Carbon

Question 1

Key features of the biochemical carbon cycle

Answer 1

• most of Earth’s carbon over 100 million PgC is stored in the lithosphere
• much of this is in fossil fuel rocks and in limestones
• the remainder is in the hydrosphere, atmosphere, biopshere and cryosphere
• carbon flows between each of these stores in a complex set of exchanges (fluxes)
• a change that shifts carbon out of one store and puts more into another (sink)
• major fluxes are between the atmosphere and the oceans and the land and the atmosphere

Question 2

The accumulation of carbon

Answer 2

• most of Earth’s carbon is geological
• weathered calcium and bicarbonates are washed to the sea and used by microscopic marine animals (microfauna) to form shells
• ocean algae also draw down co2 from the air
• when microfauna die their shells sink to the ocean floor and compressed to form sediments of carbonate rocks
• carbon locked up in carbonate rocks can be stored for millions or hundreds of millions of years
• carbon is stored in rocks where dead plant material built up faster than it could decay to become coal, oil and natural gas
• carbon is also stored in compressed clay deposits called shales

Question 3

The release of carbon…..

Answer 3

• carbon is emitted to the atmosphere through volcanoes
• during subduction heated rock recombines into silicate minerals releasing co2
• when volcanoes erupt they vent the gas to the atmosphere and cover land with fresh silicate rock
• this process also occurs at mid ocean ridges and at volcanic hot spots

Question 4

Weathering….

Answer 4

• atmospheric co2 combines with water vapour to form a weak carbonic acid that falls as rain
• this acid dissolves rocks and releases calcium, magnesium, potassium and sodium ions
• through their growth plants also break up surface granites and microorganisms hasten the weathering with enzymes and organic acids in the soil

Question 5

Key points of ocean sequestration

Answer 5

• ocean store of carbon is very large
• the ocean carbon pump operates in several ways;
  phytoplankton - near surface take co2 from atmosphere

through absorption into their cells and using energy from sun - use photosynthesis

downwelling and upwelling ocean currents move dissolved co2 around the ocean

as phytoplankton and other animals die they sink and form sediments on ocean floor

Question 6

Key points of terrestrial processes

Answer 6

• plants on land sequester carbon from atmosphere
• during photosynthesis plants absorb co2 and sunlight to create carbohydrates and other sugars for building plant structures

Question 7

Carbon is returned back to the atmosphere through…

Answer 7

• respiration - animals eat the plants and breakdown sugar to get energy - other animals eat the herbivores and carbon thus flows through an ecosystem
• decomposition - plants and animals die, decay and are eaten by bacteria
• combustion - natural fire consumes plants

Question 8

Carbon fluxes on land vary…..

Answer 8

• diurnally - during daylight = fluxes are from atmosphere to land and at night = reverse
• seasonally - during spring and summer = fluxes are from atmosphere to land and during autumn and winter = reverse

Question 9

Key points on soil based processes

Answer 9

• soils store between 20-30% of global carbon and sequester about 2x the quantity of carbon as the atmosphere and 3x the terrestrial vegetation
• carbon is stored as dead organic matter with larger amounts in tropical rainforests and smaller amounts in tundra regions
• most soils like clays hold more carbon than sandier soils

Question 10

Key points on the greenhouse effect

Answer 10

• natural concentrations of co2 and methane in the atmosphere are major elements of greenhouse effect
• if greenhouse effect was not present global temperatures would be 30 degrees cooler
• GHGs reradiate heat back to the surface too
• global temps are warmer and therefore precipitation rates are greater

Question 11

Photosynthesis key points

Answer 11

• photosynthesis regulates the NPP of vegetation around the world and plays a role in regulating atmospheric co2 levels and global temps
• NPP is highest in tropical rainforests and warm shallow oceans
• NPP is lowest in the arid and tundra areas

Question 12

Soil health

Answer 12

• amount of carbon in soil determines its health
• soil health determined by net carbon balance between inputs (plant/animal remains) and outputs (erosion and decomposition)
• strong positive correlation between soil health and ecosystem productivity

Question 13

Key points of fossil fuel combustion

Answer 13

• people have influenced the carbon cycle where fossil fuels have been mined and burnt
• burning produces around 21pg of co2 per year and natural processes only absorb some of this so increase in net 8.5pg of atmospheric co2 per year
• co2 is a GHG that enhances atmospheric heating and contributes to climate change

Question 14

The key relationships between the water cycle, carbon cycle and climate change are……

Answer 14

• changes in carbon cycle are causes of climate change through greenhouse effect and enhanced greenhouse effect
• climate change continues to have an affect on the water cycle like more evaporation and/or more precipitation in some regions
• climate change is having an effect on carbon cycle as increase in release of co2 from permafrost as climate increases
• more extreme weather events
• melting of ice caps
• declining ecosystem biodiversity and coral bleaching

Question 15

Energy security

Answer 15

• affordable and competively priced energy supply
• accessible and available energy supply
• energy mix dependent on domestic rather than imported sources of energy
• reliable and uninterrupted energy supply

Question 16

What is consumption of energy measured by?

Answer 16

• per capita kilograms of oil equivalent - measure of economic development
• energy intensity - measure of energy efficiency

Question 17

What does energy consumption depend on?

Answer 17

• availability of energy - some areas are energy rich (USA) whereas others are energy poor (Africa)
• cost of energy production - depends on the accessibility of resources and whether subsidies exist
• level of economic and technological development - determine demand for and availability of energy
• standards of living and attitudes to energy use - determines rates of energy use and wastage
• climate - some countries make greater use of energy to either heat or cool external weather conditions
• environmental priorities - there are varying governmental attitudes to the cost of the environment vs need for cheap energy

Question 18

The energy mix of a country varies depending on…..

Answer 18

• availability of resources
• government attitudes to development of either primary or secondary sources
• government attitudes to development of renewable or non renewable sources

Question 19

Reliance on fossil fuels - supply vs demand - OIL

Answer 19

• oil reserves were mainly in the middle east; the USA and canada had large tar sand deposits
• USA accounted for majority of the non OPEC output - it took over from Saudi Arabia as worlds largest oil producer
• largest consumption per capita was in North America, Western Europe, Australia Saudi Arabia and Russia

Question 20

Reliance on fossil fuels - supply vs demand - NATURAL GAS

Answer 20

• gas reserves were greatest in Iran Russia Qatar and Turkmenistan
• USA was worlds leading producer
• consumption per capita was highest in western europe and USA

Question 21

Reliance on fossil fuels - supply vs demand - COAL

Answer 21

• major reserves of coal were in usa, china, russia, india, australia, and indonesia
• global coal production fell by 2% with declines in both china and ukraine
• china and india were major consumers; there was a 7% decline in EU

Question 22

Key points on pathways

Answer 22

• energy is transported by a number of pathways - shipping routes, pipelines, road and rail
• routes are subject to disruption due to accidents, politics and terrorist attacks
• number of key energy pathways;
  oil - 61% of global oil consumption traded between countries (pipelines)

natural gas - pipeline shipments from russia to western europe are significant; shipping routes of lng are increasingly important

coal - shipping movements from russia, australia and indonesia to china and india

Question 23

Key points of biofuels

Answer 23

• fuelwood is a long established form of biofuel - its use is still important in some developing areas of the world
• biofuel crops are becoming increasingly popular
• biomass can be converted relatively cheaply into ethanol or biodiesel
• increased production of biofuels means there is less land for food crops

Question 24

What are some of the impacts when a critical threshold of ocean acidification is crossed?

Answer 24

• growth of coral reefs is reduced
• bleaching of coral takes place killing parts of reefs
• creatures that live in coral reefs have their habitats slowly disrupted
• ecosystem service that coral provides is therefore impaired

Question 25

Key points on health of forests

Answer 25

• the enhanced greenhouse effect and resultant climate change is impacting on worlds forests
• climatic belts are shifting polewards
• droughts in forested areas are increasing - eg - in amazon there was major droughts in 2005 and 2010
• tropical rainforests in particular are therefore under threat as major carbon stores

Question 26

Key points of forest loss and human wellbeing

Answer 26

• as people reach higher levels of wealth societies reach a tipping point when the costs of environmental exploitation are fully realised
• at this point resource conservation and protection come to the fore and there may be an expansion of forests
• means it could be argued forest loss has a positive impact in longer term

Question 27

Rising temps….

Answer 27

• there has been a loss of sea ice
• much of the sea to the north of canada and siberia is now ice free for several months per year
• permafrost in canada and siberia is melting
• tundra plants in these areas are growing at faster rates which increases carbon uptake
• a lower albedo is created as previous white snowy surfaces are replaced with a darker plant covered surface - further warming

Question 28

Key points on declining ocean health

Answer 28

• global stocks of fish and crustaceans are declining and changing their distributions
• people who depend on fishing for everyday life are having to adapt
• aquaculture is becoming more important
• tourism is also being affected as coral reefs die/need protecting

Question 29

What are some uncertainties in future changes in carbon cycle and water cycle?

Answer 29

• rate of increases in atmospheric concentration of co2 due to combustion and/or permafrost melting
• whether a further enhanced greenhouse effect will create even more climate warming
• degree to which carbon sinks continue to operate
• whether people adopt more sustainable economic systems - have more renewable energy supplies and curb population growth