ELSS SG6 Flashcards
How are the carbon and water cycles linked via the atmosphere?
Both water and carbon are stored and transferred to and from it
How are the carbon and water cycles linked via the oceans?
Global warming - atmospheric CO2 levels rise. More infrared radiation is trapped within the atmosphere which causes the enhanced greenhouse effect. This leads to global warming
What are four impacts of global warming on oceans?
Sea surface temperatures rise causing more evaporation, As oceans warm thermal expansion occurs which contributes to rising sea levels, The ability of the oceans to absorb CO2 decreases leading to a higher atmospheric store, Increased melting of ice sheets and glaciers causes sea levels to rise
How are the carbon and water cycles linked via the vegetation and soil?
Changes in the water cycle, soils and vegetation leads to implications on carbon cycle stores and transfers
How are the carbon and water cycles linked via the cryosphere?
A change in the cryospheric store of water not only causes a change in the flows and stores of water, but creates a positive feedback loop which changes the stores and flows of carbon
What are four global management strategies to protect the carbon cycle?
Afforestation, Wetland restoration, Improving agricultural practices, International agreements to reduce carbon emissions
Define Afforestation
Planting trees in deforested areas, or in areas which have never been forested
What are three reasons afforestation can protect the carbon cycle?
Planting trees removes CO2 from the atmosphere through photosynthesis, Tree planting could sequester 1.1-1.6 GT/year of carbon, Agroforestry grows quicker and absorbs higher rates of CO2 than normal forests
What are two limitations of afforestation?
Total global greenhouse gas emissions equivalent to 50 GT of CO2 in 2004 greatly exceed the amount that can be sequestered by afforestation schemes, The high cost of afforestation means it is not done on a large scale
Define Wetlands
Where the water table is at or near the surface causing the ground to be permanently saturated e.g. marshes, peatlands and floodplains
What are wetlands a large store of carbon?
Decomposition is greatly reduced in waterlogged soil from lack of oxygen
Why have wetlands been destroyed in the past?
Population growth, economic development and urbanisation have put huge stress on wetland areas
What is the impact of destroyed wetland?
Huge amounts of CO2 and CH4 transferred to the atmosphere
Define Wetland Restoration
Rehabilitates a degraded wetland or re-establishes a wetland that has been destroyed
What does wetland restoration focus on?
Raising local water tabes to re-create waterlogged conditions
What are three reasons wetland restoration WILL have a significant impact on protecting the carbon cycle?
One hectare of seagrass can store 2x as much carbon than an average terrestrial forest the same size, Coastal wetlands store 50% of the seabed’s rich carbon reserves, Coastal wetlands sequester enough CO2 to offset the burning of 1 million barrels of oil
What are two reasons wetland restoration WON’T have a significant impact on protecting the carbon cycle?
Not all wetlands are effective as carbon sinks - some are sources due to slow decomposition of organic matter, Wetland drainage releases CO2 into the atmosphere
What % of greenhouse gas emissions come from land use or soil management?
40%
What % of greenhouse gas emissions is methane from livestock?
30%
What % of What % of greenhouse gas emissions is from deforestation?
20%
What % of greenhouse gas emissions comes from wetland rice and manure management?
10%
What are four problems of current farming practices?
Tillage, Tree clearance, Soil compaction, Ploughing
Define Tillage
Turning the soil to control for weeds and pests, and to prepare for seeding
How does tillage impact the carbon cycle?
Intensive soil tillage can increase the likelihood of soil erosion, nutrient runoff into nearby waterways and the release of carbon into the atmosphere
How does tree clearance impact the carbon cycle?
As forests are cleared, they expose the land to direct attack from wind and rain causing soil erosion which releases carbon (and other nutrients) into the atmosphere and rivers
How does soil compaction impact the carbon cycle?
The use of heavy machinery on wet soils leads to compacted subsurface soil layers which decrease infiltration and increase runoff, leading to soil erosion
How does ploughing impact the carbon cycle?
Ploughing progressively destroys soil organic matter by oxidation as it is exposed to the atmosphere, leading to carbon being released to the atmosphere