3.a. Human factors can disturb and enhance the natural processes and stores in the water and carbon cycles.

Question 1

what is the impact of fossil fuel combustion and carbon sequestration on flows and stores of carbon?
what do fossil fuels drive? what was total energy used in 2013?

Answer 1

for past 2 centuries, fossil fuels have driven global industrialisation and urbanisation - despite development of renewables, global economy is still overwhelmingly dependent on fossil fuels.
- in 2013 87% of the total energy used - this releases 10 billion tonnes of carbon into the atmosphere per year

Question 2

what is the impact of fossil fuel combustion and carbon sequestration on flows and stores of carbon?
what has the anthropogenic c02 emissions been? what does it impact?

Answer 2

since 1750 anthropogenic co2 emissions have been 2000 gigatons - 3/4 coming from fossil fuels.
- although anthropogenic emissions account for less than 10% the natural flux from the biosphere and oceans into the atmosphere - it impact on the size of the atmosphere, ocean + biosphere carbon stores
- carbon emissions rising faster

Question 3

what is the impact of fossil fuel combustion and carbon sequestration on flows and stores of carbon?
what is a solution to carbon sequestration? how does it work?

Answer 3

carbon sequestration - long-term storage of waste carbon.
- solution = capture and store
- capture the co2 released from power stations + industries
- co2 is captured and compressed and piped to be stored - injected into porous rocks deep beneath the ground where it is to be stored permanently.
- could play important role in reducing carbon emissions
- in USA 40% of carbon emissions come from power stations –> CCS could reduce it by 90%

Question 4

what is the impact of fossil fuel combustion and carbon sequestration on flows and stores of carbon?
what are the issues with CCS?

Answer 4

• is very expensive
• the effectiveness of CCS is limited by economic and geological factors - costs in excess of $1 billion
• • need for deep porous rocks, overlain by impermeable rocks so the site is suitable for storage.