"what we see in our lifetime is simply weather." 
Well generally true, but over the years one can note an increase in global warmth (climate change). 
One can also find out that there is an increase in CO2 in the atmosphere. 
The error is to claim that the warming is due to the CO2. 
One only has to look to Mars and see that its polar areas have shrunk as well, to make the astounding conclusion that there exist a solar system-wide warming event. It is probably cyclical and the cataclysm of earth's demise has been over stated. 
All that does not detract from the need to keep our environment as clean and healthy as possible.