One of the key fingerprints - aka 'tenets' - of the anthropogenic global warming (AGW) hypothesis is that fossil fuel combustion emissions will create a mid-troposphere tropical hotspot due to a surplus of trapped CO2 molecules. The hotspot warming then initiates positive climate feedbacks that amplifies the warming trend, which is predicted to be robustly higher than the warming trend on Earth's surface.
But has that taken place as predicted?
Since December 1978, satellites have monitored the mid-troposphere, and the evidence shows that global surface temperatures have in reality been warming at a rate that is nearly two times as fast (1.9x) as that of the hypothetical "amplified" tropical mid-troposphere warming rate.
This reversal of the expected outcome is contrary to the experts' hypothesis.
Compounding this failure of this AGW hypothesis tenet is the empirical evidence that there has been a very minor cooling/flat trend in the mid-troposphere tropics since August 2013.
This modest cooling happened in spite of a huge amount of CO2 greenhouse gas (GHG) emissions from fossil fuel combustion and other GH gases, such as methane from cows.
Also, this 10-year period of slight cooling took place even with the two large El Niño temperature spikes of 2014–2016 and 2018–2019. Plus, another new spike of temperatures is currently taking place in 2023 from the developing El Niño, as seen in this chart.
The second chart is a scatter plot that allows for the calculation of the R2 relationship strength between the two variables, CO2 atmospheric levels and the mid-troposphere tropic temperature anomalies.
A typical strong relationship would produce a R2 of at least +0.70.
In this case, the R2 = +0.0001.
That microscopic R2 indicates there is no relationship between atmosphere CO2 and tropical temperatures in the mid-troposphere.
That is a completely unexpected outcome that undercuts the hypothesis that the trace CO2 gas will have a powerful impact on current and future climate temps, especially in the region of the predicted atmospheric tropical hotspot.
And without the requisite AGW 'hotspot', the likelihood of the amplified rapid acceleration of warming from the climate's positive feedback mechanisms becomes a very possible non-event.
Additional global and regional temp charts.
Note: Excel used for all calculations and plotting. Source of UAH satellite monthly mid-troposphere temperature anomalies. Source for CO2 monthly data.