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Politics : Politics of Energy -- Ignore unavailable to you. Want to Upgrade?

To: Brumar89 who wrote (5110)	2/19/2009 8:13:03 AM
From: RetiredNow	Respond to of 86356

I can't explain it. It was a good point he made in his article. All I was pointing out is that our measurement systems are more reliable over the last 100 years. As such, any conclusions from regression testing (correlation analysis) will be more accurate over the last 100 years than when using proxy measurement systems over the last 500 million years. He rightly points out that the correlations over the last 100 years are imperfect. I'll see if I can look around and find someone who has calculated the R-squared on it, so we can see just how correlated the two are.

To: Brumar89 who wrote (5110)	2/19/2009 8:16:15 AM
From: RetiredNow	Read Replies (1) \| Respond to of 86356

I don't know Brumar. I look at charts like the one below and I don't even need to see the correlation analysis to conclude that CO2 and temp are highly correlated, if the data below can be trusted. The real question then becomes, which came first? CO2 or temperature rise? For more than 2 million years our earth has cycled in and out of Ice Ages, accompanied by massive ice sheets accumulating over polar landmasses and a cold, desert-like global climate. Although the tropics during the Ice Age were still tropical, the temperate regions and sub-tropical regions were markedly different than they are today. There is a strong correlation between temperature and CO2 concentrations during this time. Historically, glacial cycles of about 100,000 years are interupted by brief warm interglacial periods-- like the one we enjoy today. Changes in both temperatures and CO2 are considerable and generally synchronized, according to data analysis from ice and air samples collected over the last half century from permanent glaciers in Antarctica and other places. Interglacial periods of 15,000- 20,000 years provide a brief respite from the normal state of our natural world-- an Ice Age Climate. Our present interglacial vacation from the last Ice Age began about 18,000 years ago. Over the last 400,000 years the natural upper limit of atmospheric CO2 concentrations was about 300 ppm. Today, CO2 concentrations worldwide average about 370 ppm. Humans may be able to take credit for some of these additions, but not all of them. Earth's plant life will respond to soak up these additions with additional biologic activity, but this takes time. Meanwhile perhaps up to 9% of CO2 concentrations in the atmosphere today may be attributable to human-related activities like agriculture, industry, and transportation. Compared to former geologic periods, concentrations of CO2 in our atmosphere are still very small and may not have a statistically measurable effect on global temperatures. For example, during the Ordovician Period 460 million years ago CO2 concentrations were 4400 ppm while temperatures then were about the same as they are today. Do rising atmospheric CO2 concentrations cause increasing global temperatures, or could it be the other way around? This is one of the questions being debated today. One thing is certain-- earth's climate has been warming and cooling on it's own for at least the last 400,000 years, as the data below show. At year 18,000 and counting in our current interglacial vacation from the Ice Age, we may be due-- some say overdue-- for return to another icehouse climate! geocraft.com

To: Brumar89 who wrote (5110)	2/19/2009 8:25:45 AM
From: RetiredNow	Read Replies (1) \| Respond to of 86356

This explanation below seems the most reasonable to me. It claims that CO2 itself may not be the initial reason for global warming, but it does play a role in feedback mechanisms. realclimate.org From studying all the available data (not just ice cores), the probable sequence of events at a termination goes something like this. Some (currently unknown) process causes Antarctica and the surrounding ocean to warm. This process also causes CO2 to start rising, about 800 years later. Then CO2 further warms the whole planet, because of its heat-trapping properties. This leads to even further CO2 release. So CO2 during ice ages should be thought of as a "feedback", much like the feedback that results from putting a microphone too near to a loudspeaker. In other words, CO2 does not initiate the warmings, but acts as an amplifier once they are underway. From model estimates, CO2 (along with other greenhouse gases CH4 and N2O) causes about half of the full glacial-to-interglacial warming