The Carbon
Cycle and
Energy
Security
Enquiry Question 3: How are the carbon and water cycles
linked to the global climate system?
, 6.7 Biological carbon cycles and the water cycle are threatened by human activity
Increased threat due to:
Increased population - increased demand for food = more deforestation, grassland
conversion
Economic development - increased demand for resources, eg: wood
Urbanisation
Industrialisation, NIC's
Rise in the middle class, China - per capita consumption increases, people wealthier =
increased meat consumption = increase in cattle = deforestation
Impact on Biological Carbon Cycle
Deforestation:
Sequestration of less carbon dioxide from the atmosphere - decrease in
photosynthesis
Increase in carbon dioxide in the atmosphere = enhanced greenhouse effect
Decrease carbon store in biomass (plants)
Decreased carbon in soils = fewer leaves/branches falling that would decompose,
leaching removes nutrients and soil erosion due to less root binding
Impact on Water Cycle
Deforestation
Increased surface runoff
Increased flooding - shorter lag time
Increased interception of rainfall
Decreased infiltration
Decreased evapotranspiration
Regional Trends
Temperate forests, such as the UK and USA have a long history of exploitation, 90%
was deforested by the 19th century, due to the Industrial Revolution
Boreal forests, have been increasingly threatened since the mid-20th century, eg: oil
sands and tar sands in Russia and Canada
Tropical forests, have lost half their area since the 1960's, especially in Africa and
South America - due to cattle ranching, timber and bauxite extraction, HEP dams
Temperate grasslands, have fertile soils prized for agriculture and suffer most from
degradation, eg: only 2% of North American prairies remain from land conversion
Tropical grasslands or savannah, eg: Africa's Serengeti, land conversion is increasing
despite often infertile soils
Cycle and
Energy
Security
Enquiry Question 3: How are the carbon and water cycles
linked to the global climate system?
, 6.7 Biological carbon cycles and the water cycle are threatened by human activity
Increased threat due to:
Increased population - increased demand for food = more deforestation, grassland
conversion
Economic development - increased demand for resources, eg: wood
Urbanisation
Industrialisation, NIC's
Rise in the middle class, China - per capita consumption increases, people wealthier =
increased meat consumption = increase in cattle = deforestation
Impact on Biological Carbon Cycle
Deforestation:
Sequestration of less carbon dioxide from the atmosphere - decrease in
photosynthesis
Increase in carbon dioxide in the atmosphere = enhanced greenhouse effect
Decrease carbon store in biomass (plants)
Decreased carbon in soils = fewer leaves/branches falling that would decompose,
leaching removes nutrients and soil erosion due to less root binding
Impact on Water Cycle
Deforestation
Increased surface runoff
Increased flooding - shorter lag time
Increased interception of rainfall
Decreased infiltration
Decreased evapotranspiration
Regional Trends
Temperate forests, such as the UK and USA have a long history of exploitation, 90%
was deforested by the 19th century, due to the Industrial Revolution
Boreal forests, have been increasingly threatened since the mid-20th century, eg: oil
sands and tar sands in Russia and Canada
Tropical forests, have lost half their area since the 1960's, especially in Africa and
South America - due to cattle ranching, timber and bauxite extraction, HEP dams
Temperate grasslands, have fertile soils prized for agriculture and suffer most from
degradation, eg: only 2% of North American prairies remain from land conversion
Tropical grasslands or savannah, eg: Africa's Serengeti, land conversion is increasing
despite often infertile soils
