Every year, about 40 billion tons of Carbon Dioxide (CO2) pollution is released into the atmosphere contributing to the Earth’s changing climate. However, about 30% of that emitted CO2 is taken in by the ocean,- the Earth’s largest carbon sink. As more and more CO2 gets absorbed by the oceans though, the chemistry begins to change. The oceans are becoming more and more acidic, and this can end up having deadly ramifications for life in the Earth’s oceans.
When we burn fossil fuels, greenhouse gasses get released into the atmosphere. The most notable and prevalent of these greenhouse gasses in the notorious Carbon Dioxide. When these gasses, along with CO2 get trapped in the atmosphere, they create a greenhouse effect, warming the planet, and ultimately causing global warming. Though, not all of the CO2 we emit goes into the atmosphere. Some of it is absorbed by natural carbon sinks, such as forests, wetlands, - and the largest sink of them all, the oceans. The oceans trap about 30% of that CO2, helping to slow down the greenhouse effect. However, all that excess CO2 in the ocean can change the chemistry of the ocean leading to disastrous results.
A series of chemical reactions occur when CO2 is dissolved in ocean water, resulting in an increased concentration of hydrogen ions. Now if you could remember from chemistry class, the greater the concentration of hydrogen ions, the more acidic the substance is. This is what we see happening in the oceans. As hydrogen ions increase, they’re likely to bond with the free carbonate ions around. This then leaves fewer carbonate ions for calcium ions to bond with. Why is this a problem?
Why is it an Issue?
Calcium Carbonate is a key ingredient in building hard shells and skeletons for several marine organisms.With the levels of CO2 in the ocean already increasing, we’re starting to see the effects ocean acidification has on marine life. Organisms that make their shells and skeletons out of calcium carbonate, such as clams, oysters, and corals, are hit especially hard.
Coral build their hard skeletons out of calcium carbonate, and with that key ingredient becoming more hard to find due to the increased acidity of the seawater, their growth rates are slowed and their structural integrity is weakened. As corals can no longer build up their skeletons, we stand to lose the great and extensive coral reefs. Some of the most biodiverse habitats on Earth. With coral reefs disappearing, countless other species will go to.
Oysters and other shellfish are incredibly important as well. A single oyster can filter and clean up to 50 gallons of water a day! Several people are also dependent on oysters as a source of income and for food. With less calcium carbonate to extract from the surrounding waters, developing larval oysters have a harder time growing their shells. The resulting oysters end up having smaller and weaker shells, making it less likely they’ll survive to maturity.
Oyster larvae in both high and low CO2 waters. The one in high CO2 waters has a harder time building its shell.
Not only are organisms with calcifying shells and skeletons affected, but so are several fish. Studies have shown that the ability to detect and evade predators is decreased in more acidic waters. As these species are threatened, the entire food webs underwater are in danger.
How we can Solve it
The oceans will continue to absorb all the excess carbon we pump out every year. In order to stop the process of ocean acidification, we’ll need to find a way to transition over to cleaner energy sources that don’t pollute and produce extra CO2. By the looks of things, we’ll need to start as soon as possible if we want to prevent any further damage to one of the Earth's greatest ecosystems