Since oceans cover roughly two thirds of the Earth, and since oceans can demonstrate signs of ecosystem health and climate change, the U.S. EPA has watched the ocean for changes in their physical property for many years. From sea level height to ocean temperature to coastal flooding occurrences to surface temperature, the EPA has closely monitored changes in these properties as an indicator of climate change.
A study published a few years ago indicated that the Atlantic coastline saw a loss in land between 1996 and 2011 – in other words, the sea level rose and part of the coastline was converted from dry land to wet land – an indication that a significant change has impacted an ocean’s sea level height. Another published study indicates that the temperature of all our oceans’ surfaces has risen steadily for decades. One of the more recent studies found that certain sections of our ocean floor may be dissolving.
It is a well-known fact that CaCO3 (commonly referred to as calcium carbonate) will readily dissolve in acidic solutions – in fact, one of my fun graduate school memories involves teaching reaction chemistry to a lab full of students by dropping handfuls of Tums into solutions of dilute hydrochloric acid. It turns out that the release of greenhouse gases (such as carbon dioxide – CO2) will cause some of it to dissolve into the ocean. Once dissolved in the ocean, some of it converts to carbonic acid (H2CO3) which lowers the pH of the solution (i.e. it makes it more acidic). It also turns out that many of the minerals found on the ocean floor are made of CaCO3. So, if you follow the chain reaction from start to finish, increasing our greenhouse gas emissions increases the amount of CO2 in the atmosphere which increases the amount of dissolved CO2 in the ocean, which increases the amount of H2CO3 in the ocean and lowers it pH, making it acidic enough to start dissolving some of the CaCO3 minerals on the ocean floor.
Now, before you run to your nearest coast and starting waving a tearful goodbye to the ocean, we should put this information into perspective. While some minerals may be dissolving on the ocean floor, the pH changes are small and they are affecting relatively small volumes of water – our oceans contain quite a bit of water, afterall! However, the changes should not be taken lightly and they should be a reminder that these resources are fragile. We take this seriously in the water testing solutions we provide and hope that we can play a part in protecting and preserving this precious resource.