Satellite observations spanning two decades have revealed a gradual change in the colour of ocean waters surrounding the Great Pacific Garbage Patch with parts of the region becoming brighter in blue and green wavelengths. Scientists believe the increasing concentration of microplastics could be contributing to this unusual shift, although further research is needed to establish a direct connection.
A study conducted by researchers at the University of Bergen found that waters within and around the Great Pacific Garbage Patch became progressively brighter between 2002 and 2022. The findings, published on November 5, 2026, in the journal Communications Earth & Environment suggest that floating plastic particles may be changing how sunlight interacts with seawater.
The research was led by PhD candidate Shea Cheatham, along with Daniel Koestner and Børge Hamre. The team analysed three long term satellite records of ocean colour, including observations collected by NASA’s MODIS instrument aboard the Aqua satellite.
Microplastics Suspected Behind the Cyan Colour Shift
Located within the North Pacific Gyre, approximately halfway between California and Hawaii, the Great Pacific Garbage Patch is a vast accumulation of floating plastic waste gathered by ocean currents. Rather than forming a solid island of rubbish, it consists of scattered debris and microscopic plastic particles spread across a large area.
According to estimates from The Ocean Cleanup, the region contains more than 1.8 trillion pieces of plastic, weighing approximately 110,000 tonnes. Although microplastics account for only around 8 per cent of the total plastic weight, they represent the majority of individual plastic fragments floating near the ocean surface.
Researchers observed that the water became increasingly reflective in blue and green wavelengths over the 20 year study period creating a subtle cyan like appearance.
Scientists believe microplastics could be responsible because these tiny particles absorb relatively little visible light while scattering substantial amounts of sunlight back towards space. This interaction could increase the brightness of ocean water and alter its appearance in satellite images.
Ocean colour can change naturally due to variations in phytoplankton, dissolved organic matter and other particles suspended in seawater.
Phytoplankton absorb blue and red sunlight while reflecting green light whereas dissolved organic matter absorbs blue wavelengths, often making seawater appear darker.
To determine whether these natural factors could explain the observed changes, the researchers conducted 1,000 computer simulations. In 500 simulations involving only phytoplankton and natural particles, just 3 per cent reproduced the cyan colour shift. However, when microplastics were included in the remaining simulations 13 per cent produced results consistent with satellite observations.
The findings indicate that plastic pollution could be contributing to the colour change, although natural changes in marine ecosystems may also play a role.
Despite the findings, researchers cautioned that satellite observations cannot directly identify microplastic particles in the ocean. The study establishes a statistical relationship between changing ocean brightness and possible plastic accumulation but does not prove that plastic waste is the primary cause.
Other factors, including satellite sensor deterioration, atmospheric correction errors and changes in plankton populations, could influence the observations.
Marine researcher Andrés Cózar Cabañas of the University of Cádiz also stressed that the findings demonstrate correlation rather than confirmed cause and effect.
The University of Bergen team has not yet verified its optical models using seawater samples collected directly from the garbage patch. Researchers plan to conduct physical measurements during an upcoming expedition to determine whether actual microplastic concentrations correspond with the satellite observations.
Satellite Monitoring Could Transform Ocean Pollution Research
If further investigations confirm the connection, existing environmental and weather satellites could become valuable tools for monitoring microplastic pollution across remote ocean regions.
Currently, researchers largely depend on expensive and time consuming ship based surveys, which involve collecting seawater samples using specialised nets. Satellite based monitoring could provide a broader understanding of where plastic pollution accumulates and how it changes over time.
However, University of Barcelona researcher Anna Sànchez-Vidal cautioned that satellite observations are not yet reliable enough to serve as a routine monitoring system for marine plastic pollution.
Researchers also emphasised that removing microscopic plastic fragments from vast stretches of open ocean remains extremely difficult. Preventing plastic waste from entering rivers and oceans in the first place remains the most practical long term solution.
The study highlights how satellite technology could help scientists better understand the growing environmental impact of plastic pollution while reinforcing the urgent need to reduce plastic waste at its source.