What role do forests play in the global carbon balance?
Each year, billions of tonnes of carbon are exchanged between the Earth’s atmosphere, oceans, and terrestrial ecosystems, including forests. Forests store large amounts of carbon that has over time been sequestered from atmospheric carbon dioxide by growing trees. Forests have the potential to either sequester more carbon (carbon sinks), or release their stored carbon back into the atmosphere (carbon sources). Most of the carbon exchanged between forests and the atmosphere is transferred by natural processes, such as tree growth, decomposition of plant material, and disturbance (for example, fire), but human actions can also strongly influence the forest’s role in the global carbon cycle. Before the Industrial Revolution, the carbon dioxide concentration in the atmosphere had been more or less stable for a few millennia at about 280 parts per million. Today, as a result of human activity, the concentration is about 380 parts per million, the highest level in at least 650,000 years. The
