1. Reads
  2. Deep Dives

All You Need to Know About Ocean Pollution and How to Clean our Oceans

Oct 18, 2019 8:12 AM 6 min read

In 2013, an 18-year-old Dutchman named Boyan Slat conceived a unique way to address the pollution challenge by trying to get rid of the planet’s oceans of plastic. He conceptualised massive U-shaped barricades in the high seas to trap and retrieve marine debris – all done passively via natural ocean currents and without using external energy.


Last year, Slat and his team used the $21.7mn they raised to deploy a 2,000-foot-long cleanup machine named “Wilson” in the Pacific Ocean. Wilson was equipped with a 10-foot barrier underneath and several underwater anchors to hold it in place. It was a project of The Ocean Cleanup, which aimed to clean the Pacific’s garbage patch in five years and deploy similar cleanup devices across the world.


What Was the Result?: Wilson failed. The marine garbage was too fast to be held. Plastic leaked from the structure and returned to the ocean. Finally, last December a 59-foot section of Wilson broke off and it was towed back to land to be repaired.



Trash Talk: The Garbage Seas in Our Oceans


Fighting a Losing Battle?: A mission by humans to clean oceans seems like a gargantuan task because it is exactly that. Besides the sheer size of oceans, there’s the sheer size of the garbage. Between 4.8 and 12.7 million tonnes of plastic enter oceans every year – that’s the equivalent of 2 million elephants. Experts estimate that it would take 67 ships one year to clean up less than 1% of the North Pacific Ocean alone. 


The Problem is Escalating: In the 1960s, 15mn tonnes of plastics were being produced annually. By 2015, this figure was thirty times higher. At present, the amount of plastic invading the seas is the equivalent of five grocery bags full of plastic going into the ocean along every foot of the coastline of every country in the world. By 2025, those five bags will be ten. Overall, the amount of plastic in the oceans itself could triple in the next decade.


Basically, cleaning oceans is like trying to empty an overflowing sink by removing excess water without turning the tap off. Turning the tap off – meaning, stemming the flood of garbage produced every minute around the world – is easier said than done. And if you’re thinking: Aren’t we investing a lot on recycling and reusing waste? Well, only 9% of plastic waste ever created has been recycled. The rest lie forgotten in landfills, forests, rivers and, yes, oceans – the final sink.


Why is Ocean Garbage Dangerous?: This is self-evident. Marine debris is a death knell to marine ecosystems. It destroys habitats, eradicates entire species of marine life, clogs coastlines, imperils navigation, and endangers the lives of ocean-based communities and economies. Already, about 86% of turtle species, 43% of seabirds and 44% of marine mammals have plastics in their glut. And the waste consumed by fishes re-enters the food chain when these organisms are consumed by larger fish, which could be consumed by human beings.


Where in the World is All the Ocean Debris?


They’re all in the oceans, yes. But it’s not like every centimetre of the seas has a plastic bottle drifting morosely across it. Some marine debris is carried by the waves and tides to accumulate on beaches. Some sink to the ocean floor while some are eaten by marine animals.


Garbage Patches: Much of the remaining is concentrated in the world’s five Garbage Patches (GPs). There are five GPs because there are five ocean gyres (one in the Indian Ocean, two in the Atlantic, and two in the Pacific). Gyres are rotating ocean currents: they pull debris together into or around one location, in a way collecting them. Not unlike massive whirlpools that slowly accumulate plastics and other garbage over time.


Of these, the Great Pacific GP in the North Pacific is the largest. The U-shaped garbage trapper that Boyan Slat and his Ocean Cleanup project were working on? It was tackling this GP, which lies mainly between California and Hawaii.


Save Our Seas: Gyres, Garbage Patches and the Plastic Clogging Our Oceans
The five Garbage Patches (GPs) of the world.


The five ocean GPs are not like vast areas of uninterrupted rotting garbage floating slowly. The gyres are mild currents, so the garbage is widely scattered across miles and miles. In fact, you could sail through one of these patches without so much as noticing any major chunks of garbage because they mainly consist of microplastics (explained later). On the surface, you’d see the blue sea under the blue sky; but below you, a giant, soupy plastic graveyard would be proliferating.


What is the Nature of Ocean Debris?


There are many verticals under which marine debris can be classified. When it comes to its source (which is majorly land-based), it can be either point or non-point. The former is when the source of pollution can be traced back to a single, specific source. For example, oil spills from tankers or leaks from factories or plants. Non-point source pollution comprises runoff from multiple, diverse sources like urban markets and sub-urban households.


What Qualifies As Marine Debris?: Virtually anything invasive or non-native to the marine environment. These range from toxic chemicals and medical waste to cigarette stubs and beverage cans. One omnipresent pollutant is the fishing net (and other fishing gear abandoned by fishermen). These nets in particular are deadly, trapping fishes and starving them to death. In the Great Pacific GP, for example, almost half of all tonnage is comprised of fishing gear.


Plastic Soup: Between 60% to 95% of marine pollution consists of plastic. Plastic easily accumulates and lingers because it taken centuries to biodegrade.


When it comes to the GPs, they are almost entirely made up of microplastics (in terms of weight, however, they amount to 8% of total GP tonnage). These are plastics less than 5mm in length and are often the result of larger bits of plastic weathering apart over time. Microplastics are often missed by the naked eye (they are the size of rice grains) and are particular threats to the marine ecosystem because they can be easily ingested by animals, thereby entering the food chain (which could end up on our dinner tables).


Save Our Seas: Gyres, Garbage Patches and the Plastic Clogging Our Oceans


The Way Forward: Action Against Ocean Pollution


The sources of ocean pollution are not scattered across the globe: they are concentrated in certain urban centres. Most polluting countries are in Asia, which is also from where most pollution comes from (China and Indonesia top the list). Scooping all this rubbish, however, is a difficult task to say the least.


Not All is Lost: That doesn’t mean no action can be or is being taken. Considering the aforementioned overflowing sink analogy, to tackle marine debris the problem must be tackled first and foremost at its source – i.e., on land. Increased and improved waste management and policy measures by top polluting governments would go a long way in stemming the garbage tide. Banning single-use plastics, microbeads and microfibres; mandating safe disposal of fishing gear; and funding regular, community-based beach cleanups are some other important solutions.


And A Lot is Being Done: Four of the UN’s Sustainable Development Goals (SDGs) have targets relevant to marine pollution. In 2017, UN Environment launched an international campaign to eliminate major sources of marine litter: microplastics in cosmetics and the excessive, wasteful usage of single-use plastic by 2022. 89 countries are signatories to the London Convention, which prohibits excessive dumping into seas.


Several local and national governments have banned plastics and shut down or relocated industries to clean their waterways (a list can be read here). In Kerala, the state sponsors “fishing for litter” schemes that have hauled in more than 250 tonnes of plastic waste since 2017. In Norway, underwater drones are being used to pinpoint underwater islands of waste so that fjords can be cleaned.


And the Ocean Cleanup project we talked about in the beginning? After it was fixed and tweaked, Wilson is now successfully retaining debris, from fishing nets to microplastics.


So, it’s not all bad news. One can only hope that the international targets to eradicate the sources of pollution are duly met. And that the existing barrages of trash in our seas are removed once and for all so that marine ecosystems can live freely and thrive again.