IB Environmental systems and societies Topic 1.2C Positive Feedback Loops Revision Notes (SL/HL)

IB Environmental systems and societies Topic 1.2C Positive Feedback Loops Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Definition

Positive feedback loop

Positive feedback loops are processes that exacerbate the effects of a small disturbance.

Positive Feedback: How Systems Amplify Their Own Change

A positive feedback loop occurs when a disturbance amplifies itself, pushing a system further away from equilibrium rather than restoring balance.
Because the change reinforces itself, it can cause rapid and sometimes irreversible shifts in natural and human systems.

Note

Negative feedback and equilibrium types are covered in 1.2B.
Every loop below can be drawn as a systems diagram: boxes for storages, arrows for flows.

Key Characteristics

Self-reinforcing: outputs feed back to strengthen the original process.
Amplifying and destabilising: it increases deviation and drives the system away from equilibrium.
Works in either direction: unlike negative feedback, it accelerates change whether a value is rising or falling.
Nonlinear: changes accelerate over time rather than staying proportional.
Common in many systems: climate processes, population dynamics, and resource depletion all show it.

Example

Population growth: more people reproduce, so the population grows even faster (exponential growth).
Species decline: fewer individuals remain, so mates are harder to find and the population falls further (extinction vortex).

Ice-Albedo Feedback: Warming That Melts Its Own Brake

How the Ice-Albedo Loop Builds

Global temperatures rise due to greenhouse gas emissions.
Ice caps and glaciers melt, reducing surface reflectivity (albedo).
Darker ocean and land absorb more solar radiation instead of reflecting it.
Temperatures rise further, which melts even more ice.

The Result: A Self-Reinforcing Warming Cycle

Nice try, unfortunately this paywall isn't as easy to bypass as you think. Want to help devleop the site? Join the team at https://revisiondojo.com/join-us. exercitation voluptate cillum ullamco excepteur sint officia do tempor Lorem irure minim Lorem elit id voluptate reprehenderit voluptate laboris in nostrud qui non Lorem nostrud laborum culpa sit occaecat reprehenderit

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

IB Environmental systems and societies 1.2C Positive Feedback Loops Notes

Positive Feedback: How Systems Amplify Their Own Change

Key Characteristics

Ice-Albedo Feedback: Warming That Melts Its Own Brake

How the Ice-Albedo Loop Builds

The Result: A Self-Reinforcing Warming Cycle

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Positive Feedback: How Systems Amplify Their Own Change

Key Characteristics

Ice-Albedo Feedback: Warming That Melts Its Own Brake

How the Ice-Albedo Loop Builds

The Result: A Self-Reinforcing Warming Cycle

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 1.2C Positive Feedback Loops Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Positive Feedback: How Systems Amplify Their Own Change

Key Characteristics

Ice-Albedo Feedback: Warming That Melts Its Own Brake

How the Ice-Albedo Loop Builds

The Result: A Self-Reinforcing Warming Cycle

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Positive Feedback: How Systems Amplify Their Own Change

Key Characteristics

Ice-Albedo Feedback: Warming That Melts Its Own Brake

How the Ice-Albedo Loop Builds

The Result: A Self-Reinforcing Warming Cycle

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account