Carbon Cycle Knowledge

Positive Feedback

1. Increased temperatures due to climate change

2. Melts glaciers/permafrost, releasing trapped greenhouse gases

3. Greenhouse effect increases temperatures

Negative feedback

1. Increase CO2 results in more plant growth and faster rates of photosynthesis

2. More plants removes more CO2 from the atmosphere, reducing rising CO2

Main carbon stores

• Marine sediments and sedimentary rocks (66,000 - 100,000 million billion metric tons)

• Oceans (38,000 billion metric tons of carbon)

• Fossil fuel deposits (4,000 billion metric tons of carbon)

• Soil organic matter (1,500 billion metric tons of carbon)

• Atmosphere (750 billion metric tons of carbon)

• Terrestrial plants (560 billion metric tons of carbon)

Natural changes to the carbon cycle (3)

• wildfires

• volcanic activity

• milankovitch cycles

How do wildfires impact the carbon cycle

• transfer carbon from biosphere to atmosphere as CO2 is released, less photosynthesis (less removed from atmosphere)

• 5.3 billion tonnes yearly in 2022

• 15 years for forests to grow back

• reduced biodiversity

• 2018 california drought

• positive feedback (CO2 → global warming → plants die → CO2)

How does volcanic activity impact the carbon cycle

• carbon stored within the earth is released during volcanic eruptions

• 130-180 million tonnes CO2 released annually

• 1500 volcanoes globally

How do the milankovitch cycles impact the carbon cycle

• interglacial/glacial periods that fluctuate temperature change. increased temperatures cause glaciers to melt, this increases CO2 levels in the atmosphere.

• Global impact but very long term - glacial periods last around 70-90 thousand years

Human changes to the carbon cycle

• Fossil fuels

• Deforestation

• Farming practices

• Urbanisation

How do fossil fuels impact the carbon cycle

• combustion, transfers CO2 to the atmosphere from a long-term carbon sink

• 30 billion tons released by humans from fossil fuels

• increasing population is increasing energy demand

• global warming increases demand for air conditioning/cooling → causes more global warming

How does deforestation impact the carbon cycle

used to clear land for farming or buildings, this rapidly releases carbon stored in plants/trees using slash and burn techniques (e.g. 80% of deforestation in the amazon is for cattle ranching)

How do farming practices impact the carbon cycle

ploughing releases CO2 in the soil + farming machinery releases CO2, growing rice, animals releasing CO2 and methane

How does urbanisation impact the carbon cycle

• exacerbates deforestation and removes vegetation. cement production releases carbon dioxide

How does increased carbon impact Earth

• sea level rise

• ocean acidification

• loss of habitat

• extinction of species

• food/water insecurity

What is the enhanced greenhouse effect

Increased levels of greenhouse gasses in the atmosphere due to human activity

Radiation is trapped from the sun, resulting in global warming

Mitigation of the carbon cycle on an individual scale

• Using cars less

• Energy efficient homes (insulation, double glazing windows)

• Buying more efficient/electric cars

Mitigation of the carbon cycle on a national scale

• reduce reliance on fossil fuels for energy

• investing in and reducing the cost of renewable energy

• reducing deforestation (only buying FSC wood products)

• restoring forests

• increasing green spaces + biodiversity (rewilding - replanting vegetation in urban areas)

• public transport

• carbon capture + storage (trapping co2 underground) - expensive, not always viable, unknown impacts e.g. carbon capture in the UK (stores carbon underground in order to achieve net-zero greenhouse gas emission by 2050) (captures 90% of carbon produced with the potential to capture half the world's CO2 emissions)

Mitigation of the carbon cycle on a global scale

• Paris Agreement (2015) to cut CO2 emissions. 196 countries to keep global warming below 2 degrees

• afforestation schemes - FSC wood

• REDD+