Sunday, November 15, 2009

200 kyr of 1000+ ppm CO2 Won't Melt Antarctica

I was really interested to see that in the geologic record there is excellent evidence for the survival of the Antarctic ice sheets in a world of 1000 ppm, and that those ice sheets survived for 200,000 years at those CO2 levels. This, is totally contrary to all the hoopla about how Antarctica is about to melt into the sea--next week and kill all those Bangladeshi's who, without the help and guidance of those comfortable Western global warming hysteriacs, would be too stupid to move out of the way.

I ran across the following in Nature about the time when the Antarctic ice sheets first grew. This occurred 33.6 to 33.5 million years ago as the CO2 content of the atmosphere dropped below ~750-850 ppm of CO2.

"First, they conclude that the slow temperature decline recorded by oxygen isotopes was concomitant with a decline of atmospheric CO2 from about 1,100 p.p.m.v. to a threshold concentration of about 750 p.p.m.v., at which the main phase of Antarctic ice-cap growth was initiated. This finding confirms model predictions that - contrary to what might be expected - the initiation and the rapid expansion of the Antarctic ice sheet occurred about 33.5 million years ago at levels of atmospheric CO2 that were more than twice the present -day value. Pearson et al. propose that the Antarctic glaciation was preconditioned by the global cooling associated with the decline of atmospheric CO2, But the glaciation really started only when Earth's orbital parameters, which change periodically, favoured the process." Damien Lemarchand, "Early Survival of Antarctic Ice," Nature, 461(2009): 1065



Similar statements to that above have appeared in the literature, but when you look at these, notice that the Antarctican glaciation began 33.6 million years ago.

"Oligocene epoch (-33.6 million years ago), followed by the onset of northern-hemispheric glacial cycles in the late Pliocene epoch, about 31 million years later'. . . . We show that the CO2 threshold below which glaciation occurs in the Northern Hemisphere (-280 p.p.m.v.) is much lower than that for Antarctica (-750 p.p.m.v.). " Robert M. DeConto, et al, “Thresholds for Cenozoic Bipolar Glaciation,” Nature, 445(2008), p. 652

"Between the Oligocene and mid-Miocene, 11 to 35 million years ago, values averaged 600 ppm, get if we extend into the Late Eocene, we see levels possibly up to 2,000 ppm. This reflects a major decrease starting in the Eocene and coinciding with the development of widespread Antarctic glaciation in the earliest Oligocene. An Eocene-Oligocene boundary fall in pC02 is supported by climate models, which indicate that large-scale Antarctic glaciation cannot occur with pC02 values above -850 ppm."Jane Whaley, “The Azolla Story: Climate Change and Arctic Hydrocarbons,” Geo Expro, 4(2007):4:66-72, p. 70-71

I was intrigued by the claim that one must be below 750 ppm CO2 in order to have Antarctican glaciation. At first glance, it seemed to me that the opposite is also likely true, that it wouldn't melt until we passed that CO2 level. But quite logically, if one thinks about it, my first thought was wrong. Once formed, it takes even higher CO2 levels to melt it (because of albedo issues--the amount of light reflected from the ice).


"The authors' second conclusion is that, although the newly formed ice cap may have shrunk somewhat, it largely survived a subsequent and rapid recovery of atmospheric CO2 back to levels of 1,000 p.p.m.v. or more."Damien Lemarchand, "Early Survival of Antarctic Ice," Nature, 461(2009): 1065

If you go look at the article you will see a couple of things. First, the rebound of CO2 was up to 1125 ppm, yet the Antarctican ice didn't melt. It didn't melt even with 200,000 years of above 1000 ppm CO2 levels. You will see that interesting fact in the following picture from that article, which I modified to show some interesting features.




Notice that the red bar that I put on the CO2 curve showing how long the earth was above 1000 ppm CO2. I copied that bar and placed it on the X-axis to show that the earth spent 200,000 years above 1000 ppm yet the Antarctic ice cap didn't melt. The authors say

"We also find a sharp Pco2 increase after maximum ice growth as the global carbon cycle adjusted to the presence of a large ice cap and there was a nonlinear hysteresis effect as the ice cap withstood this transient Pco2 atm rise." Paul N. Pearson et al, "Atmospheric Carbon Dioxide Through the Eocene-Oligocene Climate Transition," Nature 461(2009), p. 1112

Two hundred thousand years is TRANSIENT????? Not by my definition. I am transient, living less than 100 years; glaciers are permanent if they last 200,000 years. Modern mankind has only been on earth for 160,000 years.


Now, we are a long long way away from 1000 ppm CO2. And even after we get there, the Antarctic ice sheet will not melt for at least another 200,000 years. Because of this, all this screaming about Antarctic ice shelves melting because of CO2 is just so much hooey. Fear-mongering sells newspapers and makes people willing to give up their freedom to anyone who will save them from the boogeyman. Anthropologists tell us that anatomically modern Homo sapiens has been on earth for 160,000 years. Thus even with 1000 ppm of CO2 for all that time, we would still be able to view the Antarctic ice sheets that was on earth when the earliest modern human appeared. Clearly the ice sheets are far far more stable than the screaming meemies today think. The science clearly says that Antarctia won't melt in our life-time,and thus, one must conclude that all of this hysteria-spreading is for the purpose of getting you to give them your tax dollars to solve a problem that doesn't exist.

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