Search results
Results from the WOW.Com Content Network
Soil carbon is a carbon sink in regard to the global carbon cycle, playing a role in biogeochemistry, climate change mitigation, and constructing global climate models. Microorganisms play an important role in breaking down carbon in the soil.
The fast or biological cycle can complete within years, moving carbon from atmosphere to biosphere, then back to the atmosphere. The slow or geological cycle may extend deep into the mantle and can take millions of years to complete, moving carbon through the Earth's crust between rocks, soil, ocean and atmosphere. [2]
Deforestation, for example, decreases the biosphere's ability to absorb carbon, thus increasing the amount of carbon in the atmosphere. [24] As the industrial use of carbon by humans is a very new dynamic on a geologic scale, it is important to be able to track sources and sinks of carbon in the atmosphere.
Carbon sequestration is part of the natural carbon cycle by which carbon is exchanged among the biosphere, pedosphere (soil), geosphere, hydrosphere, and atmosphere of Earth. [ citation needed ] Carbon dioxide is naturally captured from the atmosphere through biological, chemical, or physical processes, and stored in long-term reservoirs.
Additionally, carbon is stored in fossil fuels and is released into the atmosphere through human activities such as burning fossil fuels. In the nitrogen cycle, atmospheric nitrogen gas is converted by plants into usable forms such as ammonia and nitrates through the process of nitrogen fixation .
These free ecosystem services are not given a market value under most current economic systems, and so forest conservation has little appeal when compared with the economic benefits of logging and clearance which, through soil degradation and organic decomposition returns carbon dioxide to the atmosphere. [19]
Soil respiration is a key ecosystem process that releases carbon from the soil in the form of carbon dioxide. Carbon is stored in the soil as organic matter and is respired by plants, bacteria, fungi and animals. When this respiration occurs below ground, it is considered soil respiration.
By the early 1980s, the United States' National Center for Atmospheric Research had developed the Community Atmosphere Model; this model has been continuously refined. [44] In 1996, efforts began to model soil and vegetation types. [45] Later the Hadley Centre for Climate Prediction and Research's HadCM3 model coupled ocean-atmosphere elements ...