Ocean acidificatuon: crumbling the shells of the sea

Photo by R. Murphy

Photo by R. Murphy

If there is one thing we know from the history of life on Earth – it is that the oceans are resilient and relentless. Nearly 4 billion years ago the first raindrops fell from our cooling planet, accumulating in low basins and forming the first oceans to exist. It is from these oceans that the first forms of life emerged, and then continued to grow, expand, and evolve. In 4 billion years, they endured centuries of change, differing compositions of gaseous atmospheres, and yet they still held the capacity to support the evolution of life – a process that created the most complex and conscious being to stand upright and walk this planet – the oceans gave rise to us.

Just as life has changed in the past, the planet continues to change today. Yet there is vastly marketed difference. No longer is the ocean changing on the scales of geological time – tens of millions of years – the ocean is changing at a rate faster than its ever seen and has a singular human cause: our rapid increase in carbon dioxide emissions. Unfortunately, these rising levels of carbon dioxide alter more than just the temperature of the planet, shifting our climate in ways that scientists call climate change, but it also changes the chemistry of the ocean in a process known as ocean acidification.

Already, we are moving into an ominous future and beginning to see the first signs of our ocean’s bounded limits. The natural world seeks balance; slowly but surely, our great ocean is absorbing the increasing levels of carbon dioxide from the atmosphere. In our interconnected planet, more carbon dioxide in the atmosphere means more carbon dioxide in the ocean.

What exactly does this mean? Well, we live in a world of chemistry. In everything we see, touch, feel, and even experience – we are a combination of atoms, interconnected and interweaving chemicals moving within, among, and around us. Our lives are made up of interacting molecules in a world of stunningly beautiful chemistry that allows all life to exist. So too, is life in the oceans, a soup of atoms, molecules, chemicals and creatures, all drifting within the web of interacting chemistry.

Ocean acidification

When carbon dioxide enters the ocean, it comes into contact with water. But it doesn’t just hit the water and remain as carbon dioxide, it creates a new molecule called carbonic acid. As always, the chemicals of life never cease to stop moving and continue colliding with one another, reforming, and reintegrating to maintain balance. Newly formed carbonic acid separates quickly into two new substances, which can then separate again as they come in contact with their surroundings and with one another. Ultimately, the soup of ocean chemistry that began with a single carbon dioxide molecule and a single molecule of water is transformed into two hydrogen atoms and an ion called carbonate.

While this may all sound like technical science talk, our understanding of this is imperative – not only to the survival of the oceans inhabitants that will be affected by this shifting chemistry, but also by the billions of humans that rely on the abundance of life delivered to us by the sea.

So what does two new hydrogen atoms and a new carbonate ion mean for the ocean? Of course, it comes back down to simple chemistry, the increasing addition of hydrogen atoms change the pH of the ocean, making the waters more “acidic” by decreasing the pH. Remember lower pH means higher acidity. This has major consequences for animals that build shells out of calcium carbonate, animals like shellfish, krill, and sea urchins, as well as corals that create the foundation for the most diverse systems in the world, coral reef ecosystems.

Consequences to marine life

While the changing chemistry of the ocean may be too small for our human eyes to see, life in the ocean definitely feels its consequences. Nearly all forms of life require specific conditions in pH that allow their cells to keep moving and their bodies to continue to function.

For calcium carbonate-builders – the shellfish like clams and oysters, the beautiful corals, and the tiny animals like krill and plankton species that form the base of the food web – they will have a difficult time building their hard outer structures as it becomes more difficult to build shells when more hydrogen atoms are around. These animals will also have a more difficult time retaining a hard shell, as acid dissolves their rigid structures. All living creatures have a limited amount of energy available to them and they must balance between growing, maintaining the health of their bodies, and reproducing to carry on the cycle of life. Even if these animals can find the shell-building materials in the growing acidic water, and even if they can survive with a smaller, weaker shell, they will still have to use more energy to pump hydrogen from their bodies in order to continue to function.

Which aspect of these animals’ lives will become compromised when they must use so much more energy just to stay alive in our acidifying ocean? It may be their size, their ability to fight disease, or their capacity to reproduce new babies that would sustain the future of their species. While all the ocean’s inhabitants will not be affected in exactly the same way, there is no doubt that if the oceans continue to become more acidic, they will continue to crumble the shells of the sea and we will live in a world with a very different ocean – most likely not with these shell-building animals.

Threats to fisheries

As we’ve seen so many times before, societal perceptions change when people begin to see the tangible consequences of our expanding environmental degradation. In the last decade, fishermen along the Pacific Northwest coast have witnessed massive declines in their once highly abundant and productive oyster fisheries. The growing acidic waters off the Northwest coast in the Pacific shed light on the true severity of the effects of our acidifying ocean.

Beginning in 2006, oyster fisherman began seeing up to 80 percent losses in the production of their oyster larvae. These shell-building animals are unable to grow or maintain their shells due to the acidified ocean environment, especially during the vulnerable young stage in their lives. To compensate for the acidity, some fishermen have added chemicals that are basic in attempts to make the ocean conditions less acidic. Others have begun relocating their oyster fisheries to Hawaii or other regions around the world.

The cool waters of the Pacific Northwest and other similar cold temperate and Polar Regions are the most at risk to the harmful effects of ocean acidification, as their waters are naturally more acidic. Cold water is able to absorb and hold more gasses, and therefore absorbs more carbon dioxide from the atmosphere. It is also in these cold regions that deep ocean water rises to the surface, carrying with it nutrients that nourish phytoplankton, krill, and pteropods (ocean going snails), animals that are near the base of the food web and on which many other species depend.

The solution

As we continue emitting carbon dioxide into the atmosphere at an ever-increasing rate, the average global temperature of the planet will continue to rise and the oceans will keep absorbing the atmosphere’s gasses.

The solution is simple: we must reduce our emission of carbon dioxide. Of course, this can only happen when our society demands creative innovation from government and businesses to solve and sustain our human energy needs without destroying the ocean planet that we rely upon to survive. As complex conscious beings, we have the immense ability to overcome adversary. While we continue to learn how the Earth works, how nature runs on renewable energy and recycles its waste, and how the biota of the planet keeps the planet habitable for all living things, we need to pay attention to these lessons from nature and adapt our ways of living to promote the health of the environment rather than undermine it. We certainly have the capacity to adapt, innovate and create sustainable lifestyles. The question is whether we have the will to change.

What we hold at stake here is not the future of the planet – for in the long-term the planet will certainly endure. As it has done for millennia before, the planet may tip, yet it will undoubtedly right itself in time. And the oceans too will find its balance, although its future may see different species inhabiting a very different ocean. But humans do not have the luxury of geological time – we live in decades and generations. Our negligent actions may have consequences that undermine the near-future conditions that sustain our lives. Truly, what we hold at stake is the future of us. This is why I always say, when you protect the ocean, you protect yourself – and the future generations to come.

Jean-Michel Cousteau (President) & Jaclyn Mandoske, Ocean Futures Society, 25 September 2014. Open letter.

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