The power of the ocean

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Eliminating carbon dioxide has been described both as humanity’s last and best hope for staving off the looming climate crisis, and as the subject of dystopian science fiction. As is usually the case, the reality is somewhere in the middle. But if we take a moment to think about what we’re doing, then maybe the ocean can come to our rescue.

Today, carbon dioxide in the atmosphere is rising faster than at any time in the past 66 million years, and has reached levels not seen in at least 800,000 years. And there is no sign that this upward trajectory will abate without a complete abandonment of fossil fuels. Despite this, global policymakers have shown little appetite for implementing the stringent measures needed to accomplish such a change.

As a result, in November, the UN-mandated Conference of the Parties declared at its last meeting (COP26) that society must take a “net zero” approach to carbon emissions. This means that we need to reduce the amount of carbon dioxide in the atmosphere as quickly or faster than human activity is forcing it to increase. This is where carbon dioxide removal (CDR) – and the ocean – may be able to help us.

Terrestrial and oceanic CDR strategies take advantage of and enhance natural processes that remove carbon dioxide from the atmosphere and safely lock it away, where it will not contribute to global warming for decades, centuries, or even more. millennia. The ocean covers more than two-thirds of the planet and already stores around 50 times more carbon than the atmosphere. So it stands to reason that the ocean offers a silver lining as we seek ways to achieve negative net emissions.

In fact, since the dawn of the industrial age, the ocean has been quietly acting on our behalf to keep the climate from going haywire by absorbing an amount of carbon dioxide equivalent to about a quarter to a third of our emissions. Once dissolved in seawater, it is part of the chemical makeup of the ocean, and through the photosynthesis of countless small algae, it is also part of its biology.

To better understand our options, the National Academies of Science, Engineering, and Math have assembled a group of experts to develop a research agenda to assess the benefits, risks, and potential of a at scale responsible for six specific ocean-based CDR strategies. that take advantage of natural processes. These include electrochemical carbon dioxide stripping, algae cultivation, alkalinity enhancement, ecosystem recovery, nutrient fertilization, and artificial ups and downs. The panel also estimated costs and identified priorities for a research program that would attempt to both fill knowledge gaps and develop a common framework for ethics, oversight and transparency. Such an effort is necessary if we hope to avert a future of severe and prolonged droughts, intense storms and flooding, as well as increasingly precarious water and food security for large swathes of humanity, while avoiding the potentially devastating consequences of unbridled geoengineering.

To be clear, changing the ocean just to suit the whims of humanity shouldn’t be our goal, and the options being considered don’t represent a way for us or fossil fuel companies to continue with emissions like usually. Instead, we need to immediately and aggressively reduce emissions while identifying gaps in our knowledge about the effectiveness of CDR and the associated risks.

We have to do it quickly because of the countdown to the climate time bomb that we have built. New data indicates that a critical Antarctic ice shelf is being undermined by a warming Southern Ocean, which could trigger the collapse of the Thwaites Glacier in as little as three years, triggering potentially sea level rise devastating. There is also a very real danger that the economic opportunities presented by a booming carbon credits market could spur irresponsible actors to seek untested ocean CDR solutions on a large scale, with unknown impacts on the ocean and land. billion people who depend on it.

We have complex and difficult decisions to make and there is currently no way to choose the right path to take because we do not yet know enough to make a decision. Instead of blindly stumbling on the path of least resistance that has led us to where we are now, we have the opportunity to do things differently and act responsibly. The ocean can help us, but first we need to make sure we know what we’re doing so that we can weigh the potential benefits against the potential harms of such ocean-based climate interventions and make informed choices.

Ken Buesseler is a senior scientist at the Woods Hole Oceanographic Institution and was also a co-author of the National Academies of Sciences, Engineering and Medicine report “A Research Strategy for Ocean Carbon Dioxide Removal and Sequestration”.


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