Yet I've read that we need to expect shortages of carbonated beverages because of a shortage of CO2. Unbelievable.

BTW haven't used up any "millions of years of carbon." First of all, we haven't used it all up, as there is a lot of oil still in the ground. Secondly, you probably think crude oil came from pressed dinosaurs like we were taught in school. If you're smart, go research the elements found in crude oil and the elements found in plants and animals. You will see some glaring mismatches. Oil is created deep in the earth by a natural process. It will never run out. Russian scientists have said so for years.