The ocean absorbs about 25% of carbon emissions that come from burning fossil fuels.
That process has been key to mitigating the impacts of climate change, but it also causes ocean acidification, which can be harmful to marine life.
Acidification was thought to be worst at the ocean’s surface. A new study from researchers with the University of Hawaiʻi at Mānoa School of Ocean and Earth Science and Technology shows that some deeper waters may be acidifying more quickly than shallow waters.
"We expected some indicators of ocean acidification to be changing more rapidly below the surface, because that was what some global studies have previously discovered, but we were very surprised that this was true for every single ocean acidification indicator," said Lucie Knor, who led a team of researchers analyzing the ocean at various depths from the surface to nearly 3 miles deep.
Co-author Christopher Sabine said the findings have implications for a number of marine organisms.
Some zooplankton, for instance, migrate up and down the water column. They travel to the ocean’s surface at night to feed, and then descend into deeper waters during the day.
"Part of that is to avoid predators in the dark, but we've always thought that part of that too would be to escape some of the consequences of the acidifying ocean," Sabine said.
"But in fact, as we've studied this more, and we're discovering that acidification can be worse down below, they may not ever really escape from that," he added.
Sabine added that increased acidification at lower depths may also affect the ocean’s ability to effectively absorb carbon dioxide.
