Carbon Flashcards
How much carbon is in the atmosphere?
720 Gigatonnes
How much carbon is stored in the oceans?
37,000 Gigatonnes
mostly in deep water oceans
How much carbon is stored in the lithosphere?
75 million Gigatonnes
How much carbon is stored as organic carbon in the lithosphere?
15 million Gigatonnes
How much carbon is released to the atmosphere by humans?
9 Gigatonnes / year
What “type” of carbon is most of the Earth’s?
Geological
Why are sedimentary carbonate rocks formed (e.g. limestone)
Geological carbon
How is carbon naturally released to the atmosphere?
Volcanic eruptions
Volcanic out-gassing at ocean ridges and subduction
zones
Chemical weathering of rocks
What sequesters carbon in surface water oceans?
Phytoplankton
Why do phytoplankton sequester carbon?
Photosynthesis
How is carbon terrestrially sequestered?
Plants (“primary producers”)
Why do plants / primary producers sequester carbon?
Photosynthesis
Where do phytoplankton sequester carbon?
Surface water oceans
What is the physical carbon pump in the ocean?
Thermohaline circulation
What force moves carbon from surface water oceans to deep water oceans?
Gravity
What is the carbonate pump?
Organisms’ carbonate shells sink when it dies, and later turn into sedimentary rocks
What is the turnover time in the atmosphere?
A few years
What is the turnover time in the deep ocean sink and lithosphere?
Indefinite; usually millenia
What is a turnover time?
How long carbon stays in a store
What is a sink?
A store that holds carbon for an indefinite time
How can carbon quickly be returned to the atmosphere by primary producers?
Respiration
How can biological carbon be returned to the atmosphere in the long-term?
Decomposition
What are the two different rates at which photosynthesis varies?
Diurnally
Seasonally
What does diurnally mean?
24-hour period
Describe the greenhouse effect?
Heat energy from the sun enters the atmosphere and is reflected by the Earth
Some of it is trapped by greenhouse gases within the atmosphere
What biological process plays a large role in regulating the composition of the atmosphere?
Photosynthesis
What is the albedo effect?
Light surfaces (i.e. ice) reflects solar radiation, which means less heat is absorbed by the Earth
How can melting ice produce a positive feedback loop with the albedo effect?
Ice melts → reduced albedo → increase temperature → more ice melting → more albedo → etc.
How have humans altered the carbon balance?
Fossil fuel combustion
Are energy pathways a key aspect of security?
Yes
What are examples of energy pathways?
Pipelines, shipping routes, road and rail
What are unconventional fossil fuel energy resources?
Tar sands, oil shale, shale gas, deep water oil
How are tar sands obtained?
Strip mining / open-pit mining
What are the benefits of unconventional fossil fuels?
Increased energy independence
What are the costs of unconventional fossil fuels?
Impact to the environment
What is EROI?
Energy-return-to-investment
What is shale gas?
Natural gas found within shale
How is shale gas obtained?
Fracking
What are the drawbacks of fracking?
Long-term impacts unknown
Research funded by industry or environmentalists
What are the concerns about fracking?
Methane escapes to atmosphere during extraction
Water contamination
How much of the water used for fracking that is returned to the ground surface is contaminated?
Up to 40%
What happens to some of the contaminated water used for fracking?
Returned to the ground surface
What is the EROI of tar sands?
4:1
What are some positives of biofuels?
They are renewable
What are some drawbacks of biofuels?
Crops could be used for food instead
They aren’t carbon-neutral
Why aren’t biofuels carbon-neutral?
The crops’ carbon uptake mightn’t offset all of carbon emissions from biofuel combustion
What is the different between carbon uptake and carbon emissions for biofuels?
63%
but this was poor methodology, funded by oil industry
What is carbon capture?
Capturing CO2 emissions and storing them in depleted oil & gas fields
How much of CO2 emissions can be captured by carbon capture?
Up to 90%
At what stages can carbon capture occur?
Pre-combustion or post-combustion
