Carbon Cycle Flashcards
What is the carbon cycle?
The exchange of carbon (gigatonnes per year) in all its forms between different storage reservoirs
Current atmospheric CO2 concentrations have not been exceed in …
the past 800k years, likely not for the past 3.5Ma
How does carbon release in the palaeocene-eocene thermal maximum and now compare?
x10 more carbon released now
How much dissolved carbon does the ocean store compared to the atmosphere?
Ocean holds x50 more carbon
How much dissolved carbon do marine sediments and rocks store compared to the atmosphere?
x100,000 more carbon
What % of the lithosphere is made from carbon?
0.032%
Who created the Gaia hypothesis and when?
James Lovelock, 1979
What is the Gaia hypothesis?
Idea that the planet is self-regulating … perturbations can lead to positive and negative feedbacks
What would happen if, hypothetically, we burnt all our known fossil fuels?
- x10 more CO2 present than pre-industrial
- temperature rise between 4.5-15ºC
What is one fast acting uptake of CO2?
Photosynthesis (lock away half of the carbohydrates generated so this is not balanced by plant respiration)
How much faster is carbon exchange with plants than geologic exchanges?
1000 times faster
How much more carbon does the ocean store compared to the terrestrial biosphere?
19 times more carbon stored
What is invasion?
Net CO2 into ocean
What is outgassing?
Net CO2 out of oceans
What is air-sea gas exchange dependent on?
Relative concentrations of CO2 and partial pressure
What is the pH of sea water?
pH 8
In what oceanic areas does invasion occur?
Downwelling zones
In what oceanic areas does outgassing occur?
Off the west coast of Central America
What is AMOC?
Atlantic Meridional Overturning Circulation
Why do these patterns of invasion and outgassing occur?
- Invasion: water sinks taking carbon with it leaving relatively free of carbon surface waters
- Outgassing: upwelling of nutrients brings carbon rich water up to the surface
In the Archean Eon (4 billion years ago) what was the atmosphere composed of?
Mainly CO2 and N2
What lead to the slow removal of carbon from the atmosphere over billions of years?
Liquid water produced carbon acid (CO2 + H20) … this then reacted with silicate rocks to produce carbonates which locks away the carbon
How much CO2 emitted since 1800 has been taken up by the oceans?
42%
What is the main storage of terrestrial carbon?
Trees
What happens to biomass growth rate with increased CO2?
- experiments show mixed results
- some show faster growth e.g. Forest pine but seems to plateau (carbon is not the only limiting factor)
What affect does tropospheric ozone have on the land carbon sink?
Reduction of carbon sink (damages vegetation)… reduces ability to absorb carbon by 0.7-1.3 Gt per year
How much carbon is stored in known fossil fuels?
4000 Pg (petagrams)
How much carbon is in the atmosphere?
600 Pg
What is the ocean biological pump?
The permanent transfer of carbon dioxide to the sea bed following uptake into the ocean, absorption by phytoplankton, consumption of phytoplankton by zooplankton then sinking of dead organisms.
