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Climate History: The Great Pacific Garbage Patch Mega Expedition

Sara Giretto

August marks the historic month that the non-profit organization, The Ocean Cleanup, began their Mega Expedition to study the Great Pacific Garbage Patch. This expedition was the largest ocean research expedition ever, spanning over three months and mapping an area of 3.5 million square kilometers between Hawaii and California. The topic of interest for the expedition, the Great Pacific Garbage Patch, is a collection of marine debris located in the North Pacific Ocean. The main content of these marine debris is various plastics, which is problematic due to their inability to break down and negative impact on aquatic ecosystems. The garbage patch presents an interesting dilemma due to its extensive size and challenges in effectively cleaning up the debris. Thus, in order to begin addressing this issue, more research needed to be conducted to better understand it.

The expedition included 30 sea vessels with 652 surface nets engaging in multiple different methods of measurement to accurately analyze the extent of this garbage pollution. The first method used was called Manta Trawl, which involved compact surface trawls being dragged behind each vessel in order to collect microplastics. Similarly, Mega Trawl was conducted by the fleet’s mothership, “Ocean Starr”, which collected plastic debris of all sizes. Finally, the custom-made application “The Ocean Cleanup Survey App” was used to help crews count and identify debris, and was also released for the public to report plastic pollution they encounter to a global database. Based on these measurements, the amount of waste in this patch is estimated to be roughly three times the size of France, which is 16 times more waste than originally estimated. Three quarters of the total mass of debris was determined to be macro and mega plastics, however, 94% of the total object count is made up of microplastics. Through further analysis and research, it was determined that 75% to 86% of the plastic debris comes from fishing activities. This includes fishing lines, ropes, and nets, which comes primarily from five countries: Japan, China, South Korea, the USA, and Taiwan.

This magnitude of waste has extensive impacts not only on surface feeding aquatic life and migratory species, but also on human beings. Microplastics in particular bioaccumulate in food chains, meaning its ingestion by aquatic creatures works its way up the food chain and ultimately ends up being consumed by humans. This exposes us to harmful toxicants which is problematic for our health. Furthermore, this level of waste is harmful to the economy, as it is estimated that marine plastic costs the economy around $6-19 billion USD yearly. Plastic in the ocean is incredibly hard to clean up due to its location as well as how it continues to break down into smaller plastics over time. This makes it a pressing issue to address sooner rather than later, so the patch does not grow larger while its individual components break down smaller.

What has happened since the Mega Expedition in 2015? To further build off of everything discovered in 2015, an Aerial Expedition took place in 2016 that quantified the extent of the debris from above. This allowed for a larger area to be studied at a time and was the first-ever aerial survey of an ocean garbage patch. After this significant amount research, cleanup efforts were able to begin. In 2018 System 001, the world’s first cleanup system to be trialed in the Great Pacific Garbage Patch, began its campaign. Unfortunately, the system named “Wilson” had to return to shore after various issues led to it not effectively retaining plastic. However, System 002 followed in 2021, named “Jenny”, and was more successful in its campaign. It successfully proved that a scalable cleanup method can remove trash from ocean garbage patches and encouraged The Ocean Cleanup to work on more systems to improve the process further. As we await system 003 and other developments in the cleaning up of the Great Pacific Garbage Patch, we can appreciate the extensive knowledge we gained from the Mega Expedition that gave this cleanup effort momentum.


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  4. Imster, Eleanor and Byrd, Deborah, “Great Pacific Garbage Patch Now 3 Times Size of France.” EarthSky, 3/27/2018,

  5. Lebreton, Laurent et. al, “Industrialised Fishing Nations Largely Contribute to Floating Plastic Pollution in the North Pacific Subtropical Gyre.”Scientific Reports, 9/1/2022,

  6. “The Great Pacific Garbage Patch.” The Ocean Cleanup,

  7. “Aerial Expedition.” The Ocean Cleanup, 2016,

  8. “System 001 - First Ocean Cleanup System.” The Ocean Cleanup, 2018,

  9. “System 002.” The Ocean Cleanup, 2022,

  10. Picture Source:


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