carbon cycle Flashcards
(10 cards)
where is carbon found?
- carbon can be found in organic and inorganic stores
- organic - carbon is found in living things
- inorganic - carbon is found in non living things e.g. rocks
lithosphere:
- over 99.9% of carbon on earth is stored in sedimentary rocks such as limestone
hydrosphere:
- carbon dioxide is dissolved in rivers, lakes and oceans
- oceans are the 2nd largest store of carbon on earth - the majority of carbon is found deep in the ocean
biosphere:
- 0.004% of earths total carbon is found in living organisms - when organisms die and decay, this carbon is transferred to the soil (pedosphere)
atmosphere:
- carbon is stored in the atmosphere as CO2 and methane
- the atmosphere contains around 0.001% of the earths carbon
cyrosphere:
- less than 0.01% of earths carbon is stored in the cryosphere
carbon cycle stores and flows
- carbon cycle - process by which carbon is stored and transferred
- the carbon cycle is a closed system
flows of carbon:
photosynthesis:
- photosynthesis transfers carbon from the atmosphere to biosphere - enables plants to grow
combustion:
- combustion transfers carbon from the biosphere to the atmosphere via burning
ocean uptake and loss:
- CO2 is directly dissolved from the atmosphere into the ocean - it is also taken up by organisms that live in them e.g. plankton
- carbon is also transferred from the ocean to the atmosphere when carbon-rich water from deep in the oceans rises to the surface and releases CO2
sequestration:
- carbon from the atmosphere can be sequestered (captured and held) in sedimentary rocks - rocks form over millions of years when dead animal and plant material in the ocean falls to the floor and is compacted
respiration:
- respiration transfers carbon from the biosphere (living organisms) to the atmosphere
decomposition:
- decomposition transfers carbon from biosphere (dead biomass) to the atmosphere and the pedosphere (soil)
weathering:
- chemical weathering transfers carbon from the atmosphere to the hydrosphere
- atmospheric carbon reacts with water vapour to form acid rain - acid rain falls onto rocks which dissolves the rocks - this may be washed into the sea
fast carbon flows:
- fast carbon flows quickly transfer carbon between sources
- photosynthesis, respiration, combustion and decomposition are examples of fast carbon flows
slow carbon flows:
- sequestration is a slow carbon flow - it takes millions of years for carbon to be sequestered in sedimentary rocks
physical factors that affect the carbon cycle
climate
- lower temps - less photosynthesis - plant growth decreases - less CO2 absorbed (opposite for warmer temperatures)
- colder oceans absorb more CO2 from the atmosphere (opposite for warmer temperatures)
wildfires
- short term: loss of vegetation - photosynthesis decreases - less carbon removed from the atmosphere
- long term: soil can become more fertile after wildfires - encourages the growth of new plants - plants take in carbon from the atmosphere for photosynthesis
volcanic activity
- carbon stored within the earth is released during volcanic eruptions - carbon is transferred from the lithosphere to the atmosphere
- recent volcanic eruptions have released much less CO2 than human activities
human factors that affect the carbon cycle
fossil fuel extraction and use:
- extracting and burning fossil fuels: we need fossil fuels for many things e.g. heating up housing and powering vehicles etc - this releases CO2 into the atmosphere
- as population has increased overtime, fossil fuel use has increased overtime
deforestation:
- forests may be cleared for agriculture, logging, or to make space for housing - reduces size of carbon stores - less carbon can be stored in trees and more carbon will enter the atmosphere
- a lot of the deforested trees are burnt - releases CO2 (rapid flow of carbon from biosphere to atmosphere)
urbanisation:
- due to urbanisation, more houses have to be built - trees are removed to make way for buildings (reduces carbon storage in the biosphere) - reduces size of carbon stores - less carbon stored in trees and more carbon will enter the atmosphere
- lots of concrete is used when urban areas expand - concrete production releases lots of CO2 - releases CO2 into the atmosphere
farming:
- population has increased - food production has increased - carbon emissions from farming practises have increased e.g. growing rice in rice paddies releases a lot of methane - more carbon stored in the atmosphere// animals release CO2 and methane into the atmosphere when they respire and digest food - carbon moves from the biosphere to the atmosphere
carbon budget
carbon budget:
- carbon budget - difference between the inputs and outputs of carbon
- inputs of carbon - volcanic eruptions, burning fossil fuels, respiration and ocean loss
- outputs of carbon - photosynthesis, sequestration and ocean uptake
- carbon source - releases more carbon than it absorbs
- carbon sink - absorbs more carbon than it releases
atmosphere, land, oceans
impacts of carbon cycle on:
atmosphere:
- more carbon - GHG increase - temperatures increase - global warming
- changes in temperature across the globe will affect other aspects of the climate e.g. more intense storms are predicted
land:
- more carbon - allows plants to grow
- more carbon - temperatures increase - reduce the amount of carbon stored in land e.g. permafrost melts - releases carbon previously stored in the permafrost into the atmosphere
- more carbon - temperatures increase - wildfires increase
oceans:
- increased CO2 in the atmosphere - increase acidity of oceans - affect marine life
- more carbon - temperatures increase - global warming - organisms sensitive to temperature e.g. phytoplankton, may not be able to survive at higher temperatures
- warmer water is less able to absorb CO2 - more CO2 in atmosphere
water and carbon
carbon and water as life support:
- carbon is a fundamental building block of life - all living things contain carbon// water is also essential for life - all living things need water to survive
- water is present in the atmosphere as water vapour, and carbon exists as carbon dioxide and methane - both GHG - natural GHG effect
carbon and water cycles depend on each other:
- carbon combines with water in the atmosphere - allows chemical weathering, which removes carbon from the atmosphere
- water is needed for photosynthesis, which removes carbon from the atmosphere
- amount of CO2 in the atmosphere affects global temperatures, which affects evaporation levels and therefore precipitation
mitigating climate change
measures at a range of scales:
individual:
- people can choose to use their cars less and buy more fuel efficient cars
- make homes more energy efficient, e.g. with double glazing, insulation and more efficient appliances
- evaluation - only effective when widely adopted// not all individuals have the financial means to make greener choices
regional and national:
- governments can reduce reliance on fossil fuels by increasing the availability and reducing the cost of renewable energy sources such as wind, tidal and solar
- afforestation can increase carbon uptake by the biosphere (evaluation - takes a long time for trees to grow)
- governments can invest in carbon capture and storage (CCS) - CO2 emitted is captured and stored underground e.g. in depleted oil and gas reservoirs (evaluation - expensive)
global:
- countries can work together to reduce emissions - the kyoto protocol (1997) and the paris agreement (2015) are international treaties to control the total amount of greenhouse gases released - participating countries agree to keep their emissions within set limits (evaluation - many countries’ targets are not strong enough to keep global warming below 1.5°C - if all countries met their current pledges, the world could still warm by 2.5–3°C, can easily pull out of the agreement e.g. the USA temporarily left the agreement under president trump, countries set only goals - no punishment if they don’t stick to it)
- international carbon trading schemes - countries and businesses are given a limit on the emissions they can produce - if they produce less they can sell the extra credits, if they produce more they need to buy more credits
amazon case study
- The Amazon is the world’s largest tropical rainforest and covers 40% of the South America
- It’s home to up to 50% of all species on earth
Water cycle:
- The water cycle causes the Amazon to be very wet - there is a lot of evaporation over the Atlantic Ocean - wet air is blown towards the Amazon - contributes to Amazon’s very high rainfall - annual rainfall 3000mm
- The water cycle affects the Amazon environment - it is populated by species that are adapted to high humidity and frequent rainfall
Carbon cycle:
- The Amazon rainforest stores lots of carbon in its vegetation and soil (sequestration) - carbon sink - stores around 200 billion tonnes
Human activities affecting the water and carbon store:
Deforestation facts:
- Approximately 20% of the Amazon has been lost to deforestation
- Deforestation is responsible for 75% Brazil’s carbon emissions
- After Bolsonaro was elected in 2019, deforestation rates increased over 60%
- In the first 6 months of Lula’s presidency, deforestation decreased by 35%
Effects on the water cycle:
- Deforestation - less interception - increased surface run off - increased flooding (local impact)
- Deforestation - less evapotranspiration - fewer clouds form - rainfall is reduced - increases the risk of drought - deforestation reduces regional rainfall by 20% (wider regional/global impact)
Effects on the carbon cycle:
- Deforestation - less CO2 sequestered in trees - more CO2 in the atmosphere - CO2 is a GHG - global warming
Climate change:
- The Amazon had severe droughts in 2005, 2010 and 2015-16
- Plants and animals living in tropical rainforests are adapted to moist conditions, so many species die in dry weather - could lead to extinction of some species
- Scientists predict that a 4 °C temperature rise could kill 85% of the Amazon rainforest
- Drought can also lead to fires - destroy large areas of forest - release lots of CO2 into the atmosphere
Mitigation:
Replanting:
- For example, a project in Peru replanted over 115 acres of forest between 2016 and 2019
- However, it takes time - newly planted trees take decades to mature and store the same amount of carbon as old trees// Additionally, replanting tends to happen on a small scale compared to the vast areas of forest lost each year - too slow and small scale to tackle climate change
Environmental law:
- The Brazilian Forest Code states that landowners have to keep 50-80% of their land as forest
- Illegal deforestation still takes place - over 90% of Amazon deforestation is illegal
Protection:
- For example, the Central Amazon Conservation Complex in Brazil was set up in 2003 and protects an area of 49,000 km^2
- However, large areas of rainforest remain unprotected and vulnerable
- Illegal deforestation still takes place - over 90% of Amazon deforestation is illegal
positive and negative feedback loops
positive feedback example:
- CO2 increases - temperatures increase - drought - wildfires - CO2 increases further
negative feedback example:
- CO2 increases - extra CO2 causes plants to grow - plants remove CO2 from the atmosphere - amount of CO2 in the atmosphere decreases
