It is an inevitable transformation. Two decades of satellite images make it clear. The Earth’s oceans are getting greener, which could reflect the impact of climate change on phytoplankton populations. The sea is changing color. What are the consequences?
These tiny microbes, including algae, use green chlorophyll to photosynthesize. So the greater their numbers, the greener their habitat. And this impacts ocean ecosystems. The heat-induced increase in phytoplankton produces already visible changes. Their sudden population increases rob oxygen from their environment. This creates hypoxic dead zones from which not all animals can escape. But there are also longer-term consequences that we do not yet know about.
Phytoplankton to blame
A team of researchers showed that 20 years of collected data could predict it. The MODIS-Aqua satellite tracked images these two decades. Phytoplankton may not be the only reason the ocean could be getting greener. But their analysis matches the predictions of an advanced model. It predicts how ocean ecosystems might be responding to climate change.
“The ecology of the surface ocean has changed significantly over the past 20 years,” the researchers write in the published paper. According to the study, ocean greening is notable around the equator.
Phytoplankton absorb CO₂. Their greater numbers could be considered a valuable carbon sink. This makes the link more complex than it appears at first glance. It is clear that phytoplankton can alter their environment. This includes temperature, nutrient availability and light levels in the water. And it is the foundation of the marine food chain. Its increase will lead to significant widespread changes in resources such as conservation areas and fisheries.
Changes that are already
This study does not delve too deeply into these consequences. But whatever this greening of the oceans means, it seems to be happening already. Thanks to this research, this information is coming to light 10 years in advance.
“It’s true, the sea is changing color. The effects of climate change are already being felt in surface marine microbial ecosystems. But they have not yet been detected,” the researchers write.