The oceans are sinking in the dark. Scientists beat the alarm
World oceans are sinking into a deeper darkness. Today, more than 20 percent of their area receives less light than two more decades ago. This is not only a change in the color of water, but a quiet, dramatic warning. Scientists are alarming – obscuring the oceans is one of the most dangerous and least noticeable effects of climate change.
An increasing part of the global ocean is in the dark. Over a fifth of its surface becomes darker, and the areas on which sea life is based, dramatically shrink. For organisms such as plankton, fish and other sea creatures are a serious challenge – disappearing light is not only an aesthetic change, but a blow to the basics of global ecological balance.
Oceans are sinking in the dark
Climate change is not only higher temperatures, extreme heat or stronger storms. Scientists warn against another, less obvious symptom of global transformations – darkening of oceans. According to the latest analyzes published in the journal Global Change Biology, in the last 20 years the depth of the fotic zone – the one to which sunlight reaches – has decreased to 21 percent of the ocean area. The reason may be changes in plankton populations. This is not a marginal difference – it is a direct threat to sea life.
– Our research shows that this process leads to universal darkening, which limits the life space of species dependent on sunlight and lunar light to survival and reproduction. These changes affect fish that go to our plates, air quality, and even our ability to alleviate the effects of climate change – says Dr. Thomas Davies from the University of Plymouth.
Where is the darkness as soon as possible? Arctic, Baltic, Celtic Sea
The research team used data from NASA satellites covering the years 2003–2022. In nearly 9 percent of the analyzed area, the Gothic Zone was swallowed by over 50 meters, and in 2.6 percent by up to 100 meters. The most dramatic changes were recorded in the regions of the bay, Arctic and Antarctica.
This process is also visible on the coasts. In the Baltic Sea, heavy rainfall is rinsed to the sea and organic matter, supporting phytoplankton blooms and darkening water. The same happens in the Celtic Sea and the northern part of the Irish Sea, although locally – e.g. in the area of the Scottish coast – the opposite trend is observed.
Less light is less life
“The ocean is more variable than we think,” comments Professor Tim Smyth from Plymouth Marine Laboratory. – Light -dependent animals will be forced to get closer to the surface, where the competition for food and other resources can overturn the entire sea ecosystem.
Reduced sunlight not only affects fish. It also limits the process of photosynthesis of plankton – the basics of the ocean food chain. Not only fish will suffer, but also sea birds and mammals that feed on them. The changes are even visible at night – for many creatures the moonlight plays an equally important role as a daytime.
There are many causes of tinting oceans: excess fertilizers flowing down from fields, intensification of rainfall, water insulation and violent algae blooms. Although the seas have become brighter for about 10 percent of the seas in the last two decades, the dominant trend is darkening. This is a disturbing signal that the ocean – the largest life support system on earth – begins to weaken.
