More than five years ago some environmental groups started publishing articles about the “Great Pacific Garbage Patch”, supposedly floating islands of mostly plastic waste caught up in the North Pacific Gyre, an area of ocean where the water tends to move in a circular manner. In some reports this floating island was so large that it was ‘visible from space’. It was not too long before scientific observers visited the area and found that there was no such thing as the Great Pacific Garbage Patch. Reports switched to tens of thousands of tonnes of plastic reportedly floating just below the surface of the ocean. Then it was plastic microparticles. Now a team of scientists who have properly studied the problem and published their results in a peer-reviewed journal have found that the problem is not quite as described by the early reports. In short, while there is a problem, the problem is quite a bit less severe than early reports have suggested, possibly sufficiently less that there is time for industry and society to deal with it before it reaches alarming proportions.
The research, published in the peer-reviewed Proceedings of the National Academy of Sciences by an international team led by Dr. Andrés Cózar of the Faculty of Ocean and Environmental Sciences of the University of the University of Cádiz, Spain, found that the global load of plastic on the open ocean surface is probably of the order of tens of thousands of tons, far less than expected from earlier unscientific reports.
Key findings of the research include:
- there has been no significant increasing trend of surface plastic concentration in fixed ocean regions since the 1980s, despite an increase in production and disposal.
- this suggests that surface waters are not the final destination for buoyant plastic debris in the ocean and that removal processes also play a part.
- the plastic load in the North Pacific Ocean could be related to the high human population on the eastern coast of the Asian continent, the most densely populated coast in the world.
- continental plastic litter enters the ocean largely through storm-water runoff, flowing into watercourses or directly discharged into coastal waters.
- a conservative first-order estimate of the floating plastic released into the open ocean from the 1970s (106 tons) is 100-fold larger than the estimate by these scientists of the current load of plastic stored in the ocean.
- examination of the size distribution of plastic debris on the ocean surface shows a peak in abundance of fragments around 2 mm and a pronounced gap below 1 mm.
- the gap in the plastic size distribution below 1 mm could indicate a fast breaking down of the plastic fragments from millimeter scale to micrometer scale. Recent scanning electron micrographs of the surface of microplastic particles showed indications that oceanic bacterial populations may be contributing to their degradation.
The data do not suggest that the problem does not exist. But they do suggest that the level of plastic in the oceans has not yet reached catastrophic proportions and that there may still be time enough to ensure that plastic waste does not kill all ocean life. Hopefully industry and society will use this less bad news to address the problem enough to ensure that the catastrophe that some have been predicting does not occur.
The article, and an abstract, can be found at http://www.pnas.org/content/early/2014/06/25/1314705111.abstract?sid=bc6d04ed-21f9-4907-9a32-6715abe5ced4