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Thread: climate science

  1. #1 climate science 
    ilg
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    Concerning the deglacial and millennium climate changes, what kinds of factors can cause the changes ?


    Some websites says SOLAR VARIABILITY is also one of the causes, however, some says this is not as it wont affect in a millennium scale, rather, it can only affect in decade scale. Which one is correct?


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    Quote Originally Posted by ilg View Post
    Concerning the deglacial and millennium climate changes, what kinds of factors can cause the changes ?


    Some websites says SOLAR VARIABILITY is also one of the causes, however, some says this is not as it wont affect in a millennium scale, rather, it can only affect in decade scale. Which one is correct?
    There can be a number of factors, but the cycling in the present day is general attributed to orbital forcing: eccentricity, tilt, and precession.

    http://en.wikipedia.org/wiki/Milankovitch_cycles


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    Solar radiation plays a role as well...there's definitely a tiny solar cycle effect at 11, 22 and 44 years. Longer cycles are less certain. Thus far non seems to contribute as much effective radiative change as changing green house gas concentrations.
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  5. #4  
    ilg
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    I have some other questions that I would like to ask. I read some websites which state that ice accumulation rate is slower in younger Dryas in Deglacial Climate Change. Yet, I think the formation of ice should somehow increase the accumulation of ice. Am I correct or the websites are correct?

    Also, I would like to ask how can delta18O values reflects the salinity of sea water ?
    Is there any relationship between delta 18O values and C values?

    I read from some website that reasons causing deglaciation may include increase in insolation and also CO2 concentration. What could possibly increase CO2 concentration ? Can I say volcanic eruption is one of the causes leading to increase in CO2 concentration? (actually I see some contradiction from other sources that volcanism cannot be one of the causes, is this right?)

    Is mountain glacier react faster to climate change than ice sheet ??

    Lastly, what may cause little ice age + medieval warm epoch ?





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    Quote Originally Posted by ilg View Post
    I have some other questions that I would like to ask. I read some websites which state that ice accumulation rate is slower in younger Dryas in Deglacial Climate Change. Yet, I think the formation of ice should somehow increase the accumulation of ice. Am I correct or the websites are correct?
    I don't know the facts, but conceptually, the accumulation rate can decrease while ice can increase, since the controlling factor is the residency time of the ice by way of an overall decrease in temperature.

    Also, I would like to ask how can delta18O values reflects the salinity of sea water ?
    It may be linked to water temperature or evaporation since colder water tends to be more saline, and evaporation preferentially selects 16O.

    Is there any relationship between delta 18O values and C values?
    It's possible there may be a link with respect to the level of insolation.

    I read from some website that reasons causing deglaciation may include increase in insolation and also CO2 concentration. What could possibly increase CO2 concentration ? Can I say volcanic eruption is one of the causes leading to increase in CO2 concentration? (actually I see some contradiction from other sources that volcanism cannot be one of the causes, is this right?)
    Volcanism can certainly be a mechanism affecting CO2 concentration.
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    The release and storage of carbon also affect atmospheric levels of CO2, such as the experiment we are now running with our planet, releasing scores of millions of years of stored carbon in a century.
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    I read from some website that reasons causing deglaciation may include increase in insolation and also CO2 concentration. What could possibly increase CO2 concentration ? Can I say volcanic eruption is one of the causes leading to increase in CO2 concentration? (actually I see some contradiction from other sources that volcanism cannot be one of the causes, is this right?)
    Yes and no. I don't know what time period you're talking about. Vocanism is the primary source over geological time scales. Lots of other things affect short term changes--ocean absorption and release, plant biomass, human industry etc. Volanism has played little role over the past few centuries.


    Is mountain glacier react faster to climate change than ice sheet ??
    Generally yes because they are less isolated.

    Lastly, what may cause little ice age + medieval warm epoch ?
    For the little ice age, a couple of competing hypothesis. One is solar irradiation change. Another is plague reducing the human populations, less farming and lots of regrowth taking up and lowering the overall CO2 levels. It's probably a combination.
    Last edited by MeteorWayne; May 10th, 2012 at 03:36 AM. Reason: edited quote tag
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    I also read a week or two ago that volcanism has been implicated to be more of a factor again with some new evidence. Now if I could just recall where I read it...
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    from what i've read, lower solar irradiation (with a lower transfer of plasma from the sun to the earth's atmosphere?) is likely the main causal factor for the "little ice age"-"year without a summer"--etc.
    failed crops and cold combined to hammer many northern populations ---estonia may have lost 70% of her population

    vulcanism
    see Tobo
    Last edited by sculptor; May 14th, 2012 at 05:18 PM.
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    Quote Originally Posted by MeteorWayne View Post
    I also read a week or two ago that volcanism has been implicated to be more of a factor again with some new evidence. Now if I could just recall where I read it...
    Was it this article?
    Volcanoes sparked - and prolonged - the Little Ice Age | EARTH Magazine
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    No, that's just a popularized summary for the layman (not a bad one at all, though!). As referenced, the paper was published in Geophysical Research Letters. That means I probably read it in Science News.
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    Quote Originally Posted by ilg View Post
    Lastly, what may cause little ice age + medieval warm epoch ?
    two short answers (sorry but no time for a long one)

    little ice age is said to be caused by the ashes of a volcanoe in indonesia... I forgot the name maybe pinatubo?

    medieval optimum is said to be only a local mid european thing, NOT global! So you should take a look at things like the North Atlantic Oscillation the Thermohaline Circullation (now called MOD: Meridional Overturning Circulation or AMO: Atlantic multidecadal oscillation)
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    1815
    tambora
    1816 was the "year without a summer"
    also the coldest year was during the maunder minimum

    and 4 more vulcanos are known to have erupted between 1580 and 1660
    .......however

    i've not read any suggestions leading to identifying specific vulcanos which may have started the little ice age circa 1275-1300

    their" "The model, which simulated various sea ice conditions from about 1150 to 1700 A.D., showed several large, closely spaced eruptions could have cooled the Northern Hemisphere enough to trigger the expansion of Arctic sea ice."
    seems to be missing any mention of any specific volcano(s)

    to postulate an unknown eruption or a series of unknown eruptions as a causal factor seems more idle speculation than hard science

    but, it does seem logical
    ..................
    pinatubo was 1991
    and dropped global mean temperuatures by about 1/2 degree C----------(this was the year i had built my 2nd solar heated building---and the efficiency of the collectors decreased by up to 17%-----gee darn---threw my calculations out the window)
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    Some websites says SOLAR VARIABILITY is also one of the causes, however, some says this is not as it wont affect in a millennium scale, rather, it can only affect in decade scale. Which one is correct?
    Neither. Both. The very long term solar effect is global brightening. The sun is now 10% brighter than is was umpty million years ago when CO2 concentrations were in the thousands ppm. The brightening effect is not discernible at millennium scales, let alone centuries or decades.

    That decade scale you're talking about is likely the 11 year sunspot cycle. Solar cycle - Wikipedia, the free encyclopedia These vary in intensity and effect but it's one of the reasons why 'climate' is statistically calculated over 30 years as against weather - which is any short term period you like to think of. The 30 year definition for climate is really just a convenient benchmark rather than a scientific 'fact' but it's very useful for ensuring that most of the very short-term impacts on weather - days, months, decades - are averaged over a long enough period to remove most of the chaos of weather. Remember, technically speaking, weather is chaotic, climate is not.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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    along with sunspots, we get CMEs which saturate the upper layers of the atmosphere with plasma
    which in turn excites the magnetosphere
    all of which are energy
    feed energy into a system and the particle exitation spreads out in energy ripples
    warming the nights
    and winters
    ................
    what a marvelous thing is our layered atmosphere
    each layer protecting us from a different threat
    and
    how much of that do we owe to the magnetic poles and the reverse layering of magnetic bands along the mid-ocean ridges?
    '''''
    alternating magnets spinning around a molten armature
    all that we know'
    all that we can engeneer
    all that we can guess
    is already all around us
    (but then again, i could be wrong)
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    Well, there is lot of wrong in there. CME's are transient phenomena, that cause mostly magnetic effects. They do not warm the nights and winters.

    The reverse layering (caused by irregularly periodic flipping of the primary magnetic dipole) don't protect us; we are most protected when the field strength is the highest. During a magnetic reversal, the overall field strength is the lowest, and we are most vulnerable to charged particle from the sun and cosmic rays.

    There are not alternating magnets, the earth's magnetic field is caused by a self sustaining dynamo driven by convection in the molton outer core combined with the earth's rotation, and the differential rotation of the core and mantle.
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