Posted on 09/30/2002 10:41:08 AM PDT by cogitator
Sources of CO2 to the atmosphere are known and quantifiable in the modern era. The Keeling Mauna Loa CO2 curve provides accurate data by which sources and sinks for carbon in the global system can be accurately quantified. That allows accurate quantification of how much CO2 being added to the atmosphere is due to human activities.
Stable carbon isotope ratios incorporated into plant material (tree rings) and into calcium carbonate formed by marine plankton allow accurate quantification of atmospheric CO2 levels in paleohistory. For example, that's how we know that CO2 was twice as high (atmospheric concentration) in the Cretaceous as now. It's also how we know that CO2 levels do not -- normally -- influence global climate as much as solar irradiance variability determined by Earth's orbital and axial variability, i.e., Milankovitch cycles. What CO2 has normally done is to act as a thermostat, helping to stabilize either warm or cold conditions.
The claim that the earth's climate has warmed 0.6 degrees C in that past century is absurd, cogitator. To qualify as scientific, the methods used to measure climate temperature in 1902 would have had to be the same as those used today (a clear "apples and oranges" problem).
The current rise in temperature has been verified by a number of methods. Perhaps the most important is the measurement of temperature variability in boreholes (the holes made by drilling, for oil/gas/water etc.). These profiles use data logging to generate a temperature history. Data logs from around the world show a temperature increase in the 20th century consistent with the record from surface stations (which has been calibrated and checked extensively). NOTED skeptics such as Patrick Michaels of the University of Virginia and Richard Lindzen of MIT accept the 0.6 C degree rise for the 20th century. There is essentially no controverting evidence. The far more difficult question is partitioning the rise into natural and human caused, because there is reasonable data that attributes at least 1/3 of this warming to solar variability.
To posit "observable effects" of this undemonstrated "climate warming" suggests that we have established a cause for those effects. But nobody has, at least, not scientifically.
But it is demonstrated. Winter freeze and spring thaw records for rivers and bodies of water demonstrate later freeze and earlier thaw (by roughly 10 days) since 1850. Satellite data documents earlier onset of spring greening. Migratory bird patterns (i.e., arrival times in spring nesting areas) have shifted to coincide with the earlier arrival of spring. Polar bear populations around Hudson Bay have shown a clear loss of weight trend coinciding with later freeze, earlier thaw of Hudson Bay, reducing the amount of time they can hunt seals on the ice. There's more if you want it. (References to peer-reviewed scientific articles are available on request.)
And note that though it's not hard to find these data and trends, I don't think that global warming is nearly as serious as other environmental issues. Of greatest concern to me is the degradataion of coastal and estuarine environments. Because I live in the Chesapeake Bay watershed (and because we're praying for rain!) you might be able to understand that.
Far from being "basic facts," it's all supposition. And this is the basis on which the globaloney spouters want to dismantle our economy.
What I stated as basic facts, were and are basic facts. If we are going to discuss the issue with the maximum of insight and the minimum of rhetoric, we need to keep those facts straight.
BTTT
Amen brother. A classic case of "begging the question", i.e., assuming as fact that which is to be proven.
You didn't state the magnitude of the warming.
I'm curious; when you say
"...preceded by a period of warming much greater than the current levels,"
to what period are you referring? Holocene or earlier?
It's not something that I've got any data on, but I would suspect not. Most of the soot is being generated in tropical countries. You've got to have a lot of mixing across several atmospheric "zones" (not being a meteorologist, I just think of them as the prevailing wind direction) before you would have any appreciable deposition in the high latitudes.
to what period are you referring? Holocene or earlier? I was referring to the recent, short term variations: the more recent Little Ice Age was preceded by the Medieval Warming Period
Now, to be fair, I should probably not have used the phrase "much greater [period of warming] than current levels". Any one of several references would have been preferable...
The debate isn't over. I wanted to know if you were talking about the MWP or something earlier, because the most marked temperature changes occurred right at the end of the last glacial period. Chaos = big changes.
The MWP was about as warm as the Earth is now, but it also persisted for 150-200 years. The key for me is that the rise in temperature into the MWP and the fall out of the MWP are about 2-3 times slower than the temperature increase in the 20th century, and 3-4 times slower than the apparent temperature increase in the last 20 years of the 20th century. And that's what the astute climatologists far more learned than I have pointed out: yes, the MWP was about this warm, but the rate of change that appears to be occurring now is much faster than what is seen in the essentially unperturbed "natural" climate cycles of the past 1500 years or so.
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