Outline the global distribution and sizes of the major stores of carbon - lithosphere.
Lithosphere - Over 99.9% of Earth's carbon is stored in sedimentary rocks such as limestone. About 0.004% of Earth's carbon is stored in fossil fuels, such as coal and oil, in the lithosphere.
Outline the global distribution and sizes of the major stores of carbon - hydrosphere.
Carbon dioxide is dissolved in rivers, lakes and oceans. Oceans contain about 0.04% of the Earth's carbon, the majority of which is found deep in the ocean in the form of dissolved inorganic carbon. A small amount is found at the ocean's surface where it is exchanged with the atmosphere.
Outline the global distribution and sizes of the major stores of carbon - biosphere.
Carbon is stored in the tissues of living organisms. It is then transferred to the soil when living organisms die and decay. The biosphere contains about 0.004% of the Earth's carbon.
Outline the global distribution and sizes of the major stores of carbon - cryosphere.
Most carbon found in the cryosphere is found in permafrost in the soil where decomposing plants and animals have frozen into the ground. The cryosphere contains about 0.01% of the Earth's carbon.
Describe how photosynthesis acts as a carbon flow.
Photosynthesis transfers carbon stored in the atmosphere to biomass. Plants and phytoplankton use energy from the sun to change water and carbon dioxide into glucose and oxygen, allowing them to grow. Carbon is passed through the food chain and released through respiration and decomposition.
Respiration transfers carbon from living organisms to the atmosphere. Plants and animals break down glucose for energy, releasing carbon dioxide and methane in the process.
Decomposition transfers carbon stored in dead biomass to the atmosphere and soil. After death, bacteria and fungi break organisms down, releasing carbon dioxide and methane in the process. Some carbon is transferred to the soil in the form of humus.
Describe how ocean uptake and loss acts as a carbon flow.
CO2 is directly dissolved into the ocean from the atmosphere. It is also transferred into the ocean when it is taken up by organisms (e.g. plankton) that live in them. Carbon is also transferred when carbon-rich water from deep below rises to the surface and releases CO2.
Chemical weathering transfers carbon from the atmosphere to the hydrosphere and biosphere. Atmospheric carbon reacts with water vapour to form acid rain. When acid rain falls onto rocks, a chemical reaction occurs, dissolving them. The molecules resulting from this reaction can be washed up by seawater and react with the dissolved CO2 to form calcium carbonate, a substance which is used by sea creature to, for example, make shells.
Carbon from the atmosphere can be sequestered (captured and held) in sedimentary rocks or as fossil fuels. Rocks and fossil fuels form over millions of years when dead plant and animal material in the ocean falls onto the ocean floor and is compacted. Carbon is sequestered until it is burnt (combustion).
How do changes in the carbon cycle affect the atmosphere and climate?
Changes in the carbon cycle affect the amount of gases containing carbon (e.g. CO2 and methane) in the atmosphere. These gases trap some of the Sun's heat and warm the earth.
As human activities like deforestation and the burning of fossil fuels lead to the increase of greenhouse gases in the atmosphere, temperatures are expected to rise.
This is global warming, and it can affect other aspects of the climate, e.g. more intense storms are predicted.
How do changes in the carbon cycle affect the oceans?
Carbon dioxide is dissolved from the atmosphere into the oceans as a part of the carbon cycle.
CO2 in oceans is used by marine organisms like phytoplankton and seaweed through photosynthesis to make calcium carbonate shells and skeletons.
Increased levels of CO2 can lead to increased levels of acidity in the oceans, as the oceans initially absorb more CO2. This can have adverse effects on marine life.
Increased global temperatures could mean that marine life sensitive to temperature such as phytoplankton cannot survive in the oceans. This causes their numbers to decrease, and so less CO2 is absorbed from the atmosphere because less is needed for them for photosynthesis.
Warmer water is less able to absorb CO2, so as temperatures rise less CO2 is dissolved into the oceans.
How can wildfires change the magnitude of carbon stores?
They can release large amounts of carbon stored in biomass into the atmosphere.
By destroying vegetation, less carbon is absorbed from the atmosphere by plants through photosynthesis.
In the long term, fires can encourage the regrowth of plants. This takes in more carbon from the atmosphere through photosynthesis. Depending on the amount and type of regrowth, wildfires can have a neutral effect on the amount of atmospheric carbon.
Forests may be cleared for agriculture, logging or to make way for developments.
Clearance of trees reduces the size of this carbon store and if they are burned there is also a rapid transfer of carbon from the biosphere to the atmosphere.
Outline the relationship between the water and carbon cycle in the atmosphere.
Water is present in the atmosphere as water vapour and carbon as CO2 and methane. These are greenhouse gases and they cause a natural greenhouse effect that prevents some heat from escaping into space and keeps it within the earth's atmosphere. This means that the earth's temperature isn't too hot to be uninhabitable.
Describe the role the water cycle plays in the Amazon environment.
The water cycle causes the Amazon to be very wet - there is a lot of evaporation over the Atlantic Ocean which is blown towards the Amazon, leading to the high levels of rainfall.
Warm temperatures mean that evaporation in the rainforest itself is also very high, further increasing the rainfall.
The rainforest has a dense canopy, leading to high interception. This means that there is less water flowing into rivers.
The water cycle affect the animal life - it is populated with species adapted to high humidity and rainfall.
Describe the role the carbon cycle plays in the Amazon environment.
The Amazon stores lots of carbon in vegetation and soil, so it is a carbon sink.
The increase concentration of CO2 in the atmosphere has increased the productivity of the rainforest as there has been more CO2 for photosynthesis, so the biomass has increased. This also means that the amount of carbon the Amazon has sequestered has also increased.
However, it has been suggested that trees are dying younger, so the rainforest may not be reliable as a carbon store in the future.
How is deforestation affecting the Amazon rainforest?
It affects the water cycle as, in deforested areas, there is not canopy cover to intercept rainfall, increasing the amount of rainwater reaching ground surface, leading to more surface runoff, increasing risk of flooding.
It affects the carbon cycle as, without roots to stabilize the soil, the carbon-rich surface layer of soil is washed away, and the carbon is transferred into the hydrosphere. Also, deforestation decreases leaf litter, so humus isn't formed. The soil cannot support much new growth, limiting the amount of potential carbon storage.
How does environmental law aim to limit human impacts on the Amazon?
Laws can help protect rainforests. For example, laws that control land use, like the Brazilian Forest Code that says that landowners have to keep 50-80% of their land as forest.
How does protection aim to limit human impacts on the Amazon?
Countries have set up national parks and nature reserves to protect rainforests. For example, the Central Amazon Conservation Complex was set up in 2004 to protect biodiversity.