Sunday morning climate rap: My simple worst-case estimate of the effect of CO2 would be harmless

 As a worst case estimate, we can assume the official +1.1 degree C. warming since 1850 is right, and 280ppm atmospheric CO2 in 1850 is right, even though both are very rough guesses.

Then we can assume the +0.4 degrees C. warming before 1975 (of the +1.1 degrees C.) was from natural causes and the +0.7 degree C. warming after 1975 was from manmade causes.

That’s a worst case estimate, since we don’t know exactly what caused the warming after 1975, and there’s no logical reason to assume 100% manmade EXCEPT for a worst case estimate.

Here’s the bottom line:  WORST CASE ESTIMATE

+0.7 degree C. warming from a manmade CO2 increase of almost +50%

The next +50% increase of manmade CO2 will cause less than +0.7 degrees C. warming (logarithmic effect of CO2).

So the worst case, based on observations since 1850, is less than +1.4 degrees C. warming for a 100% CO2 increase, but let’s assume some water vapor positive feedback, so +1.4 degrees C. is okay.

How long will it take for CO2 to increase another +50%, from 415ppm currently, to 830ppm, at +2,5ppm per year = 166 years

Expect a +1.4 degree C. warming in over the next 166 years, if CO2 is the only cause of global warming, and CO2 continues to increase +2.5ppm per year.

That's a worst case +0.08 degrees per decade global warming -- less than one tenth of a degree C. per decade.  Think the human race will survive?  By the way, most of the "global" warming will be in colder climates, during winters, and at night (TMIN), just like the 1975 to 2022 warming.

Back to reality: It could also be colder in 166 years!

You would not like that.