The carbon cycle is a biogeochemical process in which carbon is exchanged between reservoirs through fluxes over a period of time. The dynamic equilibrium of the carbon cycle is heavily disrupted due to human emissions from burning fossil fuels and land degradation, leading to increased levels of carbon dioxide. The Keeling curve is the longest recorded graph of CO2 concentration in the atmosphere on Earth; it indicates that CO2 levels today are the highest in 800,000 years.