Exam Questions Water And Carbon Cycles Flashcards
Explain the concept of dynamic equilibrium in relation to the water cycle (4 marks)
-Dynamic equilibrium refers to the tendency towards a natural state of balance within the hydrological cycle
-The cycle is a closed system as no water enters or leaves the system; it is simply recycled around the system.
-The drainage basin element of the hydrological cycle is an open system where the inputs and outputs can change.
-The dynamic equilibrium is easily upset by extreme events such as storms or droughts.
-Human activity can also cause disruption to the dynamic equilibrium eg. By more impermeable, urban surfaces in the drainage basin.
-This causes disruption or interference to the dynamic equilibrium and is evidenced through flooding for example.
-Such events and processes cause sudden changes in the state of the system and disrupt or interfere with dynamic equilibrium as is the case with flooding.
Describe the different strategies to mitigate the impacts of climate change (4 marks)
-This refers to means to reduce or prevent the effects of climate change.
-Using alternative renewable energy sources, such as solar, wind or hydroelectric power can reduce the reliance on hydrocarbons and fossil fuels meaning less carbon in the atmosphere.
-Carbon capture and storage (CCS) can remove up to 90% harmful pollutants from power stations, storing it underground or in deep ocean- this joining the slow carbon cycle.
-Afforestation or planting trees: acts as a natural carbon sink to absorb carbon.
-International agreements such as the 2005 Kyoto protocol and 2015 Paris agreement became international laws- mandating countries to act and pledge to reduce their overall carbon emissions.
Explain the concept of feedback loops in relation to the carbon cycle (4 marks)
-Feedback loops can either be positive (multiplying change) or negative (dampening/trying to return to dynamic equilibrium) in the carbon cycle.
-Example of positive feedback loops: Increasing levels of atmospheric CO2 causes increased temperatures (as carbon is a greenhouse gas which blocks solar radiation leaving our atmosphere)- leading to global warming which in turn leads to high rates of sea ice melting. (An important store of carbon in the atmosphere-thus increasing co2 levels further).
-Example of negative feedback loop: levels of carbon increase slightly, about 33% of which is regulated in the oceans- here it is dissolved within water and circulated, thus joining the slow carbon cycle, reducing atmospheric carbon levels- this is known as the ocean solubility pump.
Outline the potential impacts of farming practices upon the water cycle (4 marks)
-Farming (particularly large scale or industrial) can have significant impacts on flows, transfers and stores of water.
-For example irrigation for plants can lower channel levels in rivers, together with groundwater levels if underground wells are the source for irrigation through excessive water abstractation.
-Farming practices may also involve changing land use, for example through deforestation and an increase in smaller, lower lying vegetation such as grasses- this leads to more rainfall reaching ground level, easily saturating soil and causing higher levels of infiltration and runoff. In the long term , this washes away soil and reduces transpiration which over time causes less precipitation- local river systems may dry up as a result.
Explain the role of cryospheric change in the water cycle (4 marks)
-Cryospheric change has a regulatory role in sea levels
-The cryosphere is a major store of water
-In a period of cooling (glacial period) the cryosphere will grow in size
-This is because the water cycle is slowed considerably as the ice restricts the return of water to the sea and ocean.
-In a period of warming, the cryosphere will add more water to the cycle. As the water cycle restarts more of the ice melts and returns water to the sea.
-This increased size of the ocean store causing sea levels to rise through increased volumes of water and thermal expansion.
Outline factors driving change in magnitude of water stores (4 marks)
-water stores can be change by a number of factors and over different time periods including:
-rates of evaporation: involving turning a liquid to a gas eg. When energy from the sun hits a body of water.
-These rates depend on solar energy, humidity and temperature of surrounding air.
-Condensation is the conversion of a Vapor or gas in the atmosphere to liquid- air is cooled and converted into droplets which then fall onto the ground and either flow into the hydrosphere or infiltrate into the lithosphere.
-Precipitation/rainfall/drought: can affect the levels of relative stores of water in the shorter term- this for example is the main input into drainage basin systems.
-Cryospheric processes and fluctuations: involve level of water held in ice and snow- one of the largest stores. Increasing levels of ice melting have slowly depleted these supplies usually melting into the hydrosphere.
Outline the relationship between water and carbon cycles in our atmosphere (4 marks)
-High levels of carbon lead to snow and ice melting (also permafrost) which exposes dark ocean or marshland during the summer. (Snow cover on land is also decreasing annually.) These are often stores of cryospheric carbon which is released into the atmosphere, thus increasing global warming further (a positive feedback of melting and carbon)
-Water vapour is a a strong greenhouse gas, the relative abundance of water in the atmosphere means it causes around 2/3 of greenhouse warming. As temperatures rise, more vapour evaporates into the atmosphere as clouds- further rising temperatures.
-Carbon dioxide and water are released via anthropogenic (human) activity/industry in the atmosphere- which acts as a catalyst for more carbon to be released (eg. Via melting) and more water to evaporate (eg. In areas of drought.)
