Part 1: HOW WE FILLED THE OCEANS WITH PLASTIC IN JUST OVER 60 YEARS
“Man-made items of debris are now found in marine habitats throughout the world, from the poles to the equator, from shorelines and estuaries to remote areas of the high seas, and from the sea surface to the ocean floor.”
Impacts of Marine Debris on Biodiversity, UNEP Report, 2012
Seabirds lead a precarious existence. Their marine habitats worldwide are littered with so much plastic trash that they often mistake plastic for food. As a result, scientists recently estimated that 90% of all individual seabirds have ingested plastic debris by now, compared to only 5% in 1960.
This finding is alarming but not surprising. An approximate 8 million tons of plastic garbage end up polluting the oceans each year and concentrations can reach up to 580,000 plastic pieces per sq km. 80% of these plastics originate from land-based sources (e.g. inadequate waste management systems, industrial activities, tourism-related litter) and 20% from ocean-based sources. (e.g. fishing gear, cargo vessel mishaps, recreational boaters, offshore oil and gas platforms).
Since this trend is not expected to stop, it is likely that “plastic will be found in the digestive tracts of 99% of all seabird species by 2050 and that 95% of the individuals within these species will have ingested plastic by the same year”.
Seabirds are not alone to suffer; the impact of plastic pollution is global and affects many marine ecosystems and wildlife.
A COSTLY DAMAGE TO MARINE ECOSYSTEMS AND BIODIVERSITY
More than 660 avian and non-avian wildlife species, including all sea turtle species, have been reported to regularly suffer damage or die from encounters with plastics. Of those, 15% are listed as vulnerable, endangered or critically endangered by the IUCN Red List. Plastic pollution is progressively degrading marine ecosystems worldwide through its direct impact on biodiversity, a process that costs an estimated $13 billions each year.
Plastic harms and kills seabirds and other marine wildlife primarily through ingestion and entanglement.
According to the 2012 UNEP report on the impacts of marine debris on biodiversity, ingestion of plastic debris “[compromises] the ability to capture and digest food, sense hunger, escape from predators, and reproduce as well as [decreases] body condition and [compromises] locomotion, including migration”. Microplastics, i.e. fragments smaller than 5mm and often invisible to the naked eye, are particularly problematic because they can be ingested by a larger variety of organisms, including the fish and other seafood we eat. Entanglement, especially by abandoned, discarded and lost fishing gear that keep ghost fishing for a long time, drowns, chokes, cuts, and starves the animals who get trapped in them.
Plastic also harms marine wildlife through more insidious ways we are only beginning to understand.
Chemicals commonly found in plastics like bisphenol A (BPA), phtalates and antimicrobials, known to have deleterious effects on human health, have been found at toxic levels in the oceans. No field studies are yet available, but lab experiments on animals have shown that such harmful chemical concentrations can affect reproduction, impair development, cause genetic aberrations and damage tissues and organs. Moreover, plastic debris, especially microplastics, soak up pollutants already present in the oceans from other anthropogenic waste sources (illegal dumping and run-offs from land-based activities) thereby introducing them to the food chain. And small marine organisms can hitch-hike on floating plastic debris and thus be transported and dispersed to new areas where they may become invasive.
A PERVASIVE, AGGRAVATING FORM OF POLLUTION
Awareness of marine plastic pollution goes back more than half a century, at the time when the modern plastic industry really started taking off.
The first accounts of plastic in marine environments came from carcasses of seabirds collected from shorelines in the early 1960’s. In the 1970’s, studies revealed that floating plastic debris were widespread on the oceans’ surface, especially in the Pacific Ocean, and the first cases of wildlife entanglement by fishing nets were reported in New Zealand, Alaska and Southern Africa.
From the early 1980’s, the presence of plastic debris in the oceans began to be recognized as a national and international pollution hazard. The first and second international conferences specifically dedicated to marine debris were held in Honolulu in 1984 and 1989. Both made recommendations to address the problem, but neither these meetings nor the ones that followed prevented marine plastic pollution from exacerbating and becoming a global phenomenon.
As plastic production grew exponentially from 5 million tons in the 1960’s to nearly 300 million annual tons in the present decade, increasingly more plastic waste found its way to the oceans. This trend isn’t slowing down, on the contrary: by 2050, global plastic production is expected to reach 400 million annual tons.
According to the 2015 Worldwatch Institute report titled Global Plastic Production Rises, Recycling Lags, “With a market driven by consumerism and convenience, along with the comparatively low price of plastic materials, demand for plastic is growing”, especially in developing countries like China where middle-classes are expanding. Much of the plastic retained at sea is indeed post-consumer plastic waste, i.e. plastic waste derived from consumed or used consumer products (household goods, clothes, food packaging, automotive parts, etc.). A considerable portion of it consists of plastic bottles and plastic packaging, the fastest growing form of packaging, which currently represents one third of total packaging sales.
Since plastics are durable they can remain almost endlessly in the oceans and travel thousands of miles. Part of the trash is washed ashore while the rest accumulates in all five oceanic gyres (see map for definition), most severely in the Great Pacific and North Atlantic Garbage Patches. There, debris is broken down into smaller pieces by bacteria and UV radiation. Depending on their density, they may either keep floating at the surface or sink to the seafloor.
It is dismaying and truly concerning that such a recent form of pollution, unleashed just over 60 years ago—not even a human lifetime—could reach this kind of magnitude. This wholly man-made problem has been aggravating because countries have yet failed to design effective sustainable systems for the production, use and recovery of plastics.