Final answer:
Deforestation and sustainable farming are activities that can increase the amount of atmospheric CO2.
Step-by-step explanation:
Activities that can increase the amount of atmospheric CO2 include deforestation and sustainable farming. Deforestation leads to significant increases in carbon dioxide emissions, as burning wood or carbon-based energy sources releases carbon back into the atmosphere. Sustainable farming methods can help decrease carbon dioxide levels by reducing greenhouse gas emissions from livestock agriculture.