Does breathing contribute to CO2 buildup in the atmosphere?

The CO2 we breathe is part of a balanced carbon exchange between the air and the earth. In contrast, burning fossil fuels injects CO2 into the atmosphere that has been stored underground for millions of years, causing a rapid buildup.

Fast cycling of carbon is seasonal. CO2 increases in colder months when plants decay and release their carbon. In the warmer months, CO2 decreases as plants take it in, along with sunlight, to produce energy and oxygen. Animals — including humans — eat plants, breathe in oxygen, and exhale CO2. Graphs of CO2 show a wave pattern reflecting this seasonal change.

Fossil fuels are part of the slow carbon cycle that operates over geological timescales. Burning fossil fuels takes carbon stored in the slow cycle and introduces it into the fast one. This activity is unique in Earth’s history; no other life-form has done anything on the same scale.