Carbon negative territories
Introduction
In general terms, a carbon sink, CO sink or carbon reducer is a natural or artificial carbon deposit, which absorbs carbon from the atmosphere and contributes to reducing the amount of CO in the air. The main sinks were the biological processes of production of coal, oil, natural gas, methane hydrates and limestone rocks. Today they are the oceans, and certain plant environments (forming forests).
Carbon sequestration is the process of extracting carbon or CO from the atmosphere and storing it in a reservoir.
Photosynthesis is the main carbon sequestration mechanism. Photosynthetic bacteria, plants and the food chain are considered carbon sinks.
The concept of carbon sink has spread with the Kyoto Protocol, created to reduce the high and growing concentration of CO in the air and thus fight against global warming. Various ways to improve natural carbon sequestration are being explored, including developing techniques (natural or artificial) to capture and store carbon.
A carbon sink is not intended to reduce CO emissions, but rather to reduce its concentration in the atmosphere.
CO storage can even increase CO emissions, as this activity inevitably consumes energy (which produces CO), but the amount of CO needed for this activity is less than the trapped CO.
Natural sinks
Forests
Trees are the planet's main natural sinks, essential for the carbon cycle. Huge amounts of carbon accumulate in the wood and in the ecosystem through photosynthesis. They absorb CO from the atmosphere, store a portion of the carbon taken in, and return oxygen to the atmosphere. Fast-growing, pioneer species (e.g. poplar, willow, birch) generally absorb little carbon. Hardwoods are denser and store more carbon and for longer, but they generally grow more slowly (centuries or millennia). At maturity, absorption is lower, but carbon represents 20% of its weight on average. When the tree dies, the wood is decomposed by bacteria, fungi and invertebrates, recycling its carbon as biomass, dead organic matter (corpses and excrement of these organisms) and, in the form of gases (CO and methane) released into the atmosphere or water. Forests and other ecosystems continue to store or recycle that carbon through natural regeneration. Only temperate forests accumulate carbon, tropical forests are often in equilibrium (source = sink).