Lecture 19: Complexity, tipping points

Question 1

What is a complex system?

Answer 1

A complex system is any set of interrelated parts that produces behaviour that is difficult to understand or predict….

Question 2

Human-environment system

What do the arrows do?

Answer 2

Create causal loops between systems and environments.

Each arrow connects two elements where the effect in each is either the same (S) or opposite (O).

Question 3

If a loop has an odd number of ‘Os’…

Answer 3

it is a balancing or negative feedback loop

Question 4

If a loop has zero or an even number of ‘Os’…

Answer 4

it is a reinforcing or positive feedback loop

Question 5

No threshold change =

Answer 5

linear response

Question 6

Step/threshold change =

Answer 6

nonlinear response

Question 7

Step/threshold change =

Answer 7

‘irreversible’ nonlinear catastrophic bifurcation

Question 8

Examples of exponential growth in human systems..?

Answer 8

Population

GDP

Question 9

Examples of exponential growth in physical systems..?

Answer 9

CO2

Methane

Question 10

Collapse in ecology

Answer 10

Study of lakes- can shift very quickly between two types of lake depending on subtle changes in the environment