Is it true that there's a solid island of plastic in the ocean, visible from space?
This claim is certainly false. The claim of “plastic islands” in the ocean which are the size of countries or even continents is false. There’s no doubt that plastic pollutes the oceans, just as it does rivers, lakes, the soil and the air. However, plastic on the ocean surface is not concentrated enough to form big islands. We can better compare it to a “plastic smog”. This “smog” does contain larger items, but a lot of the pollution is made up of trillions of tiny micro- and nanoplastics, and spread out over large distances. Plastic accumulation zones on the sea surface are also not easily visible from space. Advanced satellite data and machine learning can help scientists identify areas of elevated plastic pollution.
If you were to see a picture of the “Great Pacific Garbage Patch”, the most famous plastic accumulation zone in the ocean, you might not actually notice it was there. The “Patch” is not a solid island that you can stand on. Images from the area show the sea - a vast grey-blue surface stretching to the horizon. This reality is in stark contrast with images used by some media outlets. Picture editors often select images of waters that are so highly polluted they are almost completely covered with trash. While local pollution like that does occur, most of these images weren’t taken in the open ocean and they don’t represent the reality of the plastic that accumulates there.
Plastic pollution is not directly visible on satellite images but in recent years, progress has been made in detecting plastics from space. This is a field of active research and re-evaluation of these findings is ongoing within the community.
Scientists from Plymouth Marine Laboratory in the UK and the University of the Aegean in Greece were able to detect smaller floating plastic patches in optical data collected by the European Space Agency (ESA) Sentinel-2 satellites. Using machine learning techniques on floating materials detected in coastal waters, they were able to distinguish suspected plastics from natural materials, such as seaweed and driftwood, with high accuracy. Other scientists from Plymouth Marine Laboratory also found that microplastics correlated with suspended particulate matter in one estuary.
Researchers from the University of Michigan in the United States developed an indirect way to detect areas with elevated plastic pollution through satellite technology, by evaluating the decrease of roughness of the ocean surface through plastics, which dampen the waves. A team of Australian and Dutch researchers found a way to detect plastics on beaches with the help of satellites by looking at the infrared light emitted by them. Some scientists are now calling for a marine plastic litter satellite mission to monitor plastic pollution more effectively.
Currently, the quantity of microplastics on the ocean surface is increasing exponentially and effective monitoring will be needed to understand whether the trend can be reversed. According to a study that analyzed a global dataset of ocean plastic pollution from 1979 to 2019, ocean plastics have increased rapidly and at an unprecedented scale since the year 2005.
It is important to remember that ocean garbage patches are evolving phenomena. They don’t remain unchanged but are influenced by ocean and weather conditions and the physics of waves and currents. They vary across seasons and the year. These are just some of the reasons that make it so challenging to “clean up” ocean plastic.
Sullivan et al., 2023, In situ correlation between microplastic and suspended particulate matter concentrations in river-estuary systems support proxies for satellite-derived estimates of microplastic flux, Marine Pollution Bulletin
Thanks toMarcus Eriksen of The 5 Gyres Institute,Clark Richards of the Bedford Institute of Oceanography, as well as Lauren Biermann and Victor Martinez Vicente of Plymouth Marine Laboratory for scientific fact-checking.
Updated on: November 3, 2023