At no time since before the age of dinosaurs did the planet exhibit such a rapid process of oceanic acidification, the conclusions of a new study indicate. The paper shows that the footprint we are leaving on our environment is a lot more severe than any natural variation can account for.
The work covered the past 300 million years, and researchers say that they were unable to find any instance during this time when ocean acidification occurred faster than it does today. The phenomenon is extremely dangerous, since it can lead to an extinction event.
In a paper published in this week's issue of the top journal Science, scientists at the Columbia University say that the geological record does not contain any indications of similar processes taking place naturally, further demonstrating that man-made pollution is responsible for the phenomenon.
CU Lamont-Doherty Earth Observatory paleoceanographer Bärbel Hönisch, also the lead author of the new investigation, specializes in studying the ancient oceans, based on data available in the geological record and other sources.
He explains that the ocean has always acted like a sponge for soaking up excess carbon dioxide from the atmosphere. Over time, this helped our planet remain inhabitable. The oceans can easily scrub whatever CO2 volcanoes release into the air.
But our activities are adding extra amounts of carbon dioxide, as well as other greenhouse gases that throw the ecosystem off-balance. Whenever CO2 comes in contact with saltwater, it forms carbonic acid, a substance that lowers the pH level of the waters.
Usually, microorganisms living in the water take up the carbon, and store it at the bottom of the sea when they die. But if the CO2 influx is too high, then this natural defense mechanism is overwhelmed, and acidification occurs at ever-increasing rates.
“We know that life during past ocean acidification events was not wiped out – new species evolved to replace those that died off. But if industrial carbon emissions continue at the current pace, we may lose organisms we care about – coral reefs, oysters, salmon,” Hönisch explains.
Corals, mollusks and certain types of plankton use carbonate ions to construct their reefs and shells. What carbonic acid does is remove these ions from the water, therefore making it impossible for these structures to be put together correctly.
“These scientists have synthesized and evaluated evidence far back in Earth's history,” US National Science Foundation
(NSF) Division of Ocean Sciences program officer Candace Major explains.
“The ocean acidification we're seeing today is unprecedented, even when viewed through the lens of the past 300 million years, a result of the very fast rates at which we're changing the chemistry of the atmosphere and oceans,” she concludes.