Carbon Cycle

Question 1

Main Transfers/Processes in the Carbon Cycle

Answer 1

Photosynthesis, Respiration, Decomposition, Combustion, Burial and Compaction, Carbon Sequestration, Weathering

Question 2

Storage of Carbon in the Lithosphere

Answer 2

• Rocks formed by the hardening of mud into shale over time
• 99% of carbon on Earth is in the lithosphere in rocks such as limestone
• 0.004% of all carbon on Earth is in fossil fuels, 40,000 billion tonnes

Question 3

Storage of Carbon in the Hydrosphere

Answer 3

• Carbon is dissolved and stored as bicarbonate and carbonate ions
• Mostly stored in the intermediate zone of the oceans, in the form of dissolved inorganic carbon
• 0.0038% of all carbon on Earth, 38,000 billion tonnes

Question 4

Storage of Carbon in the Pedosphere

Answer 4

• Dead material from organic matter is stored as soil organisms and plant remains
• 0.0031% of all carbon on Earth, 31,000 billion tonnes

Question 5

Storage of Carbon in the Cryosphere

Answer 5

• Stored in frozen masses and methyl clathrates, molecules of methane frozen into ice crystals.
• 0.0018% of all carbon on Earth, 18,000 billion tonnes

Question 6

Storage of Carbon in the Atmosphere

Answer 6

• Stored as gaseous carbon in carbon dioxide and methane mostly
• 0.0017% of all carbon on Earth, 750 billion tonnes

Question 7

Storage of Carbon in the Biosphere

Answer 7

• Stored in living organisms
• 20% in tropical forests
• 10% temperate grasslands
• 9% in agriculture
• 26% in boreal rainforests
• 8% in tundra
• 8% in tropical savannahs
• 7% in wetlands
• 7% in temperate forests
• 5% in deserts
• 0.0012% of all carbon on Earth

Question 8

Processes that cause carbon to move quickly

Answer 8

• Photosynthesis
• Respiration
• Volcanic Activity
• Combustion
• Ocean-Atmospheric Exchange

Question 9

Processes that cause carbon to move slowly

Answer 9

• Fossilisation
• Formation of sedimentary rocks
• Subduction and Volcanism
• Chemical Weathering

Question 10

Natural Factors Affecting the Carbon Cycle over time

Answer 10

• Natural Climate Change
• Wildfires
• Volcanic Activity

Question 11

Human Factors Affecting the Carbon Cycle over time

Answer 11

• Hydrocarbon Fuel Extraction and Burning
• Farming Practices
• Land Use Changes

Question 12

How does Natural Climate Change affect the Carbon Cycle over time

Answer 12

• Long Term Glacial or Interglacial periods. In Glacial periods, ice levels rise, sea levels fall, more vegetation grows, absorbing more CO2, glacial surfaces act as carbon sinks. Colder ocean water absorbs and dissolves more CO2.
• Milankovitch Cycles:
  1. Eccentricity of Earth’s orbit
  2. Axial Tilt of the Earth causes variation in warming
  3. Precession, a charge in angle of the Earth’s axis

Question 13

How do Wildfires affect the Carbon Cycle over time

Answer 13

• Uncontrolled, unplanned combustion of vegetation
• Act as a very fast transfer of carbon:
  1. Complete combustion occurs in the presence of O2, releasing CO2
  2. Incomplete Combustion occurs in the absence of O2, releasing CO
  3. Decomposition occurs as black carbon settles and sequesters
• Wildfires tend to occur in certain regions more often due to specific environmental conditions and vegetation types, such as having diverse surface vegetation and high fuel loads

Question 14

How does Volcanic Activity affect the Carbon Cycle over time

Answer 14

• A very rapid transfer of carbon from the lithosphere to the atmosphere
• In the short term, volcanic sulphur dioxide cools the Earth, but CO2 causes warming
• Sulphur dioxide is converted to sulphuric acid, which condenses rapidly to form fine sulphate aerosols, which increase solar reflection
• Human emissions are 100-244 times larger than volcanic emissions

Question 15

How does Hydrocarbon Fuel Extraction and Burning affect the Carbon Cycle over time

Answer 15

• 90% of anthropogenic carbon release is due to the burning of fossil fuels
• Extraction has more than tripled since 1970, with a 45% increase in fossil fuels
• The Industrial Revolution caused a substantial increase in emissions since the 1950s
• Well developed and rapidly developing nations tend to emit more greenhouse gases
• Huge, long-term but fast transfer of carbon to the atmosphere
• Methane is the largest component of natural gas. Oil is made top of C, H2, N2 and S

Question 16

How do Farming Practices affect the Carbon Cycle over time

Answer 16

• The global need to increase consumption of food per capita, as well as the rapidly growing population
• Clearing natural biomes, such as tropical rainforests, for agriculture reduces carbon sequestration. The deforestation involved releases stored carbon dioxide.
• Draining peatlands and the drying-out of peat beds led to a huge release of stored CO2 in the form of methane
• Waterlogged fields for farming rice foster methane-producing bacteria
• Cattle release methane during digestion, the increasing need to increase the size of cattle leads to increased digestion due to over-feeding
• No-till agriculture by not aerating the soil helps to retain soil carbon
• Agroforestry, cover crops, enhanced weathering all prevent carbon release

Question 17

How do Land Use Changes affect the Carbon Cycle over time

Answer 17

• Urban Sprawl, the growing global middle-class and the growth of cities due to rural-urban migration has increased urbanisation
• Increased consumption, leads to increased emissions for transportation of products
• Increased construction, reduction of rural areas, energy needs
• technological advancements in transport, energy or construction reduces emissions
• Regulations keep and protect green areas (AONBs)
• Urban areas contribute to 75% of global carbon emissions