But, thanks to people burning fuels, there is now more carbon dioxide in the atmosphere than anytime in the past 15 million years. A More Acidic OceanĬarbon dioxide is naturally in the air: plants need it to grow, and animals exhale it when they breathe. Second, this process binds up carbonate ions and makes them less abundant-ions that corals, oysters, mussels, and many other shelled organisms need to build shells and skeletons. First, the pH of seawater water gets lower as it becomes more acidic. There are two important things to remember about what happens when carbon dioxide dissolves in seawater. Acidification ChemistryĪt its core, the issue of ocean acidification is simple chemistry. Beyond lost biodiversity, acidification will affect fisheries and aquaculture, threatening food security for millions of people, as well as tourism and other sea-related economies. Some organisms will survive or even thrive under the more acidic conditions while others will struggle to adapt, and may even go extinct. What we do know is that things are going to look different, and we can't predict in any detail how they will look. Although scientists have been tracking ocean pH for more than 30 years, biological studies really only started in 2003, when the rapid shift caught their attention and the term "ocean acidification" was first coined. However, while the chemistry is predictable, the details of the biological impacts are not. Overall, it's expected to have dramatic and mostly negative impacts on ocean ecosystems-although some species (especially those that live in estuaries) are finding ways to adapt to the changing conditions. In fact, the shells of some animals are already dissolving in the more acidic seawater, and that’s just one way that acidification may affect ocean life. Such a relatively quick change in ocean chemistry doesn’t give marine life, which evolved over millions of years in an ocean with a generally stable pH, much time to adapt. As those surface layers gradually mix into deep water, the entire ocean is affected. (Scientists call this stabilizing effect “buffering.”) But so much carbon dioxide is dissolving into the ocean so quickly that this natural buffering hasn’t been able to keep up, resulting in relatively rapidly dropping pH in surface waters. Scientists formerly didn’t worry about this process because they always assumed that rivers carried enough dissolved chemicals from rocks to the ocean to keep the ocean’s pH stable. In the past 200 years alone, ocean water has become 30 percent more acidic-faster than any known change in ocean chemistry in the last 50 million years. Even though the ocean is immense, enough carbon dioxide can have a major impact. When carbon dioxide dissolves in seawater, the water becomes more acidic and the ocean’s pH (a measure of how acidic or basic the ocean is) drops. But in the past decade, they’ve realized that this slowed warming has come at the cost of changing the ocean’s chemistry. Since the beginning of the industrial era, the ocean has absorbed some 525 billion tons of CO 2 from the atmosphere, presently around 22 million tons per day.Īt first, scientists thought that this might be a good thing because it leaves less carbon dioxide in the air to warm the planet. At least one-quarter of the carbon dioxide (CO 2) released by burning coal, oil and gas doesn't stay in the air, but instead dissolves into the ocean. Ocean acidification is sometimes called “climate change’s equally evil twin,” and for good reason: it's a significant and harmful consequence of excess carbon dioxide in the atmosphere that we don't see or feel because its effects are happening underwater.
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