The Carbon Cycle Flashcards
Slow Carbon Cycle
Operates over millions of years and cycles carbon between land and atomospheric or ocean stores due to weathering and tectonic processes.
E.g., tectonic uplift
Fast Carbon Cycle
Operating on a daily basis - cycling carbon between land and the atmosphere as living things breathe and digest food
E.g., photosynthesis, respiration, decompostion, combustion
Carbon sink
More carbon enters a store than leaves it
Carbon source
More carbon leaves a store than enters it
Carbon flux
Carbon moving between these stores
The global carbon cycle is a closed system
There is no change in the total amount of carbon , where matter does not enter or leave, carbon moves between
Carbon stored within the lithopshere
- Sedimentart carbonate rocks
- Biologically deprived carbon is coal, oil, shale and volcanic rocks
Carbon sequestration
A natural or artificial process by which carbon dioxide is removed from to atmosphere and held in solid or liquid form
Movement of carbon
Biological pump
Organisms moving carbon is one direction is often called the biological pump.
Dead exoskeletons sink to the bottom. They decay, releasing carbon dioxide in to the deep water.
Carbon rich sediment layers form.
Over millions of years, physical processes may turn these sediments into rocks. This can lock up cabon for millions of years.
The stores of carbon
Largest to smallest
Lithosphere
Hydrosphere
Biosphere
Atmosphere
Carbon in the hydrosphere
When organisms die, their dead cells, shells and exoskeletons sink into deep water.
These materials form carbon rich layers, eventually into sedimentary rocks due to chemical and physical processes.
Sources of carbon in the biosphere?
Living vegetation (20%)
Plant litter
Peatland
Animals
Human influences on the carbon cycle
Hydrocarbon burning
Land use change
Animal agricultural
Human influences on the carbon cycle
- Hydrocarbon burning
Fossil fuels for from millions of years ago, plants and animals which died and did no decompose due to lack of oxygen. They turn into fossil fuels due to pressure.
These have been extracted and burnt for energy.
Human influences on the carbon cycle
- Land use change
Carbon is released by soil degration from farming processes.
Ploughing breaks up fungal networks, releasing carbon back into the atmosphere
Human influences on the carbon cycle
- Animal agriculture
Cows release CH4/Methane into the atmosphere which is potent.
14.5% of GHG emissions are from animal agriculture. These emissions released account for the animals themselves and tractors, transport etc.
The Amazon Rainforest
How is it a negative feedback loop?
More CO2 in atmosphere
Trees grow quicker due to trees absorbing CO2
Less CO2 in atmosphere due to trees
Trees die quicker, so CO2 is released back into the atmosphere through decomposition
How does deforestation effect the carbon cycle?
Trees and vegetation in a forest usually absorb CO2 through the process if photosynthesis, acting as a carbon sink, however when deforestation takes place, the reduction in vegetation causes a reduction in carbon absorbed frim vegetation.
The burning and decay from deforestation causes more CO2 to be released, as the trees are releasing the carbon they stored when they were alive.
The reduction in vegetation and trees means a reduction in below ground biomass. Less trees mean less roots and less litter from vegetation which store a lot if carbon
Natural carbon sequestration
The removal if carbon from atmosphere into natural stores
Mitigation to reduce GHGs in the atmosphere. Positives and negatives.
Terrestrial sequestration e.g. Afforestation, Peat restoration
Negatives is that it is a slow going process of mitigation.
Positive is that we could increase the workds forest cover by 0.9 billion hectres without effecting existing cities or agriculture
Afforestation, forest protection, or reforestation.
Positives and negatives?
Positive
- protection of existing forest will preserve current soil carbon stores
- increasing tree density, increasing biomass density = + carbon density
Negative
- darker trees reflect less heat, which causes more warming
- wrong tree in wrong place for example in peatlands, peatlands would reduce or and invasive species of tree in an area.
Carbon budget
The amount if carbon stored and transferred within the carbon cycle on global or local scale
Carbon footprint
The amount of GHGs produced tonsupport human activities and expressed in gigatones of carbon dioxide per year (GtG/yr)
What is happening to the ocean sink as carbon dioxide emissions increase?
As the carbon emissions increase, the amount of the carbon in the ocean steadily increases.
The sinks cannot absorb all of the carbon emissions.
Impacts of the increase in CO2 on the oceans?
Ocean acidification
Ocean warming
Melting sea ice
Sea levels rise
Ocean acidification
Dissolving carbon dioxide in the ocean creates carbonic acid. This makes the slightly alkaline ocean become a little less alkaline.
How does ocean acidification negatively impact?
Coral and many plankton species rely on carbonate ions to help create their calcium carbonate shells.
Less carbon available, the animals need to expand with more energy to build shells. as a result of this the shells end up being thinner and more fragile.
Significant coral reef loss due to a lack of carbonate ions, this causes a fall in marine biodiversity and threatens costal communities.
Melting sea ice
When sea ice melts, the ocean is more able to absorb more sunlight, causing further warming. Less sea ice means that surface is darker therefore reflect less sunlight. As a result, sea temperatures rise further causing more warming.
How does melting sea ice negatively impact?
Threatening wildlife. Animals like polar bears, seals and walruses depend on sea ice for hunting and breeding. Melting sea ice forces them to adapt or face population decline.
What are the impacts of increased tempurature of the oceans?
If there is less sea ice, the amount of energy the earth absorbs will increase, as the dark colour of the ocean absorbs the heat energy rather than reflects it like the bright white ice would.
What are the impacts of changing ocean salinity?
It can directly impact the ocean currents as it will effect the waters density, which will drive the currents to change.
Reasons for sea levels rising
Thermal expansion
When water heats up, it expands. About half of the past centurys rise in sea levels is thought to be from thermal expansion
Reasons for sea levels rising
Melting terrestrial ice
Particulary from glaciers and ice sheets, contributes to rising sea levels as the meltwater flows into the oceans
The effects of changes in the carbon cycle on the land
