NASA satellite images from the past 20 years show that the oceans are getting greener. Such changes have also attracted the attention of researchers, who believe that rapid climate change has also affected phytoplankton living in the oceans, including plant-like algae that use chlorophyll for photosynthesis. Accordingly, the greater their number, the greener the water becomes, writes “Science Alert“.
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NASA satellite images show that over the past 20 years, approximately 56 percent of the world’s oceans have turned green. These changes are especially pronounced in tropical regions near the equator.
Not all green is good
Since the start of the fight against climate change, green has become a symbol of saving the world for many. But the repainting of the oceans in green does not bode well. The rapid growth of phytoplankton is likely to cause many chain reactions in the ocean ecosystem.
For example, the sudden growth of the phytoplankton population deprives the surrounding environment of oxygen, creating hypoxic or so-called “dead zones” from which not everyone can escape in time.
Photo: AFP/Scanpix/LETA
Long-term consequences
One of the unanswered questions is how long it takes for changes in the ocean ecosystem to be recorded. Previous estimates suggest that at least 30 years of observations would be needed to detect changes. But a group of researchers from the United States and the United Kingdom proved that the last 20 years of data obtained from the Modis-Aqua satellite are enough. Accordingly, it is already possible to observe and respond to climate change.
Faster data became possible thanks to NASA satellite images in which color changes can be observed. Processing snapshots is a much simpler research method than studying the phytoplankton population using, for example, measuring the amount of chlorophyll.
Scientists thought they would need many more years of data before they could spot signs of climate change in the colour of the oceans https://t.co/mBGfBV2Fgy
— nature (@Nature) July 14, 2023
While the researchers acknowledge that phytoplankton are not the only cause of the greening of the oceans, their analysis fits closely with a model that predicts how the ocean ecosystem might respond to climate change.
At the same time, it must be taken into account that phytoplankton absorb carbon dioxide (CO2) and are also able to change many things in their environment, including temperature, nutrient availability and light levels in the water. In addition, phytoplankton are the foundation of the marine food chain, their increase can also cause extensive and significant changes in the ocean’s fishing resources.
Long-term effects were not looked at in depth in this study. But whatever the greening of the ocean means, it has already begun – and thanks to the latest research methods, the changes have been detected ten years earlier than they would have been in the past.
The study can be read in the journal “Nature“.
2023-07-22 19:30:15
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