The effect of increased carbon dioxide resulting from human activity on the oceans is quite clear. There is a direct relationship between increasing levels of carbon dioxide in the atmosphere and the increasing acidification of the oceans. The chemistry has been well documented. Carbon dioxide (CO2) when dissolved in water (H2O) forms carbonic acid (H2CO3). This acidification has been implicated in the destruction of coral. Recent evidence has also demonstrated that increased acidity in the oceans also has a deleterious impact on oyster larvae as well.
As I have reported earlier (http://joesciencecorner.blogspot.com), it has been shown that increased acidity in the oceans has placed increased stress on phytoplankton, an organism that is a fundamental part of the food web in the world’s oceans. They account for one-half of all oxygen production as a result of photosynthesis on the planet.
In this article we will review the impact increased acidity is having on the world’s oceans in greater detail. Currently, human societies are collectively depositing gigatons of carbon dioxide per year into the earth’s atmosphere – a gigaton is equivalent to one billion tons. According to Lee Kump, a geochemist at Pennsylvania State University, this kind of growth in the level of carbon dioxide emissions as a direct result of human activity on the earth may be considered, “as one of the most notable, if not cataclysmic events in the history of the planet.”
It is estimated that there has been a drop of 0.1 pH unit in the global ocean since the beginnings of the industrial revolution with a .026 drop within the last fifteen years. These are disturbing data. Computer modeling predicts that if this trend continues the pH will have dropped to 7.8 from the 8.2 value in the pre-industrial age, where pH is a logarithmic measure of the concentration of hydrogen ions – a solution having a pH below 7.0 is considered to be acidic. By way of comparison, the pH of the stomach is around 2.0.
According to Richard A. Kerr in an article published in the June 18 2010 Science, decreasing pH impacts species that build shells or skeletons of calcium carbonate in the following way, “These organisms include tropical corals, echinoderms, mollusks, microscopic foraminifera floating in surface waters and certain algae. When the hydrogen ion concentration of seawater gets high enough, the calcium carbonate in these organisms begins to dissolve.”
The oceans provide much of the world’s supply of food. These data taken together with the warming effect on the earth’s oceans as a result of increased carbon dioxide in the earth’s atmosphere and its resulting effect on weather patterns, paints an alarming picture in regards to the changing natural environment and the future of humanity.