No, not at all. Humans indeed exhale over three billion tons of carbon dioxide every year, but the carbon we exhale is the same carbon that the plants we consume "inhaled" from the atmosphere. This process is called "respiration" and it's how organisms produce energy for their lives. When we die, our bodies begin to decompose quickly in hot climates or more slowly in cold climates. The carbon in our bones and teeth returns to the atmosphere through respiration by bacteria, while the carbon in our flesh returns to the atmosphere through decay. Over time, humanity as a whole adds its share to the global CO2 pool. The amount of carbon dioxide we add to the atmosphere each year is far greater than what can be explained by human activity alone. An additional source is the carbon dioxide stored in forests, grasslands, and other vegetation grown for fuel or food. When these lands are cleared for agriculture or industry, they no longer take up carbon dioxide and so become sources of emissions instead. Removing carbon dioxide from the air is difficult because it requires direct exposure to the sun's light without any clouds or water present. Carbon dioxide molecules are colorless and odorless, which makes them hard to track as they move around the planet.