Carbon Intensity Methodology
The Carbon Intensity layer on the TSM Atlas shows facility-level Scope 1+2 GHG emissions per tonne of metal, color-coded against published global averages. This page documents the formula, the tier thresholds, and the primary sources behind every number.
What you see on the map
When you open /maps/?layer=carbonIntensity, each marker is a single producer facility (smelter, refinery, mine, EAF mini-mill). The marker color is its tier (green / yellow / orange / red), and the popup links straight to the producer's own sustainability report or industry-association disclosure. No estimates, no proxies, no third-party scoring rubric — just the producer's published number.
Tiers
Well below global average
Below or at global average
Above global average
Well above global average
Each tier is computed relative to the global average for that specific metal — not across metals. Steel at 1.92 t CO₂/t and aluminium at 15.1 t CO₂/t are not comparable in absolute terms; they are comparable in ratio terms (i.e., how far above or below their own industry average a producer sits).
Formula
if ratio < 0.5 → Low
if ratio < 1.0 → Moderate
if ratio < 2.0 → High
else → Very high
Producer CI = the producer's most recent disclosed Scope 1 + Scope 2 GHG emissions
per tonne of saleable metal, in t CO₂e / t metal, cradle-to-gate
(i.e., from ore extraction to cast house / refinery gate; downstream transport excluded).
Global average CI = the latest industry-wide average published by the recognized industry association for that metal — never a TSM estimate.
Global averages (current baselines)
| Metal | Global avg | Unit | Source |
|---|---|---|---|
| Primary aluminium | 15.1 | t CO₂e / t Al | IAI — Global Primary Aluminium GHG Intensity |
| Crude steel | 1.92 | t CO₂ / t crude steel | worldsteel — Sustainability Indicators 2025 |
| Refined copper | 4.6 | t CO₂e / t Cu | International Copper Association — global cradle-to-gate |
| Gold | 0.792 | t CO₂e / oz Au (≈ 792 kg / oz) | S&P Global — Skarn Associates gold sector benchmark |
| Class-1 nickel | 13 | t CO₂e / t Ni | Argus / CarbonChain — nickel sector benchmark |
Worked examples
Why HYBRIT (Sweden) is green
HYBRIT — the SSAB / LKAB / Vattenfall hydrogen-DRI pilot in Luleå — reports
< 0.05 t CO₂ / t steel for fossil-free direct-reduced iron.
Versus the worldsteel global average of 1.92, that is a ratio of
0.05 / 1.92 ≈ 0.026× — far below the 0.5× green threshold, so the marker is
Low. Source:
HYBRIT Development.
Why Sibanye-Stillwater (US PGM) is red
Sibanye-Stillwater's US PGM operations report
9.98 t CO₂e / oz (Scope 1+2, palladium-equivalent basis) in their 2023 climate report.
Versus the Skarn Associates gold sector benchmark of 0.792 t/oz, that is a ratio of
9.98 / 0.792 ≈ 12.6× — well past the 2× red threshold, so the marker is
Very high. PGM mining is intrinsically more energy-intensive than gold
(deeper ore, lower grade, harder rock), but on a CO₂-per-saleable-ounce basis the relative tier is what we display.
Source:
Sibanye-Stillwater — Climate Change Report.
Why Hydro CIRCAL recycled (Norway) is green
Hydro CIRCAL recycled aluminium reports 2.3 t CO₂e / t (Scope 1+2+3, third-party verified).
Versus the IAI primary aluminium average of 15.1 t/t, that is a ratio of
2.3 / 15.1 ≈ 0.15× — far below 0.5×, so the marker is Low.
Source:
Hydro — Integrated Annual Report.
What we don't do
- No proxy estimates. If a producer has not disclosed Scope 1+2 GHG intensity for a facility, that facility is not on the map. Silence over invented numbers.
- No third-party scoring overlay. No MSCI ESG rating, no Sustainalytics, no S&P CSA score. The producer's number speaks for itself.
- No Scope 3 by default. Scope 3 disclosure is uneven and not directly comparable across producers. When a producer publishes Scope 1+2+3, we note it in the popup, but the tier is computed on Scope 1+2 to match the industry-average baselines.
- No country-aggregated tiers. Industry bodies do not publish country averages for most metals (only IAI and worldsteel publish regional aggregates, and even those are not country-level). So we plot facilities, not countries.
Source-of-truth chain
- Each facility marker on the map links to the producer's own disclosure (sustainability report, environmental fact sheet, ASI/RTA audit, climate report, LME passport).
- The global-average baseline links to the industry association's most recent public methodology.
- Every datapoint carries a fetch timestamp and a per-source URL back to the original publisher.
- This page describes the formula. The Atlas page renders it.