If humans continue to fill the atmosphere with carbon dioxide …Ohh brother. Have all plants on the planet held their breath? CO2 atmospheric concentrations are still in the paltry 0.039 percent range (that's a mere 390 parts per million). The atmosphere cannot be “filled” with this gas any time soon, even if all the world’s volcanoes put out double the amount they normally do all of a sudden.
exactly that is only 100 ppm more then what plants need to stay alive while the average CO2 levels of the earth have been nearly 10 times what they are today