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Ocean acidification, global warming's 'evil twin', threatens marine ecosystems

By Scott Sutherland
Meteorologist/Science Writer
Thursday, May 29, 2014, 9:21 AM

Human activities - industry, transportation and energy production - release billions of tons of carbon dioxide into the atmosphere every year, which is gradually warming our planet and throwing off the balance of the climate. However, this carbon dioxide is also having an impact on the oceans, threatening marine ecosystems and possibly posing an even greater threat to us.

Carbon dioxide (CO2) levels have risen dramatically since the Industrial Revolution. The atmosphere had an average of around 270 parts per million (ppm) back before then, and currently it's at just over 400 ppm and rising. The atmosphere isn't the only part of our planet that's seeing a rise in CO2 levels, though. A significant amount is dissolving into the oceans, and it's changing the chemistry of the marine environments. The chart below shows the rise in CO2 concentration in both the atmosphere, measured at Mauna Loa in Hawaii, and in the ocean at Ocean Station Aloha - a 10-km-radius patch of Pacific Ocean north of Hawaii - and the resulting impact on the ocean's pH levels:

Credit: American Meteorological Society via

Credit: American Meteorological Society via

pH is a way that we measure the acidity or alkalinity of something. The scale runs between 1 and 14, with pure water coming in at pH 7, which is considered neutral. Anything below 7 is increasingly acidic and anything above 7 is increasingly alkaline. 

The graph above only shows pH levels back to around 1990, but for at least for the past few million years, seawater has had a fairly consistent pH of around 8.2, and that is what sea life has adapted to live in. This slightly-alkaline environment is useful for many marine creatures, since they produce calcium carbonate shells to support them and protect them from the water pressure and from predators. However, as more CO2 is dissolved into the ocean, which turns into carbonic acid, this is lowering the pH of the seawater. The current pH of the water is between 8.05-8.1, which may not seem like a big loss, but it's a logarithmic scale. So, going from pH 8 to 7 is a 10-fold increase in the acidity of the water, and pH 8.05 water is 1.5 times as acidic as pH 8.2 water. The video below, from the Center for Ocean Solutions, shows the dramatic effect a more acidic ocean can have on these forms of life, and even on the ground we stand on:

When the subject of carbon dioxide and its effects on global warming and climate change comes up, the focus is usually on the most visible effects - on the weather, and on Arctic sea ice or Antarctic and Greenland glacier melt. However, the excess carbon dioxide we're emitting into the atmosphere is affecting far more than what we can directly see. Scientists are working on giving us the best look at exactly what kind of damage we are doing to the planet, but we can't wait for the full assessment to act. By then, it will be too late. The key now is to start making the changes necessary to get us off this path and onto one that will do the least amount of damage possible. It may seem like a daunting task, but we hold the power here. 

The people we vote into office are the ones that have the ability to not only fund research efforts, but also to change policy, to shift us away from our dependence on fossil fuels. That's only small steps now, but at the moment we can still afford small steps. The longer we wait, the bigger our steps will need to be, and thus harder and more expensive, so we need to act now.

More by this author
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