The GHG Protocol splits an organization's carbon footprint into three scopes. Each glowing platform below is one scope, streaming particles toward the central inventory tower — the tower's height and colored bands are the live emissions inventory, exactly like a stacked bar chart redrawn every frame.
Scope 1 = Σ(activity × emission_factor) — onsite combustion, fleet fuel
Scope 2 = electricity × grid_factor × (1 − renewable_share) — market-based
Scope 3 = Σ(purchased goods, transport, product use, …)
Net = (Scope1 + Scope2 + Scope3) − offsets
- Scope 1 — direct fuel — onsite boilers, furnaces and owned vehicles burning fuel directly; the orange platform.
- Scope 2 — electricity use — purchased grid electricity and heat; the blue platform. Its real emission factor depends on the grid mix, not just how much is consumed.
- Grid renewable share — the market-based lever from I-REC / PPA / Guarantees of Origin certificates: buying renewable power cuts Scope 2's effective factor toward zero even if consumption is unchanged.
- Scope 3 — value chain — purchased goods, logistics, business travel and product use downstream; the purple platform, usually the largest and hardest to control.
- Carbon offsets — verified removals/avoidance credits (VCS, Gold Standard) that only count after genuine reduction — they subtract from the net total, never from the gross inventory shown by the tower bands.
- Efficiency −20% — a flat activity-reduction lever across all three scopes, the "avoid and reduce" step that should always come before offsetting.
- Electrify fleet — shifts a slice of Scope 1 fuel combustion into Scope 2 electricity demand; it only lowers net emissions once the grid (or renewable share) is clean enough to make that trade worthwhile.
Real-world relevance: this is why a credible net-zero pathway sequences measures — reduce activity and switch fuels first, green the electricity supply second, and use verified offsets only for the residual that can't yet be eliminated.