Acidification and the Ocean
The ocean is the largest body of water on Earth. It contains 97% of the planet’s water and accounts for over 70% of Earth’s surface area, making it a vitally important part of our life and our environment.
The ocean has a huge influence on the planet’s climate, as it is a large heat reservoir and stores carbon in its oceans. It also transfers heat from the tropics to the poles, as well as supplying air temperature and precipitation for coastal regions and much further inland.
In the modern world, the ocean is being threatened by climate change, pollution and overfishing. One of the biggest threats is the rise in ocean acidification, which is caused by the release of carbon dioxide into the atmosphere.
Increases in CO2 level since the Industrial Revolution have lowered the pH of seawater, affecting coral reefs and other shelled organisms that use calcium carbonate to make their shells. The process is a simple chemical reaction, whereby the dissolved carbon dioxide dissolves in the seawater to create carbonic acid, which lowers the pH of the ocean’s waters.
Scientists say that by the end of this century, if current trends continue, the ocean’s pH could fall to 7.8 and even lower, causing an alarming loss of many ocean ecosystems. This is because fish that don’t have their own shells, such as sardines and tuna, may be unable to build their own shells, and other animals that live in the ocean could die of starvation as they eat the less-abundant calcium carbonate ions found in ocean water that has become more acidic.
It is thought that the current rate of ocean acidification is unprecedented in human history, and has not occurred naturally for millions of years. The carbon dioxide levels released into the atmosphere by human activity and the continued burning of fossil fuels are causing these changes, which are occurring faster than ever before.
There is no way to predict how long this trend will continue, but scientists do know that the rate at which carbon dioxide dissolves into the seawater is increasing dramatically. As it does, the dissolved carbon dioxide in the water binds up and binds out the soluble calcium carbonate that is so crucial to coral reefs and oysters, and other shelled organisms.
This is what causes the water to lose its pH, and it’s why corals, oysters and other shelled organisms that haven’t yet adapted to this new acidity will disappear from our planet’s seas.
The pH of the ocean has already fallen by 0.1 units from preindustrial times to the early 21st century, and this is just the beginning. If our current emissions of carbon dioxide continue, the ocean’s pH will drop by another 0.3 units by the end of this century.
The ocean is a vital part of our life on Earth, as it supplies oxygen to the surface and forms the basis of the carbon cycle. It is also a major heat reservoir and a significant source of atmospheric greenhouse gases. As a result, it is important for the health of all living things on the planet.