IB Biology Topic D4.3.2 Positive Feedback Cycles in Global Warming Revision Notes (SL/HL)

IB Biology Topic D4.3.2 Positive Feedback Cycles in Global Warming Revision Notes (SL/HL) | RevisionDojo

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Positive feedback cycles amplify warming and can push the climate past no-return tipping points

A positive feedback cycle occurs when an initial rise in temperature triggers processes that cause even more warming.
Unlike negative feedback, which stabilises a system and dampens change, positive feedback reinforces change and makes it harder to reverse.
These loops amplify climate change, making it more severe and speeding up the rate of temperature rise.

Definition

Positive feedback loop

A process where an initial change causes further changes that amplify the original effect, making it stronger and self-reinforcing.

Analogy

Positive feedback is like a snowball rolling downhill.
As it rolls it picks up more snow, growing larger and moving faster.
The initial push, warming, sets off a chain reaction that amplifies the effect.

Five self-reinforcing cycles turn warming into more warming

Release of carbon dioxide from the warming ocean: as the atmosphere warms, so do the oceans.
1. Warmer water holds less carbon dioxide ($CO_2$), so it releases $CO_2$ back into the atmosphere.
2. This extra $CO_2$ strengthens the greenhouse effect and warms the planet further.

Example

Opening a warm soda can shows the same physics: warm liquid holds less dissolved gas, so it escapes faster.
In the same way, warmer oceans release more $CO_2$.

Definition

Albedo

Albedo ($\alpha$) measures the reflectivity of a surface.

Loss of reflective snow and ice (ice-albedo effect): snow and ice reflect sunlight, keeping the Earth cooler.

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Paywall

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

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Tip

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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.

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Positive feedback cycles amplify warming and can push the climate past no-return tipping points

A positive feedback cycle occurs when an initial rise in temperature triggers processes that cause even more warming.
Unlike negative feedback, which stabilises a system and dampens change, positive feedback reinforces change and makes it harder to reverse.
These loops amplify climate change, making it more severe and speeding up the rate of temperature rise.

Definition

Positive feedback loop

A process where an initial change causes further changes that amplify the original effect, making it stronger and self-reinforcing.

Analogy

Positive feedback is like a snowball rolling downhill.
As it rolls it picks up more snow, growing larger and moving faster.
The initial push, warming, sets off a chain reaction that amplifies the effect.

Five self-reinforcing cycles turn warming into more warming

Release of carbon dioxide from the warming ocean: as the atmosphere warms, so do the oceans.
1. Warmer water holds less carbon dioxide ($CO_2$), so it releases $CO_2$ back into the atmosphere.
2. This extra $CO_2$ strengthens the greenhouse effect and warms the planet further.

Example

Opening a warm soda can shows the same physics: warm liquid holds less dissolved gas, so it escapes faster.
In the same way, warmer oceans release more $CO_2$.

Definition

Albedo

Albedo ($\alpha$) measures the reflectivity of a surface.

Loss of reflective snow and ice (ice-albedo effect): snow and ice reflect sunlight, keeping the Earth cooler.

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

Duis aute irure dolor in reprehenderit

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

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.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D4.3.2: Positive Feedback Cycles in Global Warming Notes

Positive feedback cycles amplify warming and can push the climate past no-return tipping points

Five self-reinforcing cycles turn warming into more warming

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 cycles amplify warming and can push the climate past no-return tipping points

Five self-reinforcing cycles turn warming into more warming

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

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics