The Carbon Cycle and Energy Security (copy)

EQ1

How does the carbon cycle operate to maintain planetary health?

What is the carbon cycle?

The biogeochemical cycle moves carbon from one sphere to another (e.g. between the atmosphere and the biosphere).

What is a carbon store?

A mass of carbon held somewhere, either a source (releases carbon) or a sink (absorbs carbon).

What is a flux? What is a flux measured in?

The movement of carbon from one store to another. Petagrams/gigatonnes - one petagram is equal to a trillion kilograms or one billion tonnes.

What are the different stores of carbon?

Atmosphere: as carbon dioxide and carbon compounds, such as methane.

Hydrosphere: dissolved carbon dioxide.

Lithosphere: as carbonate in limestones, chalk and fossil fuels, as pure carbon in graphite and diamonds.

Biosphere: as carbon atoms in living and dead organisms (includes terrestrial and oceanic locations).

Where is the majority of carbon found?

Carbonate rocks, mostly limestone (formed in the oceans when calcium carboinate is dumped on the sea floor), or shale/clay which is created biologically. There are over 100m petagrams of carbon in the lithosphere.

What is reservoir turnover?

The rate at which carbon enters and leaves a store.

How does chemical weathering effect geological stores of carbon?

Carbon dioxide in the atmosphere reacts with rainwater to form weak carbonic acid that then falls, landing on surface minerals and dissovling them, releasing carbon.

Pockets of CO2 in the Earth’s crust can be released when earthquakes or volcanoes happen. It can also be outgassed at mid-ocean ridges, subduction zones and magma hotspots.

What is the thermohaline circulation system?

The global system of surface and deep ocean currents driven by temperature and salinity differences between different parts of the ocean. It can be seen as a giant conveyor belt.

What is the biological pump?

Moves carbon dioxide from the ocean surface to marine plants called phytoplankton through photosynthesis.

This effectively converts carbon dioxide into food for zooplantic (microscopic animals) and their predators. 

Most of the carbon dioxide taken up by phytoplankton is recycled near the surface. About 30% sinks into deeper waters before being converted back into carbon dioxide by marine bacteria. 

What is the physical pump?

Moves carbon compounds to different parts of the ocean in downwelling and upwelling currents.

Downwelling occurs in parts of the ocean where cold, denser water sinks.

These currents bring dissolved carbon dioxide down to the deep ocean. 

Once there, it moves in slow-moving deep ocean currents, staying there for hundreds of years. 

Eventually, these deep ocean currents, part of the thermohaline circulation, return to the surface by upwelling. 

The cold deep ocean water warms as it rises towards the ocean surface and some of the dissolved carbon dioxide is released back into the atmosphere. 

What is the carbonate pump?

Sediments from dead organisms fall to the ocean floor, especially the hard outer shells and skeletons of fish, crustaceans and corals, all rich in calcium carbonate. 

Outline terrestrial sequestration

Plants (primary producers in an ecosystem) sequester carbon out of the atmosphere during photosynthesis. In this way, carbon enters the food chains and nutrients cycles of terrestrial ecosystems.

When animals consume plant matter, the carbon sequestered in the plant becomes part of their fat and protein. Respiration, particularly by consumer animals, returns some of the carbon back to the atmosphere.

Waste from animals is eaten by micro-organisms (bacteria and fungi) and detritus feeders (e.g. beetles).

As a consequence, carbon becomes part of these creatures. When plants and animals die and their remains fall to the ground, carbon is released into the soil.

How is biological carbon stored?

Soils are the largest carbon stores. Here, biological carbon is stored in the form of dead organic matter. This matter can be stored for decades or even centuries before being broken down by soil microbes (biological decomposition) and then either taken up by plants or released into the atmosphere. 

Soils store approximately 30% of global carbon. They sequester about twice the quantity of carbon as the atmosphere and three times that of terrestrial vegetation.

What is the greenhouse affect, and how does the concentration of atmospheric carbon affect it?

The sun emits short wave radiation towards the Earth.

The Earth's atmosphere absorbs this heat and then radiates long wave (infrared) radiation away from Earth.

Greenhouse gases (carbon dioxide, methane etc) act as a barrier in the atmosphere so they re-radiate some of this heat/long wave radiation, keeping it in the atmosphere. This is what maintains our warm climate so makes life possible on Earth.

What role does terrestrial photosynthesis play in regulating the composition of the atmosphere?

Keeps carbon dioxide levels relatively constant and thereby helping to regulate the Earth's mean temperature. 

The amount of photosynthesis varies spatially, particularly with net primary productivity (NPP), (this is the amount of organic matter that is available for humans and other animals to harvest or consume). NPP is highest in the warm and wet parts of the world, particularly in the tropical rainforests and in shallow ocean waters.

How is soil health influenced and why is it important?

Soil health is influenced by the amount of organic carbon stored in the soil. The storage amount is determined by the balance between the soil's inputs (plant and animals remains, nutrients) and its outputs (decomposition, erosion and uptake by plant and animal growth.)

Carbon is the main component of soil organic matter and helps to give soil its moisture-retention capacity, its structure and fertility. A healthy soil has a large surface reservoir of available nutrients which, in their turn, condition the productivity of ecosystems. This explains why even a small amount of surface soil erosion can have such a devastating impact on soil health and fertility. 

What is the impact of fossil fuel combustion on the carbon cycle?

Fossil fuel combustion is the number one threat to the global carbon cycle as it is changing the balance of both the carbon stores and the fluxes. 

Climate implications: about half the extra emissions of carbon dioxide since 1750 have remained in the atmosphere. The rest have been fluxed from the atmosphere into the stores provided by the oceans, ecosystems and soils. The rate of carbon fluxing has sped up.

Greenhouse effect climate changes: a rise in the mean global temperature, more precipitation and evaporation, sudden shifts in weather patterns, more extreme weather events such as floods, storm surges and droughts.

Ecosystem implications:

sea level - this is rising because of melting ice sheets and glaciers; many major coastal cities around the world are under threat from flooding by the sea

ecosystems - a decline in the goods and services they provide; a decline in biodiversity; changes in the distributions of species; marine organisms threatened by lower oxygen levels and ocean acidification; the bleaching of corals etc.

Water cycle implications: increased temperatures and evaporation rates cause more moisture to circulate around the cycle. 

What is energy security?

When there is an uninterrupted availability of energy at a national level and at an affordable price.

Four key aspects of energy security are:

• availability

• accessibility 

• affordability - competitively priced energy supply

• reliability - uninterrupted

How is energy consumption measured?

Consumption of energy is measured in two ways:

1. In per capita terms, i.e. as kilogrammes of oil equivalent or megawatt hours per person. In general, this measure rises with economic development

2. By a measure known as energy intensity, which is assessed by calculating the units of energy used per unit GDP. The fewer the units of energy, the more efficiently a country is using its energy supply. In general, energy intensity values decrease with economic development

What is an energy mix?

The combination of different energy sources used to meet a country's total energy consumption.

Made up of:

Domestic and foreign sources

Primary and secondary sources

Primary = found in nature, not converted/transformed. It can be renewable (water/wind/sunlight) or non-renewable (coal/oil/gas)

Secondary = derived from transformation of conversion of primary sources, usually more convenient (electricity)

What factors affect per capita consumption?

Physical availability, cost, technology, public perception, level of economic development and environmental priorities (of governments)

USA vs France

What is an energy pathway?

The route taken by any form of energy from its source to its point of consumption. The routes involve different forms of transport, such as tanker ships, pipelines and electricity transmission grids. 

What is OPEC and what is its role?

OPEC (Organisation of Petroleum exporting countries) has 14 member countries*, which between them own about two-thirds of the world's oil reserves.

It is in a position to control the amount of oil and gas entering the global market, as well as the prices of both commodities.

OPEC has been accused of holding back production in order to drive up oil and gas prices. 

Who are the other key players in energy supply?

TNCs - Gazprom, ExxonMobil, PetroChina and Royal Dutch Shell. Nearly half of the top 20 companies are state-owned (all or in part) and, therefore, very much under government control. Because of this, strictly speaking they are not TNCs. Most are involved in a range of operations: exploring, extracting, transporting, refining and producing petrochemicals. 

Governments - guardians of national energy security and can influence the sourcing of energy for geopolitical reasons.  

Consumers - the most influential consumers are transport, industry and domestic users. Consumers are largely passive players when it comes to fixing energy prices. 

Energy companies - companies that convert primary energy (oil, gas, water, nuclear) into electricity and then distribute it. Most companies are involved in the distribution of both gas and electricity. They have considerable influence when it comes to setting consumer prices and tariffs. 

Mismatch?

How can energy pathways be disrupted?

Internal problems, wars, OPEC reducing global production, sanctions against a country, a country stopping supplies to another, piracy, leaks, sudden demand increase.

What is an unconventional fossil fuel? Give examples.

Energy resources that are not easily accessible.

Tar Sands - a mixture of clay, sand, water and bitumen (a heavy, viscous oil). Tar sands have to be mined and then injected with steam to make the tar less viscous so that it can be pumped out.

Oil Shale - oil-bearing rocks that are permeable enough to allow the oil to be pumped out directly. Either mined, or shale is ignited so that the light oil fractions can be pumped out.

Shale gas - Natural gas that is trapped in fine-grained sedimentary rocks. Extracted by fracking: pumping in water and chemicals forces out the gas.

Deepwater oil - Oil and gas that is found well offshore and at considerable oceanic depths. Drilling takes place from ocean rigs; already underway in the Gulf of Mexico and off Brazil.

What are the costs of using unconventional fossil fuels?

They are all fossil fuels, so their use will continue to threaten the carbon cycle and contribute to global warming.

Extraction is costly and requires a high input of complex technology, energy and water.

They all threaten environmental damage, from the scars of opencast mines and land subsidence to the pollution of groundwater and oil spills. Certainly, the resilience of fragile environments will be sorely tested.

What is renewable energy? What are the main sources of renewable energy?

An energy resource that is replaced rapidly from an existing constant natural process.

Hydro, wind, solar, geothermal and tidal.

Not all countries have renewable energy to exploit as not all countries have coasts, strongly flowing rivers or climates with either long sunshine hours or persistently strong winds

Partly because of this, there are very few, if any, countries where renewables might completely replace all the energy derived from fossil fuels. 

What are some negatives of renewable energy?

The relative financial costs of using non-renewable and renewable energy sources. When oil and gas prices are low, renewables become a more expensive option. 

The harnessing of renewables is not without environmental costs. River valleys have to be drowned to create HEP reservoirs, and large areas of land/the offshore zone are covered by solar or wind farms. 

While the majority of people believe that we should make greater use of renewable sources, most suddenly go off the idea when constructing a wind or solar farm near them is proposed (NIMBYism).

What are recyclabes and what are their negative factors?

An energy resource that can be reused once people or nature have processed it, such as HEP.

Risks to do with safety and security (accidents and terrorism) (nuclear).

The disposal of radioactive waste with an incredibly long decay life (nuclear)

The technology involved is complex and therefore its use is only an option for developed countries.

Although the operational costs are low, the costs of constructing and decommissioning power stations are high.

What is a biofuel? What crops are used to make biofuels?

A fuel derived immediately from organic matter.

The most widely grown biofuel crops include wheat, maize, grasses, soy beans and sugar cane. In the UK, the two main crops are oilseed rape and sugar beet. Most of these two crops are converted into ethanol or biodiesel, which are mainly used as a vehicle fuel. 

What are the downsides of biofuels?

Each hectare of farmland used to grow energy crops means a hectare less for growing much-needed food in an increasingly hungry world.

They are supposedly carbon neutral, since the carbon dioxide they produce when burnt, is only that they took from the environment whilst growing, but there is uncertainty over how carbon neutral they actually are. (Since what was on the land before them, e.g. a forest, is destroyed.) 

What are examples of radical technologies used to reduce carbon emmisions?

Carbon capture and storage - involves 'capturing' the carbon dioxide released by the burning of fossil fuel, and burying it deep underground (very expensive, carbon might re-release).

Hydrogen fuel cells - combine hydrogen and oxygen to produce electricity, heat and water. They will produce electricity for as long as hydrogen is supplied and never lose their charge (hydrogen doesn’t occur naturally as a gas, no cheap and easy way to get it yet).

How are changes in land-use cover affecting the carbon cycle?

Deforestation - less carbon is absorbed and stored, livestock farming in deforested areas increases methan emmissions, reduced evapotranspiration creates a drier climate which stresses trees.

Grassland conversion - temperate and tropical grasslands have also become heavily exploited by agriculture. The simple act of ploughing leads to an immediate loss of both carbon dioxide and moisture, as well as a change in runoff characteristics.

Urbanisation - ecosystem destruction, more GHG emissions, huge water demand.

What is ocean acidification?

Involves a decrease in the alkalinity/pH of oceans, caused by the uptake of carbon dioxide from the atmosphere, released by burning fossil fuels.

It occurs because oceans are a carbon sink.

The situation is now approaching the point that there is a real risk of some marine ecosystems and their goods and services passing the critical threshold of permanent damage.

The decrease in pH creates a weak carbonic acid which has the ability to dissoblve calcium carbonate, the mineral forming limestone rocks and shells of sea creatures and coral reefs.

How is forest health being challenged?

Enhanced greenhouse effect → climate change

Deforestation, poleward shift of climatic belts, increasing drought.

These factors are meaning that forests are able to store less carbon, affecting the cycle.

What are the impacts of forest loss?

Less carbon dioxide sequestered from the atmosphere.

Less carbon stored.

Less moisture transferred from the soil back into the atmosphere by evapotranspiration.

Outline the Kuznets curve in reference to environmental degradation

1. UK pre-industrial revolution, remote Amazonia, Indonesia pre 1970s - little income, little environmental degradation.

2. Indonesia today, China in the 20th century - increase in income, large increase in environmental degradation. Rising income worsens environmental impacts.

3. China today - shallower gradient, almost at peak environmental degradation, middle level income.

4. UK today - (post-industrial service economy), rising income reduces environmental impact.

How are increasing temperatures from GHG emissions effecting the environment?

Increased evaporation rates and the amount of water vapour. In turn, this is affecting:

• precipitation patterns

• river regimes

• drainage basin stores

• the cryosphere

How do threats to ocean heath pose threats to human wellbeing?

The decline in ocean health caused by acidification and bleaching is resulting in changes to marine food webs. In particular, fish and crustacean stocks are both declining and changing their distributions.

The FAO estimates that fishing supports 500 million people, 90% of whom live in developing countries

Millions of fishing families depend on seafood for income as well as food.

Seafood is also the dietary preference of some wealthier countries, notably Iceland and Japan. 

Tourism is also affected as previously visited coral reefs (as in the Caribean) are now showing signs of degradation meaning that fewer tourists visit and people relying on the industry struggle.

What uncertainties are there about the carbon cycle’s future?

The level of GHG emissions - will they continue to rise?

GHG concentration levels in the atmosphere - is there a limited capacity?

The resilience of other carbon sinks and stores- what are their capacities and could they store more?

The degree of climate warming - how much warmer?

Feedback mechanisms such as the release of carbon from peatlands and thawing permafrost - what volumes of carbon are likely to be released?

The rate of population growth - when, if ever, will it level off?

The nature and rate of economic growth - will it always be so carbon-based?

The harnessing of alternative energy sources - will fossil fuels be completely replaced?

The possible passing of tipping points relating to aspects as forest dieback and irreversible alterations to the thermohaline circulation - will disaster be sure to follow?

Why are predictions about the future very hard to make?

There are many unknown variables.

What is the difference between adaptation and mitigation?

Adaptation: changing our ways of living in such a manner that we are able to cope with most, if not all, the outcomes of global warming.

Living with the problem, not solving it.

Mitigation: reducing or preventing GHG emissions by devising new technologies and adopting low-carbon energies (renewables and recyclables).

Tackling the root cause of the problem.

Outline different adaptation strategies

Water conservation and management -

Resilient agriculture systems -

Land-use planning -

Flood-risk management -

Solar radiation management -

What are the costs and benefits of these methods?

Water conservation and management -

Resilient agriculture systems -

Land-use planning -

Flood-risk management -

Solar radiation management -

Outline different mitigation strategies

Carbon taxation - the carbon price floor tax sets a minimum price companies have to pay to emit carbon dioxide. It was unpopular with both industry and environmental groups and had a debatable effect on emissions.

Renewable switching - the relationship between the big energy producers and the government dictates the amount of switching from fossil fuels to renewables and nuclear power.

Energy efficiency - energy-saving improvements to homes, such as efficient boilers and lighting, and improved insulation. Energy suppliers must comply with the Energy Company Obligation scheme to deliver energy-efficient measures to households. 

Afforestation - helping carbon sequestration.

Carbon capture and storage - (seen before)

Change through mitigation requires global scale agreement and national actions both of which have proved to be problematic.