New IMO study shows global shipping emissions growth

The International Maritime Organization (IMO) has released the Fourth IMO GHG Study which is the first iteration since the adoption of the initial GHG strategy.


Back in 2018, the IMO adopted the Initial IMO Strategy on reduction of greenhouse gas (GHG) emissions from ships under which IMO Member States have pledged to cut emissions from international shipping and to phase them out as soon as possible.  

The new study estimates that total shipping emitted 1,076 million tonnes of CO2 in 2018, accounting for about 2.89% of the total global anthropogenic CO2 emissions for that year. Total shipping emissions in 2018 increased from 977 million tonnes seen in 2012.

 Under a new voyage-based allocation method of international shipping, the share of international shipping represented 740 million tonnes of CO2 in 2018, increasing from 701 million tonnes in 2012.

“Due to developments in data and inventory methods, this study is the first IMO GHG Study able to produce greenhouse gas inventories that distinguish domestic shipping from international emissions on a voyage basis in a way which, according to the consortium, is exactly consistent with the IPCC guidelines and definitions,” according to IMO.

For the first time, the study includes estimates of carbon intensity. Overall carbon intensity has improved between 2012 and 2018 for international shipping as a whole, as well as for most ship types. The overall carbon intensity, as an average across international shipping, was between 21 and 29% better than in 2008. 

Emission projections 2018 – 2050

Emissions are projected to increase from about 90% of 2008 emissions in 2018 to 90-130% of 2008 emissions by 2050 for a range of plausible long-term economic and energy scenarios .

Specifically, emissions could be higher (lower) than projected when economic growth rates are higher (lower) than assumed here or when the reduction in GHG emissions from land-based sectors is less (more) than would be required to limit the global temperature increase to well below 2 degrees centigrade.

“Although it is too early to assess the impact of COVID-19 on emission projections quantitatively, it is clear that emissions in 2020 and 2021 will be significantly lower,” the IMO said.

“Depending on the recovery trajectory, emissions over the next decades maybe a few percent lower than projected, at most. In all, the impact of COVID-19 is likely to be smaller than the uncertainty range of the presented scenarios.”