Flashcards in 1.1- Systems Framework And Their Application Deck (28):
Explain how the cycling of water and carbon are central to supporting life on Earth
- cycling of water and carbon are central to supporting life on Earth and an understanding of these cycles underpins some of the most difficult international challenges of our times
- water cycle helps to tie together the Earth’s lands, oceans and atmosphere into an integrated physical system
- in addition, water vapour is the most important greenhouse gas and is a major factor in determining climate- understanding the global complexities of the global water cycle is essential if we are to better manage this vital resource
- carbon is everywhere- in our oceans, rocks, soils and all forms of life, as well as in our atmosphere- the health of our planet depends on carbon and how it cycles through the Earth’s system
- carbon cycle plays a key role in regulating global temperature and global climate by controlling the amount of carbon dioxide, another greenhouse gas in our atmosphere
What is a system?
An assemblage of interrelated parts that work together by way of some driving process- they are a series of stores or components that have flows or connections between them
What are the 3 types of property in a system:
- elements (things that make up system of interest)
- attributes ( perceived characteristics of elements)
- relationships (description of how the various elements and their attributes work together to carry out some sort of process)
Most systems share the same characteristics:
- structure that lies within a boundary
- generalisations of reality, removing incidental detail that obscures fundamental relationships
- they function by having inputs and outputs of material (energy and/or matter) that is processed within the components causing it to change in some way
- involve flow of material between components
What are the 3 classifications of systems?
- isolated systems
- closed systems
What is an isolated system?
- system that has no interaction with anything outside the system boundary
- there is no input or output of energy or matter
- many controlled laboratory experiments are this types of system and are rare in nature
What is a closed system?
transfers of energy both into and beyond the system boundary but not transfer of matter e.g. global water cycle
What is an open system?
Where matter and energy can be transferred from the system across the boundary into the surrounding environment e.g. most ecosystems
On a global scale, both the water and carbon cycles are what type of system?
Closed as there are no inputs to or outputs from the system I.e. nothing is gained or lost to space
On a local scale, both the water and carbon cycles are what kind of systems?
Open- within the global water cycle, a drainage basin an open system as precipitation is and input and runoff or oceans is an output
- within the global carbon cycle, a forest is an open system as precipitation dissolved with carbon dioxide is an input to the forest and dissolved within runoff is an output
Explain how an ecosystem is a good example of an (open) system
- inputs= precipitation, leaf fall during Autumn and seeds carried by wind and birds
- stores/components= water, soil, plants
- flows/ transfers= photosynthesis, infiltration and transpiration
-outputs= evaporation, seed dispersal
Why use a systems approach?
Because physical and human environments interact in very complex ways so a system model can help us to simplify reality and break it down into its different parts to help us better appreciate how both natural change and human activities can impact upon an environment
What is an input?
The addition of matter and/or energy into a system e.g. woodland carbon cycle= precipitation with dissolved carbon dioxide and drainage basin= precipitation
What is an output?
The loss of matter and/or energy from the system into the surrounding environment e.g. woodland carbon cycle= dissolved carbon within runoff and drainage basin= runoff
What is energy?
Power or driving force e.g. woodland carbon cycle= glucose synthesised from photosynthesis and drainage basin= latent heat associated with changes in the state of the water
What is a store/component?
A part of the system where energy/ mass is stored or transformed e.g. woodland carbon cycle= trees and soil and drainage basin= puddles and soil
When there is a balance between the inputs and outputs then the system is said to be in a state of
Dynamic equilibrium = stores remain constant = state of balance maintained within a constantly changing system
If one of the elements of the system changes, e.g. one of the inputs increases without any corresponding change in the outputs, then the stores change and the equilibrium is upset- this is called
What are the two types of feedback?
- positive feedback
What is a flow/transfer?
A form of linkage between one store/component and another that involves movement of energy of mass e.g. woodland carbon cycle= combustion, absorption and drainage basin= infiltration, groundwater flow, evaporation
What is positive feedback?
A cyclical sequence of events that amplify or increase change. Positive feedback loops exacerbate the inputs of a system, driving it in one direction and promoting environmental instability
What is negative feedback?
A sequence of events which dampen down or neutralise the effects of a system promoting stability and a state of dynamic equilibrium
How would dynamic equilibrium be maintained with a carbon woodland and drainage basin?
Remote and unaffected drainage basin/woodland where there has been no significant natural or human impacts, or one that has had time to adjust to change
What’s an example of positive feedback in a system?
1- global temperature rise
2-increased oceanic temperatures
- warm water less able to dissolve gas
3- dissolved carbon dioxide released by warmer oceans
- carbon dioxide back into the atmosphere
4- more carbon dioxide in the atmosphere
- more carbon dioxide to act as a greenhouse gas
= GLOBAL TEMPERATURE RISE
What’s an example of negative feedback within a system?
1- increased use of fossil fuels
2- increase in atmospheric carbon dioxide
- global temperature increase
3- increased plant growth
- increased rate of photosynthesis (increased uptake of carbon dioxide)
4- reduces atmospheric carbon dioxide
- reduced carbon dioxide has a ‘dampening’ effect and reduces global temperatures
Explain how the Earth can be studied using a systems approach
- indeed Earth as a whole could be considered a closed system
- energy comes into the system in the form of solar energy
- this is balanced by radiant energy lost by the Earth
- it could be related to the concept of ‘spaceship Earth’ and encouraging everyone on it to act as a harmonious crew working towards the greater good
At the global level the Earth has 4 major subsystems:
Each of these can be considered to be an open system that forms part of a chain; a cascading system