Carbon cycle Flashcards
What forms can carbon exist in?
- CO2
- Methane
- Calcium carbonate
- Hydrocarbons
- Bio-molecules
What is anthropogenic CO2?
CO2 generated by human activity
What does carbon sequestration mean?
Capture of carbon from large-scale sources like power plants and put into long term storage
What is a carbon sink?
Store of carbon that absorbs more carbon than it releases
What is weathering?
Breakdown of rocks in situ by a combination of weather, plants and animals
What are sizes of the major stores of carbon?
Lithosphere - 99.985% Hydrosphere - 0.0076% Pedosphere - 0.0031% Cryosphere - 0.0018% Atmosphere - 0.0015% Biosphere - 0.0012%
In what forms is carbon stored in the lithosphere?
Inorganic
Organic
What inorganic ways can carbon be found in the lithosphere?
- Litter
- Organic matter
- Humic substances
What organic ways can carbon be found in the lithosphere?
- Fossil fuels (oil, gas, coal)
- Carbon based sedimentary (limestone)
What happens when organism die in the hydrosphere?
1) Dead shells and other parts sink into deep water
2) Decay releases CO2 here
3) Some material sinks to bottom and forms layer of carbon
4) Over millions of years, processes turn these sediments into rocks
What are the ways carbon is stored in the biosphere?
- Living vegetation
- Plant litter
- Peat
- Animals
- Soil humus
What 2 large forests contain most forest carbon?
Russia - 25%
Amazon - 20%
What is plant litter?
Fresh, undecomposed and easily recognisable plant debris
How much carbon is in atmosphere?
400 ppm
What has happened to the ppm of carbon over recent time?
Increased
What is the movement of carbon through stores know as?
Transfers or fluxes
What is a carbon source?
More carbon leaves than enters
What is carbonic acid?
CO2 dissolved in water
What is the geological component?
Where carbon cycle interacts with rock cycle
What processes are in geological component?
- Weathering
- Burial
- Subduction
- Volcanic eruptions
What carbon processes affect the biosphere?
- Photosynthesis
- Respiration
- Combustion
- Decomposition
What does photosynthesis do?
- Take in CO2
- Release O2
What does respiration do?
- Take in O2
- Releases CO2
What is decomposition?
Leaf litter broken down by decomposers (bacteria, fungi)
What does decomposition do?
Releases CO2 into air and ground forming humus
What carbon processes affect the hydrosphere?
- Calcification
- Compaction
- Ventilation
- Acidification
- Photosynthesis by phytoplankton
What is ventilation?
CO2 out of hydrosphere
What is calcification?
Where shells and coral take carbon ions and convert into carbonate to build shells
What is compaction
Marine plants and animals (fish) die and decompose on sea bed, compacted under sediment to form hydrocarbons
What is combustion?
Carbon released by fires
What carbon processes affect the lithosphere?
- Weathering
- Tectonic uplift
- Hydrocarbon from organic matter
- Sedimentary rocks from inorganic matter
- Volcanic activity
- Compaction
How does weathering affect the carbon cycle?
Carbon in atmosphere mixes with H2O to create carbonic acid which dissolves rock into calcium ions which run-off takes to ocean
How does tectonic uplift affect the carbon cycle?
Reveals sedimentary rocks
How does volcanic eruption affect carbon cycle?
Releases CO2 back to atmosphere
What fluxes are in the fast carbon cycle (years, decades) ?
- Photosynthesis
- Respiration
What fluxes are in the slow carbon cycle (millions of years) ?
- Compaction
- Weathering
How does the carbon cycle change over time due to natural variation?
- Temperature
- Volcanic activity
- Wildfires
How does human impact on carbon cycle change over time?
- Land use
- Deforestation
- Agriculture
- Hydrocarbon
How does cold temperatures affect the carbon cycle over time?
- Low co2 every 100,000 years
- Less flow into hydrosphere/pedosphere
- Less decomposition
- Less forest cover
- More weathering
How does hot temperatures affect the carbon cycle over time?
- More co2 every 100,000 years
- Melting of permafrost (Siberia) release of CO2 and methane
How do volcanic eruptions affect carbon cycle over time?
- 542-251 million years more active
- 130-380 million tonnes/year
What land use change affects carbon cycle over time?
- Urbanisation
- Cement production
- Transport
- Industry
How is land use increasing over time?
- Important stores (vegetation and soils) replaced
- Urban population to reach 60% by 2030
- Growing 1.3 million people a week
What % of global emissions does cement production make?
2.4% - 5% of global emissions
How is deforestation increasing over time?
- Replaced with grassland therefore absorption reduced
- 13 million ha cut down every year
What % of global emissions does deforestation make?
20 - 30%
What is the major worry about deforestation?
Sink to source
How is agriculture increasing over time?
- Movement to meat diets - emissions from animals up 11% (2001-11)
- Rice yields up 25% due to more CO2, but methane up 40%
- 44% from Asia for last 10 years
How does agriculture affect the carbon cycle?
- Fertilisers based on fossil fuels
- Machinery emissions
- Livestock (cows releasing methane_
- Rice paddies produce methane,
- Ploughing breaks down organic matter quicker releasing carbon
How has hydrocarbon emissions increased the carbon emissions over time?
-Increased since Industrial Revolution,
- 2013 - 61% higher than 1990
Top 3 emitters (China, USA, India) all growing
- Burning fossil fuels and industry responsible for 78% of increase in last 40 years.
What are examples of sinks?
- Plants
- Oceans (shells,coral)
- Rocks, soils
- Permafrost
- Rainforests
What is carbon sequestration?
When CO2 is removed and held in solid or liquid long-term store/sinks
What are the 3 levels the carbon cycle operates at?
- Plant
- Sere
- Continental
Give an example of a sere?
The Boreal Forest
What is a sere?
A community of plants in a particular environment (ecosystem)
Why is the Boreal forest a sere?
- Slower decomposition
- Climatic conditions,
- Waxy nature, smaller surface area of pine needles,
- Presence of peat (store carbon for thousands of years?
Give an example of a continental scale carbon cycle?
Siberian Tundra regions
How do Siberian Tundra regions work?
- Carbon has accumulated over 2.5m years, trapped it in tens of metres of soil
- Permafrost melts, carbon stored as methane and CO2 is released
- There is also negative feedback as higher temperatures have stimulated plant growth which at present absorbs more CO2 so it is currently a sink.
What is the carbon budget?
The balance of carbon between the different stores
Where is the the greatest exchange of carbon between stores?
Atmosphere and both the hydrosphere and the biosphere
What stores are the main sinks?
- Hydrosphere
- Pedosphere
- Biosphere
What store is the main source?
Lithosphere
What stores absorb the most CO2?
1- Atmosphere
2- Biosphere
3- Hydrosphere
Is earth in dynamic equilibrium?
No
There is more carbon being given out than being absorbed
What is the higher source of carbon natural or human?
Natural, but human are increasing imbalance
How does an increase of CO2 affect the land?
- Carbon fertilisation, more CO2
- Plant growth increases - less CO2 - negative feedback
- Increase decomposition, 55 trillion kg by 2050
How will plant growth have negative effects?
- Plant growth limited by other factors e.g. availability of water, nutrients especially nitrogen, sunlight
- If plants grow faster can become more susceptible to diseases
- Water stressed plants become more susceptible to fire and insects
How does an increase of CO2 affect the atmosphere?
The greenhouse effect
What is the greenhouse effect?
1) Incoming shortwave radiation from sun (UV)
2 )Heats the earth’s surface, some reflected by clouds
3) Earth’s surface radiates this heat out as longwave radiation which heats the air above it (infrared)
4) Some of this longwave radiation escapes back out into space whilst some is trapped by the greenhouse gases
The enhanced greenhouse effect is due to an increase in anthropogenic gases
An increase in these gases results in more longwave radiation becoming trapped, further increasing the temperature of the planet.
The balance between the incoming and outgoing radiation is called the radiative forcing
Name the greenhouse gases?
- CO2
- Methane
- Water vapour
How do greenhouse gases affect our temperature?
The average temperature of our planet is 15℃, without the greenhouse effect it would be -18℃
What causes an enhanced greenhouse effect?
Anthropogenic gases
What is the impact of the carbon cycle on the ocean?
- Ocean acidification
- Albedo
- Ocean salinity
How does ocean acidification occur?
- CO2 increases in atmosphere so CO2 increases in the seawater.
- The pH of the ocean decreases .
- Dissolving CO2 creates carbonic acid which increases the acidity - ocean acidification
- Carbonic acid reacts with carbonate ions to form bicarbonate (reduces carbonate)
- Less calcification (creation of calcium carbonate)
What does it mean if there’s less carbonate in the oceans?
- More energy needed to build shells which are thinner and more fragile
- Coral reef loss, providing food for 500 million as well as coastal protection
- More acidic the better it dissolves calcium carbonate rocks so more carbonate
- Warmer ocean will lead to less phytoplankton therefore limiting ability to take in carbon by photosynthesis
- Carbon fertilisation
What are the causes of sea level change?
- Melting of terrestrial ice - increase temperatures in summer and less precipitation in winter
- Thermal expansion, as water heats up it expands
- Sea levels rose by almost 6 inches in the 20th Century. Projected to rise by 0.8-2.0m by 2100.
What is albedo?
The fraction of sunlight that is reflected
What is the fraction of sunlight reflected on ice?
0.9
What is the fraction of sunlight reflected on open water?
0.1
