Carbon cycle revision Flashcards
(11 cards)
6.1b) Most of the earths carbon is geological; This results in the formation of sedimentary rocks
The largest carbon store is geological; most of this carbon is stored in limestone a form of sedimentary rock and this is formed when calcium carbonate is deposited on the ocean. The himilayas is one of the earths largest carbon stores because mountains are rich in calcium carbonate that gets weathered and eroded and transported back to the oceans. This calcium is then used to form sedimentary rocks which store 80% of geological carbon.
6.1c) Chemical weathering removes carbon from silicate rocks through volcanic outgassing.
The earths crust contains pockets of carbon dioxide that can be disrupted through volcanic or seismic activity. The release of this gas is known as volcanic outgassing and the tectonic activity brings these carbonate rocks into contact with extreme heat which causes chemical changes in the rocks, releasing carbon dioxide into the atmosphere.
6.2a) Phytoplankton sequester carbon through photosynthesis in ocean waters.
How does the ocean sequester carbon? through the 3 pumps, biological, carbonate and physical pump.
Biological pump - Biological pump moves carbon from the ocean surface to marine plants through photosynthesis; Photosynthesis turns the carbon into food for microscopic organisms like phytoplankton that recycle the carbon or take around 30% of it down to the deep ocean where it is sequestered for many years.
Carbonate pump - the carbonate pump relies on inorganic carbon sedimentation; the carbonate pump forms sediment from dead organisms that fall to the ocean floor, these sediments are rich in calcium carbonate which marine organisms use to build their shells. When these marine organisms die their shells form a row of sediment at the sea bed and physical and chemical processes lead to the formation of sedimentary rocks from this sediment - sedimentary rocks store 80% of global carbon and do not allow an easy return back to the ocean surface which means that carbon is sequestered
Physical pump - The physical pump moves carbon to different parts of the ocean through down dwelling and upwelling currents. Down dwelling currents occur in parts of the ocean where the water is colder and denser, which brings the dissolved carbon to the deep ocean where it is stored for hundreds of years. Eventually, due to thermohaline circulation these deep water currents return to the surface in a process called upwelling; the cold water warms as it gets closer to the surface and some of the dissolved carbon is released back into the atmosphere.
6.2b) Terrestrial primary producers sequester carbon during photosynthesis, some of this carbon is returned to the atmosphere during respiration.
Plants sequester carbon out of the atmosphere through photosynthesis, which leads to the carbon that has been sequestered entering the food chains of these terrestrial ecosystems. When animals consume the plant matter, the carbon sequestered becomes a part of their fat and protein. Respiration causes some of this carbon to be returned back to the atmosphere.
Carbon sequestering is more prominent during the day because there is more sunlight so more photosynthesis occurs - at night less photosynthesis occurs and more respiration occurs which means that less carbon is sequestered. During the winter carbon dioxide concentrations increase because there is a lack of plant growth and therefore photosynthesis.
6.2c) Biological carbon can be stored in dead organic matter or returned through biological decomposition over hundreds of years
20-30% of global carbon is stored in soils as dead organic matter; The amount of carbon stored in some soils is affected by climate and vegetation cover. This is because warmer climates increase decomposition of the organic matter and vegetation cover affects the supply of dead organic matter. Organic matter is heaviest in tropical rainforests due to the high levels of plant growth that means that more carbon is sequestered.
Biological processes sequester carbon on land and in the ocean?
Carbon can be sequestered in the ocean through the biological pump, carbonate pump and physical pump.
Carbon can be sequestered on land through primary producers and photosynthesis
Carbon can also be sequestered through organic matter stored in soils.
6.1) Geological processes influence the amount of carbon in the atmosphere
The amount of carbon in the atmosphere is influenced by:
Formation of sedimentary rocks like limestone and the amount of volcanic outgassing.
Formation of sedimentary rocks - The Himalayas can be seen as one of the largest carbon stores; this is because the mountains are rich in calcium carbonate which gets weathered and eroded and transported back to the oceans. This calcium carbonate is deposited on the ocean floor and over time sedimentary rocks are formed. Oceans can be seen as a carbon sink because they form sedimentary rocks and these rocks store 80% of geological carbon.
The amount of carbon can also be influenced by volcanic outgassing. The Earths crust has little pockets of carbon that can be released by volcanic eruptions or seismic activity. Tectonic activity brings the carbonate rocks into contact with extreme heat - this heat causes chemical changes in the rock, which releases carbon dioxide into the atmopshere - the release of this gas is known as volcanic outgassing.
6.3 - A balanced carbon cycle is important in sustaining earth systems but it is increasingly altered by human activities.
6.3 a) The concentration of atmospheric carbon influences the greenhouse effect which influences the distribution of temperature and precipitation
The greenhouse effect - The earths climate is driven by short wave solar radiation; 31% of this radiation is reflected back into space through clouds and the remaining 69% is absorbed by the earths surface. Much of this radiation absorbed at the surface is re-radiated as long wave radiation that is prevented from returning to the surface by clouds - the trapping of this long wave radiation is what causes the greenhouse effect, controlling global temperature.
Human activity is increasing the amount of potent greenhouse gases which influences the greenhouse effect. For example, CFC’s can be found in China which are a potent greenhouse gas that will stay in the atmosphere longer than C02. This is an industry gas made to stabilise electricity which means its demand will increase in next years due to more resource demands from a population and an increase in technology.
6.3c) The process of fossil fuel combustion has altered the balance of carbon pathways which has implications for the climate, ecosystems and hydrological cycle
Human activity like fossil fuel combustion can have implications for the CLIMATE, ECOSYSTEMS AND THE HYDROLOGICAL CYCLE
Fossil fuels have been burned at an alarming rate since the industrial revolution and pose a great threat to the carbon cycle because it affects carbon stores and fluxes.
Implications for the CLIMATE - Changing temperatures and salinity levels of the oceans as a result of fossil fuel emissions could affect the thermohaline current - This could lead to the Gulf stream slowing or reversing and at the moment the Gulf stream is used to keep temperatures 5 degrees higher than they should be - Changes to this would result in unpredictable weather patterns and the climate would be colder which would affect plant growth and ecosystems.
Implications for ecosystems - Ecosystems help to regulate carbon cycle however rising temperatures from fossil fuel combustion is leading to higher rates of ocean acidification - Ocean acidification is a reduction in the ph of the ocean caused by an increased uptake of co2 from the atmosphere. Ocean acidification causes the shells of marine organisms to dissolve, which creates a positive feedback loop because the carbon stored in their shells is then released back into the atmosphere. The decrease in the Ph affects marine organisms because they cannot adapt to the changes in the pH of the ocean which causes them to die - ocean acidification causes coral bleaching which means polyps have no where to live.
Implications for the hydrological cycle - increased evaporation rates as temperatures increase, which means droughts are more likely - droughts mean that vegetation dies so less photosynthesis occurs and less carbon is sequestered.
Increased global temperatures also mean that spring comes earlier so snowmelt occurs earlier, which increases the risk of flooding - rivers already at maximum capacity.
6.4a) Energy security is key goal for countries relying on fossil fuels
Energy consumption is the amount of energy a country or person uses
Their energy mix is the amount of different energy sources they use - this can be renewable or non-renewable sources
Energy security - this is how secure a country’s energy is - do they have lots of reliance on non-renewables like fossil fuels that are a finite resource or do they invest into renewables - is their energy domestic reserves or foreign - foreign relies on good political relationships and transport costs make the cost higher for the consumer.
USA - energy consumption - USA are the least successful at achieving energy security because they do not have a diverse energy mix and most of their reserves are in fossil fuels. The USA have large domestic reserves on fossil fuels like petroleum which makes them energy secure at the moment. However fossil fuels are a finite resource which means they will run out in the future. This makes them vulnerable because 11% of their energy mix is in renewables at the moment which will not be able to support their country in the future as they have high consumption and unsustainable habits to energy, due to high levels of technology in the developed country. They are still using petrol cars not electric cars.
France - France are the most successful country in achieving energy security because 72% of their energy comes from nuclear a recyclable resource that will not run out. France have achieved energy security because they have large deposits of nuclear energy in the country which means that they do not have to import it. This reduces transport costs and means that they do not have to rely on political relationships to get their energy - this makes them energy secure.
France has little reliance on fossil fuels, only 0.3% of their energy mix is coal - public perception of nuclear is bad because its an attractive site for terrorist attacks - if the government can increase public perception they can increase their reliance on nuclear.
UK: the uk is the 2nd most successful country in achieving energy security because they have a mixture of renewable and non-renewable energy sources in their energy mix, this reduces their reliance on one source of energy. The UK has a temperate climate which has led to wind power contributing to 27% of their energy mix and solar contributing to 4%. 37% of their energy comes from gas but 48% of this is from domestic production which reduces C02 emissions and transport costs - The rest of their gas comes from Norway a country they have good political relationships with promoting their energy security.
