Fleet Carbon Intensity

Method & caveats

• cAER is the capacity-normalised carbon-intensity figure (grams of CO₂ per deadweight-tonne nautical mile), the IMO cAER basis. The median is the headline because it is naturally robust; the mean is clipped to a physical ceiling so a single stuck-at-anchor ship (whose tiny distance denominator inflates cAER into the thousands) cannot corrupt a segment average — a * marks segments where ships were clipped.
• Spread is the mean’s distance above the median, as a share of the median. It describes how lopsided a segment is — a wide spread means a minority of high-intensity ships sits well above the typical ship — and it is not a direction, so it carries no good/bad colour. On fewer than 100 reports it is shown quiet and excluded from any “widest” claim.
• Year-on-year is the change in a segment’s mean cAER between reporting years. It can move because the reporting cohort changed — ships entering or leaving the sample — as well as because ships changed, so a rise is not on its own evidence that a segment’s ships got dirtier.
• The A–E band is our own peer-relative carbon-intensity ranking of the reported cohort (A = cleanest fifth, E = least efficient) — it is not the official IMO CII rating and should not be read as one.
• Coverage is the reported ships as a share of the segment’s catalogued fleet. Verified reporting only covers ships above 5,000 GT calling at EU ports, so coverage is thin for smaller-ship segments — this makes that explicit rather than passing the sample off as the whole fleet.
• Modelled bands are estimated for the non-reporting in-distribution fleet, and are kept in a separate panel so reported and modelled coverage are never silently merged. Segments with no modelled cohort say so rather than dropping out of the panel.
• Segments use the platform’s single shared vessel-class classifier (gas, tanker, container, bulker, other), so this can never drift from the valuation, fleet-supply or owner-stats views.