Count the whole journey, not just the flame

A fuel's carbon intensity (CI) is measured in gCO₂e per megajoule of energy, across its whole lifecycle — growing or collecting the feedstock, converting it, transporting it, and finally burning it. This is the well-to-wake view.

Tailpipe-only accounting would make every fuel look similar at the engine. Lifecycle accounting is what reveals the real differences — and it's what CORSIA uses.