Over the past two decades, the colors of the Earth’s oceans have undergone significant changes due to climate change. American and British researchers analyzed satellite images from this period and reached a troubling conclusion: the waters of the world’s oceans are becoming greener, potentially reflecting the impact of global warming on phytoplankton populations. The shift in ocean color is substantial. The research team emphasized that this is not merely a result of natural fluctuations from year to year. They found that these color changes, although imperceptible to the human eye, have already affected more than half of the world’s oceans. This phenomenon covers an enormous area that exceeds the total landmass of the Earth.
Researchers explain that the color of the ocean is a reflection of its inhabitants and the materials present in its waters. As a result, this color change indicates that the ecosystems at the ocean’s surface are also undergoing transformations. Currently, scientists cannot precisely determine how marine ecosystems are changing in response to these color shifts. However, they strongly suspect that human-induced climate change is the primary driver.
Color Change Linked to Phytoplankton
According to researchers, the greening of the oceans is occurring due to an increase in phytoplankton driven by global warming processes. These tiny microbes, including plant-like algae, utilize green chlorophyll for photosynthesis. The more phytoplankton there are, the greener their environment becomes. While the green hue may seem appealing, the rising phytoplankton population is likely to lead to numerous side effects for oceanic ecosystems. Serious short-term consequences are already being observed. A sudden population boom depletes the surrounding environment of oxygen, creating hypoxic dead zones from which not all marine life can escape.
As noted by Sciencealert, the long-term consequences of changing ocean colors have yet to be thoroughly studied. It remains unclear how much data is necessary to detect these changes. Preliminary estimates suggest that three decades of observation are needed to identify shifts in ocean ecosystems. While studying 20 years of satellite data is sufficient to understand that climate change requires a faster response, processing these images is somewhat easier than attempting to measure phytoplankton populations through chlorophyll assessments. Researchers also acknowledge that phytoplankton is not the only reason the ocean is turning greener. However, all changes in the oceanic ecosystem are interconnected with climate change, which must be addressed as soon as possible.
Phytoplankton: Friend or Foe?
Researchers point out that the greening of the ocean is particularly noticeable around the equator. Since phytoplankton absorbs CO2, its increased presence can be viewed as a valuable carbon sink. Therefore, this relationship is far more complex than it appears at first glance. However, phytoplankton can significantly alter the surrounding environment. It can greatly influence temperature, nutrient availability, and light levels in the water. Moreover, phytoplankton forms the foundation of the marine food chain. Thus, its increase could also lead to widespread significant changes in resources, such as conservation areas and fisheries.
The conducted study does not delve too deeply into these consequences. However, regardless of what the greening of the ocean signifies, it has been occurring for at least the past ten years. Researchers note that overall, these results indicate that the impacts of climate change are already being felt in surface marine microbial ecosystems, even if they have not yet been fully identified. Therefore, monitoring phytoplankton at the ocean’s surface and understanding its response to climate change is a priority for scientists.