IB ESS 1.2 - Systems

System

Made of individual parts working together to perform a particular function

systems approach

is a holistic approach to visualise a complex set of interactions

Emergent Properties

The properties of a complex system that arise from the relatively simple interactions of its component parts.

(the whole is greater than the parts)

What is a system made out of?

A system is comprised of storages and flows

The flows provide inputs and outputs of energy and matter.

Different types of flows

Transfer - change in location

Transformation - change in state or chemical composition, or a change in energy type

Open System

Energy + matter freely exchanged with environment

-All ecosystems come under this

Closed System

Exchange only energy with the environment

Very rare and usually only exist experimentally

Isolated System

Exchanges neither matter nor energy

Hypothetical

The entire Universe as a system can be considered an isolated system

Model

-Simplified representation of a complex matter

How would you answer: Evaluate the use of models as a tool in a given situation, for example, climate change predictions. (4 marks)

-State what the model is

-State advantages

-State disadvantages

-Give own judgement

Biosphere

(all living organisms and their interactions)

Hydrosphere

Earth's water bodies

Cryosphere

Ice/snow covered areas

Geosphere

Solid rock and minerals part of the Earth

Atmosphere

the layers of gases immediately surrounding the earth

Anthroposphere

Parts of the Earth that are affected by and interact with humans.

Gaia Hypothesis

The world acts like a single biological being made up of many individual and interconnected units (A SYSTEM ).

-The Gaia theory was introduced to explain how atmospheric composition and temperatures are interrelated through feedback control mechanisms

Negative feedback

Return a system to its original state

Stabilise systems as they reduce change by counteracting it

Positive feedback

Change a system to a new state

Destabilise systems as they increase change

Equilibrium

is the tendency of a system to return to its original state after a disturbance

steady state equilibrium

Continuous inputs and outputs of energy and matter (open systems), but the system as a whole remains in a more-or-less constant state

-Maintained by stabilising negative feedback loops

Static Equilibrium

No inputs or output of matter or energy (isolated systems)

No changes in the system over time

If there is a disturbance the system will adopt a new equilibrium

No natural systems are in static equilibrium

Stable Equilibrium

Tends to return to the same equilibrium after a disturbance

Unstable Equilibrium

The system returns to a new equilibrium after a disturbance

Resilience

Tenency of a system to avoid tipping points to maintain stability

What increases resilience of a system?

More complex systems (more interactions)

Higher biodiversity (species and genetic)

Larger storages within systems

Higher productivity (and hence a larger storage)

More mature ecosystems

Species with faster reproductive rates and wider geographical ranges

How does complexity increase stability of a system?

Many flows between storages and feedback loops, a change is less likely to affect it.

Example of system with low resilience

-Irish potato famine - monoculture of potatoes all were affected by potato blight, people died from lack of food as they were extremely dependent on the food.

Tipping point and issues monitoring them

(Tipping point is minimum amount of change needed to cause destabilisation within a system; system then changes to new equilibrium.)

-Change in ecosystem is too far to stabilise it

Cannot be precisely predicted using models

Changes are long lasting and hard to reverse

The effects of processes can often take a long time to see (time lag)