A report by Anna Kucirkova for Caribbean News Now.
Climate change and global warming have been hot topics for the last couple of decades. The phrase ocean acidification may not sound quite as familiar as the other two phrases, but it’s a growing environmental concern frequently described as the “evil twin of global warming.”
Opinions on the severity of climate change vary, and it’s understandable that a lot of passion is vested on all fronts. On one side of the argument, it’s been asserted that ocean acidification is clearly due to humankind’s burning of fossil fuels. That verdict has helped lead the charge for a broad emphasis on reducing human production of carbon emissions. However, some believe that’s not the whole story, and that additional factors are unrelated to the human element.
For example, research was done by NASA (the National Aeronautics and Space Administration) states that “people aren’t the only players changing the ocean carbon cycle. Over decades, natural cycles in weather and ocean currents alter the rate at which the ocean soaks up and vents carbon dioxide.”
Clearly, there are no quick answers, and nothing is simple about the aim to meet the challenges of ocean carbon balance. Rising ocean temperatures are likely related but may not be solely due to human threats to oceans. Nature herself could also be a key player.
What is ocean acidification?
To better understand ocean acidification and how it’s linked to marine life threats, and to examine the arguments fairly, you need to understand the chemistry behind two terms closely related to ocean acidification – carbon dioxide and pH.
Carbon dioxide, or CO2, is a gas found naturally in the earth’s atmosphere. It’s part of what is given off by humans and animals each time they exhale. Plant life needs carbon dioxide and sunshine to grow, and then, in turn, plants give off oxygen which humans and animals need to survive. CO2 and other gases in the atmosphere help to trap the sun’s heat much like a greenhouse does. Without this happening, our earth would be a frozen planet. As for the ocean, greenhouse effects are believed to be a source of warming.
The second word – pH – is a measure of how acidic or alkaline a solution is, such as ocean water. The pH of solutions is measured on a scale of 0 to 14, with plain water being neutral on the pH scale. Pure water, without the calcium and other minerals that are found in seawater, has a pH of 7.
If there’s acid present in water, the number of the pH will be less than 7. When it’s more alkaline, the number will be greater than 7. So, a lower number on the pH scale means the acid level is higher, and a higher number means the water is more alkaline. Got a general idea?
The exchange of carbon on our globe happens all the time since carbon is chemically the backbone of all life on earth. Between the atmosphere, plant and animal life, the waters of the ocean, the processes of erosion, volcanic activity, and man’s burning of fossil fuels which add to carbon emission effects, there’s a steady, continuous movement of carbon known as the carbon cycle.
Carbon dioxide is freely absorbed by ocean water, which is a good thing. In fact, carbon exchange occurs quite easily between the ocean’s surface waters and the atmosphere. Masses of carbon are stored in the deepest ocean depths. About 93 percent of CO2 is found in the oceans.
Almost half of all human-made CO2 ends up being absorbed into the ocean. The more carbon that the ocean stores, the less carbon there is left in the atmosphere. The ocean’s ability to do this has been an amazing balancing act up to this point!
The quick absorption of CO2 has prevented the earth from experiencing a much greater progression of climate change. Many more serious changes would most likely have occurred already if all the carbon dioxide had stayed in the air.
If CO2 in the atmosphere continues to increase – whether it’s from human-made activity or natural emissions of carbon – a possible outcome would be the formation of more carbonic acid in ocean water, mainly near the surface of the ocean. Surface acidity would increase. This outcome is a major reason for concern among many members of the scientific community.
A technical but clear explanation from the Environmental Protection Agency about how ocean water becomes more acidic is useful:
“Once carbon dioxide dissolves in water, carbon dioxide molecules react with water molecules to form carbonic acid. Carbonic acid can be further transformed to bicarbonate and carbonate ions. These four different forms of carbon exist in balanced proportions in seawater. As more carbon dioxide is added to seawater, the balance shifts and carbonate is lost as it is transformed to bicarbonate due to increasing acidity.”