The Carbon Cycle - Global scale Flashcards
What is a carbon sink?
Any store that takes in more carbon than it emits. E.g. Tropical rainforest.
What is a carbon source?
Any store that emits more carbon than it stores. E.g. Damaged tropical rainforest
Where did our carbon emissions come from (1750-2012)?
Coal - 673 Gt
Land use - 590 Gt
Oil - 496 Gt
Gas - 202 Gt
Cement - 36 Gt
Where did our carbon emission get stored (1750-2012)?
Atmosphere - 879 Gt
Ocean - 590 Gt
Land - 528 Gt
What are the main carbon stores? (6)
In order of magnitude:
Marine sediments&sedimentary rocks, oceans, fossil fuel deposits, soil organic matter, atmosphere, terrestrial plants
How do marine sediments & sedimentary rocks store carbon?
Lithosphere - long term.
Biggest store of carbon. The rock cycle and continental drift recycle rock over time, but this may take thousands, if not millions of years
How do the oceans store carbon?
Hydrosphere - Dynamic.
Second biggest store but only a small percentage compared to the largest store.
Carbon is constantly utilised by marine organisms, lost as an output to the lithosphere, or gains as an input to rivers and erosion
How to fossil fuel deposits store carbon?
Lithosphere - Long term but currently dynamic.
humans exploit these rapidly, thought 4000 billion metric tons remain as fossil fuels
How does soil organic matter store carbon?
Lithosphere - mid term.
Soil can store carbon for over a thousand years. Deforestation, agriculture, and land use change are affecting this store.
How does the atmosphere store carbon?
Atmosphere - Dynamic.
Human activities caused CO2 in atmosphere to increase by around 40% since the industrial revolution.
How do terrestrial plants store carbon?
Biosphere - mid term but very dynamic.
Vulnerable to climate change and deforestation - carbon storage annually declining.
How is carbon storage in the lithosphere distributed?
The lithosphere is the main source of carbon but unevenly distributed.
E.g. oceans in southern hemisphere are larger than northern hemisphere and most biosphere occurs on land.
Terrestrial plant storage is focussed in the tropics and northern hemisphere
What changes has there been to non-tropical forests according to climate change information?
Increase in carbon sequestration in recent (especially Europe & Asia), due to conversion of agricultural land and plantations to new forests
What changes has there been to forests in industrialised regions according to climate change information?
Expected to increase by 2050.
But in global south, forested areas will decrease
What changes has there been to the rate of forest loss according to climate change information?
Decreased from 9.5 million hectares per year to 5.5 million hectares per year in 2010-2015
What are the 8 countries with the largest forested areas?
Russia, brazil, china, canada, USA, DRC, Australia and Indonesia
Why is brazil relevant to climate change?
Has the most carbon stored (rainforest) on land and the most extensive deforested area
Why is china relevant to climate change?
Has the largest amounts of afforested areas
What is Net Primary Productivity (NPP)?
Amount of carbon absorbed by forests. For tropical rainforests, this is positive all year round. But deciduous forests have a negative in winter, but a positive for the whole year
What are natural processes that alter the carbon cycle? (2)
Wildfires, Volcanic activity
How do wildfires alter the carbon cycle?
Biosphere - Atmosphere. CO2 released by burning.
Burning can encourage future plant growth.
Global warming allows more conditions for wildfires
How does volcanic activity impact the carbon cycle?
Mainly CO2 gas. Contribute a relatively low proportion of CO2 to the overall carbon cycle. Sometimes also produce SO2, which can reduce radiation from entering (cooling temperatures temporarily).
May reduce photosynthesis - which then impacts the water cycle
What are the human impacts which alter the carbon cycle? (3)
Fossil fuel use, Deforestation (+land use change), farming practices
How does fossil fuel use impact the carbon cycle?
Combustion - Lithosphere-Atmosphere. Long term carbon sink
How do farming practices impact the carbon cycle?
Pastoral farming releases CO2 as animals respire. Ploughing can release CO2 in soils. Farming machinery can produce CO2
What are fluxes?
Changes to the magnitude of carbon stores. May happen rapidly or over thousands of years.
Human impacts are causing unprecedented flux in CO2 from fossil fuel combustion
What is the carbon budget?
The balance between carbon inputs and outputs to a store at any scale or the balance of exchanges between the four major stores
What is a carbon source?
A store that emits more carbon than it absorbs
What is a carbon sink?
A store that absorbs more carbon than it emits
