# 🌱 Cheatsheet: Sustainable Living and Climate Awareness

By Better Wise

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A lookup card for the whole course. Use it to check a term, pick a swap, or defend a decision.

beginner

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## Module 1: Climate Science in Plain Terms

### 1.1 The Greenhouse Effect Without the Jargon

**The chain in one line:** sunlight in → surface warms → surface re-emits heat as infrared → greenhouse gases absorb and re-radiate that heat → some escapes to space, some returns to warm the surface.

```mermaid
flowchart TD
    Sun["☀️<br/>Sunlight in"] --> Surface["🌍<br/>Surface absorbs, warms"]
    Surface --> IR["♨️<br/>Infrared heat out"]
    IR --> GHGs["🫧<br/>GHGs absorb and re-radiate"]
    GHGs --> Space["🚀<br/>Some heat escapes"]
    GHGs --> Back["🔁<br/>Some heat returns to surface"]
```

| Term | Plain meaning |
| --- | --- |
| Greenhouse gas (GHG) | A gas that traps outgoing infrared heat |
| Main GHGs | CO2, methane (CH4), nitrous oxide (N2O), fluorinated gases |
| Concentration | How much GHG is in the atmosphere; rising concentration traps more heat |
| Radiative forcing | Net change in energy balance from a factor (positive = warming) |
| Feedback | A change that amplifies (positive) or dampens (negative) warming |

Key facts:
- CO2 is the largest long-lived contributor; methane is far more potent per molecule but shorter-lived.
- Burning fossil carbon moves carbon that was locked underground into the atmosphere.
- More GHGs → more heat retained → warming trend, not a one-off.

> **Note:** 
> The greenhouse effect itself is natural and keeps Earth habitable. The problem is the *enhanced* effect from added GHGs.

### 1.2 CO2e, Scopes, and Reading a Carbon Footprint Number

**CO2e (CO2 equivalent):** a common unit that converts each gas to the warming of an equivalent mass of CO2, so different gases can be added up.

**Scopes** (how emissions are categorized for an organization or product):