Carbon cycle and energy security

What is the carbon cycle?

The movement of carbon from one sphere to another.

What are stores and fluxes?

Stores: where carbon is held.

Fluxes: transfer of carbon between stores.

What are the different carbon stores?

Atmosphere → carbion dioxide/methane

Hydrosphere → dissolved carbon dioxide

Lithosphere → carbonates in limestone + fossil fuels

Biosphere → living/dead organisms

Cryosphere → stored in permafrost

What is the difference between stores and sinks?

Stores → add carbon to the atmosphere

Sinks → remove carbon from the atmosphere

Where is carbon geologically?

• Centred on the significant carbon stores in rocks and sediment.

• Formation of sedimentary carbon rocks (limstone) in oceans.

• Carbon derived from plants and animals in shale/coal/ other rocks

What geological processes release carbon?

Chemical weathering → atmospheric carbon reacts with moisture to form carbonic acid, this falls as rain and dissolves surface minerals.

Volcanic outgassing → volcanic eruptions and earthquakes release carbon dioxide pockets within the crust.

What are the three carbon pumps?

Biological, carbon, and physical

How does the biological pump work?

• Phytoplankton carry out photosynthesis.

• Zooplankton eat the phytoplankton, with carbon moving through the marine food web.

• Marine organisms die and sink to the marine floor.

• Carbon becomes part of sediments, forming fossil fuels or carbonate rocks e.g. Dover White Cliffs

What is carbon sequestration?

The process by which carbon dioxide is removed from the atmosphere.

How do phytoplankton sequester carbon?

• Half of the world’s oxygen is sourced from phytoplankton within the sunlit surface sea layer.

• Releases the same amount of oxygenas all land plants, although their biomass is 100x smaller.

• Consume 10x more carbon dioxide anually than humans release by burning fossil fuels.

What is the carbonate pump?

• Marine organisms utilise calcium carbonate to make hard outer shells and inner skeletons.

• When they die and sink, the shells dissolve and carbon becomes part of deep ocean currents.

• Those that do not dissolve build up into limestone, e.g. White Cliffs of Dover.

How does the physical pump work?

• CO2 is absorbed by diffusion in the ocean surface.

• Downwelling → surface water sinks in cold, dense waters.

• Thermohaline circulation globally distributes carbon.

• Colder water absorbs more CO2.

• Upwelling → warmer water rises, releasin CO2 back to the surface.

What is thermohaline circulation?

• The global system of surface and deep ocean currents.

• Driven by differences in temperature and salinity.

• Responsible for circulating carbon.

What is terrestrial sequestration?

• Plants sequester carbon during photosynthesis

• When animals eat plants, carbon becomes part of their fat and protein.

• Respiration of animals returns some carbon back into the atmosphere.

• Animal waste is eaten by micro-organisms.

• During decomposition, carbon is released into the soil.

• Most productive in tropical rainforests.

What is biological carbon?

• Carbin within living organisms.

• 20-30% of global carbon is stored as dead organic matter in soils.

• Soils are the biggest terrestrial carbon store.

• Sequester twice that of the atmospher and thrice of vegetation.

What does the amount of carbon stored in soils depend on?

Climate → rate of plant growth and decomposition increase with temperature and precipitation.

Soil type → clay-rich soils have a higher carbon content, as it protects it from decomposition.

Vegetation cover → affects the supply of dead organic matter.

Land use → cultivation and other disturbance increase the rate of carbon loss (have lost 40-90 billion tonnes since 1850).

What is the greenhouse effect?

• Influenced by the concentration of atmospheric carbon (CO2 and methane).

• Climate is driven by incoming shortwave solar radiation.

• 31% is reflected by clouds, aerosols and gases in the atmosphere/land surface.

• 69% os absorbed → half at the surface (oceans), half is re-radiated into space as longwave radiation.

• Longwave radiation is deflected back by greenhouse gases, which increases temperature.

What physical processes maintain a balanced carbon cycle?

Photosynthesis → keep CO2 level constant, regulating global temperatures, highest productivity in warm, wet regions (tropical rainforest/shallow oceans)

Soil health → dependent on the amount of organic carbon stored within, determined by the balance between inputs and outputs.

• Carbon is the main component of soil, giving it its moisture-retention capacitym structure and fertility.

How are fossil fuels formed?

Oil → formed from the remains of small aquatic animals/plants, occurs in small pockes in rock.

Natural gas → made of fractions of oil molecules.

Coal → giant plants died in swamps which were buried under water and dirt over millions of years, heat and pressure formed coal.

How has fuel combustion altered the balance of carbon?

• Without human activity, carbon in fossil fuels would flow into the atmosphere slowly through volcanic activity.

• The fast cycling of burning fossil fuels has impacted global climate, ecosystems and the hydrological cycle.

• Half of extra emissions of carbon dioxide since 1750 have remained in the atmosphere.

What is the impact of fossil fuel combustion on climate, ecosystems, and the hydrological cycle?

Climate → UN climate change panel explicitly linked gas concentration to fossil fuel emissions.

Ecosystems → marine life is threatened by ocean acidification/lower oxygen.

Hydrological cycle → changes in precipitation, reduction in cryosphere, increased evaporation.

What is energy security?

The uninterrupted availability of energy sources at affordable prices.

Key aspects → affordability, accessibility, availability, reliability.

Why is energy consumption increasing?

• Global population growth

• Development and rising standard of living

• Neccessity of energy in everyday life

What is an energy mix?

The combination of different energy sources used to meet a country’s total energy demand.

What is the difference between primary and secondary energy?

Primary → resources in their natural, unaltered state e.g. coal/oil.

Secondary → produced by converting primary sources e.g. electricity.

What are the main primary energy sources used to generate electricity?

Non-renewable → fossil fuels e.g. coal, oil, natural gas.

Recyclable → nuclear energy, biomass.

Renewable → water, wind, solar, geothermal, tidal.

What factors affect consumption and availibility?

Physical availability → if not available/accesible, energy has to be imported and increases cost.

Cost → costs of physical exploitation, processing, and delivery.

Technology → increases ease of exploitation, requires more energy to return.

Public perception → cost is relative.

Economic development → developed countries are less sensitive to cost, but have increased consumption.

Climate → warmer climates have higher consumption, due to increased climate regulation.

Environmental priorities → may use more expensive methods to meet energy needs.

USA and France energy consumption

USA:

• 2nd highest energy consumer

• Population of 334 million

• Different climates require regulation

• 75% of energy is from fossil fuels

• 10% is renewable

• 8% from nuclear

• Only imports 15% of energy supplies

France:

• 10th highest energy consumer

• Population of 65.6 million

• 50% of energy is from fossil fuels

• 10% is renewable

• 41% from nuclear

• Imports 46% of energy supplies, including uraniam for nuclear power

Who are the players in energy?

TNCs → 50% of players in oil and gas are state owned e.g. BP (technically not TNCs), involved in exploloring, etracting, transporting, refining and producing.

OPEC → Organisation of the Petroleum Exporting Countries, 13 members owning 2/3 of global oil reserves, controls the amount and price of oil and gas.

Energy companies → majority are involved in primary and secondary energy, exerting a stong influence over prices and tariffs.

Governments → impacts on how energy is sourced and energy security.

Consumers → little influence or impact.

How is there a mismatch in fossil fuel supply and demand?

Coal → consumption is decreasing whilst production is increasing, main producers are typically main consumers, China and USA are the largest consumers and producers.

Oil → significant mismatch, main suppliers are OPEC whilst consumers are in Europe.

Gas → supply is dominated by the USA and Russia, importers are Western Europe and Japan.

What are energy pathways?

The route taken of any energy from the source to its consumption.

What are the significant energy pathways of different fossil fuels?

Coal → mainly transported by bulk carrier ships and rail, low density and high weight make costs high.

Oil → transported by tanker ships from the Middle East to Europe, Asia and North America, and by pipelines.

Gas → mainly transported by pipeline, especially Russia to Europe.

Russian export of gas to Europe

• Russia is the second largest producer of gas.

• Majority of its exports are delivered through 5 pipelines to Europe.

• 3 of these cross Ukraine.

What are the unconvential fossil fuel sources?

• Tar sands

• Oil shale

• Shale gas

• Deepwater oil

What are tar sands?

• Mixture of clay, sand, water and bitumen (oil).

• MIned and then injected with steam to reduce viscosity, so it can be pumped out.

• Tar sands produce 40% of Canada’s oil output.

What is oil shale?

• Oil-bearing rocks that are permeable enough for oil to be extracted.

• Mined or ignited so light oil fractions can be pumped out.

• Little exploration has taken place.

What is shale gas?

• Natural gas that is trapped in fine-grained sedimentary rocks.

• Extracted by fracking - pumping water and chemicals to force out gas.

• Shale gas provided 25% of the USA’s gas supply in 2015.

What is deepwater oil?

• Oil and gas found offshore at considerable oceanic depths.

• Drilling takes place from ocean rigs.

• Significant oil deposits were discovered off the Brazillian coast in 2006.

What are the costs and benefits of alternative fossil fuels?

Costs:

• Exploitation threatens the carbon cycle and contribute to global warming.

• Extraction is expensive and can cause environmental damage.

Benefits:

• Improve energy security for countries that rely on imported energy.

• Provides a source of fuel whilst renewable energy are further developed.

What are the alternatives to fossil fuels?

Renewable: hydro, wind, solar, geothermal and tidal.

Recyclable: nuclear and biofuels.

What are the costs and benefits of renewable energy?

Costs:

• Becomes less attractive if oil prices drop.

• Can have negative environmental impacts e.g. HEP dams flooding valleys.

• Limitations associated with physical geography e.g. lack of sunlight and solar

Benefits:

• Will not run out and reaps environmental benefits.

• Saves money long-term, as operation and maintenance costs ar lower.

• Reduces reliance on imports.

• Creates employment.

What are the costs of recylable energy?

Safety → nuclear incidents such as Chernobyl.

Disposal → highly toxic radioactive waste.

Technology → only accessible to the most developed countries.

Cost → despite operational costs being low, building and decommissioning are high.

What are biofuels?

• Derived from organic matter e.g. crops, waste.

• There are two forms:

  • Primary: fuelwood, wood chips, used unprocessed for heating/cooking.

  • Secondary: derived from processing of crops e.g sugarcane, to fuel vehicles and generate electricity.

Biofuels in Brazil

• Began to diversify energy sources in the 1970 to improve energy security.

• Now the largest producer of sugar cane, becoming the leading exporter of this and ethanol.

What are the radical technologies to reduce carbon emissions?

Carbon capture:

• Capturing CO2 released by fossil fuels and burying it underground.

• Expensive due to advanced technology needed.

• Uncertainty over whether it will leak.

Hyrogen fuel cells:

• Combine hydrogen and oxygen to produce electricity, heat and water.

• Hydrogen is high in energy and produces next to no pollution.

How has the UK’s energy mix changed?

1990:

• 75% of UK energy came from coal and oil.

• 20% from nuclear energy.

• Less than 5% by renewable energy.

2014:

• 50% of energy came from coal and oil.

• 19% from nuclear energy.

• 19% from renewables.

How has growing resource demands affected land use?

• Biosphere sequesters ¼ of fossil fuel carbon emissions anually, which capacity is being reduced due to land conversion.

• Deforestation: clearance of forests reduces interception so erosion and surface runoff increases, reduced photosynthesis.

• Afforestation: commercial trees store less carbon and use more water e.g. palm oil.

• Grassland conversion: agriculture exploitation, ploughing leads to loss of carbon dioxide and moisture.

• Urbanisation: increases surface runoff and carbon emissions.

What is ocean acidification?

• Their increased uptake of carbon dioxide has caused to a decrease in pH and therefore acidification.

• Estimated to be 25% more acidic then the pre-industrial era.

How dooes ocean acidification impact marine ecosystems?

• Extra hydrogen ions from the CO2 reacton bind with carbonate ions.

• Reduced carbonate ions mean animals such as coral spend more energy when building their shells.

• This leads to thinner, more fragile shells.

• Major functions such as reef building may collapse.

• 1 in 7 people rely on seafood as their main protein.

Amazon changing climate

• Acts as a global regulator.

• Absorbs 25% of CO2 absorbed by land, pumps 20 billion metric tonnes of water into the atmosphere daily.

• A more extreme drought and flood cycle has developed since 1990, due to shifts in the Inter-tropical Convergance Zone.

• Its diminishing health means it is declining as a carbon store, sequesters less CO2 from the atmosphere, and reduced role in the hydrological cycle.

How does forest loss have an impact on human wellbeing?

• 1.6 billion people depend on forests.

• Source of 80% of global biodiversity.

• 13 million hectares of forests between 2000 and 2010 were affected by deforestation.

What services do forests provide?

• Nutrient cycling

• Regulate climate, floods, and disease

• Water purification

• Provision of food, medicine and wood

Why has net less of deforestation reduced?

• Due to afforestation, explained by the environmental Kuznets curve.

• As countries become post-industrial the increased income leads to environmental improvement.

What are the effects of increasing temperatures?

Arctic:

• Acts as an early warning system for environmental impacts.

• Arctic temperatures have risen twice as fast as the global average within the past few decades.

• Sea ice has declined 40% since 1978.

• Arctic albedo: climate change causes icemelt, ice has high albedo (reflection), ocean is a dark surface so more is absorbed, temperature further increase.

How do threats to ocean health impact human wellbeing?

• Fishing supports 500 million people, 90% of whom live in developing countries.

• Marine organisms may be responding to climate change faster than terrestrial ones.

• Coral reefs act as coastal defences.

Why is there uncertainty surrounding future global warming?

• Unkown rise of greenhouse gases.

• Potential limited capacito of stores or sinks.

• Rate of population and economic growth.

What are the projected future of terrestrial and oceanic carbon sinks?

Terrestrial:

• Modelled to increase until 2050.

• When saturation is increased they begin to act as sources.

• E.g. thawing of permafrost.

Oceanic:

• Increased store in sea grasses and algae, but overall reduction as a sink.

• Tropical oceans have decreased absorption as they become warmer.

• Decreased efficicency of the biological pump.

What is the difference between adaptation and migation?

Adaption → changing ways of living to cope with oucomes of global warming.

Mitigation → reducing or preventing emissions by devising new technologies.

What are the different adaptation strategies?

• Water conservation

• Resilent agriculture

• Land-use planing

• Flood-risk management

• Solar radition management

What are the costs and benefits of water conservation and resilient agriculture?

Water conservation:

• Cannot match increases in demand.

• Lowered groundwater abstraction and resources used.

Resilient agriculture:

• Expensive, controversial.

• Help resistance to climate change, lead to healthier soils.

What are the costs and benefits of landuse planning, flood-risk management and solar radiation management?

Land-use planning:

• High-risk areas are inaccessible due to existing infrastructure.

Flood-risk management:

• Land ownser require compensation, constant maintenance is required.

• Simple changes can reduce flood risk.

Solar radiation management:

• Would not eliminate worst effects e.g. acidification.

What are mitigation strategies?

Carbon taxation → sets a minimum price companies pay to emit carbon dioxide.

Renewable switching

Energy efficiency → encourages energy-saving improvements

Afforestation → tree planting

Carbon capture and storage

How can mitigation help rebalance the carbon cycle?

• IPCC stated increase can be within 2C average if fossil fuel use is significantly reduced and eliminated by 2100.

• If emissions stay consistent, temperature will exceed 4C.