Climate Change

The ultimate externality

Content

TBD.

Transcript

Appendix

Climate Change as an Earth–Economy Problem

Learning objectives

After this chapter, you should be able to:

Explain why climate change is the archetypal Earth–economy problem.
Identify the climate system as a global stock–flow system.
Describe how emissions create a long-lived externality.
Compare the main climate policy instruments: taxes, permits, and standards.
Explain why partial-equilibrium thinking often fails for climate policy.
Describe how Earth–economy models integrate climate, land, and the economy.

Why climate is different

Many environmental problems are local:

a polluted river,
a depleted fishery,
a damaged forest.

Climate change is different.

Emissions anywhere affect people everywhere.
Damages unfold over decades and centuries.
The key variable—atmospheric CO₂—is a global stock.
The most affected people are often not the emitters.
Future generations have no voice.

This makes climate change the purest expression of the ideas in this book:

externalities,
stocks and dynamics,
public goods,
intergenerational tradeoffs,
and institutional failure.

It is the canonical Earth–economy problem.

Climate as a stock–flow system

Let:

E = annual emissions (flow),
C = atmospheric concentration (stock).

Each year:

C_next = C + E - natural_removal

Key features:

CO₂ persists for centuries.
Reducing emissions slows growth of C.
Net-zero emissions stabilize C.
Negative emissions reduce C.

Damages depend primarily on C, not E.

This creates a trap for intuition:

“We reduced emissions this year”
does not mean
“The problem is shrinking.”

The problem shrinks only when the stock shrinks.

The climate externality

Each ton of CO₂:

raises global temperature,
increases extreme events,
affects agriculture, health, and ecosystems,
and imposes costs on others.

But the emitter:

pays for fuel and equipment,
does not pay for climate damage.

This is the textbook negative externality—
scaled to the entire planet and future centuries.

The economic solution is conceptually simple:

Align private incentives with social cost.

The practical implementation is politically and institutionally complex.

Core policy instruments

Carbon pricing

Two main forms:

Carbon tax: a fixed price per ton of CO₂.
Cap-and-trade: a fixed quantity of allowed emissions with tradable permits.

Both:

internalize the externality,
reward low-carbon choices,
let firms and households find the cheapest abatement.

Differences:

Feature	Carbon tax	Cap-and-trade
Control	Price is fixed	Quantity is fixed
Certainty	Cost certainty	Emissions certainty
Revenue	Predictable	Depends on permit price
Volatility	Low	Can be high

Both are tools for steering a complex system.

Standards and regulations

Examples:

fuel economy rules,
clean power standards,
building codes,
appliance efficiency requirements.

They:

bypass price signals,
target specific sectors,
can be faster to implement,
and often face less public resistance.

They are blunt but effective.

Public investment

Climate transitions require:

new infrastructure,
new technologies,
new skills.

Markets underprovide these because:

benefits are diffuse,
risks are high,
spillovers are large.

Public investment:

accelerates innovation,
builds networks,
and reshapes the feasible set.

Why partial thinking fails

A partial-equilibrium view asks:

“What happens in the electricity market?”

An Earth–economy view asks:

“What happens to land, food, trade, income, and ecosystems?”

Examples:

Biofuel mandates raise crop prices and drive deforestation.
Carbon taxes shift trade and production across borders.
Renewable expansion changes mineral demand and land use.
Adaptation alters migration and labor markets.

Climate policy ripples through:

land systems,
food systems,
energy systems,
and livelihoods.

Ignoring these feedbacks leads to:

leakage,
rebound,
regressive outcomes,
and political backlash.

Climate inside Earth–economy models

Earth–economy models integrate:

energy production,
land use,
emissions,
atmospheric stocks,
climate damages,
and economic response.

They can simulate:

policy pathways (taxes, standards, investment),
technological change,
land-use change,
and feedbacks.

Outputs include:

emissions paths,
temperature outcomes,
GDP and income,
land cover,
ecosystem services,
and inclusive wealth.

This allows questions like:

Does this policy reduce emissions but increase deforestation?
Does this pathway protect the poor?
Does this transition build long-run wealth?

Climate policy becomes a system design problem.

The Doughnut perspective

Climate overshoot pushes society:

beyond the ecological ceiling,
and often below the social foundation (through heat, floods, food insecurity).

A climate transition that ignores equity:

may reduce emissions,
but deepen social shortfall.

The Doughnut reminds us:

Climate policy is not just about carbon.
It is about building a safe and just future.

Earth–economy modeling is how we test whether we are doing that.

Open resources you can remix for this chapter

All are compatible with a CC BY-NC-SA Quarto book.

Natural Resources Sustainability: An Introductory Synthesis (CC BY-NC-SA)
Use for: climate, sustainability framing.
https://uen.pressbooks.pub/naturalresourcessustainability/
Principles of Economics (UMN Libraries Publishing, CC BY-NC-SA)
Use for: externalities, taxes, public goods.
https://open.umn.edu/opentextbooks/textbooks/principles-of-economics
InTeGrate teaching materials (many CC BY-NC-SA)
Use for: climate data, mitigation pathways, policy exercises.
https://serc.carleton.edu/integrate/teaching_materials/index.html

Exercises

Stock vs flow.
Explain why cutting emissions by 10% does not “solve” climate change.
Instrument comparison.
Compare a carbon tax and a clean electricity standard.
Which gives more certainty? Which is easier to explain politically?
System ripple.
Choose one climate policy.
Describe two indirect effects it could have outside the energy sector.

Chapter roadmap

Next, we examine uncertainty, risk, and tipping points.
You will see why climate change challenges standard cost–benefit logic and demands new decision frameworks.