a) If we knew the consequences that happen if lived exactly the same way as we do right now, I'm pretty sure that we would do many things completely differently.

From the beginning we would care about the CO2 output and try to control it. We would have a look for alternative energies and not just use the oil resources.

b) Everything we know right now. We did many things wrong, especially we didn't really think about what we are doing when we built all those factories and started using the limited resources.