Warming Significant?

    when YOUR HOME IS UNDER WATER

    here in south Fla we are low and sinking FIRST
    avg elevation under 10 feet [my home is on a ridge at 12+ and thats rare]
     
  11. Apr 30, 2005 #10
    http://www.nasa.gov/vision/earth/environment/earth_energy.html
    "Scientists have concluded more energy is being absorbed from the sun than is emitted back to space, throwing the Earth's energy "out of balance" and warming the globe."

    When it comes to the original question, all changes are significant. How significant is extremely difficult to decide.
     
  12. Apr 30, 2005 #11

    SpaceTiger

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    If anything, I find this extremely encouraging. Why? Two reasons:

    1) The discovery of fusion will almost certainly lead to a drop and hopefully an eventual halt to human-induced global warming rates. Even if I were to be extremely pessimistic and say that it's going to take us 100 years to get it working, your quoted rate leads only to a 2 degree rise in temperature, well below the quoted mass extinction level.

    2) From what I've heard, humans have already induced a large number of extinctions by way of habitat destruction, hunting, etc. Although I'm never one to celebrate the loss of any life, it seems as if the combined effects of global warming might pale in comparison.

    Of course, point 1 assumes that warming rates remain constant, something which is hard to be sure of from either the climatological or sociological standpoint. Even so, however, it seems like there's still quite a lot of breathing room.
     
  13. Apr 30, 2005 #12
    How about the discovery of fission?
     
  14. Apr 30, 2005 #13

    SpaceTiger

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    Are you nitpicking my wording or being serious? In any case, for those who aren't sure, I'm referring to the use of fusion for power generation, not its discovery as a phenomenon.
     
    Last edited: Apr 30, 2005
  15. Apr 30, 2005 #14
    What advantages might it have over fission?
     
  16. Apr 30, 2005 #15

    SpaceTiger

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    I think this sums it up pretty well.
     
  17. Apr 30, 2005 #16

    Astronuc

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    Remember the caveat!

    First of all, we do not yet have a feasible commercial reactor design, so one cannot for now minimize this issue.

    As for an accident, the radiological inventory of a fusion reactor certainly appears much less than a typical commercial reactor. On the other hand, after 20 years in the nuclear industry, I hesitate to minimize the issue.

    ===============================

    But this thread is about global warming, specifically "When is Global Warming Significant?". Well it could be significant now - given all the weather related disasters like hurricanes, tornadoes, floods etc that have happened during the last decade. Then consider the droughts and continued desertification in various parts of the world.

    Warm weather also allows for more undesirable insects like mosquitos to thrive. I think Ivan's last post is particularly relevant and disconcerting.
     
  18. Apr 30, 2005 #17

    SpaceTiger

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    Perhaps this should be a separate thread, but I'm curious about your viewpoint on the safety of nuclear power. Do you think the public is being overly paranoid or do you think the concerns are well justified? I'm not familiar enough with the current safety standards to have a strong opinion on it.
     
  19. May 1, 2005 #18

    Astronuc

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    It would appear so far that commercial nuclear power is generally safe, with the exception of Chernobyl.

    I don't think the general public really understands nuclear power, and for that matter, the general public does really understand most technology.

    I simply hesitate to minimize the safety issue. Not long ago, the folks at Davis Besse found that some of the carbon steel pressure vessel head had corroded away, and only a 3/8" stainless steel liner was holding back 2230 psi of reactor coolant water. Had that failed, then we would have had a LOCA event, and then we would have found out how well the safety systems would perform, how well the training prepared everyone involved, and how well the containment would have confined the problem.

    http://www.nrc.gov/reactors/operating/ops-experience/vessel-head-degradation.html

    I should point out that the plant personnel were aware of a leak and had planned to inpsect the head. Ideally, they should have inspected more thoroughly during the previous refueling outage, but there was a lot of pressure to get the plant back online.

    As for fusion reactors, I am not sure how to assess the radiological hazard or an accident scenario. I was trying to think back a couple of decades to the concepts that were proposed and what type of accidents might be of concern, such as a confinement magnet failing and the consequences of such a failure.

    I had ordered two books on Fusion Research, but the order was cancelled so I will have to look elsewhere for some system designs.

    Current nuclear plants have safety systems, such as Emergency Core Cooling Systems (ECCS). Then there are the structure like the containment building, which is designed to withstand postulated accidents.

    Then as part of the operation, there is training of personnel, and there are periodic inspections and testing of various systems, much more than was the case when TMI happened, and all as a result of TMI.

    Is that enough? Probably. Nevertheless, I simply hesitate to dismiss safety concerns.
     
  20. May 1, 2005 #19

    SpaceTiger

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    Oh yes, that was very interesting, thank you.
     
  21. May 2, 2005 #20

    Astronuc

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    Oops. SpaceTiger, please excuse me, but when I wrote, "It that enough?", I was referring to the steps taken to ensure safety in commercial nuclear plants:

    Otherwise, I would have addressed you directly with something like, "Have I answered your question to your satisfaction?"

    The key question is - "Has the nuclear industry, specifically the operating utilities, suppliers of the technology and regulators done enough to ensure the safe operation of nuclear power plants?". Obviously, those opposed to nuclear will power will summarily argue, NO. Proponents will argue, YES.

    If one argues, YES, then one can ask, "How do know that operating power plants are safe?" Simply saying the event at TMI-2 did not result in harm to the public (other than severe emotional distress for a lot of folks) is not enough to prove that nuclear power is inherently safe, or that other plants are not at risk for a catastrophic event that may compromise the safety of the plant personnel or public.

    We demonstrate safety by a sustained program of inspection and training, and monitoring the performance of materials and systems during operation.

    Take for example the steam generators (SGs) in many PWRs. The principal material for SG tubing was Inconel 600. The SGs and the tubes were designed with the intent of operating for the lifetime of the plant (40 yrs). However, in the mid 1980's, the rate of failure of SG tubing started to increase, particularly in high temperature PWRs (Thot > ~ 320°C). The Inconel 600 tubing was failing after about 15-20 years, and many PWRs have had to replace the SGs, at costs on the order of $50-100 million/SG. The safety issue was related to the reactor coolant (with some level of radioactivity) escaping from the primary system and entering the secondary system.

    On the BWR side, cracks were found in certain internal structures that were supposed to operate for the life of the plant. The cracks were caused by Intergranular Stress Corrosion Cracking (IGSCC), which was related to the electrochemical potential (ECP) and oxygen potential of the reactor coolant environment in which the stainless steel components were operating. Remedial steps have been taken to address this issue.

    Many plants still have years, and in some cases decades of operation, even without the industry trend to 'extend' operation of many plants to 60 years. The major issue is "can we ensure 'safe' and reliable operation?"

    I am hopeful, but cautious.

    ========================

    Now, the question of this thread, is when is Global Warming Significant? Well, if Global Warming is now the cause of more floods and storms that cause an increase in destruction of property and loss of life, and drought, then it would seem that it is significant now.

    There are two questions however:

    1) What is the precise cause of global warming - a) is it a natural process? or b) is it due to man-made greenhouse gases?

    2) If global warming is a 'significant' problem, what steps 'must' be taken to mitigate / remediate the problem.
     
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