The Bangkok Declaration on Combating Marine Debris in ASEAN Region was adopted by leaders of the 10-member Association of Southeast Asian Nations, which includes four of the world’s top polluters. ASEAN members Indonesia, the Philippines, Vietnam and Thailand, along with worst offender China, throw the most plastic waste into oceans, according to a 2015 report co-authored by environmental campaigner Ocean Conservancy. The declaration was commended by environmentalists as a good first step for the region, though doubts remained that implementation will be a challenge because the group has a code of non-interference that would leave necessary policymaking in the hands of individual member countries. Neither the declaration nor its accompanying Framework of Action specifically mention bans on single-use plastic or imports of foreign waste, as environmental groups previously demanded ahead of the summit. The declaration came ahead of this week's G20 summit in Japan, which assembles 20 major economies and will also aim to tackle marine plastic pollution. On this edition of the big picture we will analyse how to tackle ocean pollution.