The Carbon Budget (AQA A Level Geography)

• The carbon budget is the amount of carbon stored and transferred within the carbon cycle on global or local scale
• The budget includes carbon emissions by various processes (i.e. burning fossil fuels) against natural or human sequestration
•  Calculated using a carbon footprint calculator and is defined as:

the total amount of greenhouse gases produced (directly and indirectly) to support human activities, and expressed in gigatonnes of carbon dioxide equivalent per year (GtC/yr)

• One GtC is a billion (1,000,000,000) tonnes and can also be referred to as a petagram (Pg)

Global carbon budget showing the amount of carbon stored and circulating through the system

• The carbon cycle impacts the Earth in many ways
  • Releases CO₂ and other greenhouse gases that absorb outgoing long-wave radiation; warming the lower atmosphere
  • Ash and gases from volcanic activity release CO₂, which again absorb insolation, cooling the earth
  • Phytoplankton can release dimethyl sulphide into the atmosphere, which can increase cloud formation (water vapour)
  • Plants remove CO₂ and release water and oxygen; areas of dense vegetation shows increased precipitation rates
• Further impacts of the carbon cycle can be categorised as follows:

Impacts of the Carbon Cycle 

Atmosphere	Land	Ocean
CO2 in the atmosphere warms the Earth through the natural greenhouse effect	Soil is made from organic matter and cycled through the carbon system, which also brings important trace nutrients to assist in further vegetation growth	Calcium carbonate is derived from carbon and is utilised by marine animals to build shells and skeletons
Increases in carbon emissions has led to the enhanced greenhouse effect and threatens the delicate atmospheric balance	Carbon stored in grass provides food for animals - hay, silage etc.	Plant and animal remains are dropped to the ocean floor and compress into sedimentary rock and hydrocarbons effectively locking carbon in a long-term cycle
Carbon is stored by vegetation and act as carbon sinks, holding carbon on a short-term basis. Wildfires and deliberate burning, releases carbon quickly into the atmosphere	Carbon also provides energy in the form of fossil fuels (hydrocarbons) and wood	Phytoplankton utilise CO2 during photosynthesis, which is then transferred along the marine food chain
Deforestation disturbs the balance between length and capability of trees to store carbon, removal of trees not only releases carbon, but also reduces the availability of oxygen and water the	Carbon also provides a valuable resource in charcoal, diamonds and graphite	Increased levels of CO2 and warming of the oceans has led to algal blooms and blocking of sunlight for photosynthesis by phytoplankton