The Carbon Cycle

Question 1

Slow Carbon Cycle/Geological Carbon Cycle

Answer 1

Terrestrial carbon, held within the mantle, is released into the atmosphere as carbon dioxide this is known as volcanic outgassing
Carbon dioxide combines with rainfall to produce a weak acid (carbonic acid) that dissolves carbon-rich rocks releasing biocarbonates through chemical weathering of SILICATE ROCKS
Rivers transport weathered carbon and calcium sediments to the oceans where they are deposited
Carbon in organic matter from animal shells and skeletons sinks to the ocean bed when they die, building up strata of coal, chalk and limestone
Carbon-rich rocks are subducted along plate boundaries and eventually emerge again when volcanoes erupt
The presence of intense heating along the subduction plate boundaries metamorphoses sedimentary rocks by baking, creating metamorphic rocks. Carbon dioxide is released by the metamorphosis of rocks rich in carbonates.

Question 2

What are the types of carbon?

Answer 2

Inorganic - found in rocks as bicarbonates and carbonate
Organic - found in plant material
Gaseous - found as carbon dioxide, methane or carbon monoxide

Question 3

Fluxes

Answer 3

Combustion
Decomposition
Diffusion
Sedimentation: e.g when organisms die and there shells sink to the ocean floor and become compacted over time to form limestone
Weathering and erosion
Metamorphosis - extreme heat and pressure forms metamorphic rock, during which some carbon is released
Volcanic outgassing

Question 4

Is there more carbon dioxide released in the northern or southern hemisphere?

Answer 4

Carbon dioxide fluxes vary with latitude. Levels are always higher in the Northern Hemisphere, because it contains a greater landmass and greater temperature variations that in the Southern Hemisphere.

Question 5

Himalayas

Answer 5

One of the largest carbon stores is the Himalayas which started off as oceanic sediments rich in calcium carbonate. Folded up by mountain building, this carbon is being actively weathered, eroded and transported back to the ocean.

Question 6

How is oil and natural gas formed?

Answer 6

Formed from the remains of tiny aquatic animals and plants
Gas and oil occur in ‘pockets’ in rocks migrating up through the crust until meeting caprocks (impermeable rock layers that seal the top of reservoirs)
Natural gas, such as methane is made up of fractions of oil molecules so small they are in gas form not liquid and usually found with crude oil.
Other hydrocarbon deposits include oil shales, tar sands and gas hydrates.

Question 7

How is coal formed?

Answer 7

Formed from the remains of trees, ferns and other plants
Soft coals such as lignite and brown coal are lower in carbon (25-35%) and energy potential; these are the major global source of energy supplies but emit more carbon dioxide than hard coals
Peat is the stage before coal and it is an important carbon source

Question 8

How are fossil fuels made?

Answer 8

Made up to 300 million years ago from the remains of organic material, organisms, once dead, sank to the bottom of the rivers and seas, were covered in silt and mud and decayed anaerobically. The deeper the deposit, the more heat and pressure exerted on the deposits.

Question 9

Carbon sequestered in limestone and sedimentary rock

Answer 9

Shell building (calcifying) organisms (coral) and plankton
These are precipitated onto the ocean floor, form layers are cemented together and turned into limestone
Other rocks contain organic organisms carbon from organic organims that have been embedded in layers of mud over millions of years heat and pressure compress the mud and carbon into sedimentary rock such as shale

Question 10

Phytoplankton

Answer 10

Phytoplankton (tiny microscopic marine plants) live in the surface ocean although minute their enormous make up half of the planets primary productivity. Phytoplankton absorb carbon by photosynthesis and have rapid growth rates. Fish and other animals eat the phytoplankton and release the CO2.

Question 11

Carbon in oceans

Answer 11

CO2 reacts with water to make carbonic acid and carbonate ions. Many organisms then use the carbonate ions to make their hard outer shells. When organisms die they either sink to the ocean bed and build up to create limestone or their shells dissolve releasing carbon back into the ocean.

Question 12

Thermohaline circulation

Answer 12

The main current begins in the polar oceans where the water gets very cold and sea ice forms surrounding sea water gets saltier increases in density and sinks
The current is recharged as it passes Antarctica by extra cold salty, dense water
Division of the main current northward into the Indian ocean and Western Pacific
The two branches warm and rise as they travel northward then loop back southward and westward
The now warmed surface water continue circulating around the globe on their eventual return to the North Atlantic they cool once again

Question 13

Why are mangroves being cleared?

Answer 13

Mangroves are being cleared for tourism, shrimp farms and aquaculture.

Question 14

Precipitation at different latitudes

Answer 14

Because solar energy is insolation is most intense over the equator, convection and low pressure systems dominate their rainfall is high all year round
As the pressure rises around 30 degrees north and south of the equator precipitation decreases
In the mid latitudes air masses of different characteristics meet and low pressure systems bring rainfall
Nearer the Poles, precipitation falls as the air cools further and is dense and dry creating polar deserts

Question 15

Carbon in soils

Answer 15

Carbon stored in soils is vital it supports the micro-organisms and maintains the nutrient cycle break down organic matter, provide pore spaces for infiltration and storage of water, and enhances plant growth.

Question 16

Urban energy usage

Answer 16

Cities consume 75% of the world’s energy
Manhattan Island in New York is home to 1.7 million people who consume more energy a year than the average Madagscan will in a lifetime
City of London generates 1.8 tonnes of carbon per capita

Question 17

Rural energy usage

Answer 17

Peru carried out a national programme of solar-panel installation and electricity was made available to 500,000 homes in remote villages across the country.In 2013 only 66% had acess to electricty.

Question 18

UK case study

Answer 18

Until 1970s relied heavily on coal
Discovery of large gas and oil reserves in North Sea
One of the global leaders of nuclear power 1950s-70s
North sea oil reserves are a viable alternative when Middle Eastern oil price increase however, it is expensive to extract so the UK rely heavily on oil exports
There are currently 150 years left of coal supplies in the UK
However, the UK’s last deep coal mine closed in 2015
Average annual household energy costs for a three bedroom house around £1700 (British gas)

Question 19

Norway case study

Answer 19

Norway is mountainous with steep valleys and plentiful rainfall and hydro electric power is a good choice
Coal from Svalbard is exported
Norsk Hydro has over 600 HEP sites which supply 97.5% of Norway’s renewable energy
GDP per capita $61,500
Average annual household energy costs £2400 (2015)

Question 20

OPEC

Answer 20

The organisation of petroleum exporting countries
Between OPEC producers they control 81% of the world’s proven oil reserves

Question 21

Coal India Ltd

Answer 21

World’s largest coal producer
Nationalised in 1972
80 mining areas and responsible for 5.9% of the world’s coal

Question 22

Gazprom

Answer 22

Put under state control in 2000
Russian gas exports to Europe have declined from 40% to 9%
Two Nord Stream pipelines built at a cost of over €20 billion lie holed on the bottom of the Baltic. Meanwhile, its share price is down 88 percent since the February invasion and the company in August was spotted flaring large quantities of unsold gas.

Question 23

Denmark’s energy mix

Answer 23

Wind turbines produce 40% of the country’s electricity
In July 2015 Denmark produced 116% of its national electricity needs from wind turbines and was able to export some to neighbouring countries
Since 1990 Denmark has reduced its greenhouse emissions by 30%

Question 24

Energy pathways are easily disrupted

Answer 24

Russian gas to Europe
Russia is the second largest producer of gas
Pipelines: Nord Stream, Nord Stream 2 (Under Baltic Sea from Russia to Germany) and the Yamal (through Ukraine)
The Yamal has a capacity of 33 billon cubic meters per year
In June, Russia cut the flow of gas to Germany by more than half, and in September of that year it stopped it altogether. On 26 September 2022, three of the four pipes of the Nord Stream 1 and 2 gas pipelines ruptured with evidence of sabotage as leaks have been reported
Piracy attacks
In December 2015 piracy attacks were carried out along the straight of Malacca between Malaysia, Indonesia and Singapore
This is the world’s second largest chokepoint criminal gangs often seize ships for hostage payments over 500 attacks occurred between 2009 and 2015
Fukushima
Nuclear plant destroyed due to earthquake that caused a tsunami
100 mile evacuation zone
FOSSIL FUELS ARE DEPLETING

Question 25

Unconventional fossil fuel reserves - deep water oil

Answer 25

Found in the Gulf of Mexico one of the largest and deepest oilfields is Atlantis
BP’s Atlantis platform produces 200,000 barrels of oil and 5.1 million meters cubed of gas a day

Question 26

Unconventional fossil fuel reserves - tar sands

Answer 26

Are a mixture of clay, sand, water and bitumen
Large amounts of energy are used to extract the oil from the mixture high pressure steam is injected underground to separate the bitumen from the sand
Estimated contribution to global warming is three times higher than conventional oil
Canada has 73% of global stocks
By 2030 it could meet 16% of all of North America’s oil needs
About 1.8 million tonnes of toxic wastewater are produced everyday
Caribou populations have fallen significantly in areas of oil extraction

Question 27

Unconventional fossil fuels - fracking for shale gas

Answer 27

US shale gas production has increased since 2007
By 2010 shale gas consitisted of 23% of US gas production in contrast to it only being 14% in 2009
Most significant fields include the Barnett Resevoir in Texas and the Marcellius Reservoir in New York, Pennsylvania
Created 600,000 jobs in 2010

Question 28

The UK’s energy mix

Answer 28

37% of the UK’s energy is imports (2022)
Wind energy could provide up to 25% of the UK’s electricity
2022 - Biowaste and energy 10.7%, Oil 36.0%, Coal 3.0% (despite having 150 years left of coal reserves and Gas 39.3%)

Question 29

Hornsea project

Answer 29

190 metre high wind turbines will provide power for a million homes
Located 121km off the coast of Yorkshire
Create 2000 construction jobs

Question 30

Biofuels strengths

Answer 30

Cars using bioethanol emit 80% less carbon dioxide
Renewable source
Provides jobs that are more sophisticated
Sugar cane is not grown in forested areas and therefore does not contribute to as much deforestation as expected

Question 31

Biofuels weaknesses

Answer 31

Food prices may increase, biodiversity reduces and water use may be stretched
Biomass requires a kickstart to fire up and some biomass produce 150% to 400% more carbon dioxide than coal
In poor developed countries food is more important
72% of palm oil plantations were in forested areas
If oil prices fall this lowers biofuel demand significantly

Question 32

Brazil biofuels

Answer 32

Bio-refineries produce the equivalent of 930,000 barrels of oil a day worth $50 billion a year
When the government reduced taxes on fossil fuels to try and control inflation biofuel plants were bankrupted and fields were returned to growing crops
In Brazil 6 million flex vehicles and 3 million other vehicles can run on hydrous ethanol and biodiesel use is increasing (soybean oil)

Question 33

Madagscar deforestation

Answer 33

The island is widely regarded as a top conservation priority due to its high biodiversity
Eastern side of the island is home to tropical rainforests while the western and southern sides of the islands are covered by ‘tropical dry and spiny forests, thorn forests, and deserts and shrub-lands’
All 50 known species of the small primates known as lemurs are found ONLY in Madgascar
75% of the population rely on subsistence farming
200,000 hectares annually are deforested
Soil erosion now exceeds 400 tonnes per hectare a year
Extensive logging of inland rainforests and costal mangroves heavy rainfall means soil is washed into streams and rivers clogging waterways with sediment

Question 34

Removal of grasslands

Answer 34

Between 2007 and 2015 a desire for biofuels increased across the midwest of America and farmers were encouraged to grow corn, soya, canola and sugar cane
Grasslands traditionally used for cattle ranching were ploughed up
Over 5.5 million hectares of natural grassland disappeared across the America midwest

Question 35

Great Barrier Reef

Answer 35

91% of the reef displays signs of bleaching
About 50% of the reef is considered extremely bleached
1.8 million tonnes of carbon is stored there
2.19 million people visit the Great Barrier Reef annually

Question 36

Drought in the Amazon

Answer 36

The Amazon has been suffering frequent droughts the drought of 2014-15 was the worst drought in 80 years
Amazon holds 17% of the terrestrial vegetation carbon store
The drought shuts down the Amazon’s function of being a carbon sink

Question 37

Indonesia

Answer 37

Indigenous people live there in Indonesia over 700 land conflicts in 2016 were linked to the palm oil industry
Endangered species like the Borneo elephant, Orang-utans and Sumatran tigers.
In May 2011 Indonesia’s president declared a ‘forest moratorium’ with $1 billion funding from the UN and Norweigan government the moratorium stopped the issuing of permits for the clearance of forest which reduced forest logging by 15% because illegal logging continued

Question 38

Kuznets curve

Answer 38

As country’s develop they become more conscious about the environment and their responsibility to protect it. Developing countries exploit and degrade the environment.

Question 39

Changes in the Arctic Water Cycle

Answer 39

Highest temperatures and evaporation rates are drying up arctic ponds
Higher temperatures will reduce the duration and extent of ice and snow cover and increase snow and ice ablation (processes which decrease snow and ice)
Some speculations suggests that by 2037 the Arctic Ocean could be free from ice
Between 1977 and 2007, 19 polar Arctic Rivers had a 9.8% discharge increase
People in the Arctic may experience building and structure collapse from the melting of permafrost

Question 40

Yukon and the Yukon River, Northwest Canada

Answer 40

Across Yukon, winter precipitation increased between 1950 and 1998 however a greater proportion fell as rain rather than snow
Snowmelt begins earlier in the Yukon region
Between 1958 and 2008 the total ice area in Yukon shrank by 22%
Since 2000 inflows to the Yukon River have increased by 39% due to increasing temperature and precipitation

Question 41

Ciguatoxic algae

Answer 41

In Vitu Levu Human health is being affected as warmer seawater leads to fish eating ciguatoxic algae which poisons people when they eat fish and numbers affected are expected to increase to 700 times current levels

Question 42

Peatlands

Answer 42

Most of the world’s wetlands are peat. Peat is the accumulation of partly decayed vegetation and stores large amounts of carbon because of the low rate of carbon breakdown in cold waterlogged soils
Warming causes peat to dry out as water tables fall increases rate of decomposition
Peatlands tend to emit carbon in the form of methane
METHANE IS 28% MORE EFFECTIVE AT TRAPPING HEAT COMPARED TO CARBON. The burning, draining and degrading of peatlands emits more than a tenth of all the global emissions burned from fossil fuels.

Question 43

Thermohaline circulationand climate change

Answer 43

The melting of ice sheets releases significant quantities of freshwater into the ocean which is lighter and less salty this blocks the conveyor belts because it prevents warm water from flowing from the tropics towards the north where the water becomes heavier and saltier.

Question 44

Adaptation strategies

Answer 44

Water conservation and management e.g Israel
Israel has used smart irrigation
Recycling sewage water for agricultural use
Managing demand by charging ‘real value’ prices for water to reflect the cost of supply
Land use planning and flood-risk management
Resilient agriculture systems
Conservation cropping is growing in use from the USA to Syria and Iraq
It involves growing crops with a no ploughing approach which uses fewer fertilisers
Solar radiation management
Aims to reflect solar rays and reduce global warming through the proposed plan of using orbiting satellites to reflect some inward radiation back into space

Question 45

Energy efficiency, Germany

Answer 45

Germany policies to increase energy efficiency: requiring residential and commercial buildings to reduce energy consumption by 25%, loans to renovate older energy consuming properties and subsidies to improve efficiencies in manufacturing

Question 46

Afforestation, South Korea

Answer 46

South Korea: Between 1961 and 1995 the area of forested land rose from 4 to 6.3 million hectares and by 2008 11 billion trees had been planted

Question 47

Renewable switching, Sweden

Answer 47

Sweden: Oil has fallen from providing 75% of Sweden’s energy in 1970 to 20% in 2016
83% of Sweden’s electricity is produced by nuclear and hydroelectric power

Question 48

Carbon capture storage

Answer 48

In 2014 Boundary Dam in Canada’s Saskatchewan Province became the world’s first commercial carbon capture coal-fired power plant
Aims to cut carbon dioxide emissions by 90%
Expected to reduce emissions by about 1 million tonnes a year

Question 49

Climate change effects on ecosystems

Answer 49

Habitat changes will mean 10% of land species with limited adaptability will face extinction
Rates of extinction could rise to 15 to 40% of all species especially in high risk polar regions
By 2080 shifting temperatures may reduce bird habitats in North America affecting 314 species
Marine diversity may be lost as fish move away from hotter areas and about 80% of coral reefs could be bleached

Question 50

What does access to and consumption of energy resources depend on?

Answer 50

• Physical availability
• Cost
• Technology
• Public perception
• Level of economic development
• Environmental priorities

Question 51

What are examples of adaptation strategies?

Answer 51

• Water conservation and management
• Resilient Agricultural systems
• Land use planning
• Flood-risk management
• Solar radiation management

Question 52

Radical technologies: hydrogen fuel cells and electric cars

Answer 52

The hydrogen reacts with oxygen across an electrochemical cell— similar to a battery—to produce electricity, water, and small amounts of heat. Hydrogen fuel cells are currently used to power the electrical systems on spacecraft and to supply electricity on earth. As of the end of March 2024 there are 1 million fully electric cars in the UK.

Question 53

Rebalancing the carbon cycle

Answer 53

Re-balancing the carbon cycle could be achieved through
mitigation (carbon taxation, renewable switching, energy
efficiency, afforestation, carbon capture and storage) but this
requires global scale agreement and national actions both of
which have proved to be problematic.

Question 54

Peatlands contribution to global warming

Answer 54

The burning, draining and degrading of peatlands emits more than a tenth of all the global emissions burned from fossil fuels.

Question 55

Water contamination from agriculture and industrial waste pollution.

Answer 55

42% of China’s sewage and 45% of it’s industrial waste is dumped into the Yangtze river every year.

Question 56

Geological carbon cycle

Answer 56

• Happens every 100-200 million years
• Carbon is emitted by non-erupting volcanoes e.g Yellowstone