The Carbon Cycle Flashcards
What is the carbon cycle?
The biogeochemical cycle in which carbon is transferred across the atmosphere, hydrosphere, lithosphere, biosphere, cryosphere and pedosphere
Describe the distribution of carbon
- Lithosphere biggest store - 100 million GtC stored in marine sediments and sedimentary rock
- Hydrosphere - around 38000 GtC
- Pedosphere (soils) - over 2000 GtC
- Atmosphere - around 800 GtC
- Biosphere - around 3000 GtC
What is a carbon sink?
A store of carbon that stores more than it releases
Describe the geological movement of carbon
- When sea creatures die, they sink to the bottom of oceans and are buried by layers of sediment
- This forms sedimentary limestone, thus storing carbon from the creatures in the limestone
- Tectonic uplift can expose this buried limestone
- When carbon rich sea floor deposits are pushed deep into the mantle, they melt and the CO2 eventually returns to the atmosphere via processes such a s volcanic eruptions
How much carbon is absorbed by plants via photosynthesis each year?
- 157 GtC/year
- Equivalent to the emissions of 37 million vehicles
How much carbon does plant litter release through decomposition?
- 60 GtC/year
How much of human carbon emissions has the ocean absorbed in the past decades?
30%
What is vertical deep mixing?
- Warm water at tropics sinks and cools, taking CO2 to the depths
- If this cold water warms and rises in low latitudes, it will release some CO2 to the atmosphere as warm water can store less CO2
Describe the biological pump in the ocean
Organisms in the ocean move carbon from the atmosphere to surface waters, then to deeper waters and eventually into rocks
How much have CO2 emissions from forest fires increased since 2001 due to climate change?
60%
What proportion of human emissions do total volcanic emissions make up?
Less than 1%
How much does cement production contribute to global CO2 emissions?
8%
How much do livestock account for anthropogenic emissions and why?
- 14.5%
- Largest source of CO2 emissions from farming is Enteric Formation - the release of methane by livestock
How much of global CO2 emissions were urban areas responsible for in 2019?
75%
What is the global carbon budget?
The amount of carbon gained (inputs) and lost (outputs) in the natural and manmade workings of the world
How much of total CO2 emissions did wildfires make up in 2024?
15%
Outline a short term change in the carbon cycle due to a climatic event
- Flooding in Midwest USA delayed photosynthesis between June-July 2019
- 100 million less tons of carbon was absorbed
How much does burning and extraction of fossil fuels contribute to CO2 emissions per year?
Around 80%
How much of global emissions did deforestation and land use change account for in 2019?
13%
How much CO2 does a mature deciduous tree absorb and how long does one take to mature?
- 22kg/C/year
- 20-30 years
Outline pre-industrial carbon levels and December 2024 carbon levels
Pre-industrial - 278 ppm
December 2024 - 425 ppm
How has ocean pH and carbonate ion concentrations changed since 1750? (Ocean acidification)
- Ocean pH dropped by 0.1 - a 30% change in acidity
- Carbonate ion concentrations declined by 16%
How much have ocean temperatures increased by since 1900 and what has this resulted in? (Ocean warming)
- Rose by 0.8 degrees
- Great Barrier Reef lost 50% of its coral due to bleaching in 2016, 2017 and 2020 due to death of symbiotic algae
How much is Arctic sea ice retreating and how much quicker is the Arctic warming than the global average? (Melting sea ice)
- Retreating at 12.8% per decade
- Arctic warming 4x faster than global average due to ice albedo feedback loop
