Skip to comments.The Cooling World (Blast From The Past Archived Newsweek Article Warning About "Global Cooling")
Posted on 10/02/2003 10:21:17 AM PDT by presidio9
click here to read article
But since you brought up the Vostok ice core, I just have to show some interesting data plots from it:
Comment: the ice core shows that over the past 400,000 years, atmospheric CO2 concentrations varied between an upper bound of ~290 ppm and a lower bound of ~190 ppm. Climate scientists are real interested in determining what determined those bounds. Atmospheric CO2 concentration is currently at ~370 ppm -- 80 ppm higher than that upper bound! But there is a lag time in the climate system. So the problem facing the climate science community is; what is the rapid increase in atmospheric CO2 concentration, out of the 400,000 year bounds, going to cause?
Here's the other plot (at the far right edge you can see how high current atmospheric CO2 concentrations are):
Comment: this shows that CO2 and temperature have been linked over the past 400,000 years. Most studies show that the warming was driven by other factors and that CO2 concentration responded to warming or cooling. The problem facing climate scientists now is that the CO2 rise is occurring in a nominally "stable" temperature regime, so it will be a forcing factor for climate change. How much the change will be, and how fast, is very uncertain.
This is the type of data I'd like to discuss with ancient_geezer. I just need some time to prepare a full treatment.
It may not be as troubling as at first look, if we consider that the current 370 CO2 is only 22 percent higher that the highest 304 from Vostok ( as I recall from the table of data) (close to this on graph).
We don't know the accuracy of CO2 and Temperature data from 300,000 years ago. I suspect +/- 22 percent accuracy of the data would be very good. The ~304 years ago may have actually been ~370.
In fact, a couple of the web references state that the CO2 concentrations lag the temperature data by 1000 to 4000 years. This means that we need to learn much more.
But it all is very interesting.
Those cycles are fascinating. I am glad to see these threads.
CO2 concentrations are not calculated from proxies; they are directly measured from bubbles trapped in the ice, and therefore are probably quite accurate. The temperature is determined from stable oxygen isotope ratios and is more uncertain.
But here is an interesting statement ---"Because air bubbles do not close at the surface of the ice sheet but only near the firn-ice transition (that is, at ~90 m below the surface at Vostok), the air extracted from the ice is younger than the surrounding ice (Barnola et al. 1991). Using semiempirical models of densification applied to past Vostok climate conditions, Barnola et al. (1991) reported that the age difference between air and ice may be ~6000 years during the coldest periods instead of ~4000 years, as previously assumed."
I need to ponder this statement. Have any thoughts on this?
This is further down in the link ---"According to Barnola et al. (1991) and Petit et al. (1999) these measurements indicate that, at the beginning of the deglaciations, the CO2 increase either was in phase or lagged by less than ~1000 years with respect to the Antarctic temperature, whereas it clearly lagged behind the temperature at the onset of the glaciations. "
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