carbon cycle

what is carbon cycle

it is the complex procceses carbon undergoes as it is transformed from organic carbon (the form found in living organisms such as plants and trees) to inorganic carbon and back again

what are the most common carbon compounds?

carbon dioxide-atmosphere,oceans,soils

methane-atmosphere,oceans,soils,rocks

calcium carbonate-rocks,shells,oceans

hydrocarbons-coal,oil,gas

bio molecules-proteins carbohydrates

what is the primary source of carbon?

is the earths interior,it was stored in mantle when earth formed ,escaped from the mantle at constructive and destructive plate bpundaries as well as hotspots volcanoes

much of c02 released at destructive margins is derived from metamorphism of carbonate rocks subducting with the ocean crust

carbon is held as biomass in living and dead organisms

carbon is removed into lpngterm storage by burial of sedimentrary rock layers

lithosphere

includes the crust and the uppermost mantle(constitutes the hard and rigid outer layer of the earth

inorganic deposits of carbon in the lithosphere includes fossil fuels like coal, oil and natural gas , limestone

organic forms of carbon in the lithosphere include litter,organic matter and humic substances found in soils

hydrosphere

the ocean stores can be divided into three

the surface layer where sunlight penetrates so that photosynthesis can take place contains 900Gtc

intermediate and the deep layer (37,100Gtc)

living organic matter(30Gtc)

dissolved organic matter(700Gtc)

when organisms die their dead cells,shells and other parts sink into this deep water.decay releases c02 into deep water.some material sinks right to the bottom where it forms layers of carbon rich sediments

over millions of years chemical and physical processes may turn these sediments into rocks

biosphere

total sum of all living matter

main stores of carbon are

living vegetation

plant litter

soil humus-originates from litter decomposition

peat-accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands or mires

animals

atmospshere

despite its relatively small concentration co2 is a potent greenhouse gas and plays vital role in regulating the earths temperature also stroes methane

Main Transfers of the Carbon Cycle

• The main transfers are: 

  • Photosynthesis

  • Respiration

  • Decomposition

  • Combustion

  • Burial and compaction

  • Sequestration 

  • Weathering 

weathering

• The main process is a form of chemical weathering called carbonation

• The atmosphere has CO₂ that combines with water vapour to produce a weak acid known as carbonic acid, this makes precipitation slightly acidic

• Calcium carbonate (calcite) in rocks, reacts with acidic water and forms calcium bicarbonate, which is soluble and is removed in solution by percolating water via streams, rivers and oceans and eventually back into the atmosphere

geological component

is where it interacts with the rock cycle in the processes of weathering,burial,subduction and volcanic eruptions

photosynthesis

phytoplankton in the sunlit durface waters of the ocenas as well as terrestrial plants,photosynthetic algae and bacteria,turn carbon into organic matter

they use sunlight energy to combine carbon dioxide from the atmosphere with water to form carbohydrates.these carbohydrates store energy

oxygen is the bi product

• Plants are primary producing organisms (they make their own food), as they use CO₂ from the atmosphere and water in the soil using energy from sunlight to produce carbohydrates

• Plants ‘fix’ gaseous carbon dioxide into solid form in their living tissues as glucose

• Oxygen is released as a bi-product

• In the oceans, microscopic organisms - phytoplankton - also do the same photosynthesising 

respiration

plants then use some of the stored carbohydrates as an energy source to carry out their life functions

• Plants, and the animals that feed on them, break down carbohydrates to release the energy that they need to grow and survive

• As they do this, they release CO₂, as a by-product, through respiration and waste gases, as they digest their food

• Life on Earth is fuelled by the breakdown of these carbohydrates which releases CO₂ back into the atmosphere

decomposition

carbon stores in plants and aniamsl which die

dead plants and animals are decomposed by bacteria

carbon respores by decomposersinto the atmosphere

process leaves carbonin the spill

oceanic carbon pumps

water is able to dissolve c02

there is a negative correlation between temperature of the water and the amount of c02 that can be dissolved-leads to vertical deep mixing

combustion

occurs when organic material reacted (burned) in the presnece of oxygen to give off the products of co2,water and energy

• Tectonic activity over thousands of years moves the sea floor towards destructive plate boundaries, where they are subducted into the mantle

• The extreme heat and pressure release the carbon in the rock back up to the surface where it returns to the atmosphere through volcanic eruptions by which 200 million tonnes are released per year

• Burning organic material releases energy, water and CO₂, industrial processes return carbon to the atmosphere that would otherwise have remained stored in rocks for millions of years

• Wildfires release stored carbon in vegetation back into the atmosphere

biomass combustion

burning of living and dead vegetation

volcanic activity

rsnges from emissipn of gases,non explosive lava emissions to extremely violent explosive bursts that may last many hours

According to United States geological survey the carbon dioxide from volcanic eruptions has never caused a detectable global warming of the armpits here because it forks fine droplets which increases the reflection of radiation from the sun back into space cooling the earths lower atmosphere

Farming practices

When soil is ploughed the soil layers invert air mixes in and soil microbial activity dramatically increased and results in soil organic matter being broken down much more rapidly and carbon being lost from soil into the atmosphere plus emissions from farm tractors increases carbon dioxide levels in the atmosphere

Land use change

Co2 emissions thst results from land use change like deforestation account up to 30% of anthropogenic co2 emission

Logging operations also remove forest also FDI urban sprawl

At the same time planting trees has resulted in forests being extablished the loss caused by deforestation in the tropics is being more than compensated for by reforestation in the temperate areas

Urban growth

Population expected to reach 60% in 2030 as cities grow land use changes from either natural vegetation or agriculture to one which is built up the co2 emissions resulting from consumption for transport industry and domestic use added to the co2 emitted in the cement manufacture

outline relationship between the water cycle and carbon cycle in the atmosphere

water is requires by plants to perform photosysnthesis

photosysnthesis moves carbon from the atmospjere to the bisphere

carbon dioxide mixes with water vapour to form acid

the process of respiration moves carbon and water from biosphere to the atmosphere

analyse the carbon sotres and transfers

lithosphere store is the largest carbon store 134,000 timedbigger thsn the smalles store(atmosphere)

atmosphere store is the smallest store but has the largest carbon transfer coming in and out where as lithosphere store gets the smallest amount of transfers measures per year even though it is the largest store

assess the magnitude of stores and flows in carbon cycle

the magnitude of carbon stores in the lithoshere is 2.5000 times larger than that stores in the atmosphere,hydrosphere and biosphere combines.carbon stores in the deep ocean is an outlier as it has 92% of all carbon not in lithosphere

explain changes in the global carbon cycle over long timescales

variations in the earths orbit and axis alter the amount of energy earth receives from the sun and leads to cycle of ice ages and warm periods

carbon dioxide in the atmosphere rose dramatically as temperatures warmed and different positive feedback mechanisms occurred to amplify this trend

asteroids also distrucpt the carbon cycle

northern hemisphere summers cooled and ice built up on land-this slowed the carbon cycle by reducing the rate of photosynthesis and respiration

cooler temperatures increased the amount of carbon transferred from the atmosphere to the ocean causing additional cooling

the global carbon cycle cannot exist without plant and the food webs they support

plants make their own food in the form of glucose sugar

heterotrophs do no photosynthesize and so must find and eat food made of carbon compounds such as proteins, carbohydrates and lipids, they break these complex organic compounds down into smaller molecules and use the carbon atoms to biosynthesize new organic carbon compounds

soil microbes,decompose dead material ,they break down larger compounds into smaller compounds-this process releases co2 to the surrounding soil to the atmosphere in the process called soil respiration -soil microbes move carbon down into the soil where it can be stores

the carbon cycle and carbon budget at plant scale

• photosynthesis is the carbon cycle process that moves carbon atoms from the air into trees and all other plants. Carbon atoms move into the biosphere and into most food webs via this process

• respiration-is is the key carbon cycle process that moves carbon atoms out of plants into the atmosphere, surrounding soil and water

• biosphere-key carbon process that generates gains in biomass. Net primary production is a measure of the amount of carbon stored mostly as biomass

if the carbon input from photosynthesis is greater than the carbon output from respiration, trees will biosynthesize more biomass resulting in greater carbon storage. The measure of NPP will be higher. Conversely, if the carbon output of respiration is greater than the carbon input of photosynthesis, less carbon will be stored and measures of NPP will be lower.

example of a positive feedback cycle

the increase of the greenhouse gas carbon dioxide increases the earth’s surface temperature, warming the atmosphere. A warmer atmosphere,combined with drought in some forests,has been creating conditions for increased pine bark beetle infestations. the beetle infestation kills more trees which then dry out, dead trees are fuel for more wildfires as they burn wildfires release greenhouse gases such as CO2 increasing the temperature

carbon budget

balance between inputs and outputs

what is the main impact of the changing budget on the land?

increased temperatures has warmed up the land.areas warming of the land increases the rate of decay of accumulated dead organic matter leading to release of methane.Thaws permafrost 1672Gtc of carbon

what is ocean acidification

dissolving carbon dioxide in the ocean creates carbonic acid ,the ph of the oceans surfaces have dropped by 30%

therefore thinner and more fragile shells

reef loss due to carbonate ions

its not that significant

ocean warming

warming of the oceans as temperatures rise-decreases phytoplankton which could limit oceans ability to take carbon from the atmosphere though biological pump

more c02 means more phytoplankton

what is the main impact of changing carbon budget on cryosphere?

it is melting-retreat at 12.8% per decade

nighlty reflective ice is replaced by more heat absorbent water,when it starts to melt40% loss of arctic sea ice in 35 yrs

ocean absorbs more sunlight

positive feedback mechanism

ocean salinity

higher levels of precipitation (dilutes)

higher temperatures melt ice(dilutes)

weskens thermo-haline circulation and therefore the oceanic carbon pump

positive

what is sea level rise

thermal expansion (warmer oceans have greater volume)

predicted to increase 0.8 to 2m 2100

melting terrestrial ice -greater increase in fresh water entering ocesns than water lost due to evaporation

what is the main impact of changing carbin budget

enhanced green house effect-causing radiactive forcing

current radiative forcing 800 terawatts. predicted temperature increase of 1.5oc between 2030 and 2050

driver feedback in hydrosphere ,weakening thermohaline circulation and biosphere-wildfires

assess the impications of changes to the climate budget

enhanced greenhouse gases effect which leads to weakened thermon -this has powerful positive feedback

-permafrost

-ice melt

-disrupt the circulation

ocean acidification is an example of a less concern it is bad for crustation but weak feedback at global scale

therefore implication associated with positive feedbacks are most cncerning

environmental sequestration

• afforestation

• peat bogs-carbon does not decompose in peat therefore an important store

• wet and restoration-carbon stored at saturation slows decay

technological sequestration

• iron fertilisation-add iron rich dust to oceans which encoursges phytoplankton growth

• urea fertilisation-add urea to ocean to encourage pyhploanton growth

• carbon capture and storage-extract co2 from the air pump it underground

assess the environmental and technological sequestration methods

environmental

• + proven , measurable costs and benefits and aesthetically pleasing

• - requires land(low value compared to urbanisation,agriculture and industry,slow,biosphere storage not as long

technological

• + compatible with current high-consumption lifestyles and capitalism

• - unproven, possible unintended consequences, requires subsidy

solutions to climate change and its challanges

• technological sequestration-unproven technology,delays shift away from fossil fuel economy

• reduce meat and dairy as well as food waste-needs change from people very hard to enforce it on people

• green taxes-not popular,more money people need to spend

• using electric vehicles and hydropowered transport-need political agreement and there has only been one successful e-journey

• global agreement unfccc-expensive and hard to get everyone to agree

• aviation-we love cheap flights

where is carbon involved in the water cycle

animals respire

plants photsynthesis

water rewuires for decomposition

carbon compounds tranferred to ocean via water cycle flows

water vapour dissolved caebon dioxide to create carbonic acid

increased carbon dioxide enchande greenhouse effect,increasing humidity in the atmosphere

carbon get frozen and stored in ice caps

calcium carbonate flux to deep oceans

carbon absorbed by ocean taken to deep oceans by carbon pump,ocean respires .carbon in tropics after centuries

carbonic acid weahters carbonate rocks

outline the relationship between the water cycle and carbon cycle in the atmosphere

increasing concentration of carbon in the atmospshere has a warming effect on the planet and leads to increased evaporation

this can increase rates of precipotation or equally higher rates of evaporation can further exacerbate aridity

photsynthesis requires both precipitation and carbon dioxide

decomposition releases carbon dioxide and requires the presence of water-may link to melting of permafrost

water and carbon cycle positive feedback

increasing atmospheric carbon increases global air temperatures

increase in sea surface temperatures

release of methane crystals on the ocean bed

increased atmospheric methane concentrations

water and carbon negative feedback

increasing atmospheric carbon increases global air temperatures

increased ice melt and release of freshwater into the arctic ocean decreasing its salinity and increasing its temperature and density

ocean conveyor could weaken meaning that warm ocean currents such as the Gulf Stream weaken and do not transfer heat from the equator to the higher latitudes

processes in the water cycle that have a relationship with factors driving change in the carbon cycle

evaporation,precipitation-photosynthesis, and respiration (plant growth)

precipitation-respiration (carbonic acid water vapour and CO2)

precipitation-weathering(carbonic rocks)

precipitation,infiltration-photosynthesis,decomposition (soil formation)

evaporation,precipitation-combustion(wildfires)

to what extent does an understanding of feedback systems in the carbon cycle help attempt to mitigate impacts of climate change

• feedback cycles describe the process where a change in a system leads to a cyclical sequence of changes which either accelerate or reverse the original change the system is dynamic equilibrium, understanding positive feedback can help mitigate climate change impacts

• e.g deforestation which releases carbon in the atmosphere as forests are turned from carbon sinks into carbon sources, this will increase the impact of climate change as it leads to greenhouse effect

• climate change has had several impacts on the carbon cycle as climate change has arisen from ghg emissions, resulting in the increased magnitude of carbon in the atmosphere, understanding feedback systems can largely help design mitigation actions but on its own, it doesn’t means mitigation will occur.

• understanding negative feedback can help mitigate against climate change

• e.g in the a,azon forest the increase in emissions has resulted in more productivity and encouraged faster growth resulting in my photosynthesis, absorbing more carbon. this can help suggest methods such as afforestation to reduce the impacts of climate change

outline how changes to the water and carbon cycles impacts the tropical rainforest environment

• deforestation will release more carbon into the atmosphere which will enhance greenhouse effect

• will increase temperature. if it increases by 2-3% 75% of Amazon will die off-longer dry seasons which will increase the risk of wildfires

• deforestation and conversion to pasture reduce the volume of dead organic matter therefore reducing transfers to the soils and lithosphere by decomposition(lower levels of soil organic carbon

outline feedback between the water and carbon cycle in tropical ranforests

incfeasing atmopsheric carbon increases global air temperatures

mass death of tropical rainforests due to increased drought in tropics

increased decomposition of and release of carbon dioxide

deforestation is reducing evapotranspiration which means the atmosphere becomes less humid and this could reduce rainfall,increasing the risk of drought.few trees remain,interception of rainfall or evaporation off leaves is reduced,further reducing evapotranpiration.risk of drought also increased due to inhanced ghg effect ,there have been two major droughts in the past 10 years

with fewer trees,most rainfall reaches the ground immediatley

relationships between the water cycle and carbon cycle

• high temperature-high precipitation/infiltration-high rate of photosynthesis-evapotranspiration as there is more plant growth-high precipitation

• high precipitation-high rate of infiltration and throughfall-extesive overland and channel flow-weathering of carbonate rocks -carbon in water-consumers in heterotrophs

rank order the extent of human impacts on the water and carbon cycle

• deforestation(20% since 1972)-reduces evapotranspiration,overland flow removes top soil so less infiltration and throughflow.Less photosynthesis therefore less carbon removed from the atmosphere and dead organic materials in soils

• mining is large but local(10% of deforestation but concentrated )vegetation clearance which reduces evapotranspiration and convection rainfall.creates large man made stores e.g dams .less photosynthesis

• agricultural practices-80% deforestation for cattle ranching,only 100000 hectares for palm,soy cultivation leads to soil compaction increading surface run off.Grassland and palm plantations reduced evapotrans.40% of regions ghg emmission are methane from cattle ranching

• climate-ippc predicts dry seasons 3 weeks longer,increases incidents of weather extremes-more intense rainfall prolonges drought,photsysnthesis declines when forest flooded,combustion from it add carbon to the atmosphere

stretegies to mitigate the environmental change in the amaxon tropical rainforest

• establishing clear property rights overland-the brazilian governemtn is keen to reduce land grabbing and illegal logging and ranching-not gonna solve the problem

• ecotourism protects rainforests from hunting logging and mining and provides local employment.the posada amazonas lodge in the peruvian amazon for example is jointly run by an eco tour operator-not a large scale solution

• encouraging markets to buy forest products from legally registered sources.The problem however is that the destination of many tropical commodities is often markets which are not eco sensitive for example amaxon rainforest timber is sold in china and india while brazilian beef is exported to russia-long term and great potential but how likely?

• paying owners not to cut down the trees.the main international effort to reduce forest clearence known as redd and its based on that rich countries should pay poor countries not to cut down trees.4.5 billion was pledged-large scale ,great potential but requires investmwnt and long term commintment

• monitoring deforestation using satellites and aeroplanes which can detect large scale illegal clearence-large scale great potential but requires investmwnt and long term commitmnt

what have they been doing to save brazilian rainforest

near real time monitoring system

700 people arrested

cut finance fore deforestation

share respnsibility in the chain of custody

50 million hectares protected

create protected areas

what are the successes

8.7 million hectares saved

stops 3 billion tones of co2 being emitted

managed a growing economy at the same time as reducing deforestation

what concerns still exist

15% of c02 emission results from deforestation

warming climate has led to beatle infestation

need to limit warming to 2c

budget of emission of 1bt of c02 until end of century-need to go down to 1 bt

5 ideas for the future

measure where,when and who is transmitting c02

disconnect development from carbon emission

share responsibility between government,busness,civil society

How are humans changing the global carbon budget

Deforestation - 13 million ha of the world forests are cut down and converted to other land uses every year

Afforestation - this is reducing the jet loss of total forest area but we are still losing 200 km of forest each day

Intensive agriculture - 6% of global greenhouse gas emissions come from the buildings urban areas are growing by 1.3 million per week

Cement production- produced approx 5% of global anthropogenic c02 emissions and increasing especially in china

Fossil fuel and combustion- 25% of global greenhouse gas emissions from from electricity and heat production and 14% from transport

The green house effect

A natural phenomenon thst sustains life on earth by raising average global temperature to 15°c without this earth would be up to 30°c cooler

It absorbs outgoing long wave radiation and send some hack to the earths surface

The earth radiates the heat as long wave radiation

Short wave radiation is absorbed by the earths surface

The enhanced green hours effect

An increase in concentration of greenhouse gases in the atmosphere due to human activities which is increasing heat trapped in the atmosphere

CFCs are by products of foam production refrigeration and air conditioning

Methane is released by landfills ajd livestock ajd during the production and transport of coal natural gas ajd oil

Carbon dioxide and nitrous oxide are released by the burning of fossil fuels

Mitigating climate change

Carbon capture and sequestration ( boundary dam ccs)

Changing rural land use

Improved aviation processes

Kyoto protocol

European emission trading scheme

Taxing system

Carbon capture and sequestration

Capture 90% of co2 emissions produced from the use of fossil fuels in electricity generation and industrial processes

E.g boundary dam ccs

Costs 800 million to build

Consumes 21% of the coals plants power output in order to scrub out the carbon dioxide and compress it into a liquid for burial ( hopes the cost will be offset by the extra oil recovered from the wet burn oil field

Helps push more oil out the floor

Kyoto protocol

Global agreement to achieve stabilisation of green house gas concentrations in the atmosphere at a low enough level to prevent dangerous anthropogenic interference with the climate system

Uk France ajd Sweden achieved targets

Raised international awareness

Bali roadmap was produced to started negotiations on a new set of emissions targets

Global agreement has been impossible to achieve

Some countries deleted signing up

USA withdress in 2001

Carbon trading ajd carbon sinks allow polluters to co tinue to pollute

Chinas emission increased by 50% since 1990

Only reduced emission by 0.5% since 2012

European emissions trading schemes

Eu set targets for 2020 to reduce its greenhouse gas emissions by 2”% of the levels there were in 1990 ets sets a limit on the emission of a pollutant but allowed companies that are within the limit to sell credits to companies that need to pollute more

Polluters pay for the damage they cause ajd creates incentive for them to invest in greener technology

It includes the high emissions industries e.g power generation

Manufacturing companies are relocating out of Europe to low cost location in developing countries therefore the cost of carbon credits uas fallen meaning it is cheaper to buy the credits and continue polluting

Taxing system

Many countries use their tax system to raise the cost of polluting for example car tax in the uk is priced by co2 emission

Polluters pay for the damage they cause ajd creates incentive to invest in greener technology

Public opposition to high taxes fuels political opposition