Annual CO₂ intensity per deadweight-nautical-mile. Used by the Poseidon Principles (banks) and the IMO operational CII regime.
Formula
$$ \text{AER} = \frac{\sum_j F_j \cdot C_{f,j} \cdot 10^6}{\text{DWT} \cdot \text{Distance}} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\text{AER}$ | Annual Efficiency Ratio | g CO₂ / (dwt·nm) | result |
| $F_j$ | Mass of fuel $j$ burned in the reporting year | t | IMO DCS |
| $C_{f,j}$ | CO₂ conversion factor for fuel $j$ | t CO₂ / t fuel | MEPC.364(79) |
| $DWT$ | Deadweight tonnage | t | ship particulars |
| $Distance$ | Total distance sailed in the reporting year | nm | IMO DCS |
| $10^6$ | Unit conversion tonnes → grams | - | constant |
Relationship to CII
AER is identical in form to the CII Attained metric of MEPC.336(76) for cargo ships where DWT is the capacity basis. The Poseidon Principles use AER as a standalone climate-alignment indicator for ship-finance portfolios, independent of IMO ratings.
Sources
- Poseidon Principles - signatories’ annual disclosure framework.
- IMO MEPC.336(76) - operational CII guidelines.
- IMO MEPC.364(79) - Cf fuel conversion factors.