Saturday, October 23, 2021

A Very Interesting Graph

Someone on Facebook commenting on my post there linked to an NOAA web page with a graph showing temperature, CO2, and insolation for the past 350,000 years. The pattern is interesting. During the previous three interglacials (yellow columns on the graph) temperature was falling. During two of the three, CO2 concentration was also falling, during the third roughly constant.

Compare that to the latest interglacial, the one we are living in. It starts on the figure about 11,000 years ago. Temperature and CO2 initially fall but after two or three thousand years the pattern reverses and they start rising.

Could we be responsible?

That is about eight thousand years too soon for the industrial revolution but only a little after the beginning of the Neolithic revolution, the rise of agriculture and just about right for the spread of agriculture to Southwest Asia. Is it possible that the change in human activity, the enormous growth in human population with the switch from hunter-gatherer to farmer and associated activities such as forest clearing, somehow caused an increase in CO2 and temperature during the interglacial? Is it possible that that increase is the reason the current interglacial, which has already lasted longer than its three predecessors, has not yet ended?

Perhaps we owe thanks to our stone age ancestors for the glaciers not yet having started south.


7 Comments:

At 4:41 PM, October 23, 2021, Blogger VangelV said...

I am sorry but the entire AGW story is fiction that is based on ignoring inconvenient truths. The simple fact is that humans have had a negligible impact on our planet for most of its history and human populations have followed rather than led temperature trends.

Being a romantic, I included a Neolithic site, Banpo Village as part of the stops during the first date with my wife. The site is just a short distance from the old city walls in Xi'an, what was once China's ancient capital. There are some things not to like about the site but overall I found it fascinating. Just as we were leaving for the tomb of the First Emperor, I heard the guide inform us that the diet of the villagers included water deer and bamboo rats. That did not seem correct so I asked my driver why it was that he never tried to get me to eat bamboo rats in any of the places that we frequented. He said that it was far too cold for bamboo in the area and that the water deer could not be found because the cold made it too dry for them to live in.

To make a long story shorter, I found out from the people working at the place that when the village was inhabited 7,000 years ago, it was 3C warmer than today. To find similar temperatures I would have to try a city like Wuhan or Chongqing. Being a skeptic, I gave my Hong Kong book guy a call and asked if he had anything about the climate history of China. He recommended HH Lamb, who had been involved in the First Assessment Report by the IPCC. A few days later I got a package that included the book and it confirmed a few problems for the global warming promoters. Today's temperatures are not particularly warm when compared to most of the periods during the last 10,000 years. They are not even warm compared to recent periods like the MWP.

 
At 1:26 PM, October 24, 2021, Blogger Unknown said...

Unfortunately, David, the temperature reconstruction is only for Antarctica. You made an error in extrapolating it to the globe.

Humanity wasn't due to for another glacial advance for thousands of years, and we've managed to put it off for at least 10 millennia more.

 
At 1:29 PM, October 24, 2021, Blogger Unknown said...

As always, "VangelV" prefers anecdote and a misapplication of HH Lamb's work.

 
At 9:32 PM, October 25, 2021, Anonymous Anonymous said...

CO2 concentration is over 400 ppm now, yet your chart doesn’t include that. Why?

 
At 8:03 AM, October 26, 2021, Blogger Karl said...

It has been suggested that human intervention has put off the next ice age, and in Fallen Angels by Larry Niven, Jerry Pournelle, and Michael Flynn, we see an ice age underway because of drastic reductions in CO2 output.

 
At 3:37 PM, October 26, 2021, Blogger Peter McCluskey said...

It has been suggested that the Little Ice Age was due to reforestation causing CO2 sequestration as a result of population declines associated with the black plague (http://news.bbc.co.uk/2/hi/science/nature/4755328.stm) and the Columbian exchange (https://www.jstor.org/stable/40863600).

 
At 9:50 AM, October 28, 2021, Blogger David Friedman said...

@Peter:
After I noticed the pattern and posted on it, someone pointed me at Ruddiman's work. He spotted the pattern, along with a similar pattern for Methane, and published on it in 2003, setting off a controversy that's still running. He has quite detailed arguments linking CO2 and temperature to the spread of agriculture resulting in widespread deforestation, starting about 7000 years ago in the current version, and CH4 increase to the development and spread of irrigated rice culture. His conclusion is that pre-industrial anthropogenic warming was somewhat over one degree and prevented glaciation in northern Canada.

His argument includes the link between past pandemics and temperature via reforestation when populations fall sharply. I'll probably put up another post on this shortly.

 

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