In the 1967 movie The Graduate, recent college graduate Dustin Hoffman is advised to pursue a career in plastics. As it turns out, this was probably good career advice. As the chart below shows, the production of plastics globally has increased more than 20-fold since then.
But what has made plastic an ideal input to most manufacturing processes - it is lightweight, inexpensive and durable - has also made it an ecological nightmare. Unlike organic matter, plastic does not break down easily and it is estimated that only about 21% of the volume produced to date has been recycled or incinerated. Much of what remains has ended up in the ocean and, more specifically, in one of several gyres or systems of circulating currents around the globe. The largest of these, dubbed the Great Pacific Garbage Patch, is located between California and Hawaii. It is estimated to occupy an area three times the size of France and includes 79 thousand tons of plastic debris. Over 90% of the volume is large objects (discarded fishing equipment such as nets, lines and buoys are common). The density of debris is low throughout much of the area but becomes increasingly elevated as you move toward the center. As a result, although the Patch sounds like a large floating island of plastic, most of it is not visible to the human eye.
The environmental risks associated with this growing volume of waterborne plastics include the direct threat to marine life. The National Oceanographic and Atmospheric Administrations estimates that over 100,000 marine mammals are killed each year by entanglement or ingestion. Damage to birds and fish populations adds to this ecological toll. Less obvious is the indirect threat to humans as a result of consuming contaminated fish and drinking water. While the long-term effects of ingesting plastics remain unclear, research has shown that some additives in plastic behave similarly to human hormones and might do damage in high concentrations.
A wide range of technologies aimed at removing plastic waste have been proposed over the years but most have suffered from either excessive costs or technical failure. The most recent effort by 24-year old entrepreneur Boyen Slat and the Ocean Cleanup Foundation is now being tested off the coast of San Francisco. This $20 million cleanup system (funded by PayPal founder Pete Thiel and Salesforce CEO Marc Benioff) took five years to develop and consists of a floating boom curved into a U-shape (see below). A skirt hanging below the boom collects debris but, because it is impenetrable, does not entangle passing marine life. Once full, a vessel collects the trash for transport, sorting and treatment on land. If successful, Ocean Cleanup estimates that the system could clean up half of the Garbage Patch within the next five years. Full deployment is expected later this month.
Ultimately, reducing the volume of seaborne plastic waste must focus both on preventing plastic from entering the ocean and removing what is already there. While it is still early days, this latest effort represents a promising step in the right direction.