I was recently involved in a discussion with a website that strongly promotes global warming and playing nice with skeptics. I have not been involved in discussion with that group before and was a little surprised by some of the discussion. That was perhaps my fault. The specific discussion was about defining CO2 as a pollutant. While some may argue that “natural” gases cannot be labeled a pollutant, I disagree as ozone is clearly natural, but also a pollutant when in the lower atmosphere.
In order to be a pollutant there has to be some hazard. Of course the main hazard for CO2 is global warming. That is where the discussion got a bit out of hand as many other topics came into play. Dana Nuccitelli did a very thorough article on the legal aspects of defining a pollutant. It was a well written and detailed article. One thing that caught my interest was the Taylor Dome CO2 chart that was prominently displayed showing the last 10,000 years of CO2. This was very interesting to me as the correlation between CO2 and temperature is a superficial confusion between cause and effect. The Taylor Dome data would nicely show that.
As I had never before reviewed the Taylor Dome data for the stable isotope (what is used to determine past temperature) I wasn’t precisely sure what to expect, but my review of many other data sources made me confident that the Taylor Dome would show declining temperatures while it also showed increasing CO2. Even I was surprised by how opposite the behavior was.
I used Dana’s CO2 direct source and then I found the stable isotope data at the University of Washington (I did smooth the data). A very rough estimate of the stable isotope data indicates each full point of change is close to 2 °C temperature change. I based that on about a 6 point change in the ratio from the coldest point of the last glacial to the peak warmth of the interglacial. That temperature change was about 12 °C, so 2 °C/stable isotope change is reasonable. Not precisely accurate, but close enough for this analysis.
As almost every ice core on Earth shows, the Earth started cooling about 6,000 years ago. The last 4,000 have been much colder than any of the previous periods before that. CO2 continues to increase over the entire 10,000 year period, even though the temperature has continued to drop the entire time. This disconnect between CO2 levels and temperature is the norm. I have not found a single ice core that would indicate that CO2 is the cause of temperature change. If you are aware of one, feel free to let me know which one so I can look at it.
In addition, the past 1,000 years have shown 4 very distinct warming and cooling periods. Any statement that the current period is the warmest of the past 1,000 years based on this ice core record is… flawed. To add insult to injury, the very last data point for the Taylor Dome indicates that as of 1990 the Taylor Dome indicates that temperatures are dropping. So much for tree ring proxy reconstructions!
To analyze even farther back, the period from 6,000-10,000 years ago was MUCH warmer than the Earth is today. While that data might be inconvenient to Dana and those at the warmist site, that is what the data says. I understand that other factors drive the climate. If anyone says that the AMO or El Nino is the other factor that caused 6,000 years of cooling, then we are in lots of trouble.
The point is that the data does not show a correlation between CO2 levels and temperature. If the CO2 data from the Taylor Dome is to be trusted, then so should the temperature data from the same source. Temperature does not show any dependence on CO2 levels in that ice core. None of the ice cores show that dependence. Why should anyone believe it if the data does not support it? The answer is simple, they shouldn’t.