W + C: The Carbon Cycle Over Time Flashcards
What is natural climate change?
the Quaternary Geological period, shows the temp and atmospheric CO2 levels during the last 800,000 years. An increase in the level of CO2 in the atmosphere leads to enhanced global warming and subsequent temp increase. Lower levels of CO2 reduce the effectiveness of the greenhouse effect, which leads to global cooling. So, CO2 levels trigger temp change
How is chemical weathering an impact of cold conditions on carbon stores and transfers?
chemical weathering processes would have been more active because cold water can hold more carbon dioxide.
How is forest coverage an impact for cold conditions on carbon stores and transfers?
Forest coverage would be very different both in total area and in geographical location. This would have affected the significance and distribution of processes such as photosynthesis and respiration
How have decomposers been impacted by cold conditions on carbon stores and transfers?
Decomposers would have been less effective, so carbon transfer to soils would have been reduced
How is water impacted by cold conditions on carbon stores and transfers?
Less water would have flowed into the oceans as it was locked up as snow and ice on land. There would be less sediment transfer along rivers and less build up of sediments on the ocean floor.
How are global temps impacted by warm conditions on carbon stores and transfers?
global temps have risen, noticeable in the higher latitudes. One effect is the melting of permafrost in Tundra regions, (e.g Siberia) Carbon stored within the permafrost (with other gases like methane) released into the atmosphere where it enhances the greenhouse effect- so increased warming. An example of a positive feedback loop
How are wildfires impacted by warm conditions on carbon stores and transfers?
Wildfires can be started naturally or by people and can have regional impacts.
- Theres been many fires in Indonesia - they released large quantities of CO2, causing a noticeable spike in the rising trend of carbon emissions. Wildfires can turn forests from being a carbon sink to a carbon source, as combustion returns huge quantities of carbon back to the atmosphere.
How is volcanic activity an impact of warm conditions on carbon stores?
Volcanic activity releases carbon that has been trapped millions of years deep within the earths crust. In the Palaeozoic era, volcanos were more active then today - now emit 130-380 million tonnes of CO2 per year. By comparison, humans emit about 30 billion tonnes of CO2 per year (mainly fossil fuels). Volcanos also erupt lava, which contains silicates that will slowly weather. This converts CO2 in the air to carbonates in solution. In this way CO2 is absorbed very slowly from the atmosphere.
How is the Milankovitch cycle an impact of warm conditions on carbon stores and trasnfers?
These regular cycles of orbital eccentricity cause slight variations in the amount of suns radiation that warms the earth. So as temps start to rise at the end of a glacial period (triggered by orbital change), there is a surge of CO2 released into the A by the warming of oceans and the unlocking of land surface that had previously been frozen. This surge of CO2 enhances the greenhouse effect, amplifying the warming trend - example of positive feedback loop.
What are anthropogenic processes?
Impacts as a result of human activity
How does fossil fuel combustion influence the carbon cycle?
- 90% of human-caused carbon comes from combustion of coal, oil and natural gas
- Vegetation and oceans help reabsorb 50%, rest absorbed by atmosphere (CO2 levels have risen by 80ppm in the last 50 years)
- Most gas and oil comes from rocks 70-11m yo - carbon remained in the deposits
- When burnt for energy, the carbon is released
- combustion of hydrocarbons release both CO2 and water vapour
- every 1000kg cement produced, 900kg CO2 released - Cement industry produces 5% of all human CO2 emissions, 50% from heating calcium carbon, 40% burning fuel to power the process).
- CO2 emissions dominated by China (28%), USA (14%) and India (7%) - all growing significantly
- 2013, CO2 from fossil fuel use and cement was 61% higher than 1990 and 2.3% higher than 2012.
How do farming practises influence the carbon cycle?
- when soil is ploughed, soil layers invert with each other (allowing air to mix in), soil microbial activity increases, so more soil organic matter being decomposed, and more carbon to atmosphere, along with CO2 produced by tractors ploughing in first place.
- a big source of CO2 is methane belched by livestock during digestion. In 2011, made up 39% of agricultural carbon emissions. This figure increased 11% between 2001-2011.
- Biological processes in rice paddies generate methane - makes up 10% of agricultural carbon emissions. The burning of tropical grasslands makes up 5%.
- 44% of agricultural greenhouse gas emissions occurred in Asia, 25% in America, 12% in Europe, 15% in Africa and 4% in Oceania.
How does land use change influence the carbon cycle?
CO2 emissions from land use change (main deforestation) account for 30% of all human induced carbon emissions
How is deforestation a land use change?
around 13 million hectares of forest are cut down and changed to other land uses every year. Most deforestation is driven by the need for extra agricultural land. Normally carried out by subsistence farmers who cut down and burn trees to free up land (known as ‘slash and burn’)
What are some of the other reasons forests are cut?
- Logging operations also remove forest. Loggers, some acting illegally, also build roads to access more remote forest (which in turn leads to further deforestation)
- Forests are also cut as a result of urban sprawl (the outward growth of towns and cities)
- Some deforestation is unintentional (e.g. wildfires and subsequent overgrazing which prevents the re establishment of young trees).
- Some of the wood may be used as wood products (so persevered for longer)
