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Thread: Explaining the ice ages: solar fluctuations vs Milankovitch

  1. #1 Explaining the ice ages: solar fluctuations vs Milankovitch 
    Forum Professor Pendragon's Avatar
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    What caused the earth's ice ages, and why did they occur at such equal time intervals (first once every 41,000 years, then once every 100,000 years)? It's a big debate in Earth Sciences, and seems to be taking a new turn recently.

    The two major explanations, if I understand them correctly, are:
    -Fluctuations in the sun's energy output, which in a model occur at either 41,000 or 100,000 years intervals (which is compatible with our data of the Ice Ages on earth);
    -Changes in the earth's orbit, called Milankovitch cycles. These would only create small temperature changes on earth, but we know several mechanisms which could enhance them and turn small fluctuations into full Ice Ages. Problem: this hypothesis doesn't explain why the regular intervals of Ice Ages suddenly changed a couple million years ago (first a regular 41,000 years, then a regular 100,000 years interval).

    The solar fluctuation hypothesis (#1) seems to become stronger, but the problem is that it's hard to observe what happens within the Sun (while changes in the Earth's orbit should be observable).

    So what's your take on this debate?


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  3. #2  
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    Well we know that some volcanoes erupt with some regularity how about one of those causing a minor temp drop triggering something larger, since volcanoes also 'dry up' after a while due to tectonics this may explain why ice ages come in sets of differing regularity, - a possibility ?


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  4. #3  
    Forum Ph.D. Nevyn's Avatar
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    Is it not possible that as the planet comes out of an Ice age, the green house gases that are trapped in the ice get realeased causing the planet to warm causing the planet to warm quicker and quicker untill the point where ice is turned into water at a fast rate causing the warm currents which were allowed to move when the ice melted to stop and stay at the equater causing another ice age as the suns rays are being abosirbed int the atmospere and the green house gases get frozen again, causing the cycles
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  5. #4  
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    there seems to be different views on "ice ages", but many feel until about one billion years ago the planet was to warm for ice. (surface). then the largest period began and peaked about 800 million years ago to about 600 million YA. then redeveloped 350 to 240 MYA. smaller or mini ages 100k YA, 12K YA and a real mini about 1000 years ago. if anything the earths extremes are leveling out. there may be a connection to atmospheric conditions since absorption of solar energy has to be a factor. even today the outer temperatures range up to 7-800 degree F. very cool below and extremely cold in outer space. that is as the degree of atmosphere could well have changed to allow more or less solar heating to hit the surface. also keep in mind any solar change means little unless there is something to act on. space temps will be the same even if the sun doubled in energy output.

    the said temperatures during the 100k,12k and 1k ages were -9, -5 and-5 compared to our current average. also note the thought average during the dino period was +9 and of course during formation was much higher.
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