Ship-sourced disposal of plastics is prohibited under the MARPOL convention for vessels flagged to parties to this convention in both exclusive economic zones and waters beyond national jurisdiction. The enforcement of MARPOL provisions needs strong monitoring, control and surveillance systems to ensure effective compliance, a key role for the flag state of vessels, from the smallest fishing vessel to large supertankers. Land-based sources of pollution entering the marine environment, \cite{2015a}which are by far the main source of marine plastic pollution, need similar monitoring and control by states.
Given the character of the problem, attention has focused on international action with measurable targets to reduce macro-plastic and micro-plastic marine pollution1. The global community has risen to similar challenges in the past. Fifty years ago, Arvid Pardo, Malta’s Ambass\ref{167621}ador to the United Nations, called for concerted actions to address what he saw as the potential for uncontrolled exploitation of the world’s oceans, threatening what Pardo recognised as areas of for the ‘common heritage of mankind’. Pardo’s calls for action led to changes in ocean governance, most notably the Third United Nations Conference on the Law of the Sea that concluded with the drafting and eventual entry into force of the United Nations Law of the Sea Convention.
An international agreement to address marine plastics could be pursued in a similar manner, but necessarily in a more integrated and broad-based approach than that attempted in the late 1960s. It could be modelled on the successful Montreal Protocol addressing ozone-depleting substances that saw replacement of chlorofluorocarbons and an increasing public awareness of the problem. A key starting point is to build on commitments made at Nairobi, reaffirming the principles contained in the Rio Declaration on Environment and Development in 19924, and the more recent commitments made in 2015 by world leaders in adopting the 2030 Agenda for Sustainable Development which, inter alia, includes 17 Sustainable Development Goals (SDGs)5. SDG 14, ‘Conserve and sustainably use the oceans, seas and marine resources for sustainable development’, provides a focus for ongoing action on marine plastic pollution.
Another related direction (advanced by work at the United Nations Environment Assembly) is to build on the commitments made at the United Nations Conference to Support the Implementations of SDG 14, also known as the Oceans Conference, held in New York in June 2017. One outcome of the Oceans Conference was the creation of Communities of Ocean Action, with marine pollution identified in SDG Target 14.1 being the clear focus of such work. A side event at the United Nations Environment Assembly was a forum for governments, non-governmental organisations and civil society groups to present innovative solutions to tackle marine pollution through voluntary commitments by members of Communities of Action.