The Carbon Cycle

What is anthropogenic CO2?

CO2 generated by human activity

What is carbon sequestration?

Process of capturing and storing atmospheric carbon dioxide.

What are the 4 major stores of carbon?

lithosphere, hydrosphere, biosphere, atmosphere

What is a carbon source?

A store that releases more carbon than it absorbs

What is a carbon sink?

Something that removes carbon from the atmosphere

What is the carbon cycle?

the flow of carbon between the atmosphere and the Earth

What is organic carbon?

Carbon stored in plant material and living organisms.

What is inorganic carbon?

Carbon stored in carbonated rocks.

How is carbon stored in the lithosphere?

As sediments and fossil fuel deposits

How is carbon involved in chemical weathering of rocks?

CO2 in the atmosphere dissolves in water to form carbonic acid. As this comes into contact with rocks, it slowly dissolves them, releasing carbon.

What processes control atmospheric CO2 concentrations over geological time?

Weathering, burial, subduction, and volcanic eruptions

How is carbon stored in the hydrosphere?

dissolved CO2

How is calcium carbonate formed in the ocean?

Formed by marine organisms

What extracts calcium carbonate from sea water?

Coral

How is subduction involved in the carbon cycle?

Carbonaceous sea-floor deposits can be pushed under continental margins through subduction, where they melt and release CO2 back into the atmosphere via volcanic eruptions or seeps.

What is the role of calcium carbonate in the carbon cycle?

acts as a long-term carbon store when it settles on the ocean floor, contributing to sedimentary rock formation.

How is carbon stored in the biosphere?

As organic matter

How is carbon stored in the atmosphere?

methane and carbon dioxide

How much carbon is stored in the atmosphere?

750 billion metric tons

What is the residence time of carbon in the atmosphere?

6 years

How has atmospheric carbon been measured since 1958?

By the Mauna Loa Observatory in Hawaii

How has global annual mean concentration of CO2​ in the atmosphere increased from 1958?

increased from 280 ppm to 317.7 ppm in March 1958 to 416.2 ppm as of May 2020.

What is the Keeling curve? What does it show?

graph showing the change in atmospheric CO2 concentrations since 1958

What is the rate atmospheric CO2 is rising per year?

currently rising at approximately 2 ppm per year.

How much carbon is dissolved in the oceans?

38,000 billion tonnes

How much carbon is stored in the soil?

1500 billion tonnes

How much carbon is stored in plants?

600 billion tonnes

How much carbon is stored in carbonate rocks?

100 million Gt

How much carbon is stored in fossil fuels?

4130 billion tonnes

How long does it take for carbon to circulate the oceans in deep currents?

Periods of 1250 years

How long has carbon been stored in carbonate rocks?

The past 150 million years

How long do plants/trees store carbon for?

decades

Describe the distribution of carbon in the oceans

Less carbon stored around equator sea surface, but more carbon concentrated around polar regions

What is the largest store of carbon?

lithosphere

What is the smallest store of carbon?

biosphere

Describe carbon fluctuations in the biosphere

The amount of carbon in the biosphere changes with seasons as plants grow and decay.

Which types of forests contain the greatest amount of carbon?

Boreal/tropical rainforests

What % of total carbon is stored in the lithosphere?

99.985%

What % of total carbon is stored in the hydrosphere?

0.0076%

What % of total carbon is stored in the pedosphere(soils)?

0.0031%

What % of total carbon is stored in the cryosphere?

0.0018%

What % of total carbon is stored in the atmosphere?

0.0015%

What % of total carbon is stored in the biosphere?

0.0012%

How much carbon is stored in peat?

250 billion tonnes

How much carbon is stored in the Surface Layer (Euphotic Zone) in the ocean?

900 billion tonnes

How much carbon is stored in the Intermediate (Twilight Zone) and Deep Layer in the ocean?

37,100 billion tonnes

How much carbon is stored in living organic matter (fish, plankton, etc) in the ocean?

30 billion tonnes

How much carbon is stored in dissolved in organic matter in the ocean?

700 billion tonnes

How were measurements of carbon in the ocean made?

By the Global Ocean Data Analysis Project (GLODAP) using data from research ships, commercial ships, and buoys.

What % of the atmosphere is made up of CO2?

0.04%

What is the role of photosynthesis in the carbon cycle?

Plants, photosynthetic algae, and bacteria turn carbon into organic matter using sunlight.

What is the role of respiration in the carbon cycle?

Plants use some of the stored carbohydrates as an energy source through respiration releasing CO2

What is the role of decomposition in the carbon cycle?

Decomposition breaks down dead organic matter, releasing carbon back into the atmosphere and soil

What affects water's ability to dissolve CO2?

temperature - colder water dissolves more CO2​.

What is vertical deep mixing?

the movement of carbon in oceans due to convection.
warm equatorial surface water carried to poles + sinks

• water returns to the surface in cycle

What does vertical deep mixing ensure?

that carbon dioxide is constantly being exchanged between the ocean and the atmosphere.

Describe the ocean's biological pump

Living things in the ocean move carbon from the atmosphere into surface waters and then down into deeper ocean layers.

What % of oxygen in our atmosphere are produced by phytoplankton?

80%

what is dial vertical migration?

a vertical mass movement of animals in the sea, which occurs every night

How does dial vertical migration affect the carbon cycle?

animals from the deep sea emerge from the depths up to surface water and migrate back down again at dawn - causes a net transfer of carbon from the surface to the deep sea.

How much carbon is drawn into the biological pump each year and how much actually makes it to the sea floor?

50Gt - only 0.2 gigatons of it makes it to the sea floor.

How much more carbon does the ocean hold than the atmosphere?

50x more

the oceans absorb about of all the carbon dioxide that are being emitted by burning fossil fuels.

One third

What is biomass combustion?

The burning of living and dead vegetation

How much of earth's land surface area is burnt by fire each year? How much carbon does this release?

3 to 4 million km2 - releases more than a billion tonnes of CO2 into the atmosphere

How does volcanic activity counteract the warming effect of CO2?

•Volcanoes emit sulphur dioxide gas, which combines with water in the atmosphere to form tiny sulphate aerosols.

•These light-coloured sulphate aerosols reflect incoming sunlight and cool the atmosphere.

Give an example of volcanic activity cooling down the atmosphere

•Mount Pinatubo's eruption - 1991

• Sulphates from the eruption cooled atmosphere by 0.5 °C

• Made 1992 and 1993 the coolest years in the past 35 years.

How can wildfires help to increase carbon sequestration?

• Releases nutrients faster than decomposition - can increase soil fertility

• Allows for increased young forest growth as saplings aren't struggling for light

How does cement manufacturing emit CO2?

• Heating calcium carbonate to produce lime and CO2

• Burning fossil fuels to power manufacturing process.

The cement industry is estimated to produce around __% of global anthropogenic CO2 emissions.

5%

How much CO2 is emitted for every 1000kg of cement produced?

More than 900kg

How does farming practices emit CO2?

Ploughing introduces air into the soil, accelerating the rate of decomposition and releasing CO2 into the atmosphere. Tractors also emit CO2.

According to a 2019 report from the United Nations Food and Agriculture Organization (FAO), of all human greenhouse gas emissions, how much is caused by agriculture and forestry?

one quarter

According to a 2019 report from the United Nations Food and Agriculture Organization (FAO), a third of all soils are degraded, releasing…?

78 billion tonnes of CO2

According to a 2019 report from the United Nations Food and Agriculture Organization (FAO), the largest source of carbon emissions is?

enteric fermentation - methane released from livestock after digestion

According to a 2019 report from the United Nations Food and Agriculture Organization (FAO), how much of all anthropogenic emissions does livestock account for?

14.5%

Greenhouse gases from rice paddies contribute ____% of total agricultural emissions.

10%

Burning tropical grasslands accounts for __% of total agricultural emissions.

5%

What % of agriculture-related greenhouse gas outputs occur in Asia?

44% - largest

What % of anthropogenic CO2 emissions result from land use change (mainly deforestation)?

30%

According to Global Forest Watch, how much tree cover was lost from 2001 to 2018? How much carbon did this release?

361 Mha - released an estimated 98.7 billion tonnes of CO2 emissions.

How does urban growth affect CO2 emissions?

• Reduces amount of surface vegetation

• Emissions from energy consumption, transport, industry and domestic use increase

In 2019, urban areas were estimated to be responsible for around __% of global carbon emissions.

75%

How does geological sequestration work?

CO2 is captured at it's source and injected in liquid form deep underground

how does terrestrial sequestration work?

Using plants to capture CO2 and store it as carbon in the stems, roots, and soil.

What are the disadvantages of terrestrial sequestration?

• Forests can lose carbon back to the air in a catastrophic fire, disease, or infestation.

• Land-based plantations are slow-growing and require monitoring and management for decades.

• The carbon within those systems is never removed permanently from the atmospheric system.

How can higher concentrations of atmospheric CO2 boost crop yields?

Carbon fertilisation - Increases rate of photosynthesis, spurring growth

How can higher concentrations of atmospheric CO2 reduce crop yields?

Reduces amount of water crops lose through transpiration

How can climate change impact the Artic?

Melts permafrost, potentially releasing methane on a massive scale

What % of the earth's added heat is stored in the ocean?

More than 80%

How does warming temperatures impact the ocean?

Warmer water holds less carbon - ocean becomes a less effective carbon pump

How does warming temperatures impact the ocean's biological pump?

could decrease phytoplankton abundance, which would limit the ocean's ability to act as a carbon sink

How does higher concentrations of atmospheric CO2 impact the ocean?

Dissolving CO2 in the ocean creates carbonic acid, increasing ocean acidity.

By how much has the pH of the ocean's surface dropped since 1750?

0.1

What is the percentage change in acidity of the ocean's surface since 1750?

30%

Describe the melting sea ice feedback mechanism

• Melting ice

• Reflective ice replaced with heat absorbent water

• Oceans absorb more sunlight - Amplifies warming process

What are the 2 ways climate change is causing sea level rise?

• Melting ice

• Thermal expansion

What is meant by thermal expansion?

warmer water takes up more space, so since the ocean's temperature is increasing, water levels are also going up

What % of future sea level rise is expected to be from thermal expansion of water?

75%

What is the enhanced greenhouse effect?

The impact on the climate from any temperature increase attributable to human activity