Does high levels of CO2 in the past contradict the warming effect of CO2?

Discussion in 'Environment' started by Matthew, Dec 23, 2010.

  1. Matthew
    Offline

    Matthew Blue dog all the way!

    Joined:
    Mar 16, 2010
    Messages:
    49,754
    Thanks Received:
    4,607
    Trophy Points:
    1,885
    Location:
    Portland Oregon
    Ratings:
    +15,209
    Does high levels of CO2 in the past contradict the warming effect of CO2?

    Geologists refer to ancient ice-cap formations and ice-ages as "glaciations." One such glaciation that occurred during the Late Ordovician era, some 444 million years ago has captured the attention of climate scientists and skeptics alike. To get some perspective on timing, that's just over 200 million years before dinosaurs began to roam the Earth.

    Unlike other glaciations in the last 500 million years, this one was exceptionally brief (lasting perhaps only a million years or so) but the main reason for generating so much interest recently is because it took place when CO2 levels were apparently sky-high. As Ian Plimer notes in his book, "Heaven and Earth", pp165:

    "The proof that CO2 does not drive climate is shown by previous glaciations...If the popular catastrophist view is accepted, then there should have been a runaway greenhouse when CO2 was more than 4000 ppmv. Instead there was glaciation. Clearly a high atmospheric CO2 does not drive global warming and there is no correlation between global temperature and atmospheric CO2."

    On the surface, Plimer does seem to have a point: if ice-caps managed to exist back then in an ultra-high CO2 environment, why are the vast majority of climate scientists worrying so much about keeping CO2 levels piddlingly low?

    To answer this, we have to fill in some parts of the puzzle that are missing. Let's start with the CO2.

    Plimer's stated value of 4000 ppmv or greater is taken from Robert Berner's GEOCARB, a well-known geochemical model of ancient CO2. As the Ordovician was so long ago, there are huge uncertainties for that time period (according to the model, CO2 was between an incredible 2400 and 9000 ppmv.) Crucially, GEOCARB has a 10 million year timestep, leading Berner to explicitly advise against using his model to estimate Late Ordovician CO2 levels due its inability to account for short-term CO2 fluctuations. He noted that "exact values of CO2... should not be taken literally."

    What about evidence for any of these short-term CO2 fluctuations? Recent research has uncovered evidence for lower ocean temperatures during the Ordovician than previously thought, creating ideal conditions for a huge spurt in marine biodiversity and correspondingly large drawdown of CO2 from the atmosphere through carbon burial in the ocean. A period of mountain-building was also underway (the so-called Taconic orogeny) increasing the amount of rock weathering taking place and subsequently lowering CO2 levels even further. The evidence is definitely there for a short-term disruption of the carbon cycle.

    Another important factor is the sun. During the Ordovician, it would have been several percent dimmer according to established nuclear models of main sequence stars. Surprisingly, this raises the CO2 threshold for glaciation to a staggering 3000 ppmv or so. This also explains (along with the logarithmic forcing effect of CO2) why a runaway greenhouse didn't occur: with a dimmer sun, high CO2 is necessary to stop the Earth freezing over.

    In summary, we know CO2 was probably very high coming into the Late Ordovician period, however the subsequent dip in CO2 was brief enough not to register in the GEOCARB model, yet low enough (with the help of a dimmer sun) to trigger permanent ice-formation. Effectively it was a brief excursion to coldness during an otherwise warm era, due to a coincidence of conditions.

    The following (somewhat simplified) diagram may make this easier to understand:

    Ordovician Glaciation

    When looking at events such as these from the deep geological past, it is vital to keep in mind that there are many uncertainties, and generally speaking, the further back we look, the more there are. As our paleo techniques improve and other discoveries emerge this story will no doubt be refined. Also, although CO2 is a key factor in controlling the climate, it would be a mistake to think it's the only factor; ignore the other elements and you'll most likely get the story wrong.

    Does high levels of CO2 in the past contradict the warming effect of CO2?
    ...
    What do you think of this? Me I think it is possible for 1# Dimmer sun=more green house gas to keep the temperature high and 2# The mountain growing effects and the other factors(cooler oceans=less co2 in Atmosphere) should cause as this says....Seems reasonable.
     
    • Thank You! Thank You! x 1
    Last edited: Dec 23, 2010
  2. Matthew
    Offline

    Matthew Blue dog all the way!

    Joined:
    Mar 16, 2010
    Messages:
    49,754
    Thanks Received:
    4,607
    Trophy Points:
    1,885
    Location:
    Portland Oregon
    Ratings:
    +15,209
    "The Late Ordovician Hirnantian Stage (∼444 million years ago) was one of three time periods during the past
    half billion years in which large continental glaciers formed over Earth's polar regions. The effects of this
    glaciation were far-reaching and coincided with one of the largest marine mass extinction events in Earth
    history. The cause of this ice age is uncertain, and a paradoxical association with evidence for high
    atmospheric CO2 levels has been debated. Precise linkages between sea level, ice volume, and carbon isotope
    (δ13Ccarb and δ13Corg) proxy records of pCO2 have been poorly understood due in part to uncertainties in
    stratigraphic correlation and the interpretation of globally important sections. Although correlation
    difficulties remain, recent Hirnantian biostratigraphic studies now allow for improved correlations. Here
    we show that consistent trends in both δ13Ccarb and δ13Corg from two well-dated stratigraphic sequences in
    Estonia and Anticosti Island, Canada coincide with changes in Late Ordovician (Hirnantian) climate as
    inferred from sea level and the extent of ice sheets. The integrated datasets are consistent with increasing
    pCO2 levels in response to ice-sheet expansion that reduced silicate weathering. Ultimately, the time period
    of elevated pCO2 levels is followed by geologic evidence of deglaciation.


    Young et al. Did changes in atmospheric CO2 coincide with latest Ordovician
    glacial–interglacial cycles?, Palaeogeography, Palaeoclimatology, Palaeoecology, 2010
     
  3. Old Rocks
    Offline

    Old Rocks Diamond Member

    Joined:
    Oct 31, 2008
    Messages:
    46,552
    Thanks Received:
    5,424
    Trophy Points:
    1,840
    Location:
    Portland, Ore.
    Ratings:
    +10,366
    Interesting research here.

    Study Bolsters Greenhouse Effect Theory, Solves Ice Age Mystery

    COLUMBUS, Ohio – Critics who dismiss the importance of greenhouse gases as a cause of climate change lost one piece of ammunition this week. In a new study, scientists found further evidence of the role that greenhouse gases have played in Earth’s climate.


    Matthew Saltzman
    In Thursday’s issue of the journal Geology, Ohio State University scientists report that a long-ago ice age occurred 10 million years earlier than once thought. The new date clears up an inconsistency that has dogged climate change research for years.

    Of three ice ages that occurred in the last half-billion years, the earliest ice age posed problems for scientists, explained Matthew Saltzman, assistant professor of geological sciences at Ohio State.
     
  4. Old Rocks
    Offline

    Old Rocks Diamond Member

    Joined:
    Oct 31, 2008
    Messages:
    46,552
    Thanks Received:
    5,424
    Trophy Points:
    1,840
    Location:
    Portland, Ore.
    Ratings:
    +10,366
    Appalachian Mountains Rock Ice Age

    North America during the late Ordovician. Credit: Dr. Ron Blakey, NAU Geology. That much CO2 should have kept the climate warm for eons, but a short 10 million years later atmospheric levels of the gas began to plummet. 5 million years after that, Earth entered a severe ice age. Seth A. Young et al., writing in the October issue of Geology, have proposed that weathering of rock in the Appalachian chain triggered the dramatic climate change. Their hypothesis is based on studying three sedimentary rock formations in Nevada, where sediments had washed down from the Appalachians 460 million years ago.
    Previous research based on oxygen isotope excursions indicate that the end-Ordovician event lasted only about 500,000 years. The rapid drop in sea levels is an indication of how quickly continental ice-sheets formed, ushering in the End-Ordovician Ice Age. This caused a worldwide reduction in sea level of approximately 260 feet (80 meters), which dried up and exposed the extensive shallow-water continental shelves that existed throughout the world at that time. This led to the extinction of large numbers of species who depended on this shallow water environment. Scientists count the extinction at the end of the Ordovician as the second worst in terms of lost marine species after the great Permian-Triassic extinction
     
  5. mdn2000
    Offline

    mdn2000 BANNED

    Joined:
    Sep 27, 2009
    Messages:
    3,766
    Thanks Received:
    278
    Trophy Points:
    0
    Location:
    conservative hell california
    Ratings:
    +278
    Gee, more CO2 found in ice, maybe thats why CO2 is dry ice.

    You know whats really great about CO2, Democrat-scientist who never left the university get to use billions of dollars of tax money on super computers to come up with super cool formulas that only super computers and billions more in tax money can refute.

    Its the perfect scam, take a simple gas that has zero ability to retain heat and wrap a billion dollar super computer formula around it.

    Bravo, tax dollars hard at work keeping all those democrat-scientist employed, talk about the perfect welfare cases, scientist in the classroom, these bums should collect food stamps like all the other leeches of society.
     
  6. Matthew
    Offline

    Matthew Blue dog all the way!

    Joined:
    Mar 16, 2010
    Messages:
    49,754
    Thanks Received:
    4,607
    Trophy Points:
    1,885
    Location:
    Portland Oregon
    Ratings:
    +15,209


    So you don't think that co2 has any ability to hold in heat(green house effect)...How about methane? That is increasing at a quick pace too.
     
  7. mdn2000
    Offline

    mdn2000 BANNED

    Joined:
    Sep 27, 2009
    Messages:
    3,766
    Thanks Received:
    278
    Trophy Points:
    0
    Location:
    conservative hell california
    Ratings:
    +278
    Zero ability to hold in heat, that is fact, that is why CO2 is not used as an insulating gas insulated windows, they get filled with Argon gas.

    CO2 is heavier than air, it sinks and is absorbed into the earth, heat rises. Further if you take a look at Titan, its atmosphere is mostly CO2 and its well below freezing.

    Methane, sorry I have no comment on methane, I have not studied Methane, not at all.
     
  8. Midnight Marauder
    Offline

    Midnight Marauder BANNED

    Joined:
    Feb 28, 2009
    Messages:
    12,404
    Thanks Received:
    1,876
    Trophy Points:
    0
    Ratings:
    +1,876
    Nf3
     
  9. Old Rocks
    Offline

    Old Rocks Diamond Member

    Joined:
    Oct 31, 2008
    Messages:
    46,552
    Thanks Received:
    5,424
    Trophy Points:
    1,840
    Location:
    Portland, Ore.
    Ratings:
    +10,366
    No NF3 in the Ordivician.
     
  10. Midnight Marauder
    Offline

    Midnight Marauder BANNED

    Joined:
    Feb 28, 2009
    Messages:
    12,404
    Thanks Received:
    1,876
    Trophy Points:
    0
    Ratings:
    +1,876
    Nf3
     

Share This Page