The impact of human activity on the carbon and water cycles Flashcards
What sequesters about a quarter of fossil fuel CO2 emissions annually, directly slowing down global warming?
The terrestrial biosphere
What biome covers over 30% of the Earth’s land area?
Forests-although only 15% are natural primary forests
What is the main driver of deforestation?
It is the increasing demand for commodity production
By 2015 what percentage of global forest had been completely cleared?
30% with 2% being degraded and the rest fragmented
Approximately how many hectares of forest are deforested annually?
13 million hectares-equivalent to 36 football fields of trees lost per minute
What did the US environmental protection agency’s renewable fuel standard policy aim on doing?
.Increase the amount of ethanol being used in petrol
.Boost the incomes of rural US states
.Reduced US dependence on overseas oil imports
.Reduce C02 emissions from transport
By 2013 what had happened to the price of corn in comparison to 2007?
It had trebled
Due to the increased encouragement to grow corn in the USA how many hectares of grassland were lost?
Over 5.5 million hectares disappeared across the American Midwest
Give two benefits to the carbon cycle of grasslands
.Absorb toxins from soil
.Act as a terrestrial carbon sink
.Act as a carbon sink ‘lung effect’
.Trap moisture
.Maintain natural habitats
Give two negatives of converting grasslands to grow biofuel crops
.Natural habitats are reduced
.The lung effect is reduced
.They need irrigation which has an impact on aquifers
.Initial removal of grasslands releases CO2 from soils into the atmosphere
.Annual ploughing enables soil bacteria to release CO2 into the atmosphere
Give two benefits of afforestation
.Reduce soil erosion of land, lowering the likelihood of landslides
.Increases CO2 intake by photosynthesis
.Provides a source of timber
.Provides wildlife habitats
.Oxygen released into atmosphere
Give two disadvantages of afforestation
.Can create a monoculture if same species are planted
.Expensive-requires a lot of manpower to plant trees
.Doesn’t release nutrients back into the soil
.Land could be used for food production
