Global warming due to CO2 == heat is trapped in the troposphere => less heat lost => colder stratosphere.

If the global warming was due to the Sun, the whole atmosphere would be warming.

On the other hand, Venus has runaway greenhouse effect and its stratosphere is abnormally cold.

...they're often frozen on the surface when found right after the fall! It's a common myth that meteorites blazing hot. In reality, the molten surface of a meteorite has plenty of time to cool during the fall through cold atmosphere, and the interior of the meteorite remains very cold.