3.1.1.1 Water and Carbon Cycles as Natural Systems Flashcards
What are systems?
A system is a set of interrelated events or components working together. It consists of.
- Inputs
- Outputs
- Stores
- Flows / Transfers
Systems can be classified as: (4)
Each one means:
- Isolated (no interactions with anything outside the system boundary)
- Closed (there is transfer of energy into and beyond the system but no transfer of matter)
- Open (both energy and matter transfer freely into an out of the system)
- Subsystem (component of a larger system)
Water Cycle - local scale inputs
- Precipitation
- Solar energy
Water Cycle - local scale outputs
- Evapotranspiration
- Runoff to sea
- Stream flow
Water Cycle - local scale stores
- Groundwater
- Soil Water
- Rivers (Channel Storage)
- Interception
- Surface
Water Cycle - local scale flows / transfers
- Infiltration
- Percolation
- Throughflow
- Surface Runoff
- Groundwater Flow
- Streamflow
- Stemflow
Carbon Cycle - global scale flows / transfers
- Photosynthesis
- Respiration
- Decomposition
- Combustion
- Diffusion
- Weathering and Erosion
- Burial and Compaction
- Carbon Sequestration
Dynamic Equilibrium
Where there is a balance between inputs and outputs.
Negative Feedback
A feedback which keeps a system in its original condition by nullifying the impacts of the original event.
Positive Feedback
A feedback where there is a progressively greater change from the original condition of the system.
Application of the system concept to the water and carbon cycle
Both the water and the carbon cycle are fundamental to life on earth and to the study of physical geography.
Both cycles are under pressure from growing populations and climate change.
The system model is used to simplify complex processes so that trends can be identified.
Example of a positive feedback loop in the carbon cycle
High levels of CO2 in the atmosphere –> increased global temperature –> increased ocean temperature –> worse conditions for phytoplankton –> less CO2 photosynthesised –> more CO2 in the atmosphere
Example of a negative feedback loop in the carbon cycle
Increase in CO2 in the atmosphere –> increased levels of plant growth because of extra CO2 –> plants remove CO2 from the atmosphere –> less CO2 in the atmosphere
Example of a positive feedback loop in the water cycle
Increase in global temperature –> melting in land ice –> less reflective ice leads to less sun rays absorbed (reduced albedo) –> further increase in temperature
Example of a negative feedback loop in the water cycle
Increasing global temperature –> more evaporation –> more clouds –> clouds reflect light rays –> fall in global temperature
