Ok many reasons why it is but I'll try this 1:

It is indisputable that increased temp causes increased atmospheric co2 - as gases are less soluble in water with higher temp, plus ground melts releasing gas.

If the reverse were also true, and increased co2 led to increased temp, then any rise in temp or co2 through history would lead to runaway heating.

The fact that earth has not had runaway heating, despite continual climate change throughout history, shows either co2 doesn't cause temp rise, or else there is some overwhelming stabilization effect.

Either way the alarmism is nonsense.

(There are many other reasons)