But those hopes are fading, the United Nations Special Envoy for the Ocean said on Monday, as a conference to assess progress in protecting marine life on the high seas got under way in Lisbon.
He did however remain confident that U.N. member states would reach a consensus this year on a treaty to protect the oceans from exploitation after failing to agree on it in March. Eleven million tonnes of plastic - which Thomson called the planet's plague - end up in the ocean each year. That could triple by 2040 unless production and use of throwaway containers are reduced, scientific studies show.
Nearby, on one of the city's beaches, protesters from climate activist group Ocean Rebellion staged a display dressed as mermaids ensnared in plastic and fishing nets.