Simply put, waste products are materials discarded as useless in a process or life function.  No living thing or machine can live or thrive in the presence of its own waste.  One principal waste product of animals and machines that convert hydrocarbons to energy is carbon monoxide.  Dumping CO2 into the very air we breathe is no different than the medieval practice of dumping a chamber pot full of feces and urine out the window to the street below.  Each practice results in an environment that does not augur well for the continuation of life regardless of the exact mechanism be it disease or increased global temperatures that are inconsistent with life.