Can humans cause atmospheric problems? Can humans fix those problems?

We can create a few pollution messes and have done it over the years. Can we create a real environmental disaster, almost but still no apple. The situation in Brazil with the ethanol and cocaine crops is sticky locally but no world disaster type yet. The SEA problems especially in Indonesia and Malaysia are getting very close to a world environmental crisis if something is not done soon. Otherwise we are many generations from any man caused potential problems coming to a head.