Water and Carbon Cycles: Systems Framework Flashcards
Define what a system is
A set of interrelated components working together towards some kind of process
What is an open system?
Matter and energy can enter and leave the system
What is a closed system?
Matter cannot leave the system, it can only cycle between stores, energy can enter and leave the system
What is dynamic equilibrium?
When there is disruption to one of the elements, so the other elements will change in order to return to a state of equilibrium, causing feedback loops
Disruptions:
Physical disruptions – storms or drought
Human disruptions – deforestation, urbanisation, water abstraction
Sudden disruptions may result in sudden change e.g. flooding
What is positive feedback?
The effects of an action are amplified or multiplied by subsequent secondary effects
What is negative feedback?
The effects of an action are nullified or reduced by subsequent secondary effects
What are elements?
A constituent part of the system
What is an attribute?
Characteristics of an element
What is a relationship?
the way in which the elements of a system interact
What are the inputs in the water cycle?
precipitation
matter and energy being added to the system
What are the outputs in the water cycle?
river discharge
matter or energy leaving the system
What are the stores in the water cycle?
ocean, groundwater, clouds
where matter or energy builds up
What are the flows in the water cycle?
channel flows
matter or energy moving from one store to another
What are the boundaries of the water cycle?
watershed
limits of the system
What is an example of a positive feedback loop?
Global temp rise -> warms oceans -> increased oceanic temperatures -> warm water is less able to dissolve gases -> dissolved CO2 is released by warmer oceans -> more CO2 back into atmosphere -> global temp rises
What is an example of a negative feedback loop?
burning fossil fuels increased atmospheric CO2 -> global temp increases -> more plant growth -> increased CO2 uptake by biosphere -> reduces atmospheric CO2 slowing rate of global temp increase
What is a threshold?
A point in a condition or process that, once passed, triggers some kind of change
Describe the varying sizes of global water stores
- oceanic stores is the largest, 1.4 sextillion litres of water which is 97% of all the water in the hydrosphere
- cryospheric store second largest (e.g. Ross Ice shelf or Greenland Ice sheets), 26 million km^3, contains 69% of freshwater (3% of all water is freshwater)
- terrestrial water next, rivers take up 1 million squared km, largest being the Amazon River
- biosphere second to last largest store, less than >1% of all freshwater, all living parts on the Earth
- atmosphere is the smallest store, clouds, rain, vapour, ice crystals, a store 10 million% smaller than ocean
Explain the sizes of the global water stores
- Large stores have the longest residency times as the scale of processes is small relative to their size and they return the same amount (e.g. hydrosphere and evaporation/precipitation)
- small stores have shorter residence times because the scale of the flows acting upon them are large relative to their size (e.g. atmosphere and evaporation/precipitation)
Describe the flows between water stores
- Evaporation, increases amount of water stored in the atmosphere, liquid water changes state into a gas
- Condensation, vapour changes to liquid water, decreases water stored in the atmosphere
- Cryospheric Processes, including accumulation and ablation, changes amount of water stored in cryosphere
What process are changing the size of the global water stores?
transpiration and respiration plant uptake percolation groundwater flow precipitation/condensation evaporation
What does the magnitude of each water store depend on?
The amount of water flowing between them
What factors control the size of flows between water stores?
- evaporation = solar energy, supply of water, humidity of the air and temperature of air
- condensation = amount of water in atmosphere, solar radiation and condensation nuclei
- cryospheric processes = global climate
What is the size of the largest water store?
Largest store is in the ocean with 1.3 million 1000km^3
What is the size of the intermediate water stores?
Freshwater stores have intermediate sizes
- atmospheric water 2.7 (1000km^3) to cryosphere 26350 (1000km^3)
What is the size of the smallest water store?
The smallest store is the atmosphere, over 10 million% smaller than the ocean store
What is the largest flow of water stores?
Ocean evaporation and precipitation 413 1000km^3/year
Q: 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
- In a period of warming the cryosphere will add water to the cycle. As the water cycle restarts more of the ice melts and returns water to the sea
What is a natural cause of variation in the water cycle?
Storm events transfer significant amounts of water from the atmosphere store to the hydrosphere and lithosphere stores.
Outline an example of positive feedback feedback in the water cycle? [4 marks]
- a system where the effects of an action are increased or
amplified by its subsequent knock-on effects - Higher temperatures increase the melting of snow and ice
leading to a reduction of surface albedo so more sunlight
absorbed by land and sea. Temperatures increase further,
which leads to further melting.
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 dynamic equilibrium is easily upset by extreme events such as storms or droughts
- 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
