Carbon Flashcards
How has the extraction and burning of hydrocarbons changed the carbon cycle?
Since the industrial revolution, particularly in the western world, we have burnt increasing quantities of fossil fuels to power industries, transport and domestic purposes.
When plants lived millions of years ago, they sequestered carbon from the Earth’s atmosphere. These plant remains were buried deep under other sediments which became sedimentary rocks. As the remains were compacted they formed oil and natural gas.
How have land use changes caused change in the carbon cycle?
- Change from intensive to extensive farming practices, associated with this is increased demand from a growing global population and increased demand for meat from new middle classes in developing countries.
- Deforestation and planting of palm oil palms and soya plantations. Also conversion of forest to grassland for grazing
- Draining of wetlands which are a massive carbon if they are maintained, because organic matter falls into the water and decomposition is very slow - so the carbon is locked away. When drained, this can’t happen.
Urbanisation means that areas which were once soil and vegetation are concreted / tarmaced over. More urban areas also means more industry and transport (so more fossil fuel use).
How has deforestation cause change in the carbon cycle?
- When trees are burnt, CO2 is released into the atmosphere. The soil is more prone to erosion, becomes less fertile and hold less CO2.
- Trees are felled or burnt so that the timber can be used for other purposes (commercial farming, hydroelectric power, cattle ranching and mining).
What is a carbon sink?
A store that absorbs more carbon than it releases.
What’s a carbon source?
A store that releases more carbon than it absorbs.
What are carbon fluxes?
The change in the amount of carbon held in each store over time (from minutes to millions of years)
How is carbon stored in permafrost? By what processes?
- organic matter Rabat frozen in the soil in tundra regions cannot decompose, which prevents the release of carbon dioxide and methane into the atmosphere / water / soil
- increased melting of the permafrost. Due to climate change it is leading to a transfer of CO2 and methane into the atmosphere as the ice melts.
How is carbon stored in the atmosphere?
- held in the atmosphere as carbon dioxide
- in recent decades, the amount carbon dioxide has increased due to emissions from power stations, vehicles and deforestation. This has led to the enhanced greenhouse effect and climate change.
How is carbon stored in living vegetation? By what processes?
- plants convert energy from the sun unto carbohydrates that support life.
- plants can store carbon for many years and transfer it to the soil, oceans, seabed, or atmosphere when they die.
- deforestation releases this carbon back into the environment.
How is carbon stored in rocks?
- this is the largest store. It’s a long term store, with rocks gaming millions of years to form.
- rocks eg chalk and limestone are mainly composed of carbon (fossilised remains of marine animals)
- fossilised organic matter is also trapped within the lithosphere, stored in coal, oil and natural gas.
How is carbon stored in soil?
- soil contains rotting organic matter and weathered rock, and are important long term stored of carbon - it can be stored for 100s of years.
- deforestation, land use change and soil regions can however release this stored carbon very quickly.
How is carbon stored in the ocean?
- dissolved carbon is stored in surface ocean waters.
- living organisms including plankton and shelled organisms extract carbon from the water and use it to form their shells and bodies.
- when organisms die, they sink to the ocean floor where carbon is stored as ocean sediments. They also decay releasing CO2 to deep ocean waters. This sinking of carbon is called the carbon pump and is a slow process.
How do cold conditions affect stores and transfers of carbon?
- when cold, soils freeze over vast areas of land, stopping transfers of carbon
- decomposers would have been less effective, so carbon transfers to the soil would have been reduced
- less water would have flowed into the oceans as it is locked in ice and snow on land. There would be less sediment transfer along rivers and less build up of sediment on the ocean floor
- chemical weathering processes would have been more active as cold water can hold more carbon dioxide
- forest coverage would be very different both in: total area and geographical location. This would have affected the significance and distribution of processes such as photosynthesis and respiration
How do warm conditions affect the stores and transfers in the carbon cycle?
Carbon stored within permafrost (containing gases such as methane) is now being released into the atmosphere which further enhances the greenhouse effect, leading to increased warming. This is an example of a positive feedback loop leading to a further destabilisation of the system.
How can wildfires have regional impacts?
They turn forests from carbon sinks to carbon sources, because combustion returns huge quantities of carbon back into the atmosphere.
What are fossil fuels composed of?
Hydrocarbons
