The carbon cycle Flashcards
(16 cards)
Hydrosphere (carbon)
Carbon in oceans- dissolved and in marine organisms)
-Second second-largest carbon store
-Forms: dissolved CO2, Carbonate and bicarbonate ions, Marine organisms: Shells/ skeletons (calcium carbonate)
-The ocean hold most of this store
-The surface ocean holds a small amount but exchanges CO2 with the atmosphere
Lithosphere (carbon)
The biggest store of carbon
-Includes: sedimentary rocks (e.g. Limestone), Fossil fuels (coal, oil, gas), soil organic matter
-Widespread globally: continental crust, ocean basins
Cryosphere (carbon
-Store in smaller, but potentially dangerous
-found as permafrost: frozen soil containing dead material
-Arctic regions
-thawing due to climate change, risk of releasing methane and CO2
Biosphere (carbon)
Carbon stored in all living organisms
- Plants, trees (especially tropical rainforests), animals and microorganisms, soil (dead organic matter)
-Higest in tropical rainforest (Amazon)
-Also significant in grasslands, temperate forests and wetlands
Atmosphere (carbon)
Carbon as carbon dioxide and methane gases
-CO2 is the main greenhouse gas
-CH4 is methane- more potent but less abundant
-Global, but higher concentrations near industrial areas
-Seasonal Variation
Photosynthesis (carbon)
-Plants absorb atmospheric CO2: convert to glucose via sunlight
-Effects: reduces atmospheric CO2 and stores carbon in the biosphere (plant biomass)
Respiration (carbon)
-Plants, animals and microbes release CO2 through metabolic activity
-Effect transfers carbon from the biosphere to the atmosphere
-Occurs at all scales, but more respiration in warmer, biodiverse regions
Decomposition (carbon)
-Dead organisms are broken down by bacteria and fungi
-Carbon returned to the atmosphere (CO2) or soil (humus)
-Faster in warm, wet environments
-Cryosphere exception: Cold, slow decomposition- accumulates in permafrost
Combustion (carbon)
-Natural: wildfires
-Human: Burning of fossil fuels and biomass (deforestation)
-Effect: Rapid release of carbon into the atmosphere
-Magnitude: major factor in rising atmospheric CO2
natural variation
- Wildfires:
-Short-term increase in atmospheric CO2 as vegetation burns
-Loss of biomass = reduced carbon sequestration
-Long-term: regrowth may absorb CO2 again (negative feedback) - Volcanic activity
-Volcanic eruptions release CO2 and sulfur compounds from the deep lithosphere
-Natural input into the atmosphere, but small overall impact compared to humans
Human impacts
- Hydrocarbon fuel extraction
-The biggest human driver of rising atmospheric CO2
-Combustion of coal, oil and gas transfers carbon from the lithosphere to the atmosphere
-Industrial Revolution to present = sharp increase - Farming practices
-Ploughing soils and using fertilisers releases CO2 and methane
-Rice paddies and cattle farming are major methane sources
-Soil degradation reduces the ability to store carbon - Deforestation
-Forests are major carbon sinks (biosphere)
-Cutting/burning trees releases CO2 and removes future sequestration potential
-Common in tropical regions - Land use change
-urbanisation: vegetation removed- concrete = no carbon uptake
-Drainage of wetlands releases stored carbon
-Petland destruction = major CO2 source
What is the carbon Budget?
-The carbon budget refers to the balance between carbon inputs and outputs in the Earth’s Carbon Cycle
-Specifically, it’s the amount of CO2 that can be emitted while limiting global warming to a target level
Impacts of the carbon cycle on Land
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-Forests, wetlands, and peatlands act as carbon sinks via photosynthesis
-Soil stores hold large quantities of organic carbon (especially peat and tundra)
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-Deforstation reduces sequestration
-Soil degradation from agriculture relases stored carbon
-permafrost melt (cryosphere- releases methane and CO2, creating a positive feedback loop
Impact on the carbon cycle in the Ocean
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-physical pump (diffusion into cold surface water)
-Biological pump (phytoplankton photosynthesis, sinking organic matter)
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-CO2 + seawater = carbonic acid = lowers pH
-Harms coral reefs, shell-forming organisms
-Warming oceans reduce the ability to absorb CO2
-Changes in ocean currents may affect long-term carbon distribution
impact on the carbon cycle in the Atmosphere
Impact of Excess CO2
- Enhanced greenhouse effect - trapping more longwave radiation
-increases global temperatures, contributing to:
-melting ice caps
-extreme weather
-Droughts, floods, wildfires
Carbon cycles’ impact on the Global climate
-Rising temperatures
-shifting climate belts
-Glacier/ ice sheet melt
: reduces albedo effect, raises sea levels
- Disruption to carbon feed backs: e.g. warming = more decomposition = more CO2 = more warming
