This appears to be a “signal to noise” argument again. The core issue being that observable impact of CO2 in nigh impossible without math wizardry or modelling. Weather is a hugely complex system making the task of isolating the impact of one forcing agent very difficult and subject to a lot of debate.
As you brought the tropospheric hot spot (THS) into the discussion, I’ll add a few notes on it. The THS isn’t a result of global warming due to changes in greenhouse gases. Instead, it’s a result of any heating due to the effects of convection – warming of any kind produces a hot spot in the upper troposphere. This warming is expected simply because of the fact that hot air rises (due to the simple physics of lower density fluids floating atop denser fluids, and hot air is a less dense fluid than cold air is). Stratospheric cooling while there is simultaneously tropospheric warming is the actual fingerprint of GHG warming. Stratospheric cooling simultaneously with tropospheric warming has been observed, so even if models are wrong about the magnitude of warming, there is no other hypothesis that matches the actual observations to date.
Finally, given the problems with measuring the temperature of the upper troposphere, there is significant uncertainty in the measurements. This uncertainty results from the fact that radiosonde data has a host of thermometer problems, there’s very little radiosonde data from the tropics to begin with, and there’s not agreement on how to separate the influence of the cooling lower stratosphere from the warming upper troposphere in the satellite data. However, given that the THS relies on the some of the most basic of physics (again, “hot air rises”), it’s more likely that the models are correct and the measurement techniques are not yet available to prove it and it is likely that the THS doesn’t exist and the models are wrong.