Carbon Cycle

Why is Carbon so necessary to life?

-Living beings are made of elements

What is a carbon pool?

-Something that stores large amounts of carbon
-Examples include the atmosphere

Define a flux

-The rate of exchange of a substance over time
-Often used to describe the movement of carbon

Fluxes and their importance

-Fluxes can create cycles and feedbacks
-An example would be CO2 in the atmosphere is taken in by the plant for photosynthesis so new plant matter can be made. Some carbon is released back into the atmosphere via respiration

CO2 in the atmosphere - What does it do?

-Captures longwave radiation reflected from the surface of the earth
-Regulates temperature on the planet
-Too much leads to climate change

Statistics on CO2 and the atmosphere

-Concentration in the atmosphere reached 30% higher than usual and is predicted to rise
-Predicted to be around 560PgC in the past (believed to be the Earth's natural upper limit)
-Result of human activities over the last 150 years

Carbon stores and their types

-Carbon Sources: Add carbon to the atmosphere
-Carbon Sinks: Removes carbon from the atmosphere

Carbon Sinks and Sources relationship

-If sinks and sources are equal

How had human activity disrupted the relationship between sinks and sources

-Processes like deforestation are shrinking carbon sinks meaning they store less carbon and is releasing it into the atmosphere

2 types of carbon forms

-Organic: Forms of biologically derived compounds such as proteins or starches

What do scientists track to help understand the carbon cycle?

-Where the carbon is stored (Pools)
-How long carbon stays in one place
-Fluxes that transfer it

How do scientists simplify the carbon cycle?

-They group large environments and similar objects and only focus on what matters on the global scale

What units are used to measure carbon?

-Petagrams (Pg) which are equal to 1 quadrillion grams
-Gigatonnes (Gt) which equal 1 Pg
-This makes the statistics involved easier to understand

What are the 4 main pools of carbon on earth?

-The Earth's crust
-Oceans
-Atmosphere
-Terrestrial Ecosystems (Ecosystems found on land)

The Earth's Crust (carbon pool)

-Largest carbon store on earth
-Sedimentary rocks found in the crust store 99.9% of the earths Carbon (100

How do sedimentary rocks form?

Any of the following:
-Hardening of mud (containing organic matter) into shale over geological time
-Collection of calcium carbonate particles from shells and skeletons of marine organisms into limestone

Oceans (carbon pool)

-Contains roughly 38

Atmosphere (carbon pool)

-Stores 750PgC with considerably smaller amounts of methane and other compounds
-Despite being one of the smallest carbon pools

Terrestrial Ecosystems (carbon pool)

-Carbon is stored in the form of plants

Plants and their effect on the carbon cycle

-Plants exchange carbon with the atmosphere rapidly in order to perform photosynthesis which contributes to the growth of new plant tissues
-Some of this carbon is released through metabolic processes (respiration) back to the atmosphere
-Woody stems are by far the best at storing carbon compared to other plant tissues

Soil and its affect on the carbon cycle

-Roughly 1500PgC is estimated to be stored in the world's soils

Different types of fluxes (Carbon)

-Photosynthesis
-Plant respiration
-Litterfall
-Soil respiration
-Ocean-Atmosphere exchange
-Fossil-fuel combustion and land change
-Geological processes

Litterfall (Flux)

-Living plants shed a portion of their leaves

Ocean-Atmosphere Exchange (Flux)

-Diffusion occurs at the surface of the water

Geological Processes (Flux)

-Includes the formation of sedimentary rocks and their recycling via tectonics

Geological Processes - Sedimentary (Flux)

-Rocks are weathered down into small particles and are mixed with plant and soil particles which are the results of decomposition and surface erosion of the shore
-These sediments eventually accumulate burying older sediments below
-This causes pressure to build that is so great

Geological Processes - Tectonic (Flux)

-The sedimentary rocks are moved and transformed through the process of plate tectonics
-Uplift in lighter plates and melting in heavier plates occurs as they are pushed deep under the surface
-Melted materials can lead to the release of emissions (carbon in a gaseous form) which are released via volcanoes

What is combustion?

-Material burning in the presence of oxygen

How can natural combustion benefit ecosystems?

-Fires can free nutrients and carbon that were previously inaccessible
-This enables growth and the creation of new habitats

How can combustion affect the carbon cycle?

-The combustion of plants and hydrocarbons releases large amount of CO2 into the atmosphere

How does precipitation cause transfers of carbon?

-Water is a form of weak carbonic acid (atmospheric or terrestrial)
-Plays a role in chemical weathering

How do chemical weathering processes break down rocks

causing a transfer of carbon?

What is Residence Time?

Time spent in a store

What is a physical ocean pump?

-Inorganic pump
-deep ocean current can store carbon for a very long time
—Latitude

What is a biological ocean pump?

-Also known as an organic pump
-Pumps 50GT of carbon per year

What is downwelling?

-Sinking in cool areas

What is upwelling

Rising in warm areas

What is carbon capture storage (ccs)

-Devices capture carbon where it is then stored underground

What is Direct Air Capture

Air is taken directly out of the air and stored underground or recycled

What is the percent of global energy received from fossil fuels

84%

Annual emissions from fossil fuels

10 billion tonnes
Three quarters of anthropogenic emissions are from the burning off fossil fuels

Current levels of CO2 in the atmosphere

415PPM

Amount of anthropogenic carbon emissions that comprise natural influx of fast carbon cycle to the atmosphere

What would the levels of carbon be if not for increased absorption from oceans and biosphere

500PPM

Why do we need CCS

Fossil fuels cause a flux from a geological store to the atmosphere
CCS is the exact opposite of

Examples of CCS in the UK

-Drax Project in North Yorkshire

What are some drawbacks of CCS

-Highly expensive
-Not properly developed
-Unsure how CO2 pumped underground would work with nearby rocks
-Both previous projects cost at least £1 billion

How does CCS work

Carbon is taken directly out of the air where a filter catches it

Benefits of CCS