A mariner who has spent years travelling “hundreds of thousands of nautical miles” to measure the impact of plastic waste in the ocean has estimated that a “raft” of plastic debris spanning more than 965,000 square miles (2.5m sq km) is concentrated in a region of the South Pacific.
Capt Charles Moore has just returned from a sampling expedition around Easter Island and Robinson Crusoe Island.
He was part of the team which discovered the first ocean “garbage patch” in the North Pacific gyre in 1997 and has now turned his attention to the South Pacific.
Although plastic is known to occur in the Southern Hemisphere gyres, very few scientists have visited the region to collect samples.
Oceanographer Dr Erik van Sebille, from Utrecht University, says the work of Capt Moore and his colleagues will help fill “a massive knowledge gap” in our understanding of ocean plastics.
“Any data we can get our hands on is good data at this point,” he told BBC News.
Capt Moore explained that the space occupied by sub-tropical gyres – areas of the ocean surrounded by circulating ocean currents – is approximately the same size as the entire land mass of the Earth, but they are now being “populated by our trash”.
The phenomenon of oceanic garbage patches was originally documented in the North Pacific, but plastic has now been found in the South Pacific, Arctic and Mediterranean.
“It’s hard not to find plastic in the ocean any more,” Dr van Sebille said. “That’s quite shocking”.
Capt Moore is the founder of Algalita Marine Research, a non-profit organisation aiming to combat the “plastic plague” of garbage floating in the world’s oceans.
For more than 30 years, he has transported scientists to the centre of remote debris patches aboard his research ship, Alguita.
Dragging nets behind the vessel, the crew sieves particles of plastic from the ocean, which are then counted and fed into estimates of global microplastic distribution.
Although scientists agree that plastic pollution is a widespread problem, the exact distribution of these rafts of ocean garbage is still unclear.
“If we don’t understand where the plastic is, then we don’t really understand what harm it does and we can’t really work on solving the problem,” said Dr van Sebille.