We have all seen the photos: birds nesting in piles of garbage along the shore, fish fatally caught in discarded netting, and huge mosaics of debris floating in the ocean. Even more alarmingly, what we see in these poignant images is only a portion of the problem. Approximately half of all plastic pollution is submerged below the ocean surface, much of it in the form of microplastics so small that we may never be able to clean them up completely.

To cut through the enormity of the ocean pollution crisis, one approach is to focus on something recognizable within these images of debris. Identify something you personally have used that may have ended up in the ocean—a water bottle perhaps. Find one in an image and ask yourself, how did it get there?

Plastic is a human-made, synthetic material that was first discovered more than one hundred years ago but did not broadly enter the public sphere until the 1950s. While currently a major culprit in ocean pollution, plastics are not inherently bad for humans or the environment. In fact, in a United Nations (UN) report on combatting the negative effects of plastics, the head of the UN Environment Programme Erik Solheim made a point to acknowledge that plastic is in fact a “miracle material.”

“Thanks to plastics, countless lives have been saved in the health sector, the growth of clean energy from wind turbines and solar panels has been greatly facilitated, and safe food storage has been revolutionized,” Solheim wrote in his introduction. Yet plastic bottles are one of the most common items within marine debris. So how did such a promising material become a symbol of human environmental desecration?

Plastic bottles are a single-use plastic, a product designed to be used only once and then discarded. Single-use plastics also include plastic packaging, for example of meats and fresh produce, which accounts for almost half of all plastic pollution. This type of plastic product is distinct from multi-use plastics, which can also pollute the ocean, but tend to amass less frequently due to their multi-use nature.

For example, refillable bottles can store water in a way that does not produce the repeated waste of a single-use plastic water bottle. Refillable bottles can be made of many materials, including plastic, but last much longer than a single-use bottle and can be recycled when they become old or damaged. For both types of bottles, how they are discarded determines their ultimate resting place and whether they become pollutants of the ocean.

A single-use plastic water bottle was manufactured, filled with water, and likely transported to a store, where it sat on a shelf waiting for a thirsty purchaser. Many of us drink out of plastic bottles several times during an average day, week, or month. Once we are finished with it, we have a choice where we leave that bottle:

• Recycling bin: Bottles destined for recycling are unlikely to end up in the ocean, in their current form, unless they are mismanaged or lost in transit to a processing facility. However, due to recent limitations in how recyclables are internationally transferred and accepted for processing, many of these bottles will unfortunately end up in landfills rather than recycling facilities.
• Trash can: These bottles also will not likely end up, in their current form, in the ocean. However, in areas across the globe with poor waste management or a lack of properly sealed landfills, as a bottle breaks down into microplastic particles over time, some particles may seep into the soil and eventually make their way into our waterways, ultimately entering and polluting the ocean.
• Litter: These bottles may very well be carried by wind, storm water, or other processes to sewers, rivers, lakes, and other waterways that may ultimately deposit the bottle in the ocean.

Multi-use plastic bottles face these same pathways at end of their life—but of course this happens much less frequently since they can be used many times.

National Geographic Explorer Heather J. Koldewey works to empower communities around the world to participate in solving the ocean pollution crisis from single-use plastics via incremental individual actions—including a campaign called One Less, which encourages people to stop using single-use plastic water bottles altogether. One Less is currently based in and focused on London, England and its inhabitants, but anyone can make the choice to use one less single-use bottle.

Once in the ocean, a single- or multi-use bottle moves with the wind and ocean currents as it faces the elements. Plastics can take hundreds of years to break down into microplastic, which gives them plenty of time to sail the seas. After a certain amount of time, much of the debris from the coast will have met an oceanic gyre—a large system of rotating currents. The Pacific Garbage Patch, a widely known icon of ocean pollution, is within one of these gyres.

National Geographic Explorer Jenna Romness Jambeck has described the movement of plastics into such ocean gyres. Her work has influenced testimony to U.S. Congress and inspired discussion in the UN regarding policies that may help mitigate the marine debris crisis. She also co-developed an app to encourage public participation in identifying and cleaning up marine debris, including plastics, enabling citizen-science solutions at the grassroots level.

Specifically, Jambeck published research findings in the journal Science that provide details about the amount of plastic that makes its way into the ocean. Jambeck noted in this publication that the quality of waste management within a country substantially influences its contribution to marine pollution. As an immediate action to combat marine pollution, Jambeck and her colleagues suggest that industrialized countries address the growing use of single-use plastics. According to a 2018 UN report, sixty countries have passed such regulations to curb the use of plastic bags and polystyrene foam (commonly called Styrofoam) products.

Hopefully, future government and community solutions to ocean pollution will move toward an end to the crisis. In the meantime, individuals can get involved in citizen-science initiatives like Jambeck’s Marine Debris Tracker app and make smart choices about how to use and dispose of plastics, particularly the single-use items that dominate marine debris.