The carbon cycle Flashcards
Where is carbon found?
Lithosphere -
. over 99.9% on earth is stored in sedimentary rocks (limestone)
. 0.004% carbon stored fossil fuels (coal and oil)
Hydrosphere -
. co2 dissolved - rivers lakes and oceans
. oceans - second largest carbon store on earth - 0.04% - deep in the ocean in the form of dissolved inorganic carbon
. surface where it is exchanged with the atmosphere
Atmosphere -
. stored as co2 and methane
. 0.001% earths carbon
Biosphere -
. living organisms - transferred to the soil when living organisms die and decay
. 0.004%
cryosphere -
. less than 0.01%
. in soil of permafrost where decomposing plants and animals have frozen into the ground
What is the carbon cycle?
The carbon cycle - processed is stored and transferred
- closed system - inputs and outputs of energy - amount of carbon remains the same - locked away in long term stores - if released (become inputs)
What flows are there in the carbon cycle? 1-4
- photosynthesis -
. transfers carbon stored in the atmosphere to biomass
. change co2 into and water into glucose and oxygen
. carbon passed through food chain and released through respiration and decomposition - combustion -
. transfers carbon stored in living, dead or decomposed biomass to atmosphere by burning
. wildfires cause carbon flow - respiration - transfers carbon from living organisms to the atmosphere
. plants and animals - break down glucose for energy - releasing carbon dioxide and methane - decomposition -
. transfers carbon from dead biomass to the atmosphere and the soil
. bacteria and fungi break organisms down - co2 and methane
. some carbon - soil in the form of humus ( leaf litter )
What flows are there in the carbon cycle? 5-7
Ocean uptake and loss -
. co2 directly dissolved from atmosphere to ocean - transferred when it is taken up by organisms
. carbon rich water from deep rises to the surface and releases co2
Weathering -
. chemical weathering - transfers carbon from atmosphere to the hydrosphere and biosphere
. atmospheric carbon reacts with water vapour to form acid rain - chemical reaction takes place dissolving rocks - washed into sea (react with co2 to form calcium carbonate - used by sea creatures to make their shells)
How do carbon flows occur over different time and spatial scales and examples?
. fast carbon flows - transfer quickly (matter of minutes, hours or days)
- photosynthesis, repiriration, combustion and decomposition
. sequestration - slow carbon flow - millions of years
. depend of spatial scales - plant scale ( respiration and photosynthesis - main flows)
- ecosystem scale ( carbon flows such as combustion and decomposition also occur)
- continental scale (all carbon flows including sequestration occur)
What are natural processes that can change the carbon cycle?
- wildfires:
. rapidly transfer large quantities of carbon from biomass into the atmosphere - loss of vegetation - less carbon being removed
. longer term - fires can encourage the growth of new plants - take in carbon - depending on amount and type of regrowth, wildfires can have a neutral effect on the amount of atmospheric carbon - volcanic activity:
. stored within magma is released during volcanic eruptions - majority entering the atmosphere
. recent eruptions have released less co2 than human activities - HOWEVER a large eruption could affect the carbon cycle significantly
What are the human impacts that change the carbon cycle?
- hydrocarbon extraction and use:
. extracting and burning of fossil fuels releases co2
. without human interaction - carbon would remain sequestered in the earth for millions of years - deforestation:
. forests cleared for agriculture, logging or developments (infrastructure)
. clearance reduces size of carbon store - forest burnt (rapid increase of carbon emissions) - farming practises:
. animals release co2 (respire and digest)
. ploughing releases co2 (tractor and soil release)
. growing rice releases methane
demand of food increasing (machinery has increased co2 levels) - land use change:
. vegetation is removed to make way for urbanisation - reduces carbon storage
. concrete production - releases co2
What is the carbon budget?
the difference between inputs of carbon into a subsystem and outputs of carbon from it
the balance of the carbon budget determines whether it acts as a carbon source or a carbon sink
. carbon source (outputs outweigh the inputs - releases more than it takes in)
. carbon sink (inputs outweigh the outputs - takes in more than it releases)
How does the carbon cycle affect the atmosphere and climate?
. affects the amount of gases containing carbon - (greenhouse gases) - trap energy from the sun keeps some of the heat in to warm the planet
. concentrations of greenhouse gases increase - warming the temperatures (global warming)
. changes in temp across the globe affects other aspects of climate - more intense weather (causing social, economic and environmental issues)
How does the carbon cycle affect the land?
. allows plants to grow - without it (no photosynthesis - no recycling of dead plant matter)
. changes can reduce amount of carbon stored (permafrost melts - high temps - releases carbon into atmosphere)
. increase in wildfires
How does the carbon cycle affect the oceans?
carbon dioxide - dissolved directly into oceans
. used by organisms during photosynthesis - others use it to create shells
. increased co2 affects acidity levels - adverse effects on sea life
. global warming - some organisms cannot survive in warmer temps numbers decrease and less carbon is removed
. warmer water less able to absorb co2
