According to a study published this week in PNAS , this sets off a feedback loop that acidifies the ocean even more quickly, a process that is already killing off foundational marine life species such as coral and threatening the balance of all ocean ecosystems on which we depend.
“Our study confirms that humans are now a geological force capable of impacting the Earth’s system, like a super-volcano or a meteoritic impact,” Olivier Sulpis, an earth science researcher at McGill University and lead author on the study, said to Motherboard in an email.
The root of the problem is that a foundational chemical reaction that keeps the oceans at pH levels that are conducive to life is being thrown out of whack.
Calcium carbonate, or calcite, lines the ocean floor. When calcite combines with carbon dioxide and water, the reaction produces calcium ions and bicarbonate ions. Because of this, the surrounding water becomes less acidic over long periods of time—think tens to thousands of years. But when you throw more carbon dioxide into the equation, all of the seafloor calcite starts to get used up to power these reactions in extremely large amounts, meaning that the ocean floor is dissolving. Now, there’s not enough calcite but more carbon dioxide than ever, driving up acidity levels.
Foundational species in the marine food chain, such as coral, are fine-tuned to thrive within a very particular range of pH levels. When those levels change for a long period of time, these species—as well as the fish, bacteria, mollusks, and ocean life that depends on them—simply can’t survive. The last time the oceans were as acidic as they are now, 96 percent of ocean life was extinct.
According to Sulpis, calcium carbonate is still dissolving carbon dioxide in the water, which means there is still a chemical force fighting against ocean acidification. But the rate at which we’re emitting carbon dioxide, which then gets absorbed by the ocean, is far greater and faster than the rate at which carbon dioxide gets taken up by calcium carbonate on the ocean floor.
Just how bad is the damage? According to the study, in the northwest Atlantic Ocean, adjacent to Europe, 40 to 100 percent of the seafloor has been dissolved at the most severe locations.
Based on our most optimistic forecasts for ocean acidification, which assume that we fundamentally restructure our society in order to mitigate climate change, 90 percent of coral reef communities will bleach by 2100. In short, we’re in trouble.
“Geologists in millions of years may look at the Anthropocene as a brown layer of sediments lost in the geological record,” Sulpis said. “It’s a bit mind blowing. So at the end of the day, when we do take a step back and contemplate these results, it becomes scary.”
motherboard.vice.com
