Changes in the carbon cycle

Question 1

Physical causes

Answer 1

• Milankovitch cycle
• Natural climate change
• Volcanic activity

Question 2

Natural climate change

Answer 2

• Quaternary period- global climates fluctuated between warm (interglacial) and cold (glacial) periods
• Higher temperatures are associate with higher levels of co2 in the air
• Increased level of CO2 leads to the enhanced greenhouse effect and subsequent global warming

Question 4

Volcanic activity

Answer 4

• Returns carbon trapped in volcanoes for millions in deep rocks in the earth’s crust
• Lava contains silicates that weather slowly and converts co2 into carbonates

Question 5

Human causes

Question 6

Combustion of fossil fuels

Answer 6

• Fossil fuels are long-term carbon stores that comprise of carbon locked away within remains of dead organic matter
• When burnt to generate energy and power the stored carbon is released as Co2 in atmosphere accelerating the rate of cycle
• Since industrial revolution, fossil fuels have been burnt in increasing quantities pumping CO2 into the atmosphere

Question 7

Land use change

Question 8

Farming practices

Answer 8

• Ploughing, harvesting, and rearing livestock uses machinery fuelled by fossil feuls
• Ferllisers based on carbon is another farming practice that releases carbon
• Livestock farming releases methane
• Rice farming also releases methane

Question 9

Deforestation

Answer 9

• Trees are removed for by felling or burning for building, ranching, mining or crop growth
• Accounts for 20% of global CO2 emissions
• Carbon is released into the atmosphere
• System has now become carbon source rather than sink

Question 10

Urbanisation

Answer 10

• Replacing countryside with concrete and tarmac
• Important stores are replaced or covered up with impermeable surfaces