The Carbon Cycle
the carbon cycle
increasing carbon in the atmosphere is becoming a problem for climate change, we need carbon to survive
stores of carbon - hydrosphere, lithosphere, atmosphere, n biosphere, pedosphere
carbon sink - inputs greater than outputs
carbon source - outputs greater than inputs
the stores
marine sediments and sedimentary rocks - 100,000 billion metric tonnes - long term and largest
ocean - 38000 - absorbed directly from the atmosphere
fossil fuel deposits - hydrocarbons like coal oil and gas are used and are so important, key cause of climate change
soil organic matter - rotting organic matter, deforestation and combustion release these stores of carbon into the atmosphere
atmosphere - increased in recent years, thus enhancing the greenhouse effect
terrestrial plants - store carbon and take in carbon
transfers
photosynthesis
respiration
decomposition
combustion
carbon sequestration
weathering
ocean uptake and loss
physical causes of change in the carbon cycle
natural climate change
during quarternary geological period global climates fluctuaed between warm interglacial periods and cold glacial periods. Trends for temperature and carbon dioxide levels mirror each other.
in theory, carbon dioxide levels trigger temperature change, but temperature change affects carbon dioxide levels.
cold conditions
chemical weathering is prominent because cold water can hold more carbon dioxide
forest coverage would be very different, affects both respiration and photosynthesis
decomposers less effective
less water would have flowed into oceans as it would have remained locked up in ice and snow on land
the soil would have frozen over vast areas of land stopping transfers of carbon
warm conditions
melting of permafrost in tundra regions eg Siberia, Russia
positive feedback leading to further destabilisation of the system
wildfires
smoke from fires can travel globally releasing great amounts of CO2 into the atmosphere, forests can turn from being a carbon sink t a carbon source, as combustion returns huge quantities of carbon back into the atmosphere,
volcanic activity
returns carbon that has been trapped for millions of years back into the atmosphere
human causes of change to the carbon cycle
about 90% of anthropogenic carbon release is due to the combustion of fossil fuels
since the 60's global levels of carbon concentration have risen from 320ppm to over 400ppm
combustion of fossil fuels
land use change
creation of cement, impermeable surfaces
farming practises
ploughing land compaction, arable farming
deforestation
releases CO2 when burning and cutting down trees, areas that were carbon sinks release carbon, less photosynthesis, less respiration.
urbanisation
impermeable surfaces, affectings urban climate, CO2 released when building, higher car ownerships emissions
The carbon budget
the amount of carbon to increase global temperatures by 2 degrees
high carbon emissions exacerbate the greenhouse effect, exlaining why global temperatures have risen by 0.8 degrees celsius since 1880
the impacts of the carbon cycle
land - responisble for formation of soil, carbon is essential for plant growth and the production of food, provides fodder for animals, fossil fuels
ocean - can be converted into calcium carbonateb, uses marine organisms to build shells
atmosphere - greenhouse effect, increased emissions, deforestation, afforestation