4a - The two cycles are linked and interdependent.

Question 1

The ways in which the two cycles link and are interdependent

atmosphere

Answer 1

• CO2 contributes/enhances the greenhouse effect in the atmosphere = increased water in the atmosphere and more water vapour store
• CO2 vital in PS, absorbed from the atmosphere by terrestrial plants and phytoplankton but require water to do this. these plants store carbon, extract water from the soil and transpire as part of the water cycle - EVTP moves water to the atmosphere- global warming due to CO2 increases this and affects stores of water.
• water is evaporated from the oceans to the atmosphere and co2 is exchanged between the 2 stores

Question 2

The ways in which the two cycles link and are interdependent

oceans

Answer 2

• ocean acidity increases when exchanges of CO2 are not in balance (ie inputs to ocean > outputs) solubility of CO2 in oceans increases with lower sea surface temps = increased CO2 diffusion into ocean
• more atmospheric CO2 increases SST and the thermal expansion of oceans, melting of ice sheets and glaciers = increases store of water in rivers and the ocean (SLR)

Question 3

The ways in which the two cycles link and are interdependent

Veg/soil:

Answer 3

• water availability influences rates of PS, NPP, inputs of organic litter to soils and transpiration, water storage capacity in soil increases with organic content. cold dry areas = low NPP
• temp/rainfall affect decomposition rates which releases CO2 into the atmosphere, limited water = less CO2 released by respiration
• evapotranspiration requires carbon in vegetation to occur due to lack of carbon = close stomata to reduce water loss

Question 4

The ways in which the two cycles link and are interdependent

Cryosphere:

Answer 4

CO2 levels in atmosphere = intensity of greenhouse affect = melt of ice/glaciers/permafrost = exposes land, sea surfaces = absorb more solar radiation = reduced albedo affect = PFL is created = and increase temp further = exposes organic material to oxidisation and decomposition = releases CO2 and CH4 = temp change = affects runoff, river flow, evaporation (stores and flows of water)

Question 5

How human activities cause changes in

carbon

Answer 5

• world relies on fossil fuels for 87% of primary energy consumption - exploitation of coal, oil and natural gas has removed billions of tons of carbon from geological store – a process that has gathered momentum in the past 30 years with rapid industrialisation, eG China and India
• currently 8 billion tons of carbon a year is transferred to the atmosphere by burning fossil feels and land used to change transfers approximately 1 billion tons of carbon to the atmosphere annually
• around two. 5 million tons of carbon is absorbed by the oceans from the atmosphere and a similar amount by the biosphere = less PS this is even more significant in phytoplankton in the oceans as they absorb more than half CO2 from burning fossil fuels, which is significantly more than tropical forests.
• Acidification of the oceans threatens the biological carbon store, as well as affecting marine life
• Soil is a carbon store, which has been degraded by erosion caused by deforestation and agricultural mismanagement
• Carbon stores and wetlands, drained for cultivation and urban development, has been depleted as they dry out and are oxidised

Question 6

How human activities cause changes in

water

Answer 6

• rising demand for water - irrigation, agriculture and public supply (sig in arid environments) = acute shortages
• Colorado basin in USA surface supplies have diminished as more water is abstracted from rivers and huge amounts evaporated from reservoirs eg lake mead
• quality of fresh water resources have declined - over pumping of aquifers in coastal regions of Bangladesh has led to incursions of saltwater, often making the water unfit for irrigation and drinking
• compared to natural ecosystems, human activities ie deforestation and urbanisation reduce evapotranspiration and therefore precipitation, increase run off, less throughflow (made worse by growing pop)
• in amazon rainforest trees are key component of water cycle - transfer of water to atmosphere through evapotranspiration, returned through precipitation - extensive deforestation has broken this cycle and caused climates to dry out and prevent regeneration of the forest

Question 7

The impact of long-term climate change on

water

Answer 7

• climate change has increased evaporation and therefore the amount of water vapour in the atmosphere. More water vapour which is a natural greenhouse gas has the feedback affect, raising global temperatures, increasing evaporation and precipitation.
• increase precipitation will result in higher run-off in the water cycle and greater flood risk
• water vapour is a source of energy in the atmosphere, which will increase extreme weather events, such as hurricanes and storms, becoming more powerful and frequent
• climate change is accelerating, the melting of glaciers and ice sheets, like Greenland and permafrost in the arctic tundra, which means that the water storage in the crisper shrinks as water is transferred to the oceans and atmosphere

Question 8

The impact of long-term climate change on

carbon

Answer 8

• higher temperatures increase rates of decomposition and accelerate transfers of carbon from the biosphere and soil to the atmosphere
• in the humid, tropics climate change may increase aridity and threaten the extent of forests. As forests are replaced by grasslands, the amount of carbon stored in tropical biomes will diminish however, in high latitudes, global warming, will allow the boreal forests of Siberia and Canada, to expand polewards.
• Carbon frozen in permafrost of the tundra is being released as temperatures rise above freezing can allow oxidisation and decomposition of vast peat stores
• Acidification of the oceans through the absorption of excess CO2 from the atmosphere reduces photosynthesis by phytoplankton, which limits the capacity of the oceans to store carbon so long term change will see and increase in carbon stored in the atmosphere, decrease stored in the biosphere and ocean carbon stores
• Movement of carbon in and out of the atmosphere will vary regionally, depending on changes in the rates of photosynthesis, decomposition and respiration