4.A - how are the carbon and water cycle interdependent?

Question 1

how are the carbon and water cycle linked by the ocean?

Answer 1

• as atmospheric CO2 concentrations increase, the enhanced greenhouse effect causes an increase in air temps which causes both a melting of ice sheets and glaciers as well as a thermal expansion of the sea
• together this leads to a eustatic (global) rise in sea level as greater amounts of water are stored in the oceans

Question 2

how are the carbon and water cycle linked by the atmosphere?

Answer 2

• CO2 is exchanged between the atmosphere and oceans as well as terrestrial ecosystems
• through respiration, combustion, decomposition and photosynthesis
• as CO2 concentrations increase plant growth can be stimulated
• and so greater amounts of water can then be taken up and transpired back into the atmosphere

Question 3

how are the carbon and water cycle linked by the cryosphere?

Answer 3

• as atmospheric CO2 concentrations increase, the enhanced greenhouse effect causes an increase in air temperatures which causes a melting of ice sheets and glaciers
• the loss of ice reduces albedo and increases absorption of solar radiation
• this increases air temperatures further and so there is greater melting of land and sea ice
• this can be seen as a positive feedback process
• it also means that there is increased surface run-off as the meltwater makes its way to the sea

Question 4

how are the carbon and water cycle linked by vegetation?

Answer 4

• as precipitation and temp increases, rates of NPP also increases
• this means there is more transpiration of water and flows of CO2 also increase as there is more photosynthesis and respiration

Question 5

how are the carbon and water cycle linked by vegetation?

Answer 5

• photosynthesis in plants requires both carbon and water.
• in places with high rainfall (e.g. TRF), rates of photosynthesis are optimised ∴ more carbon is sequestered.
• in areas where deforestation has occured (removal of carbon from biosphere) there is increased surface runoff and higher floodrisk. there is also a reduction in the cycling of water ∴ lower rates of precipitation. this is more exacerbated in TRF areas where rates of deforestation are high
• ↑ surface run off causes soil carbon to be washed off of the land into rivers which can cause silting and eutrophication. can also ↓ fertility of the land due to a loss of soil carbon material
• however, after deforestation, the water cycle continues whereas the carbon cycle virtually stops.

Question 6

how are the carbon and water cycle linked by vegetation? evaluation!

Answer 6

• will have more impact in the amazon than the arctic

Question 7

how are the carbon and water cycle linked by the cryosphere?

Answer 7

• winter in the tundra results in freezing of the water stores which stops any flows of carbon (e.g. stops photosynthesis and decomposition)
• in summer, warming temps result in melting water, allowing greater flows (via transpiration), causing more convection and precipitation
• ↑ atmospheric CO2 is causing ↑ temps. this is melting the ice in the tundra to expose darker surfaces (altering albedo and ↑ melting). this melting is causing methane to be released (positive feedback as this will ↑ warming) but will also cause more flows of photosynthesis as the plants are able to grow
• this will also cause more decomposition resulting in greater cycling of carbon
• the greater amounts of water vapour could cause greater warming as water vapour is a GHG causing a positive feedback loop

Question 8

how are the carbon and water cycle linked by the atmosphere?

Answer 8

• carbon can dissolve into water vapour which creates acid rain
• as CO2 ↑ in atmosphere causes warming climate there is more energy and heat to cause greater evapotranspiration, therefore more water vapour in atmosphere (positive feedback loop)
• greater CO2 levels causing warming leads to greater rates of photosynthesis in vegetation ∴ water is cycled more quickly by this vegetation
• as higher rates of atmospheric CO2 occur resulting in global warming, ice sheets melt resulting in rising sea levels (EUSTATICALLY), ↑ the amount of water in the oceans

Question 9

how are the carbon and water cycle linked by the oceans?

Answer 9

• carbon can be dissolved in the oceans via the physical pump. this can be downwelled into deep water where it can be stored for 1000s of yrs.
• as atmospheric CO2 ↑ leading to warming climate, it causes sea temps to ↑and ∴ this rate of diffusion slows down
• in the oceans, carbon can be sequestered via the biological pump as phytoplankton photosynthesise and remove carbon from atmosphere
• this carbon can then initiate food chains. these carbon lifeforms can die and be sedimented on the sea floor and eventually be lithified and form sedimentary rocks (moving from fast to slow carbon cycle)
• as higher rates of atmospheric CO2 occur resulting in global warming, ice sheets melt resulting in rising sea levels (eustatically) ↑ the amount of water in the oceans

Question 10

how are the carbon and water cycle linked by cryosphere? evaluation!

Answer 10

• seasonal, carbon and water cycle is mostly stopped in the winter months
• arctic sea ice is 50% smaller in summer
• no impact on rainforest
• glacial vs interglacial periods (LT = much more ice)

Question 11

how are the carbon and water cycle linked by atmosphere? evaluation!

Answer 11

• can vary seasonally
• global impact of ice sheets melting and eustatically rising sea levels

Question 12

how are the carbon and water cycle linked by oceans? evaluation!

Answer 12

• large scale
• big store of carbon - phytoplankton and dissolving CO2
• global, LONG TERM impact

Question 13

how does photosynthesis link the carbon and water cycles?

Answer 13

• increase in photosynthesis will enhance the sequestration of carbon in terrestrial biome (plants)
• but also ↑ interception, transpiration and localised precipitation in the water cycle

Question 14

impacts of human activities on water and carbon cycles - LAND USE CHANGE

Answer 14

• land use change (mostly deforestation) transfers approx 1 billion tonnes of carbon to the atmosphere annually
• massive deforestation has ↓ the planet’s forest cover in historic times by nearly 50%
• thus the amount of carbon stored in the biosphere and fixed by photosynthesis has ↓ steeply

Question 15

impacts of human activities on water and carbon cycles - EXTENSIVE DEFORESTATION

Answer 15

• massive deforestation has ↓ the planet’s forest cover in historic times by nearly 50%
• thus the amount of carbon stored in the biosphere and fixed by photosynthesis has ↓ steeply
• in Amazonia, forest trees are a key component of the water cycle, transferring water to the atmosphere by evapotranspiration which is then returned by precipitation
• extensive deforestation has broken this cycle, causing climates to dry out and prevent regeneration

Question 16

impacts of human activities on water and carbon cycles - ACIDIFICATION OF OCEANS

Answer 16

• acidification of the oceans threatens absorption of CO2 by phytoplankton as well as affecting marine life

Question 17

impacts of human activities on water and carbon cycles - RAPID POPULATION GROWTH

Answer 17

• rapid population and economic growth, deforestation and urbanisation in the past 100 yrs have modified the size of water and carbon stores and rate of transfer between stores
• the impact and scale of these changes is most apparent at regional and local scales

Question 18

impacts of human activities on water and carbon cycles - FOSSIL FUELS

Answer 18

• the world relies on fossil fuels for 87% of its primary energy consumption
• has removed billions of tonnes of carbon from the geological store (a process that has gathered momentum in the past 30 years w/ the rapid industrialisation of the Chinese and Indian economies)
• around 10 bill tonnes of carbon/yr are transferred to the atmosphere by burning fossil fuels

Question 19

impacts of human activities on water and carbon cycles - IMPACT ON AQUIFERS

Answer 19

• rising demand for water for irrigation, agriculture and public supply, esp in arid environments, has created acute shortages
• e.g. Colorado Basin
• the quality of fresh water resources has declined
• over pumping of aquifers in the coastal environment of Bangladesh has lead to incursions of salt water, unfit for irrigation and drinking

Question 20

impacts of LONG TERM CLIMATE CHANGE on water and carbon cycles - WATER VAPOUR

Answer 20

• global warming has increased evaporation and ∴ the amount of water vapour in the atmosphere
• more vapour, which is a natural GHG has a feedback effect helping to ↑ global temps, ↑ evap and ↑ precip

Question 21

impacts of LONG TERM CLIMATE CHANGE on water and carbon cycles - EXTREME EVENTS

Answer 21

• ↑ precip will result in higher run off in the water cycle and greater flood risks
• water vapour is a source of energy in the atmosphere releasing latent heat in condensation
• with more energy in the atmosphere, extreme weather events such as hurricanes and mid-latitude storms become more powerful and more frequent

Question 22

impacts of LONG TERM CLIMATE CHANGE on water and carbon cycles - MELTING

Answer 22

• global warming is accelerating the melting of glaciers and ice sheets like Greenland and permafrost in the arctic tundra
• thus water storage in the cryosphere shrinks, as water is transferred to the oceans and atmosphere
• carbon frozen in the permafrost of the tundra is being released as temps rise above freezing and allow oxidation and decomposition of vast peat stores

Question 23

impacts of LONG TERM CLIMATE CHANGE on water and carbon cycles - ACIDIFICATION OF OCEANS

Answer 23

• acidification of the oceans through the absorption of excess CO2 from the atmosphere ↓ photosynthesis by phytoplankton, limiting the capacity of the oceans to store carbon.
• thus LT climate change will probably see an ↑ in carbon stored in the biosphere and possibly a similar ↓ in the ocean carbon stores
• movement of carbon into and out of the atmosphere will vary regionally, depending on changes in rates of photosynthesis, decomposition, and respiration

Question 24

impacts of LONG TERM CLIMATE CHANGE on water and carbon cycles - CLIMATE CHANGE

Answer 24

• higher global temps will ↑ rates of decomposition and accelerate transfers of carbon from the biosphere and soil to the atmosphere
• however, in the humid tropics climate change may ↑ aridity and threaten the extent of tropics.
• as forests are replaced by grasslands the amount of carbon stored in tropical biomes will diminish
• in contrast, in high latitudes global warming will allow the boreal forests of siberia, canada and alaska to expand polewards

Question 25

impacts of LONG TERM CLIMATE CHANGE on water and carbon cycles - CARBON CYCLE

Answer 25

• the impact of global climate change on the CO2 cycle depends on:
• rising temps
• and geographical differences in rainfall amounts

Question 26

who are the BRICS nations?

Answer 26

• brazil
• russia
• india
• china
• south africa

Question 27

how much coal, gas and oil do the BRICS nations use?

Answer 27

• they control 40%, 8% and 25% of the world’s coal, oil and gas reserves
• they account for more than half of the total emissions of the 43 countries in the G20
• global division of labour - these countries have cheaper labour so TNCs exploit them

Question 28

what is the population of Las Vegas?

Answer 28

2,900,000
(2.1% increase from 2022)

Question 29

how many tourists visit Las Vegas annually?

Answer 29

38 million

Question 30

how much water does Las Vegas use daily?

Answer 30

• the average household uses 222 gallons of water per day = results in approx 489 million gallons of daily water consumption from the residents alone.
• lake mead has been drained of 4 trillion gallons of water over the last decade and is now under half full

Question 31

how has lake mead changed?

Answer 31

lake mead has been drained of 4 trillion gallons of water over the last decade and is now under half full

Question 32

what is the average yearly rainfall in the state of Nevada?

Answer 32

• 10.3” state wide
• but only 7.1” in southern nevada

Question 33

where does las vegas get its water from?

Answer 33

• southern nevada gets nearly 90% of its water from the colorado river
• Las Vegas has complete reliance on Lake Mead, America’s largest reservoir, created by the Hoover Dam in 1936

Question 34

what is the impact of las vegas on the water cycle?

Answer 34

• water has to come from somewhere and it is very isolated.
• needs a water supply to sustain 38 mill annual tourists
• rivers are so low that 27 mill young migrating salmon are having to be taken to the ocean in trucks
• colorado river doesn’t make it to the Gulf of California anymore
• aquifers are very low
• UNSUSTAINABLE USE OF WATER