Cheatsheet: Sustainable Living and Climate Awareness
A lookup card for the whole course. Use it to check a term, pick a swap, or defend a decision.
beginner
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.
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):
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