Climate Change and Our Oceans: Dissolving Shells

The world knows of the harmful effects anthropogenic CO2 has on our atmosphere, but few people know how harmful it can be to our oceans. When carbon dioxide is absorbed into sea water it increases the hydrogen ion concentration, and as a result, decreases the pH of the water, making it more acidic. Over a long time, the erosion of rocks from land into the oceans balances out the acidification, but because of the abnormal amount of CO2 humans are putting into the atmosphere the oceans are absorbing more CO2 than they can safely handle, resulting in a dangerous decrease in ocean pH. Just like our atmosphere, the oceans aren’t used to dealing with such a large influx of CO2 in such a short time period.

What does this mean for life in our oceans?

Scientists have found that within the next 90 years, if we continue to pump CO2 into the atmosphere at the same rate as we are now, the oceans will become too acidic to sustain many of its keystone species, such as those who rely on calcium carbonate shells to survive. These species will find it more and more difficult to produce their shells, in addition to maintaining their thickness and even form.

The majority of plankton species have a calcium carbonate shell component in at least one stage of their life. Plankton is at the bottom of the oceans food web. It starts with phytoplankton, which are eaten by zooplankton, which are then eaten by small fish and invertebrates, who are eaten by bigger fish and so on and so forth until we get to dolphins, whales and sharks which are at the top of the web. Without plankton, life in our oceans would be very different.

A recent National Geographic article looked at an ocean environment off the coast of Costello Aragonese, an island in the Tyrrhenian Sea that allows scientists to look at what the future holds for a CO2 saturated ocean. In the waters surrounding the island, CO2 arises from volcanic vents and dissolves into the water to form carbonic acid, mimicking what’s going on in the worlds oceans on a much faster timescale. At first the divers noticed an absence of barnacles along the waters’ edge and then limpet shells that were so thin that they were almost transparent. There were blades of sea grass without the regular creatures that normally encrust their surface, and an absence of sea urchins that were otherwise a norm outside the area.

View Costello Aragonese in a larger map

These waters are what the worlds’ oceans are forecasted to be like by the year 2100 if we don’t do something soon about our carbon emissions. It’s our responsibility to preserve our oceans so that future generations may have the fortune of a prosperous ocean, full of life and beauty.