Cruise methodology
Verified tracked cruise vessels
PaperStraw estimates cruise emissions from observed AIS movement for verified ocean cruise vessels. Coverage is improving over time and should not be read as complete global cruise coverage.
AIS-based observations
AIS provides vessel position, speed, heading and static/voyage messages when they are broadcast and received. PaperStraw uses a global AIS feed with local filtering, then stores positions only for vessels that are already public-eligible under the verified registry and MMSI-link rules.
Verified cruise registry
A vessel starts as an accepted registry entry only after manual evidence review. The registry records ocean-cruise identity by exact IMO and excludes non-cruise vessels such as ferries, RoPax vessels, river vessels, yachts, excursion craft and other out-of-scope passenger vessels.
MMSI review workflow
AIS static data can reveal an MMSI for an accepted registry IMO. Those discoveries enter a review queue. A human reviewer must approve a safe exact-IMO match before the MMSI becomes linked. No fuzzy name, operator, type, destination or dimension matching is used for public eligibility.
Public-eligible vessels
Public cruise statistics include only vessels with a verified ocean-cruise registry match and a high-confidence MMSI-linked verification record. Accepted registry entries, MMSI-linked vessels and observed vessels are related but different counts.
Emissions estimates
Cruise CO2 estimates are derived from observed vessel positions and available movement data. Where annual references such as EMSA THETIS-MRV disclosures are available, they can inform baseline context; daily public values remain estimates from observed activity, not official real-time emissions measurements.
CO2 comparisons
Tree comparisons are illustrative. They estimate how many newly planted trees would be required to absorb the same amount of CO₂ over an assumed 45-year lifetime, not how many trees would offset the emissions immediately or annually. Actual absorption varies by species, climate, survival rate, soil conditions, and forest management.
Coverage limitations
Cruise totals are tracked since PaperStraw monitoring began. They are not necessarily year-to-date global cruise totals and do not claim all cruises worldwide. AIS reception, vessel broadcast behavior, MMSI coverage, registry completeness and observation windows can all affect the numbers shown.
Why unverified vessels are excluded
AIS passenger traffic can include ferries, regional passenger vessels, river ships, excursion vessels and other craft that fall outside the PaperStraw cruise scope. Excluding unverified candidates protects the public dataset from inflated or misleading cruise emissions totals.