Since the 1950s, the production and use of plastics in the world has been increasing and so is the accumulation of plastic waste in oceans. The main reasons for this increase are: Design flexibility -- plastics can be modified for a wide variety of end-uses; high resistance to corrosion; low weight; shatter resistance; water resistance; and air impermeability.

The same qualities that make plastics useful also make them hazardous to marine wildlife. After plastic reaches oceans from land-based sources and is exposed to the elements, plastic photo-degrades (it breaks up into smaller pieces when exposed to sunlight). These smaller pieces persist in the marine environment but never degrade. Many species of wildlife are known to ingest plastic, mistaking it for food. They can also become entangled in it. These species mostly include birds, turtles and other marine wildlife. Even zooplankton and marine invertebrates are known to ingest small plastic fragments.

In an open ocean, currents and wind combine to form massive, swirling vortexes called gyres. The North Pacific Subtropical Gyre is one of five major gyres on earth and stretches between the coasts of Japan and California. In this area, a combination of high atmospheric pressure and the earth's rotation slows ocean currents and moves them in a clockwise spiral. Historically, the Northern Pacific Gyre (NPG) has created a rich concentration of plankton and other organisms.

Recently, however, the gyre has become home to plastic waste drawn from all over the world, particularly from Pacific rim countries. The result is two enormous masses of plastic trash. One, dubbed the western garbage patch, is located west of Hawaii and east of Japan. The second is the eastern garbage patch, near the northwestern Hawaiian Islands. Together, these masses are known as the Great Pacific garbage patch (the Patch).

Ocean currents carry plastic trash to the patch from all over the world, and debris that ends up in territories of the US may have originated thousands of miles away.

A curious question to ask is how much of world plastic reaches oceans and how much gets to the patch? Different sources inform us that since its production in the 1950s, plastic production has increased from 5 million tonnes (mt) per year in 1955 to close to 225 mt per year in 2009.

Adding all this plastic over the past 60 years and assuming that very little of it would actually biodegrade, yields about 5050 mt of plastic produced in the world since its discovery and widespread use. As per Greenpeace, of the 5,050 mt of plastic, 505 mt (10 per cent) ends up in oceans. Further, of the 505 mt, 152 mt (30 per cent) floats on or just below the surface, and 353 mt (the remaining 70 per cent) sinks to the bottom of ocean floor.

How about plastic accumulating in the patch? The size of the patch is difficult to determine because it is expanding.

According to different sources, the size of the eastern patch is around twice the size of Texas; combined, the eastern and western garbage patches are double the size of the US or 18 million sq km. On the other side, the size of all the oceans is about 335 million sq km (70 per cent of the surface area of earth). Thus, if areas of the patch and the oceans scale the mass of plastic that floats as well as sinks in the oceans, one get 8 mt of floating plastic and 19 mt of sunk plastic in the patch alone. Even if for one moment one considers that these estimates based upon area scaling are at best conservative, and there might be more plastic in the patch considering the geographical factors, the amount of plastic in the patch and world oceans is extremely large.

As per derived estimates, this great increase in the number of plastic fragments in the patch affects at least 267 species worldwide, including 86 per cent of sea turtle species, 44 per cent of seabird species, and 43 per cent of marine mammal species. In the patch, it was reported that nearly half of the albatross chicks hatched every year die.

A study by the Environmental Protection Agency found that the chicks that died from starvation or dehydration had twice as much plastic in their stomachs compared with those that died for other reasons.

Considering the scale of the problem, what can we do about it? The amount of plastic in the world oceans, including the patch, is enormous to be cleaned up by the budget of a single country. Also, the problem is largely unaddressed by the law. Thus, there is an urgent need to formulate a new international treaty that involves different nations in a cleanup of plastic in the world oceans. This treaty should consider the plastic issue as a global problem where resources of different developed and developing nations could be pooled together.

But without plugging the source of plastic from the land to the oceans each year, the ocean plastic cleanup might be less than a partial solution to the whole problem.

Thus, in addition to cleaning up the plastic that already exists in oceans, there is an urgent need to give impetus to land-based cleanup methods such as recycling as well as development of standards that promote better handling and transport of nurdles from place of manufacture to place of use.

In addition, there is a need for individuals to inculcate better habits of disposing plastic waste in efficient ways.

The writer is a doctoral scholar at Carnegie Mellon University, Pittsburgh and knowledge editor of Financial Chronicle