The carbon cycle - changes over time

quaternary period

last 2.5 million years

Milankovitch cycles

regular cycles or orbital anomalies that cause variations in the amount of solar radiation that reaches the earth

3 natural causes of change in the carbon cycle

natural climate change, volcanic activity, wildfires

relationship between temp and CO2 level in natural climate change

higher temperature associated with higher CO_² concentration

changes to atmospheric carbon in recent years

above 400ppm

2 impact of warm conditions on stores and transfers

high temperature causes melting permafrost releasing more carbon dioxide - positive feedback loop

more wildfires

5 impacts of cold conditions on carbon stores and transfers

decomposers less effective so transfer to soil reduce

more chemical weathering as cold water can hold more carbon dioxide

differences in forest cover affect photosynthesis and respiration

less water in ocean and more locked up in snow and ice - less sediment transfer along river and less build up on ocean floor

frozen soil can stop carbon transfer

how much carbon dioxide is released from volcanoes

130-380 million tonnes per year

how do volcanoes impact the carbon cycle

releases carbon that’s been trapped in the earth’s crust into the atmosphere.

what does lava contain and how does this impact the carbon cycle

contains silicates that slowly weather which converts carbon dioxide in the atmosphere to carbonates in a solution.

how much carbon dioxide released from human activity

30 billion per year

at what speed is carbon absorbed from the atmosphere

slowly

time variation of volcanic activity

lithosphere gains carbon slowly then releases it quickly through eruptions

outline wildfires

natural and human induced. don’t impact the climate significantly. Seasonal variation due to climate (high temperature and dry conditions in summer)

examples of a wildfire

South East Asian Haze, 2015 - burning peatland for weeks releasing CO2 into the atmosphere

time variation in the impact of wildfires on the carbon cycle

can release more carbon in short term but promote more plant growth in the long term.

6 anthropogenic (human) impacts on carbon cycle

Hydrocarbon fuel extraction and burning, agriculture, land use changes, urban growth, deforestation

how much of the total carbon released by human activities is from burning fossil fuels

90%

how does burning fossil fuels release carbon

most gas and oil come from rocks that contain carbon that’s been locked up for millions of years. Combustion of hydrocarbons releases carbon dioxide and water vapour into the atmosphere causing global warming.

of all human-induced global CO2 emissions, how much does the cement industry produce

5% - most from heating of calcium carbonate and burning of fossil fuels to power the process

percentage increase in global CO2 emissions between 1990 and 2013

released 36 GtC in 2013 - 61% higher than 1990. 43% emissions in 2013 from burning coal

which countries dominate CO2 emissions

China (28%), USA (14%)

How does ploughing affect the carbon cycle

soil layers invert allowing air to mix in increasing soil microbial activity leading to increased decomposition of organic matter so more carbon released.

how does livestock impact the carbon cycle

methane produced during digestion

in 2011 what percentage of all agricultural emissions was due to methane produced by livestock

39% - increase of 11% since 2011

how does farm machinery effect the carbon cycle

releases carbon dioxide

how do rice paddies impact the carbon cycle

biological processes in rice paddies produce methane - makes up 10% of all agricultural emissions

what percentage of all human induced carbon emission result from land use change

30%

how many hectares of forest are changed to other land use per year

13 million

what is deforestation driven by

need for agricultural land - normally carried out by subsistence farmers who use slash and burn practices

outline logging operations

logging operations remove trees - often illegal and build roads to access more remote areas of forest

how can some land use changes be unintentional

wildfires, overgrazing - prevents re-establishment of young trees

how does deforestation impact the carbon cycle

biomass burned releasing previously trapped carbon dioxide. wood could be used for other purposes so CO2 remains locked up

Forest clearing accelerates decay of organic matter

reduced photosynthesis, reduced carbon store in trees

deforestation exposes soil to sunlight increasing the rate at which soil is oxidised and CO2 released

impacts of afforestation

afforestation led to forests being extended or established on abandoned agricultural land - reduced net loss of total forest areas

impact of urban growth on carbon cycle

urban sprawl means land use change from natural vegetation to built environment

CO2 emissions from transport, industry etc

what percentage of worlds population expected to live in cities by 2030

60%

in 2012, what percentage of global carbon emissions from cities

47% - expected to increase to 49% by 2030

where are urban carbon emissions concentrated

concentrated around most polluting cities - 21 most polluting cities contribute 10% of all energy related carbon emissions