Systems

Introduction and overview

David Holmes

May 2020

OCR GCE Geography Series

dave905947

Structure and content

What are systems and why are the important?

Systems with GCE Geography (specialised concepts)

Systems frameworks Different types of systems, including

carbon and water Summary and review

Part 1 Systems and why they are important

Systems – why bother?

Geographers employ systems to develop analytical models with which they seek to understand and explain spatial patterns and interactions

Human geographers, for example, use the systems model to examine human migration patterns, the diffusion of ideas, and the spread of information.

Research about physical geography relies on understanding the natural systems in which physical processes operate.

Geographers are interested in identifying, explaining, and predicting flows in human and physical systems. They also seek to identify, describe, and explain cycles and patterns. Furthermore, they are concerned with changes in flow, cycle, and patternbecause such changes are indicators of possibly significant alterations (perturbations) in the larger system.

Systems and links in OCR Geography There are lots of links to systems within both the human and

physical content of the specification.

Sometimes the systems links are slightly hidden, but they do help you understand processes, as well as longer term and shorter term.

ACTIVITY 1What has happened in this system?

Part 2 Systems frameworks and terminology

Important systems characteristics1.Systems have a structure that is defined by its parts and processes.2.Systems are generalizations of reality.3.Systems tend to function in the same way. This involves the inputs and outputs of material (energy and/or matter) that is then processed causing it to change in some way.4.The various parts of a system have functionalrelationships that allow the flow and transfer of some type of energy and/or matter.5.Systems often exchange energy and/or matter beyond their defined boundary with the outside environment, and other systems, through various input and output processes.

This information is useful for an evaluative conclusion for instance.

Inputs are those elements that enter a system to be processed. They are fed into the system in order to create outputs.

Key systems terminology

Outputs are the outcome of processing within the system. Outputs may be of use to the next element in the system, or they may be unintended outcomes which may not be of use.

Stores ( or components) are where amounts of energy or matter are held, and nut transferred until the appropriate processes are in place to move them.

A simple landscape system

• The sediment budget for this beach would have three input terms (longhore drift, cliff erosion, onshore transport) and two output terms (longshore drift and offshore transport).

Positive Feedback Loop (1)

Positive feedback (or exacerbating feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the magnitude of the perturbation

MUTUAL CAUSAL INTERACTION

FEEDBACK LOOP

(1) Methane hydrates can be unstable so that a warming ocean could release more methane, which is also a greenhouse gas.

(2) Peat, occurring naturally in peat bogs, contains carbon. When peat dries it decomposes, and may additionally burn. Peat also releases nitrous oxide.

(3) Global warming affects the cloud distribution. Clouds at higher altitudes enhance the greenhouse effects, while low clouds mainly reflect back sunlight, having opposite effects on temperature

Positive Feedback Loop (2)

Negative Feedback Loop

This system is being dampened. A negative feedback loop is a reaction that causes a decrease in function. It occurs in response to some kind of stimulus. Often, it causes the output of a system to be lessened; so, the feedback tends to stabilize the system.

EQUILIBRIUM

HOMEOSTASIS

Impact of ice melt on Sealevel?

Impact of ice melt on Temperature ?

Arctic Ocean ice

No impact , as the ice is already in the ocean

Major impact due to albedo feedback as sea ice melts thermal expansion

Eurasianpermafrost

Minor impact CO2 and methane release as permafrost organic matter decays could lead to large rises

Greenland ice sheet

Major impact if significant melting occurred in future

Possible disruption to ocean currents in North Atlantic

Himalayanglaciers

Significant impact now Minor

Contributions to sea level rise from the last IPCC report.Between 1993 and 2003

thermal expansion contributed most, followed by glaciers, then the 2 major ice

sheets.

Impacts = feedbacks

Tipping Points and Thresholds

ACTIVITY 2

Part 3 Different types of systems

Closed System or Isolated System - is a system that transfers energy, but not matter, across its boundary to the surrounding environment. Carbon is closed at a global scale.

Open System - is a system that transfers both matter and energy can cross its boundary to the surrounding environment. Most ecosystems are example of open systems as is carbon locally.

Morphological System - this is a system where we understand the relationships between elements and their attributes but don’t have full understanding. Aspects of the carbon cycle is an example.

Cascading System - this is a system where we are primarily interested in the flow of energy from one element to another and understand the processes that cause this movement. In a cascading system, we do not fully understand quantitative relationships that exist Complex hydrological systems might be an example.

Different types of systems

You have the knowledge!

Same thing….but with numbers

These numbers shows inputs or outputs or flows – some more of a “cascading system”. Remember these are approximations only, averaged over a period of time

Stores

These are the relative proportions or amounts of different stores of water -classified

A familiar system (1)

An example of a morphological system

model.Its semi-closed, but the

model accepts that’s its actually a

subsystem of a much larger system (outputs escape the confines)

A familiar system (2a)

A familiar system (2b)

Different conditions within the system provide different responses. This is

because the different components of the system are altered, e.g. size of stores

Systems – bit abstract

In many ways these leaves can be “read” just like the hydrographs. The variable I'm interested in is catchment shape and size.

How does this help us to understand more about the components|?What is the link between these systems components and flood risk or

resilience?

These are unusual systems?

An example of a coastal system

An example of a fluvio-glacial system

Open and closed systems

Sediment cells are dynamic because the sediment is constantly generated in the source region, transported through the transfer region and deposited in the sink region. A source region may be an eroding coastline. A sink region may be an outbuilding coastline.They are really semi-closed systems because that makes them easier to manage and understand!

An open system - where a system receives inputs and transfers outputs of energy or matter across the boundaries within it. Most naturalsystems, such as drainage basins and carbon cycle, are open systems. Systems contain inputs, outputs and stores; material is moved bytransfers/flows/fluxes

A closed system - where there is transfer of energy, but not matter, between the system and its surroundings. The Earth itself is an example of such a system as is the global hydrological cycle.

Carbon system diagram

• Looks fiendish, but it’s really about understanding stores and fluxes

• ...then moving on to how human activity has altered the system

The global carbon cycle can be viewed as a series of reservoirs of carbon in the Earth System, which are connected by exchange fluxes of carbon. An exchange flux is the amount of carbon which moves between reservoirs each year.Be prepared to embrace the complexity surrounding the topics. Don’t be too afraid of the big numbers, work of proportions and significance (bigger and smaller etc).

Fluxes are in red (pg / year)Stores are in blue (pg of

carbon) • Crust and oceans are huge

stores compared to atmosphere or plants.

• Big range in fluxes (<.1 to 120).

• Most important loss to atmosphere (+) is ocean

loss, plant and soil respiration

• Most significant sequesters(-) photosynthesis and

oceans

Balance of fluxes: Oceans = (out: 90 – in: 92) -2 pg/CTerrestrial = (out: (6+60+60+0.1+0.9) – in:

(120+60+0.8=0.1) = - 53But is not that simple as there are flows between

stores

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More accessible

Key summaries

Systems are critical to and understanding in geography

Systems exits within other systems and are often nested so closed systems are rather a coinvent idea of scale only

You are unlikely to get a pure “systems” question, but you will fine the knowledge and understanding really helps you to explore relationships, feedbacks and complexities.

Don’t stop exploring!