We already know plastic waste leads to a colossal level of marine pollution and threatens the lives and habitats of many animals and plants.

We also know sunscreen can bleach coral and destroy whole reefs and that even traces of drugs can tip the hormonal balance of various marine animals.

Man is to blame for a large portion of the damage the underwater world has been subjected to, but as if that weren't bad enough, it turns out we're causing the ocean another problem, according to a study published in Earth and Planetary Science Letters.

Global warming isn't the only problem caused by excess CO2 emissions

Research conducted by scientists at the University of Cardiff in Wales found that carbon dioxide levels will soon be as high as they were 14 million years ago, when the average temperature on Earth was three degrees Celsius higher. Due to rapid global warming, the pH will have dropped dramatically by 2100.

Ocean acidification occurs when the pH of water drops, due to the absorption of CO2 from the atmosphere. One third of CO2 emissions are caused by the burning of fossil fuels, which has been ongoing since the beginning of the industrial revolution: 525 billion tons of CO2 have been released into the oceans since that period began.

 Smoke is seen from a chimney in Altay, Xinjiang Uygur Autonomous Region
Image: Thomson Reuters

The ocean's pH will soon be as low as it was 14 million years ago

The scientists examined the pH value of the water and the CO2 content of the past 22 million years.

"Our new geological record of ocean acidification shows us that on our current 'business as usual' emission trajectory, oceanic conditions will be unlike marine ecosystems have experienced for the last 14 million years," said lead author of the study Sindia Sosdian in a statement.

But even the current pH value is alarmingly low: "The current pH is already probably lower than any time in the last 2 million years," said Carrie Lear, co-author of the study. She added: "Understanding exactly what this means for marine ecosystems requires long-term laboratory and field studies as well as additional observations from the fossil record."

The catastrophic damage to marine life can no longer be averted

Though scientists still have to conduct further experiments to establish the precise ramifications this change will entail within the next next few decades, one thing is clear.

If we continue as we have done up until now, the over-acidification will not only kill off existing and future coral reefs entirely; it will cause catastrophic damage to many ecosystems, in which many animals rely on underwater plants for food sources.