Guest contribution by Willis Eschenbach
As a result of my last post on the question of CO2 and COVID, I came up with an interesting question, namely:
What is the lag time between changes in CO2 emissions and Mauna Loa measurements of background CO2?
I didn’t know what a fight this would be. I started looking for weekly CO2 emissions data … ho, ho, ho. Rightly or wrongly, I consider myself a sensible seeker of data. However, finding weekly emissions data proved to be a dead end.
So I looked for weekly CO2 data. It took a while, but I finally got weekly Mauna Loa data here from NOAA. With that hand I looked for the emissions data again … still no joy.
I can’t tell you how many dead ends I went down without finding cute Fanny Adams. After venting a cornucopia of bad words to a remarkable extent, I had to digitize the data from this story in Nature magazine …
Figure 1. Emissions from 2019 and part of 2020. SOURCE
After digitizing the emissions data, I grouped them into weekly data using the same weeks as the Mauna Loa data. Then I used a cross correlation to find out how many weeks there were between the emission of CO2 and the resulting change in atmospheric CO2.
Here are the results … that really surprised me …
Figure 2. Standardized CO2 emissions and standardized data on CO2 concentration from Mauna Loa.
Hmmm … now there are a couple of options. On the one hand, CO2 emissions and atmospheric CO2 each have an independent annual cycle and peak values at different times.
The other is that what we see above is actually the relationship between emissions and atmospheric CO2. The size of the relationship tends to support the latter. A total of 2.13 Gt of carbon is emitted for every 1 ppmv increase in atmospheric CO2. The relationship shown above gives a relationship of 3 Gt carbon per ppmv, certainly within specifications. However, this can only be a coincidence.
Here’s another curiosity. Without thinking much about it, I had always accepted the following explanation for the annual carbon cycle
There is more carbon dioxide in winter and a little less in summer. This is the collective breathing of all plants in the northern hemisphere.
“Plants accumulate carbon in spring and summer when they are active, and release carbon into the air in autumn and winter.”
However, when I looked at my Figure 2 above, I said … what? Does that seem the way I see it in my character?
Fearing I made a mistake, I went back to the Mauna Loa dates. I averaged every single month, and here is what I got:
Figure 3. Average monthly CO2 anomaly and NH land temperature index
Curious. CO2 peaks in May and then drops. It certainly doesn’t seem to me that plants accumulate carbon in spring and summer when they are active. The meteorological spring is from March to May and the meteorological summer is from June to August.
According to the accepted theory, CO2 levels should drop from March to August. Instead, they start to decline from May and only rise in October.
And that doesn’t even take into account the ~ 4 month lag between surface changes and changes in the air shown in Figure 2. If so, a decrease in atmospheric CO2 from May would correspond to a decrease in surface CO2 from February.
But what do I know, I was born yesterday.
Let me make it clear that I take no position on any of this other than to call it the most interesting.
My best to everyone. You have no doubt heard of the Lunar New Year? …
Well, this is going to be Looney New Year, so stay tuned during these troubled times.
w.
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