Ocean acidification, one of many devastating effects of the warming earth, has been well-documented. It’s no longer up for debate. We now know that this process is adversely affecting many of the species that are the cornerstone of major oceanic ecosystems.
The public has been focusing on recent hurricanes in the Gulf of Mexico, along with massive wildfires and record heat waves in the West, as dangers of global warming. However, what has been ignored is the other danger, the increasing atmospheric carbon dioxide concentrations — the increasing acidification of our oceans!
Ocean acidification is well understood by scientists and can be found in any textbook on environmental chemistry. As atmospheric concentrations of carbon dioxide increase, the concentration of CO2 in the waters underneath will increase. This dissolved CO2 will then react with the water to form carbonic acid, which decomposes to form the bicarbonate ion and the hydronium ion, the acid form of water. Some of the bicarbonate ions will also decompose to form another hydronium ion and the carbonate ion. As the concentration of the hydronium ion increases, the pH, which is one means of indicating the hydronium ion concentration or acidity of the water, will decrease and the water will, thus, become more acidic. The water itself may still be considered basic with a pH above 7.0, but the fact that the pH is decreasing makes it becoming more acidic.
Now why is this important? First, it affects coral reefs which are already being devastated by repeated yearly bleach events caused by the warming of the ocean by global warming. Recent research has now documented that more acidic waters also weaken the glue that holds the coral reefs together.
Second, numerous research studies have demonstrated in labs that decreases in pH make it much harder for the larvae and young of creatures with calcium carbonate shells to develop their shells. This was first noticed in the wild when more acidic waters were killing oyster larva in the Pacific Northwest.
Now, for the first time, scientists have documented just how severely this increase in acidification has impacted much larger areas of the ocean and affected more than just oysters. The scientists decided to pull plankton samples along the same route taken by the HMS Challenger Expedition in 1872-78. When they compared their shelled plankton samples against the 150-plus-year-old samples from the Challenger Expedition, they found all of the modern species had shells that were 76% thinner. This is a very significant decrease. This shows that we are literally endangering species at the very foundation of oceanic food chains around the world. When these species die out because they can no longer grow sufficiently thick shells, whole ocean ecosystems could collapse.
Fortunately, we still have time if we are willing to start drastically cutting back on our carbon emissions. We will also have to start the process for removing substantial quantities of carbon per year from the atmosphere (to reduce the CO2 concentration by 1 ppm of CO2 requires the removal of approximately 7.8 billion metric tons).
Unlike climate, which has a multi-decade response to reductions in carbon emissions, the processes described above are rapidly reversible. Thus, if we can stabilize atmospheric CO2, the above processes stop.
Two good first steps in addressing this issue would be to enact H.R. 763, the Energy Innovation and Carbon Dividend Act, and to rejoin the Paris Climate Accord.
Furthermore, if we actually start to remove enough CO2 to reduce those concentrations, the oceans will start outgassing CO2, and the processes reverse, thus reducing the hydronium concentrations. The technologies exist to start addressing, and even reducing, the buildup of carbon dioxide in the atmosphere; it is just a matter now of generating the political will to act while we still can.
Thomas H. Pritchett has been a practicing chemist for more than 40 years, having served as a member of the U.S. EPA and as an environmental consultant before joining the faculty in the Department of Chemical & Physical Sciences at Cedar Crest College in Allentown. He is also a member of the Lehigh Valley Chapter of the Citizens’ Climate Lobby.
Thomas H. Pritchett, lehighvalley.com, 12 September 2020. Article.