What processes are contributing to the global oceans reducing the depths where sunlight reaches, also called ocean darkening? This is what a recent study published in Global Change Biology hopes to address as a team of scientists investigated how ocean darkening has increased over the last two decades. This study has the potential to help researchers, climate scientists, and the public better understand the dangers that marine life faces and potential steps that can be taken to mitigate them.
For the study, the researchers used a combination of satellite data and computer modeling to estimate the amount of ocean darkening that has allegedly occurred between 2003 and 2022. The motivation behind this study was that 90 percent of marine life lives in photic zones, which is where sunlight or moonlight can reach. In the end, the researchers found that 21 percent of the global oceans experienced darkening, which included both coastal and open ocean regions. Despite this, the researchers also found that approximately 10 percent of the global oceans experienced increased levels of light.
Global diagram depicting ocean darkening (red) and ocean lightening (blue). (Credit: University of Plymouth)
“There has been research showing how the surface of the ocean has changed color over the last 20 years, potentially as a result of changes in plankton communities,” said Dr. Thomas Davies, Associate Professor of Marine Conservation at the University of Plymouth and lead author of the study. “But our results provide evidence that such changes cause widespread darkening that reduces the amount of ocean available for animals that rely on the sun and the moon for their survival and reproduction. We also rely on the ocean and its photic zones for the air we breathe, the fish we eat, our ability to fight climate change, and for the general health and wellbeing of the planet.”
The researchers identify numerous reasons for ocean darkening, including global ocean circulation changes and increased sediments along coastlines. The researchers note how climate change contributes to global ocean circulation changes, with a myriad of past studies also confirming these statements. Therefore, addressing climate change could help alleviate ocean darkening and help save marine life across the globe.
What new discoveries about ocean darkening will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: Global Change Biology, EurekAlert!