Study shows modern ocean acidification is fast outpacing changes in the past

A new study is showing that the current rate that we are turning our oceans acidic is quite alarming, possibly ten times faster than it has ever happened in the history of our planet.

Ocean acidification is possibly one the biggest problems we’re facing today, as we deal with the consequences of releasing billions of tons of carbon dioxide into our atmosphere through the burning of fossil fuels. A large percentage of the CO2 being emitted is dissolving into the oceans, changing the chemistry of the water, and turning it more acidic with time. This has happened before, as the amount of carbon dioxide in the atmosphere has waxed and waned throughout time, but a new study from researchers at the Earth Institute at Columbia University is showing that it has never before happened at the pace we’re seeing today.


The deep-sea benthic foram Aragonia velascoensis went extinct about 56 million years ago due to rapid ocean acidification. (Credit: Ellen Thomas/Yale University)

The period in time the researchers found that is about as close as they can get to what we’re seeing in modern times is the Paleocene-Eocene Thermal Maximum (PETM), over 55 million years ago. Examining the fossils of plankton that would have lived at the ocean surface in that time showed that the pH level of the oceans fell by 0.3 over a period of a few thousand years. By comparison, current ocean pH levels have dropped by about 0.1 in recent years, and are expected to see a drop by another 0.3 by the year 2100.

“This could be the closest geological analog to modern ocean acidification,” Bärbel Hönisch, a paleoceanographer at Columbia University’s Lamont-Doherty Earth Observatory, said in a press release. “As massive as it was, it still happened about 10 times more slowly than what we are doing today.”

The worst part about this is that, although the pH of the oceans eventually returned to a level that could better support forms of life that develop carbonate skeletons, it took roughly 70,000 years.

“We are dumping carbon in the atmosphere and ocean at a much higher rate today – within centuries,” Richard Zeebe, a paleoceanographer at the University of Hawaii who co-authored the study, said in the press release. “If we continue on the emissions path we are on right now, acidification of the surface ocean will be way more dramatic than during the PETM.”

This is yet another example of how, although similar events occurred in the past, the situation we have created – for the planet and for ourselves – is going to be far worse due to the rate at which we’re driving changes to the environment. Changes in the past happened on their own, over long periods of time, giving the ecosystem a chance to adapt. The much shorter time-scale that changes are taking place over now is going to make things a lot harder for everyone concerned.

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