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The hockeystick of 600 million years

  1. Oct 31, 2004 #1
    In the other thread we were discussing the hockeystick as valid proof for global warming due to anthropogenic increase in greenhouse gasses. However the purpose of that thread was more philosophycal, intended to identify the truly important. And it was centered around Rich Muller priceless remark:

    But we strayed to ice ages when as intermezzo, I showed a (old) carbon dioxide graph going back 600 million years with seemlingly little correlation between ice ages and carbon dioxide level in the atmosphere.

    So why don't we try and make our own 600 million years hockeystick, the relation between global temperatures and carbon dioxide.

    For starters I found a more recent carbon dioxide graph from the same author:

    Carbon Dioxide through Geologic Time

    and the dispant past ice ages or rather global temperatures. Here is something:

    Also good ref:
    Pre Mesozoic Ice Ages John, C Crowell 1999 GSA
    ISBN 0-8137-1192-4

    Note that the Ordovician – Silurian 440 Mya is about 18 times more CO2. The Devonian – Carboniferous border 350-360 million years (Mya) correspond with 3-4 times times the current carbon dioxide level while the Late Carboniferous - Early Permian era boundary, 290-286 Mya, is about level with nowadays. We also have the greenhouse - Ice house graph that shows the lack in correlation of CO2 especially in the 450 - 480 Mya time frame and a remarkable corrolation around the 300 Mya. On the other hand, between 200 - 100 Mya an inverted corrolation seems to exist with temps gradually rising and CO2 gradually lowering.

    But how accurate is all of this? Can we make a more accurate approximation and see how the Carbon dioxide - greenhouse correlation really looks like.

    There are however several more noise factors, the tectonics send the continents all around the globe. Formation of a big cluster of continents will affect global temperature, also when a sizeable continent passes the poles, a ice sheet will likely be formed, although one might wonder if that could happen with 18 times the current CO2 if the global warming idea was right. We also have no idea about the variability of the sun.
     
    Last edited: Oct 31, 2004
  2. jcsd
  3. Oct 31, 2004 #2
    There are far to many variables and it is absolutely rediculous to go back 600 million years the structure content shape patterns winds were completely different. It is best to look at the past 100,000 years and check the correlation of ice ages with the present topography. This will yeild far more accurate results. There has been supposedly spikes in CO2 in all recent ice ages according to core samples. Since we are pesently off the charts this is a potentiality in the not so distant future.

    On a side note of something which I have thought of was it may be that part of the reason an ice age occurs is the sudden loss of land mass due to rising waters. In the distant past the oceans were not as deep so the oceans would have been warmer regardless of the carbon dioxide content.

    There is also the theory that the deeper waters in the atlantic which are heated by an undertow of warm water are impeded by the excess waters. These things may trigger different wind patterns etc... and all these things working in conjunction creates the ice age. The question is when did the first ice age happen and the second and so on.
     
  4. Nov 1, 2004 #3
    Well I agree about that and indicated already some problems but perhaps we could take those caveats into consideration.

    More than happy to do that (have been peeking already) but we would restrict ourselves, missing the relevance of the long cycles. Some milankovitch but the most important one definitely not. 1,000,000 years would be better to have a full view on the 100,000 year cycle.

    First ice ages may be billion of years. If we limit ourselves to the middle to late Pleistocene ice ages there are several ideas about the onset. Particulary when we see that seemingly fresh plant remains are found under 3 kilometres of ice in Greenland we seem have a lot of mysteries to solve.
     
  5. Nov 1, 2004 #4
    Nice pictures. So did you carbon date the plant matter you brought up and at what depth was it in the ice. How much deeper is the ice from where the plant matter was extracted? Also is there a fairly linear time line for ice depth and time passage? What is the time per depth for this ice?

    Note: I do think the shallow seas and different topography along with a warmer planet due to it's younger stage of development are why there was no ice age in the distant past. Plant coverage per surface area may also be a factor. Green plants capture the suns energy and transforms it into latent potential. Deserts flip flop like the wind due to low humidity/less plant density which helps towards humidity since plants capture water. The more of the planet we make into a concrete jungle the more potential of the temperate swings. This is presently not an effect because of the massive amounts of fossil fuel burned. What would happen if you cooled all the areas without the burn of fossil fuels or electrical energy???????? What is the total sum of fossil fuel output accoss the planet for a single year? What does that average per surface area is it negligable or is the presence of a city causing the shift of wind patterns which cause other things. To many varaibles all working in unison. Planets core, volcanic activity, meteors/comets strikes.
     
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