IMO: Thin layer of biofouling can increase GHG emissions by 25 percent


(LONDON) — Keeping ships’ hulls free from just a thin layer of slime can reduce a ship’s greenhouse gas (GHG) emissions by up to 25 percent, according to the preliminary findings of a new study previewed at the United Nations Climate Change Conference (COP 26) on Nov. 4.

The preliminary findings of the study, “Impact of Ships’ Biofouling on Greenhouse Gas Emissions,” reveals that a layer of slime as thin as 0.5 millimeters covering up to 50 percent of a hull surface can trigger an increase of GHG emissions in the range of 20 to 25 percent, depending on ship characteristics, speed and other prevailing conditions.

IMO photo

Biofouling is the buildup of microorganisms, plants, algae or small animals on surfaces. One of the most significant factors impacting the efficiency of all ships in service is associated with the resistance generated by the underwater area. Maintaining a smooth and clean hull free from biofouling is of paramount importance.

More severe biofouling conditions can lead to higher emissions, showing the importance of good biofouling management. With a light layer of small calcareous growth (barnacles or tubeworms), an average length containership can see an increase in GHG emissions of up to 55 percent, dependent on ship characteristics and speed.

To reduce the GHG emissions from the maritime industry, the International Maritime Organization (IMO) has adopted a series of legally binding ship design and operational performance indices that must be achieved by individual vessels. The aim is to ensure that ship operators consider options to improve the efficiency of their vessels throughout their life cycle.

The report clearly shows the importance of good biofouling management. It illustrates how the perceived impact of biofouling is likely to have been historically underestimated by the shipping community.

The report on the preliminary results of the study was launched by the Global Industry Alliance (GIA) for Marine Biosafety, a group of leading companies that have joined forces to develop solutions and address barriers to improve biofouling management. The GIA operates under the framework of the GEF-UNDP-IMO GloFouling Partnerships project (

Click here to download the preliminary results of the study.

– International Maritime Organization

By Professional Mariner Staff