Human changes in the carbon cycle Flashcards
What percentage of human related carbon release is from the combustion of fossil fuels?
90%
Apart from fossil fuels, what are the other human causes of carbon release?
land-use change, deforestation, land drainage, agricultural practices
How old is the rocks that we currently extract gas and oil from?
70-100 million years old
How much has the global concentration of carbon dioxide increased since the 1960s?
from about 320ppm to over 400ppm
What are fossil fuels mainly composed of?
carbon and hydrogen
Why has the global concentration of carbon dioxide rapidly increased since 1960?
because of the industrial revolution which has increased the demand for fossil fuels because of rapid industrialisation
What % is land use change responsible for carbon release globally?
about 10%
How does the farming practices: ploughing, harvesting, using machinery affect the carbon cycle?
the machinery is fueled by fossil fuels, as well as artificial fertilisers releases carbon
What is the main source for carbon emissions on a farm?
artificial fertilisers
Apart from the use of fossil fuels and fertilisers what other farming practice releases greenhouse gases?
methane
How does farms produce high levels of methane?
From livestock, especially cattle as when they ruminate food it produces methane as a by-product
How many tonnes of methane is released into the atmosphere per year by cattle in the USA?
5.5 million tonnes
What % of the total methane emissions in a year come from cattle in USA?
20%
Apart from cattle, what else produces high levels of methane?
the cultivation of rice
What % of the total global methane released a year is produced by the cultivation of rice?
20%
What % of the population of the world is rice their primary source of food?
50%
Why does deforestation occur?
for building, ranching, mining or to clear land to grow crops such as palm oil or soya
Where does deforestation mainly occur?
its widespread across the world but is particularly concentrated in tropical reasons, such as Indonesia
In total what % of global carbon dioxide emissions does deforestation account for?
20%
What is the carbon neutral system?
when a tree dies and decomposes very slowly and releases carbon over a long period of time. Then during that time new vegetaton starts to grow quickly which compensates for the carbon being released by the dead tree
Apart from when a tree decomposes, how else does deforestation increase the amount of carbon in the atmosphere?
less trees to absorb carbon, if trees are burnt it releases the carbon that it stores
How is deforestation changing the carbon sink?
making it more of a carbon source rather than a sink
What is the main change that urbanisation causes?
replacing open countryside with concrete and tarmac
How does replacing the open countryside with concrete and tarmac impact the carbon cycle?
important stores such as vegetation is replaced or soils is covered up by impermeable surfaces
