3.3 the carbon cycle
where in the earths crust is carbon cycle found?
(sedimentary rocks, graphite, coal, oil and natural gas), atmosphere, soils and oceans
what are the sizes of the global carbon stores?
-Atmosphere 600 Gt (Gigatonnes - 1 Gt = 1 billion tonnes) -Ocean surface 700 Gt -Ocean deep layer 38 000 Gt -Sedimentary rocks 60 000 000-100 000 000 Gt -Soil 2300 Gt -Terrestrial biomass 560 Gt -Fossil fuels 4130 GMLA
how does the atmosphere impact the carbon budget?
-CO is the most important gas for controlling the Earth's temperature. -Scientists have calculated that CO causes about 20% of the Earth's greenhouse effect, water vapour about 50% and clouds 25%. The rest is caused by aerosols and methane. -While carbon dioxide contributes less to the overall greenhouse effect, it is the gas that sets the temperature, so CO controls the amount of water vapour in the atmosphere and thus the size of the greenhouse effect
what is the impact of oceans on the carbon cycle?
-Ocean acidification - dissolving CO in the ocean creates carbonic acid, which increases the acidity of water. -Carbonic acid reacts with carbonate ions; with less carbonate, shell-building animals such as corals have thinner and more fragile shells. -Coral reefs are threatened and there is a fall in marine biodiversity. -Warmer oceans are a product of the greenhouse effect. Phytoplankton grows better in cool, nutrient-rich waters and so the ocean's ability to take carbon from the atmosphere could reduce. -CO is also essential for the growth of phytoplankton and an increase in CO could increase the growth of some species. -Ocean warming also kills algae, which corals need to grow, leading to bleaching and eventual death of reefs. -When sea ice melts, the ref lective ice is replaced by more heat-absorbent water; the ocean absorbs more sunlight, which amplifies the warming process. -Ocean salinity is decreasing in the North Atlantic, probably due to a knock-on effect from higher levels of precipitation which through runoff eventually enters the sea, and the melting of ice sheets, which also adds fresh water to the sea. Such changes impact the circulation of the North Atlantic waters and eventually impact the climate of north-west Europe. - Melting terrestrial ice and thermal expansion are causing global sea levels to rise - rates of 3.5 mm per year since the early 1990s have been recorded. This is a eustatic rise in sea level
how do wildfires change the carbon cycle over time?
-Plant carbon enters the atmosphere in the event of a wildfire - Dense areas of carbon-storing plants are removed and plants are eliminated that would take CO out of the atmosphere as they grow. -Soil is exposed, which releases carbon from decaying plant matter. -Vegetation is replaced by young plants, crops or alternative land uses that store less carbon, so there is a net decrease in the carbon store -All of these effects increase the CO in the atmosphere. -As carbon dioxide is the most important gas for controlling the Earth's temperature, the process of greenhouse heating is accelerated
what is the impact of farming practices on the carbon cycle?
-Ploughing introduces air into the soil, decomposition accelerates and carbon is released to the atmosphere. -Emissions from tractors increase the level of CO in the atmosphere. -Livestock release methane gas to the atmosphere as a by-product of digestion - Rice paddies generate methane
how is the biosphere/terrestrial a store of carbon?
-organic matter in soils, plant litter, soil humus and peat -as organic molecules in living and dead organisms
what is the process of respiration?
-plants release co2 back to the atmosphere due to respiration (about half of the terrestrial portion). -in soil respiration, microscopic organisms living in soil also release co2 through respiration
how does urban growth impact the carbon cycle?
-urban growth reduces the amount of surface vegetation -co2 emissions from energy consumption, transport, industry and domestic use increase -there is an increase in co2 emissions from cement manufacture required for building increase
how much of the global carbon emissions is caused by deforestation?
20%
how is the atmosphere a store of carbon?
CO2 gases in the atmosphere- a 'trace' gas accounting for 0.04% of the atmosphere, but this does not reflect its importance to life on earth and the fact that CO2 is a potent greenhouse gas that plays a vital role in regulating the earths surface temperature
what is the process of carbon sequestration in oceans and sediments- the oceanic carbon pump and the biological pump?
CO2 moves from the atmosphere to the ocean by the process of diffusion. At lowlatitudes warm water absorbs CO2. At high latitudes where cold water sinks the carbonis transferred deep into the ocean. Where the cold water returns to the surface andwarms again it loses CO2 to the atmosphere. In this way CO2 is in constant exchangebetween the oceans and the atmosphere. This vertical circulation is a process calledthe 'oceanic carbon pump'. Phytoplankton also fix CO2 through photosynthesis - thecarbon passes through the oceanic food web. Carbonate is removed from the sea byshell-building organisms. When organisms die, the shells sink into deep water; decayof marine organisms releases some carbon dioxide into the deep water (the biologicalpump). Some material forms layers of carbon-rich sediments which over millions ofyears turn to sediments in rocks
what is the oceanic carbon cycle?
Carbon is held in a dissolved form in the water of the ocean and in the tissues of oceanic organisms. Inputs and outputs to this cycle take place through gas exchange with the atmosphere and through an input of organic carbon and carbonate ions from continental runoff. Because of the size of the oceanic carbon store, small changes in carbon cycling have global impacts. Ocean sediments are an important long-term carbon store.
up to a half
Of the carbon dioxide (CO2) released by burning fossil fuels over the past 200 years has been absorbed by the world's oceans. Limits sea organisms ability to form hard parts like shells
how does land impact the carbon cycle?
The amount of carbon that plants take from the atmosphere has risen in recent years. -With more atmospheric carbon dioxide to convert to plant matter through the process of photosynthesis, plants have been able to grow more - this is carbon fertilisation. -Plants will continue to grow and absorb CO until they reach a limit in the amount of water or nitrogen available. -Wildfires are generally extinguished, preventing large amounts of carbon from entering the atmosphere from this source. -In some parts of the world more intensive agriculture has allowed some farmland to return to more dense vegetation, which can store more carbon. -In other parts of the world where temperatures are high, dry trees are more susceptible to fire and forests may burn more, releasing CO. - In areas of water scarcity, trees slow their growth and take up less carbon or die and release their stored carbon into the atmosphere.
what is the terrestrial carbon cycle (fast cycle)?
This relates to the uptake of CO2from the atmosphere by plantsduring photosynthesis. CO2 is released back to the atmosphere during plant and animal respiration and CO2 and methane are released back during the decomposition of dead organic matter. The cycling of carbon between the soil, vegetation and atmosphere is relatively rapid and is sometimes referred to as the 'fast' carbon cycle
how does deforestation impact the carbon cycle?
When deforestation occurs by burning, carbon dioxide is immediately released into the atmosphere. Where the land is then used for different purposes, such as cattle ranching, there is a reduction in the system's ability to absorb carbon dioxide in the future. Deforestation has major impacts on the terrestrial carbon stores. Firstly, there is a reduction in photosynthesis to absorb the CO2. Less absorption of CO2 means a reduction of carbon in the stores, and more in the atmosphere. Secondly, the amount that was stored in the biomass above and below ground decomposes to release more CO2. Deforestation leads to a reduction in interception and infiltration. This in turn, increases surface runoff and soil erosion, leading to an increased risk of flooding. Without the vegetation returning the water to the atmosphere by evapotranspiration, a reduction in annual rainfall can be seen
what is an ecosystem?
a community of living organisms, their relationships between each other and the environment
what is carbon sequestration in oceans?
as they absorb co2, it sinks into deep ocean stores within weeks and circulates for thousands of years
what are the stores/pools of carbon?
atmosphere, ocean surface, food web, phytoplankton, shellfish and corals, deep ocean currents, deep sea sediments, sedimentary rocks, coal, oil, gas, soil and organic carbon
what is the atmospheric carbon cycle?
atmospheric carbon occurs as co2 and methane. methane is more powerful greenhouse gas but is short lived in the atmosphere through interactions with the terrestrial and oceanic carbon cycles, eg. photosynthesis or water absorption
what is a carbon pool?
carbon stores
what is geological sequestration?
co2 is captured at its source and injected in liquid form deep underground
why is the carbon cycle important?
cycling of the element carbon is vitally linked to life on earth. carbon is present in molecules that are found in all living creatures.
what is a carbon budget?
difference between the inputs of carbon into a subsystem and outputs of carbon from it
how is the earths carbon system in imbalance?
fossil fuel combustion and land use change
what is the process of combustion?
fossil fuels (coal, oil ad natural gas) contain carbon captured by living organisms over millions of years and stored in the earths crust. since the industrial revolution these fuels have been mined and combusted and serve as a primary energy source. the main by-product of fossil fuel combustion is CO2
when can the carbon budget be in dynamic equilibrium?
if the carbon moving into any given pool was the same as the carbon bring transferred out of the pool
what is the enhanced greenhouse effect?
impact on the climate from the additional heat retained due to the increased amounts of carbon dioxide and other greenhouse gases that humans have released into the earths atmosphere since the industrial revolution
how is the hydrosphere a store of carbon?
oceans= -surface layer= photosynthesis by plankton -intermediate and deep layer, carbon passes through the marine food chains and sinks to the ocean bed, where it is decomposed into sediments -living and dissolved organic matter -calcium carbonate shells in marine organisms
what are the drivers of the carbon cycle?
photosynthesis, erupting volcano, soil respiration, respiration, photosynthesis, respiration, diffusion, sinking, decomposition, burning and burning fossil fuels
what is process of photosynthesis?
plants use energy from the sunlight and combine CO2 from the atmosphere with waterfrom the soil to form carbohydrates. Virtually all organic matter is formed from thisprocess. Carbon is stored (or sequestered) for long periods of time as trees can live forhundreds or thousands of years and resistant structures such as wood take a long timeto decompose
how is the lithosphere a store of carbon?
sedimentary rock deposits (limestone, dolomite, chalk) and fossil fuel deposits
what are the 4 subsystems of the carbon cycle?
terrestrial carbon cycle, oceanic carbon cycle, atmospheric carbon cycle and slow carbon cycle
what is the slow carbon cycle?
the 'slow' carbon cycle refers to the cycling of carbon between rock stores and the atmosphere and oceans through the processes of weathering over millions of years. weathering of rocks on continents creates a net carbon sink in the oceans. chemical weathering of rocks by carbonic acid produces carbonate runoff, which is transferred to the oceans. here organisms use it to create shells, when the organisms die the carbonate sediment produced eventually forms limestone. this long-term carbon store is released to the atmosphere through volcanic activity
what is carbon sequestration?
the capture of carbon from the atmosphere and placing it in long-term storage it can be achieved in a couple of ways: geological sequestration, oceans, plants
what is the impact of volcanic activity in the carbon cycle?
the full impact of volcanic activity remains uncertain. however, volcanic expositions release a large amount of sulfur dioxide into the upper atmosphere. this can reduce the amount of incoming solar radiation. this is often counterbalanced by the absorption of outgoing terrestrial radiation by greenhouse gases emitted. the resulting climate change remains uncertain
what is the process of decomposition?
the process of decomposition by fungi and bacteria returns co2 to the atmosphere. decomposition also produces soluble organic compounds dissolved in runoff from the land surface. greenhouse gases (GHGs) are released as a by-product
what is the carbon cycle?
the transfer of carbon from one store/pool to another
what is the greenhouse effect?
the trapping of the sun's warmth in a planet's lower atmosphere
what is biological sequestration
using plants to capture and store co2 in stems, roots and soil
what is the process of weathering?
weathering processes (driven by the atmosphere, rain and groundwater) break downrocks on the Earth's surface. These small particles are combined with plant andsoil particles and eventually carried to the ocean. Large particles are deposited onthe shore. The sediment accumulates. Layers build and eventually, due to surfacepressure, shale rock is formed. Within the ocean dissolved sediments mixwith theseawater and are used by marine organisms to make skeletons and shells containingcalcium carbonate. When these organisms die, the carbonate collects at the bottom ofthe ocean and sedimentary rocks (for example, limestone) form.
