Marine Pollution: From and Through the Atmosphere

Pollution reaches, and can adversely affect, the ocean from a variety of sources and by a variety of pathways.  One such pathway is the atmosphere or the air that makes contact with the surface of the ocean. Article 212 of UNCLOS directs States to “adopt laws and regulations to prevent, reduce and control pollution of the marine environment from or through the atmosphere, applicable to the air space under their sovereignty and to vessels flying their flag or vessels or aircraft of their registry.” UNCLOS Article 212(1).  One serious consequence of atmospheric pollution of the ocean is “Ocean Acidification” which occurs when airborne carbon dioxide (CO2) is absorbed by seawater, causing chemical reactions that reduce seawater pH and may affect many marine organisms. The pace of ocean acidification has been accelerating, causing the scientific community to focus more of its study power on its potential impacts and how those impacts may cascade through the marine food chain and affect the overall structure of marine ecosystems.

One strategy for reducing the presence of CO2 in the atmosphere is referred to as Carbon Capture and Storage which generally involves the capture of CO2 directly at industrial or power plant sources, followed by its removal to secure subsurface reservoirs for permanent storage. At the international level, measures have been enacted under the London Convention/London Protocol and the regional Convention for the Protection of the Marine Environment of the North-East Atlantic (the OSPAR Convention) to regulate the injection of carbon dioxide into sub-seabed geologic formations for the purpose of climate change mitigation.

Vessels can be a significant source of marine pollution, certainly from dumping of pollutants directly into the marine environment, but also from emissions of their exhaust gases into the atmosphere.  MARPOL Annex VI offsite link limits the main air pollutants contained in ships’ exhaust, including sulfur oxides and nitrous oxides.  It also prohibits deliberate emissions of ozone depleting substances, controls emissions of volatile organic compounds from tankers, and regulates shipboard incineration. The Maritime Pollution Prevention Act of 2008  is the implementing authority in the United States.

Last updated February 6, 2018