ELSS-Carbon Flashcards
What is the importance of the carbon cycle?
-Used by humans for energy (stored in living organisms)
-‘building blocks of life’
-Regulates climate as it traps heat in the earths atmosphere (cycle helps balance carbon levels preventing excessive warming or cooling)
-Marine organisms use carbon for photosynthesis
-used for photosynthesis to be turned to O2 as CO2 is toxic to humans
-Prevents carbon depletion or accumulation, which could disrupt ecosysms
What are the consequences of disruptions to the carbon cycle?
-Sea level rises (80cm by the end of the century)
-Forest fires become more frequent and areas losing the amazon could feel the greatest impact
-Food shortages - wheat yields have decreased by 40% in Africa
Is the global carbon system an open or closed system?
Closed as the amount of carbon on the earth doesn’t change, it only changes form
What is an example of an open carbon system?
Forest - Trees can be cut down or die, and leave the carbon system Any system that carbon can leave or enter is open.
What are the 3 largest global carbon stores?
1st: Lithosphere - stored as fossil fuels and in rocks, the lithosphere stores most of the carbon on Earth
2nd: Oceans - stored as dissolved carbon and calcium carbonate in the shells of marine life. Only 4% of carbon is stored near the surface
3rd: Biosphere - stored in organic molecules in living or dead plants and animals. Decaying releases CO2 to the atmosphere.
4th: Atmosphere - Stored as the gas CO2
What are key fluxes in the carbon cycle?
-Precipitation
-Respiration
-Carbon sequestration
-Photosynthesis
-Weathering
-Decomposition
-Combustion
How does the carbon cycle influence precipitation?
An increase in CO2 levels have led to a dramatic increase in the acidity of seawater and therefore rainfall.
What is the role of respiration in the carbon cycle?
-6 O2 + C6H12O6 —> 6 CO2 + 6 H2O + ATP
-Plants and animals absorb oxygen to provide energy which is needed for metabolism and growth
-The volume of carbon exchanged by respiration and photosynthesis each year is 1000x higher than through the slow carbon cycle
-Stays in balance with photosynthesis (biosphere -> atmosphere -> biosphere.)
What is the carbon sequestration physical pump in the carbon cycle?
Physical inorganic pump:
-CO2 enters the ocean from the atmosphere by diffusion.
-Surface ocean currents then transport the water and dissolved CO2 towards the poles where it cools, becomes more dense and sinks
-Downwelling carries dissolved carbon to the oceans depths where individual carbon molecules remain for centuries
-Eventually deep ocean currents transport the carbon to areas of upwelling causing the water to rise and CO2 to diffuse into the atmosphere
What is the carbon sequestration biological pump in the carbon cycle?
Biological pump:
-Marine organisms (phytoplankton) combine sunlight, water and dissolve CO2 to produce organic material
-This causes carbon to be locked in the sediment on the ocean floor or decomposed to release CO2 into the ocean
-Some crustaceans extract carbon and calcium ions from sea water to manufacture shells and skeletons
-Most carbon-rich material ends up on the seafloor undergoing lithification to form chalk or limestone
What is photosynthesis?
-6 CO2 + 6H2O —> 6O2 + C6H12O6
-Using the sun’s energy to cover the light energy into chemical energy for the formation of glucose and growth in plants
-O2 is released balancing respiration
What is weathering?
*Check coasts section
What is decomposition?
Bacteria or fungi break down dead organic matter, extracting energy and releasing CO2 into the atmosphere.
This occurs faster in warm humid environments (places with rainforest).
What is combustion?
-Organic material earths or burns in oxygen, releasing CO2 as well as sulphur dioxides and nitrogen oxides
-Usually occurs from human activity (deliberate firing of forest & combustion of fossil fuels) but occurs naturally in forest fires
-This increases the amount of CO2 in the oceans and atmosphere adding to the greenhouse gas effect
How does temperature influence carbon moving between the atmosphere and oceans?
Increase in temperature - speeds up diffusion of CO2 out of the ocean but slows absorption into the ocean from the atmosphere.
As temperatures increase due to global warming more carbon will be released from pumps resulting in a downwards spiral.
What processes does the fast carbon cycle include?
Includes the processes of photosynthesis, respiration, combustion, decomposition & air-sea gas exchange.
Carbon moves between the atmosphere, oceans and biosphere.
Phytoplankton are key components in absorbing CO2 from the atmosphere.
What processes does the slow carbon cycle include?
-Includes the processes of chemical weathering, fixing dissolved carbon, volcanic activity & subduction
-Marine organisms fix dissolved carbon with calcium to form calcium carbonate
-Decomposed organic material is buried beneath younger sediments.
-Lithification (sediments compact under pressure gradually turning into a solid)
What are the diurnal changes in the carbon cycle?
-There is a significant change in the flux of photosynthesis over the course of the day
-The respiration flux remains constant throughout the course of the day
-During the day, more carbon is stored as biomass in the plant, and during the night more carbon is released from the biomass through the process of respiration
what are the seasonal changes in the carbon cycle?
-During the Summer, more carbon is released as dead plants decompose, so the biosphere store decreases and the soil and atmosphere stores increase
-During the summer there are much higher rates of photosynthesis and respiration meaning there is less carbon in the atmosphere and soil, and more in the biosphere
-Carbon cycle is much slower in the winter
What is the correlation between CO2 ppm in the atmosphere and global temperatures over the earth history?
There is a very strong correlation between temperature and CO2 ppm, because when the graphs have a very similar shape. When the levels of CO2 rise, so does the temperature, suggesting a strong link of causality between the 2.
What are the impacts of long term climate change on the carbon cycle stores?
-At times of glacial maxima CO2 concentrations fall to around 180ppm, while in warmer inter-glacial periods they are 100ppm higher
-The carbon pool in vegetation shrinks during glacials as ice sheets advance
-Expanses of tundra beyond the ice-limit sequester huge amounts of carbon in permafrost
-As forests are replaced by grasslands due to human activity the amount of carbon stored in tropical biomes will diminish
-Global warming will allow the boreal forests of Siberia and Canada to expand polewards increasing the biosphere store
-long-term climate change will probably see an increase in carbon stores in the atmosphere, a decrease in carbon stores in the biosphere and possibly a decrease in the ocean carbon stores
What are the impacts of long term climate change on the carbon cycle fluxes?
-As vegetation decreases due to human activity NPP and the total volume of carbon fixed in photosynthesis will decline.
-During glacials an overall slowing of the carbon flux and smaller amounts of CO2 returned to the atmosphere through decomposition
-Higher global temperatures will in general increase rates of decomposition and accelerate transfers of carbon from the biosphere and soil to the atmosphere
-Carbon frozen in the permafrost of the tundra is being released as temperatures rise above freezing and allow oxidation and decomposition of vast peat stores
-Acidification of the oceans through the absorption of excess CO2 from the atmosphere reduces photosynthesis by phytoplankton
-Movement of carbon into and out of the atmosphere will vary regionally, depending on changes in rates of photosynthesis, decomposition and respiration.
What are changes in the carbon cycle (forestry)?
-Plantations result in an increased carbon store – mature plantation forest trees in UK contain 170-200 tonnes C/ha (10x grassland, 20x heathland)
-When felling occurs (to renew growth in forests) then the above ground carbon store will reduce and the soil will be more vulnerable to oxidation and erosion without the binding effect of plant roots. This may reduce the soil organic carbon
-Soil has even larger carbon pool through the addition of roots (below ground biomass). In England forest soil carbon around 500 tonnes C/ha
-Forest trees sequester CO2 from atmosphere for hundreds of years. Most carbon is stored in wood of trunk
-Forest trees only absorb more than they release for the 1st 100 years after planting, then levels off and balanced by inputs of litter to soil, respiration and soil decomposers. Consequently plantations have a rotation period of 80-100 years. They are then felled and reforestation begins.
How does burning fossil fuels influence the carbon cycle?
-Releases large levels of CO2 into the atmosphere
-Reduces the amount of carbon stores as fossil fuels in the lithosphere
