For thousands of years, writers have come up with increasingly creative ways to describe the “windark sea.” However, new research suggests that modern poets may face slightly different palettes.
A study published Thursday in the Science Journal found that the oceans change as they warm.
By analyzing satellite data from 2003 to 2022, researchers at Duke University and Georgia Tech noticed that water near the equator turned blue and areas near the pole were turning greener.
Lead author Haipeng Zhou calls it “this green green or blue blue phenomenon.” The perpetrator says he is a tiny, tiny, plant-like creature that forms phytoplankton, a component of the marine food network.
Phytoplankton is filled with a green pigment called chlorophyll, which can absorb energy from sunlight through photosynthesis. When the water near the equator warms, the water appears blurry as it is too kind to microscopic creatures.
At the poles, cold water is much more nutritious, so there is much more for more phytoplankton to turn around, and there is a rich green hue in the water.
It’s not a new phenomenon. Known as a stunning turquoise sea land, the Arctic seas contrast to the flow of ivory ice around it.
However, Zhou began his research at Duke University and completed it as a postdoctoral researcher at Georgia Tech, and discovered that the phenomenon has become stronger as the ocean warms.
Their research only looked at the open ocean, not the coastal ocean. Near the coast there are many complex factors that make it difficult to clearly point out phytoplankton as the main source of color changes, such as water-floating dirt, sand, wind, pollution, and even sea grass.
To understand phytoplankton concentrations, the research team relied on a national marine and atmospheric management database consisting of samples scooped from various research cruises around the world. This database and satellite imagery helped to show the color changes in different regions of the ocean.
Changes in levels of phytoplankton can be bad news for tropical fish and communities that rely on those fish. But it could also be a boon for their northern and southern cousins.
“We all know that phytoplankton is at the bottom of the food chain. The effects on phytoplankton will affect its predators,” Zhou said.
Phytoplankton requires the sun and nutrients to thrive, but as the ocean warms, the individual layers that make up the ocean become more layered, making it difficult for phytoplankton to float up and down the water column and access the same light and nutrients.
Therefore, scientists can clearly say that warm water leads to less phytoplankton, and know that climate change is one of the main reasons why oceans are getting hot, but it is not clear whether climate change is the reason for color change.
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“We need a long record of 30 or 40 years, whether it is linked to climate change or global fluctuations,” Zhou said.
This study only saw data for about 20 years. Zhou said it was enough to confidently say something has changed, but not long enough to know what caused the change. Other factors could affect water temperatures, such as changes in trade winds over the Atlantic that led to the marine heat wave killing corals in 2023.
“The research period was too short to rule out the effects of recurring climate phenomena like El Niño,” wrote Susan Rosier, dean of the University of Science at Georgia Tech.
But Zhou may very well discover that in so many more, this trend of colour change will continue into the future as the climate change that humans have suffered continues to heat up the oceans.
“The temperature of the water is rising. There is no evidence that this progress will slow down, but there is a very high chance that there will be warm water in the future, meaning it can have a continuous impact on marine ecosystems.”
The story was originally published by the Miami Herald and was shared in collaboration with the Martin Room Initiative, founded by the Florida Creemate Report Network, the Miami Herald, the South Florida Sun Sentinel, the Palm Beach Post, the Orlando Sentinel, the Orlando Sentinel, WLRN Public Media, and the Tampa Bay Times.
