1 - The Carbon Cycle Flashcards
(31 cards)
What is the carbon cycle?
Carbons route on Earth, within which carbon is transformed from organic carbon (in living organisms) to inorganic carbon (ores and minerals) and back again.
Name the 7 carbon stores (FALSBOS)
- Fossil fuels
- Atmosphere
- Lithosphere
- Soils
- Biosphere/vegetation
- Oceans
- Sediments on the ocean floor
Name the 7 carbon flows.
- Photosynthesis
- Combustion
- Ocean uptake and loss
- Sequestration
- Respiration
- Decomposition
- Weathering
Describe the 3 main carbon forms.
Carbon Dioxide (CO2) - gas found in the atmosphere, soils and oceans.
Methane (CH4) - gas found in the atmosphere, soil, oceans and sedimentary rock.
Calcium Carbonate (CaCO3) - a solid compound found in calcareous rocks, oceans and in skeletons and shells of ocean features.
Give an example of positive feedback in the carbon cycle.
Increase in global temp. > Oceanic temp. increases > Dissolved CO2 released by oceans > More CO2 in atmosphere > Increase in global temp. …
Give an example of negative feedback in the carbon cycle.
More fossil fuels burnt > Increase of CO2 in the atmosphere > Increased global temp. > More vegetation grows > More CO2 taken in by plants > Reduced CO2 in atmosphere > Global temp. ‘dampens’ due to less atmospheric CO2
Describe the different time scales that carbon flows happen over.
The fastest carbon flows (minutes-days) include photosynthesis, respiration, combustion and decomposition.
The slowest carbon flow (millions of years!) is sequestration.
Describe the different spatial scales that carbon flows happen over.
Plant scale = photosynthesis and respiration
Ecosystem scale = Combustion and decomposition
Continental scale = all flows!!
Explain photosynthesis as a carbon flow.
Transfers carbon from the atmosphere to the biosphere.
Energy from sun + CO2 + H2O -> Glucose + O2
Tiny marine plants (phytoplankton) in the sunlit waters of the oceans, as well as all terrestrial plants, photosynthetic algae, and bacteria turn carbon into organic matter by photosynthesis.
Explain decomposition as a carbon flow.
Transfers carbon from the biosphere to the atmosphere and soil.
This is when the majority of the remainder of carbon left in living things when they die is released by decomposers that break down the cells and tissues in dead organisms.
Explain respiration as a carbon flow.
Transfers carbon from the biosphere to the atmosphere.
Glucose + O2 -> CO2 +H2O + Energy
By the process of respiration, plants use some stored carbohydrates as an energy source to carry out their life-functions.
Explain combustion as a carbon flow.
Transfers carbon from the biosphere to the atmosphere.
Combustion is the burning of living and dead things e.g. wildfires which are naturally caused by lightning strikes but can also be due to humans.
Explain carbon sequestration as a carbon flow.
Transfers carbon from an environment (the atmosphere or the hydrosphere) and to new store (the biosphere, lithosphere, sediments on the ocean floor, or an artificial store)
Sequestration is the trapping of carbon and its isolation in a natural or artificial store.
Example:
Atmospheric CO2 is removed and dissolved in water = CaCO3, reaches Earth as rain and dissolves minerals on Earth’s surface through chemical weathering, releasing ions that are carried by surface waters into the oceans and settle out as minerals that marine organisms use in shells and coral. These creatures die and their skeletons sink to the bottom of ocean, are buried for millions of years and become sedimentary rock. Through subduction, CO2 can be released back into the atmosphere from this rock.
Carbon sequestration can also happen in plants but is released much quicker when plants combust or decompose.
Explain weathering as a carbon flow.
Transfers carbon from the lithosphere to the hydrosphere.
Weathering is the breakdown or decay of rocks by mildly acidic carbonic acid when rainwater absorbs CO2. The carbon in rocks is held in a solution as the rock dissolves and is transported by the water cycle to the oceans.
What are the 2 types of changes in the carbon cycle?
Natural variations
Human impacts
What are the 2 main natural variations that create change in the carbon cycle?
Wildfires and volcanic activity.
What are the 3 main human impacts that create change in the carbon cycle?
Farming practices, land-use change (deforestation and urbanisation), and hydrocarbon extraction + burning (fossil fuels)
What are the effects of wildfires as a natural variation that creates change in the carbon cycle? (Short and long term)
Short term:
They rapidly transfer large quantities of carbon from biomass or soil to the atmosphere = more carbon in atmosphere
Loss of vegetation = decrease in photosynthesis = less CO2 removed from the atmosphere = more carbon in atmosphere
Long term:
Fires can encourage the growth of new plants = increase in photosynthesis = less carbon in atmosphere.
Fires therefore can have a neutral effect on the amount of atmospheric carbon.
Fill in the blanks: What are the effects of volcanic ____ as a natural variation that creates change in the carbon cycle?
United ____ geological ____: CO2 released from volcanic ____ “has never caused ____ global warming of the planet”
541-251 ____ years ago volcanoes were much more ____.
Recent eruptions haven’t released enough ____ from the lithosphere to the ____ to make any real ____
Volcanic eruptions can actually ____ global temp…
- sulphuric ____ emitted counterbalances emitted CO2 and increases ____ of solar radiation.
- eruptions release ____ into the atmosphere = block incoming solar radiation.
activity, states, survey, eruptions, detectable, million, active, CO2, atmosphere, difference, reduce, acid, reflection, ash
What are the effects of farming practices as a human impact that creates change in the carbon cycle?
Ploughing, harvesting, rearing livestock, using machinery fuelled by FF and using fertilisers based on FF all release carbon!
Livestock, especially cattle, ruminate which produces CH4 as a by-product. Cattle in USA emit 5.5 million tonnes of CH4 per year…20% of total USA CH4 emissions.
CH4 is also produced in the cultivation of rice. Rice may contribute up to 20% of global CH4 production and is the primary food source for 50% of the world’s population.
What are the effects of land-use change as a human impact that creates change in the carbon cycle?
Deforestation: when def. by burning occurs, carbon is immediately released and if the land is then used for a different purpose the future absorption of CO2 from the atmosphere by new vegetation will be reduced. The system has become a carbon source rather than a carbon sink.
Urbanisation: rural areas -> urban areas = replaces vegetation and covers up soil which are both important carbon stores with impermeable surfaces. Urban areas are a major source of carbon emissions…transport, industry, conversion of land use and cement manufacturing. Highest polluting cities = Seoul, Guangzhou, New York, Hong Kong, Los Angeles.
What are the effects of hydrocarbon extraction and burning (fossil fuels) as a human impact that creates change in the carbon cycle?
Fossil fuels are important long-term carbon stores. Most of the world’s oil and gas is extracted from 70-100 million year-old rocks. When burnt, stored carbon is released, primarily as CO2, into the atmosphere, accelerating the carbon cycle. FF burning accounts for 80% of all human induced carbon emissions.
Budget = looks at the relationship of the inputs and outputs of a system
What is the carbon budget?
How much carbon is emitted by various processes compared to what can be absorbed by nature or captured by people.
Give 2 examples of a carbon budget.
Trees hold more carbon in the day due to the process photosynthesis, and less carbon at night due to the process respiration.
Deciduous forests hold more carbon in the summer as there is more vegetation, and less carbon in the winter due to less vegetation (drop leaves!!)
