In a recent study, a group of scientists hailing from renowned institutions such as MIT and the National Oceanography Centre in the U.K. made a remarkable discovery. Over the course of the last 20 years, these diligent researchers have observed intriguing changes in the color of our oceans.
What’s even more fascinating is that these alterations cannot be solely attributed to the usual fluctuations that occur from one year to the next in a completely natural manner.
In their groundbreaking paper, the team asserts that the variations in ocean color witnessed throughout the past two decades simply cannot be explained by the regular ups and downs we typically encounter in the ebb and flow of nature.
What could be causing this anomalous phenomenon?
The vast expanse of our planet’s oceans, which encompass a staggering 56% of its surface, holds immense importance, surpassing even the entirety of its landmass. Remarkably, subtle alterations in color have been occurring within these expansive watery realms, although they remain undetectable to the naked eye.
Notably, regions of tropical waters located near the equator have been steadily adopting a greener hue as time progresses. This intriguing transformation in ocean color holds significant implications, as it directly mirrors the presence of various marine organisms and components inhabiting its depths.
Consequently, it strongly suggests that the ecosystems thriving within the uppermost layers of the ocean are also undergoing notable changes.
While the precise cause behind the shifting hues of the ocean remains a mystery to diligent researchers, they hold a strong conviction that human-induced climate change is the probable culprit.
Over the years, these dedicated scientists have been engaged in simulations that have provided them with insights into the anticipated occurrence of such alterations in ocean color. However, witnessing these surprising changes unfold in real life leaves them deeply unsettled.
Furthermore, these observed variations align with the patterns expected from climate changes triggered by human activities.
In the words of Dr. B. B. Cael, the lead author and a recipient of a Ph.D. in ’19 from the National Oceanography Center in Southampton, U.K., “This gives additional evidence of how human activities affect life on Earth over a huge spatial extent. It’s another way that humans are affecting the biosphere.”
Color of the ocean is the manifestation of components present within
The color we perceive in the ocean is a visual manifestation of the components present within its upper layers. Typically, deep blue seas exhibit minimal signs of life.
However, when the waters take on a greener hue, it indicates the presence of ecosystems, particularly phytoplankton. These microscopic plant-like organisms are abundant in the upper ocean and possess the green pigment known as chlorophyll.
This pigment plays a crucial role for plankton, as it aids them in harnessing sunlight. Through the process of photosynthesis, phytoplankton absorb carbon dioxide from the atmosphere and convert it into carbohydrates.
As the cornerstone of the marine food chain, phytoplankton supports a diverse range of species, including krill, fish, seabirds, and marine mammals. Additionally, phytoplankton plays a vital role in the ocean’s capacity to absorb and store carbon dioxide.
Given their immense ecological significance, scientists are eager to closely monitor the distribution and changes in phytoplankton populations across the vast expanse of the ocean’s surface. By doing so, they hope to gain a better understanding of the dynamic nature of these vital organisms and their crucial role in shaping the oceanic ecosystem.
Model to analyze ocean colors
In 2019, Dutkiewicz and her colleagues conducted additional research that introduced a new model to analyze ocean colors. Their findings revealed that the natural variation in colors other than chlorophyll is considerably smaller.
This means that detecting climate-change-induced alterations in ocean color should be relatively easy compared to minor natural variations in other colors.
They projected that such changes would become visible within a monitoring period of 20 years, rather than the previously estimated 30 years.
This is the summer climate change got real, got scary, and it happened… unbelievably fast.
Canada burning, heat domes scorching, floods roaring. Marine heatwaves with ocean temperatures off the charts, impacting everything from marine life to global heat storage. 1/8 pic.twitter.com/BwRT1aeUwF
— ❤️ Umair (@umairh) July 11, 2023
Moderate Resolution Imaging Spectroradiometer (MODIS)
To further investigate the phenomenon, Cael and his team analyzed ocean color data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite. This satellite has been continuously monitoring ocean color for a period of 21 years.
The MODIS instrument measures seven visible wavelengths, including the two colors commonly used to assess chlorophyll levels. These color differences were observed and analyzed by the satellite.
Cael conducted a statistical analysis of the seven ocean colors captured by the satellite between 2002 and 2022.
Initially, he examined the extent of variation in these colors across different regions within a single year, providing insights into their natural variances. He then expanded his analysis to observe how these annual changes in ocean color evolved over a span of two decades.
Pattern of color change
Through this research, a distinct pattern emerged, surpassing the regular year-to-year variation. To determine the cause of this pattern, Cael referred to Dutkiewicz’s 2019 model, which considered the influence of greenhouse gases on ocean color.
According to the model, significant trends would arise within the next 20 years, resulting in observable changes in ocean color. Cael emphasized the importance of these findings, stating that the color of the oceans has indeed changed.
It is evident that alterations in ocean color reflect shifts in plankton communities. This, in turn, will impact the entire food chain dependent on plankton and even influence the ocean’s carbon absorption capabilities since different types of plankton have varying abilities to perform this function.
Cael and his colleagues urge the public to take these findings seriously, emphasizing that the changes are not solely predictions made by models, but observable transformations happening in real time, indicating that the ocean is undergoing significant change.