Five great “garbage patches” pollute the world’s oceans. Swirling vortexes of plastics, bottles, ropes, and fishing nets, these heaps of trash are the sad result of what happens when human trash gets stuck in cycling, ring-like systems of currents. The largest of these is the Great Pacific Garbage Patch, which, according to research announced Thursday, is 16 times larger than previous estimates assumed.

Located between Hawaii and California, the Great Pacific Garbage Patch consists of two distinct collections of debris, bound together by the North Pacific Subtropical Gyre. In Scientific Reports, researchers from the Ocean Cleanup Foundation calculated that at least 79 thousand tonnes of plastic are floating inside this area. Three-quarters of the mass is debris larger than 5 centimeters, and 46 percent of it comprises fishing nets. This new analysis of the region, the researchers write, suggests that ocean plastic within this patch “is increasing exponentially and a faster rate than in surrounding waters.”

marine debris, seal
The impacts of marine debris, such as floating nets, are wide ranging.

Previous estimates of the amount of trash within the Great Pacific Garbage Patch were determined by scientists floating out plankton nets behind boats, hoping to capture broken-down microplastics. In the new study, the scientists combined aircraft surveys with the boat-net system, utilizing 18 ships and 652 nets designed to capture both microplastics and larger debris. In this way, they determined the patch contains 1.8 trillion pieces of plastic.

Although microplastics made up 94 percent of the total number of pieces of plastic, they accounted for just 8 percent of the total 70,000-tonne mass. The bulk of the patch is larger trash, things like lids rope, and buoyant plastics larger than two inches. The oldest piece of plastic they found dated to 1977. They estimate that 20 percent of the plastic likely washed into the patch because of the 2011 Japan earthquake and tsunami.

With this knowledge, the Ocean Cleanup Foundation is leading a charge this summer to clean it up. They hope that a full-scale deployment, ultimately costing $370 million, will clean up 50 percent of the Great Pacific Garbage Patch in five years.

Overall, plastics make up approximately 99.9 percent of all debris in the ocean — the leftovers from the 320 million tonnes of plastic consumed annually around the world. Sixty percent of plastic produced is less dense than seawater, meaning it’s practically ready-made to get caught in surface currents and winds, degraded into smaller pieces, and fill the ocean. By understanding the distribution of plastics, the researchers hope to design better solutions to collect it all before the problem becomes even worse.