What is the carbon cycle?

Life on earth is based on carbon

The carbon cycle is the continuous geochemical cycle of carbon between the atmosphere, the earth and the oceans. The process of photosynthesis in all living plants extracts sunlight and CO2 from the atmosphere to produce carbohydrates. Respiration is the process of releasing CO2 back into the atmosphere.

CO2 is also released when decomposers and detritus feeders break down dead organic matter. Reservoirs of carbon exist in the form of plant matter such as forests, in oceans, in the lithosphere in the form of fossil fuels, and as calcium carbonate in the shells of marine organisms.

Stores of carbon are thus known as ‘carbon sinks’. Carbon is continuously cycled through these reservoirs and processes in what is known as ‘the carbon cycle’. However, since the industrial revolution, humans have increased the levels of CO2 in the earth’s atmosphere and oceans, altering the natural balance of the carbon cycle.

This has been primarily due to the increase in fossil fuel burning which releases CO2 into the atmosphere and the loss of carbon sinks due to rapid deforestation to facilitate agriculture. The change is in the concentration of carbon that is now found in the atmosphere and not in living organisms, this relates again to the greenhouse effect and the increase in global atmospheric temperature.

The Carbon Cycle Diagrame

 What is Carbon Sequestration?

The storage of carbon, including anthropogenic CO2 that would otherwise affect global climate change, in large-scale carbon sinks, such as forests.

The carbon can be siphoned off at the point of emission and then placed in underground reservoirs (geological sequestration), injected in deep oceans (ocean sequestration), or converted to rock-like solid materials.

Why do we need Carbon Sequestered?

Most scientists believe that the rapid increase in atmospheric CO2 has resulted in some human-induced global warming. Most experts agree that if the warming trend continues, climate change is inevitable.Temperatures will rise, as will sea levels.

Atmospheric levels of CO2 have risen from preindustrial levels of 280 parts per million to present levels of 375 parts per million.Levels of carbon in the atmosphere are likely to continue to rise, mainly due to increasing use of fossil fuels for energy, unless major changes are made in the way we produce and use energy, specifically, how we manage carbon.

How can Carbon Sequestration help?

By storing carbon we balance out the release of carbon into the atmosphere.Slowing the greenhouse effect and ensuring that the world can continue to develop sustainably.

How can Carbon be sequestered?

There are three main ways in which carbon can be sequestered.

Terrestrial Sequestration, Geological Sequestration, and Ocean Sequestration.

Terrestrial Carbon Sequestration

Carbon sequestration in terrestrial ecosystems can be one of two things: Removing CO2 from the atmosphere, or stopping CO2 emissions from terrestrial ecosystems entering the atmosphere. The terrestrial biosphere is estimated to sequester approximately 2 billion metric tons of carbon per year.We can improve terrestrial sequestration in Forest lands, by planting more trees. Research is ongoing into the use of Agricultural lands, Deserts and degraded lands, Boreal wetlands and peatlands. For example the restoration of desertified or damaged land will increase its carbon sink properties.

Geological Carbon Sequestration

Where CO2 is sequestrated in geologic formations such as: depleted oil and gas reservoirs, shale formations with high organic content, unmineable coal seams, and underground saline formations.

Since 1996, Statoil has been storing approximately one million tons per year of recovered CO2 into the Utsira Sand, a saline formation in the North Sea. The amount being sequestered is equivalent to the output of a coal-fired power plant.

Ocean Carbon Sequestration

CO2 is soluble in ocean water, and oceans both absorb and emit huge amounts of CO2 into the atmosphere through natural processes. It is widely believed that the oceans will eventually absorb most of the CO2 in the atmosphere. However, ocean carbon sequestration is extremely slow.

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