Ocean Acidification

Humans today are relying very heavily on carbon dioxide to fuel our way of life. We expel tons of carbon into the atmosphere every year from industry, agriculture, and from our own daily activities. Carbon emissions stay trapped in the atmosphere and cause a greater level of insulation of the sun’s heat, causing the earth’s temperature to increase. This phenomenon commonly referred to as global warming.

The greenhouse effect explains how increased levels of carbon dioxide contribute to the increased temperatures of earth.

While many people are familiar with the concept of global warming, significantly fewer people know about an equally problematic result of carbon emissions: ocean acidification. About 30-40% of carbon emissions get sucked into the oceans and have drastic effects on ecosystems. Some of this carbon combines with water and forms carbonic acid. An increased amount of carbonic acid causes there to be more hydrogen ions and thus a lower pH because there is a higher acidity. From 1751 to 1994, the oceanic pH dropped from 8.25 to 8.14 with an almost 30% increase in hydrogen ion concentration.

Increased acidity could have many negative effects on the ocean and on sea life. It could cause organisms to have lower metabolic rates and less responsive immune systems, both of which could lead to death.

Acidification also adds to coral bleaching. Corals have a symbiotic relationship with an algae called zooxanthellae. The algae provides the corals with increased nutrients from photosynthesis while the coral provides it with a home. Due to increased acidity levels, the coral cannot sustain the algae so it expels it and the coral turns white because the algae give it color. Because it lacks the algae, the coral therefore cannot get as many nutrients and is therefore more likely to perish. The carbonic acid resulting from ocean acidification also causes calcium carbonate to disintegrate, which is the substance that corals use to create their skeletons. It is therefore harder for corals to grow and even if they do have algae with them, they are more likely to die.

Corals are the most diverse ecosystems in the ocean (25% oceanic animal species live in them even though corals make up less than 1% of the ocean floor) and if they perish, so will all of the species that call reefs home. Coral death would cause many organisms to be without homes and many food chains would be disrupted. The diversity in the ecosystem would greatly decrease, and many organisms which we might even use for food would also die. Many animals would die and humans would also be unable to get many kinds of food. 

Sources:
http://www.pmel.noaa.gov/co2/story/Ocean+Acidification
http://www3.epa.gov/climatechange/kids/basics/today/greenhouse-effect.html