Ocean pollution is a major problem – satellite images now show the meter-long plastic clouds in the Mediterranean. They can also be found in popular holiday regions, where bathers are in danger of swimming in rubbish.

Plastic bottles, nets, bags, masks: there are already huge amounts of garbage in our oceans, sometimes forming entire carpets of garbage. Using satellite images, researchers were now able to a comprehensive map of plastic accumulations in the Mediterranean The study by the European Space Agency (ESA) was published in the journal Nature Communications.

The research team discovered 14,374 so-called “litter windrows” in the Mediterranean. Some of them were up to 23 kilometers long. According to the study, the garbage covered a total of 94.5 square kilometers. That’s almost the size of Paris.

Particularly large amounts of garbage in front of Italian coastal towns

On a satellite image that the scientists created as part of their research, the red markings clearly show which coasts have the most garbage deposited. Large accumulations were discovered in Italy, Albania, Morocco and Tunisia, but also in France, Greece and Spain.

The graphic shows that the following popular holiday regions are particularly affected:

• In Italy Meter-long swathes of plastic float mainly between Venice and Trieste, in the region around Naples, off Calabria and also between Pisa and Genoa.
• In France Monaco is particularly affected.
• In Spain Apparently there is a lot of garbage floating between Barcelona and Valencia.
• Other regions such as Tetuan in Morocco and Sfax in Tunisia are marked in deep red on the map.

The study also explains how the garbage plumes come about. “During heavy rainstorms, the garbage ends up in the Mediterranean,” explains Andrés Cózar from the University of Cadiz co-leader of the project in the ESA press release. The respective currents are responsible for the distribution of the garbage on the coasts. However, the researchers also documented that a large part of the garbage remains near the regions through which it entered the sea.

This is how the researchers went about identifying the garbage

As part of the study, the researchers tested new methods to detect plastic waste in the ocean. To do this, the team analyzed a Period of six years a total of 300,000 satellite images. These documented the state of the Mediterranean every three days, from July 2015 to September 2021. The team used state-of-the-art computers and algorithms to evaluate the data.

The study was funded by ESA and the Spanish Ministry of Science and Innovation. The research team included scientists from space companies and research institutes in six countries.

According to co-director Manuel Arias of the Spanish Institute of Marine Sciences, the tool used could also be used in other regions of the world: “I am convinced that it will teach us a lot about the phenomenon of littering, for example by identifying the sources and routes into the sea.”

Development of an improved tool would also be useful for other areas

However, there are still problems with the accuracy of the data, explains Andrés Cózar. Garbage plumes of less than ten meters in size are not currently detected by the satellite sensors. Therefore, a sensor would have to be developed that can specifically identify floating objects of one meter in size. This would also be useful for monitoring oil spills, the loss of cargo or even for search and rescue operations at sea useful, says the ESA statement.

Sources used: Study published in Nature Communications, ESA press release