Explore the science behind falling ocean pH and the impact this has on marine ecosystem balance
Ocean acidification occurs when carbon dioxide (CO2) is absorbed rapidly into the ocean.
It reacts with water molecules (H2O) to form carbonic acid (H2CO3). This compound then breaks down into a hydrogen ion (H+) and bicarbonate (HCO3–). These hydrogen ions decrease seawater pH.
In chemical terms, ocean acidfication is described like this:
CO2 + H2O → (H+) + (HCO3–)
The rising CO2 problem
Since the beginning of the Industrial Revolution in the early 1800s, the rise of fossil fuel-powered machinery has been the catalyst for the emission of billions of tonnes of carbon dioxide (CO2) and other greenhouse gases into our atmosphere.
Carbon dioxide levels have now risen by 30 per cent since the Industrial Revolution.
Scientists now know that about a quarter of carbon dioxide emissions have been absorbed by the oceans.
Monitoring shows that burning fossil fuels has caused unprecedented changes to ocean chemistry due to ocean uptake of millions of tonnes of CO2 each year.
Falling pH
Surface ocean waters are alkaline; on average pH 8.1. But because a quarter of human CO2 emissions are taken up by surface seawater this could drop to pH 7.8 by the end of the century, lower than at any time in human history.
The change in ocean acidity will not make it more dangerous for us to swim or surf in.
Seas are not actually going to be acidic – they will still be more alkaline than tap water.
Ocean acidification is happening rapidly worldwide. We have shown that this has knock-on effects that degrade marine ecosystems and impact fishing industries and food supplies. Plans are in place to ensure that University of Plymouth research is strategically aligned to inform the United Nations Decade of Ocean Science for Sustainable Development (2021-2030) and embed solutions that slow ocean degradation and build recovery of our coastal resources.
…
University of Plymouth, 9 September 2021. Full article.
