Oceans, caught between devil and the deep blue sea… (Pun intended!) – XX

Plastic Garbage in the oceans…

The oceans are so vast and deep that until relatively recently, we assumed that no matter how much trash and chemicals humans dumped into them, the effects would be negligible. Proponents of dumping in the oceans even had a catchphrase: “The solution to pollution is dilution.”

However, this “dilution” policy has pushed the planet, once a flourishing ocean / earth ecosystem, on the brink of collapse.  As mentioned in the last article, world-over one truckload of plastics garbage goes into oceans, every thirty seconds, because we believe in “dilution” policy!  By the time you will finish reading this article 150 more tonnes or 15 more truckloads of plastics would have gone in oceans somewhere on this planet. 

So, let us start with a question, how much plastic does the world produce? In the chart below we see the evolution of annual global plastic production, measured in tonnes per year, shown from 1950 to 2015.  Around 1950 the world produced only 2 million tonnes plastic per year. Since then, annual production has increased by nearly 200 fold, reaching 381 million tonnes in 2015. For context, this is roughly equivalent to the 75% of the mass of the world population! Below graph shows ever successful growth of plastic production year on year! The short downturn in annual production in 2009 and 2010 was predominantly the result of the 2008 global financial crisis


So what is the fate of this humungous plastic produced globally?  Look below figure.  It summarises that:

  • Cumulative production of polymers, synthetic fibers and additives was 8300 million tonnes (83000,00,00,0000 KGs);
  • 2500 million tonnes (30 percent) of primary plastics was still in use in 2015;
  • 4600 million tonnes (55 percent) went straight to landfill or was discarded, which means majority out of it reached oceans)
  • 700 million tonnes (8 percent) was incinerated;
  • 500 million tonnes (6 percent) was recycled (100 million tonnes of recycled plastic was still in use; 100 million tonnes was later incinerated, and 300 million tonnes was later discarded or sent to landfill).


As production graph of plastics is sky-rocketing year on year, proportionately plastic waste is increasing too year on year.  With the largest population, China produced the most substantial quantity of plastic waste, at nearly 60 million tonnes. The United States followed  China with 38 million, Germany at 14.5 million and Brazil at 12 million tonnes.

The biggest concern about plastic waste problem is concern about mismanaged and inadequately managed waste.  Mismanaged waste is material which is at high risk of entering the ocean via wind or tidal transport, or carried to coastlines from inland waterways. Mismanaged waste is the sum of material which is either littered or inadequately disposed.

In the world map below we see estimates on the share of plastic waste that is defined as inadequately managed and therefore at risk of entering the oceans. We see vast differences in the effectiveness of waste management across the world:

  • High-income countries, including most of Europe, North America, Australia, New Zealand, Japan, and South Korea have very effective waste management infrastructure and systems; this means they store discarded plastic waste in secure, closed landfills. Across such countries, almost no plastic waste is considered inadequately managed. Note this does not mean there is no plastic at risk of entering the natural environment — see the section on littering below.
  • Across many low-to-middle-income income countries, inadequately disposed waste can be high; across many countries in South Asia (especially India) and Sub-Saharan Africa, between 80-90 percent of plastic waste is inadequately disposed of, and therefore at risk of polluting rivers and oceans. Such inadequate disposal is strongly reflected in the global distribution of mismanaged waste and inputs from river systems.


Majority of mismanaged or inadequately managed plastics end up in oceans.  However, tracking ocean plastic inputs and distribution in the ocean is notoriously tricky.  There is a large discrepancy between the annual inputs of plastics to the ocean and estimates of surface plastic accumulation. Annual estimate of ocean plastic input is in the order of up to 10 million tonnes; whereas total surface plastic accumulations are in the order of 10s to 100s of thousand tonnes. 

Plastic in our oceans can arise from both land-based and marine sources. Plastics pollution from marine sources refers to the pollution caused by fishing fleets that leave behind fishing nets, lines, ropes, and sometimes abandoned vessels.  Marine sources also include pollution induced by the shipping industry.  There is often intense debate about the relative importance of marine and land sources for ocean pollution. What is the relative contribution of each?  Various estimates suggest that, globally,  approximately 80 percent of ocean plastics come from land-based sources and the remaining 20 percent from marine sources.

The main question is, what are the consequences and how do they affect humanity?  Let us read that in the next article.


  1. Bottles, bags, ropes, and toothbrushes: By Daniel Cressey
  2. Our world in data
  3. National Geogrphic

Milind Joshi


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