Unfortunately due to Poe's Law [1] and the fact that "contrails are the government spreading chemicals" is a prevailing conspiracy, I cannot take this seriously. Can someone knowledgeable on the subject weigh in?
On one hand, it's a short term phenomenon. The effect of mitigations takes effect very quickly (and is mostly governed by the planet's thermal mass). Mitigations might be relatively easy, too (just taking it into account when planning flights would make a big difference).
On the other hand, contrails have a pretty immediate warming effect and aren't a slow process like CO2 forcing. Contrail forcing isn't making the overall problem any better, and if there's any tip-over in methane emissions, etc, from warming, contrails could be a part of the near-term trigger.
https://www.sciencedirect.com/science/article/abs/pii/S03603...
The author in question is actually a well-known crank: https://www.desmog.com/albert-parker/
After all, Feynman was also a bongo-playing womanizing crank and single author on multiple papers.
Sorry-- I can't read every paper by every known crank and debunk it. It's an unattainable goal. I would have to pull all the data and analyze it again myself.
If you have an author who has committed great methodological errors in data analysis multiple times in the past and this is a documented fact, you stop taking that person seriously.
Here, it shares a lot of characteristics with papers he's written in the past-- possible censoring of data (picking one country, and a dubious date range for the comparison series) and ignoring other well known effects related to the COVID shutdowns (reduction in particulate emissions causing a pop in daily temperatures).