THE global shipping fleet emitted 614m tonnes of carbon dioxide in 2019, according to the first emissions-collection database compiled by the International Maritime Organization. 

A report on the IMO Data Collection System, as it is officially known, seen by Lloyd’s List, shows containerships, tankers and bulkers accounted for 78.6% of the total CO2 emitted by international shipping. Another 10 ship types accounted for the remainder. 

The data system covers only vessels of 5,000 gross tonnes and above and is based on emissions reporting from shipping companies.

While the three conventional ship types accounted for the majority of emissions, they also accounted for almost 92% of global deadweight tonnes-nautical miles. Bulkers alone took up over 41% of this share.

The report further shows significant filtering and removal of some ships, where there have been obvious errors in reporting, which indicates that if the reporting had been accurate, the total levels of emissions would have been higher. 

For example, the original population of tankers, bulkers and containerships that reported to the DCS was 22,342. After the filtering, the three ship types had a combined 21,401 vessels.

All in all, there were a total of 27,907 vessels originally. After the filtering, there were 26,555 vessels left, marking a 4.85% cut from the original fleet size.

This is the first global database of its kind, but there is an existing regional counterpart.

The European Union’s own data collection system, which also covers vessels of 5,000 gross tonnes and above but only for ship voyages related to the European Economic Area, has recorded 2019 emissions at around 145.5m tonnes of CO2. 

While the IMO system and the EU database show a very similar share of containerships and tanker emissions, there is an evident difference in bulkers. The latter take just over 11% of emissions in the EU’s database but more than 27% in the IMO DCS. 

Unlike the with the EU database, the identities of individual vessels are not disclosed using the IMO system, something that does not allow for the same kind of granularity in the analysis.

Carbon intensity improvements and uncertainties 

The 2019 report also revealed significant improvements in average carbon intensity, a metric that is particularly important for the IMO’s 2030 target of reducing average CO2 per transport work by at least 40% by 2030 compared with 2008. 

However, these improvements come with important caveats that could limit both their accuracy and, potentially, their future utility. 

The global fleet’s average annual efficiency ratio, which is based on fuel consumption, deadweight tonnage and distance travelled, fell by 32.3% from 2008 to 2019, according to the report.

Meanwhile, the global average energy efficiency operational indicator, which also take into consideration the amount of cargo carried, improved by 44% from 2008 to 2019, meaning that it has already surpassed the 2030 target. 

The IMO DCS does not require companies to report data on cargo carried so this reduction rate is based on tonne-mile data from Clarksons Research.

These reduction rates are based on seven representative “mainstream cargo ship types”, accounting for 90.3% of total CO2 emitted by the 13 ship types. 

Although the DCS figures show notable reductions in carbon intensity since 2008, comparisons between the two years’ figures could be problematic. 

The DCS report seen by Lloyd’s List repeatedly warns that comparisons between its own 2019 dataset and the 2008 values may be inappropriate because of different methodologies and other factors. 

Just like the data 2018 emissions data reported in the fourth IMO GHG study that was published in the past year, the 2008 emissions levels are derived from models based on satellite and other data.

On the other hand, the IMO DCS is based on direct emissions reporting from shipowners and operators. 

This discrepancy creates a challenge for regulators at the IMO on deciding how to use the DCS data, especially when it comes to monitoring emissions progress compared with 2008, the year that they have selected to judge the fleet’s energy-efficiency progress against. 

The next session of IMO Marine Environment Protection Committee that meets in June will likely discuss the data and how to use it in finalising new operational efficiency measures for ships.