On June 8^th, take a moment to appreciate the ocean – it’s World Oceans Day – an annual event established at the 1992 Global Forum in Rio de Janeiro and officially designated by the United Nations General Assembly in 2008.  It’s a day to celebrate the ocean by engaging in ocean-based education, dialogue, and activities.  Although formally divided into the Pacific, Atlantic, Indian, Arctic, and Southern Ocean basins, they are one interconnected water body that unites communities across the world.

 

 

Spanning over 70% of the Earth’s surface, the ocean holds more than 96% of the planet’s water, and its role in influencing and mitigating climate change is unrivaled. As the planet’s biggest carbon sink, the ocean has absorbed over half the human-generated carbon emissions to date.  NASA reports that 90% of climate-related warming has occurred in the top few meters of ocean waters, which store as much heat as Earth’s entire atmosphere.  A system of deep and surface currents, “the global ocean conveyor belt”, circulates throughout the ocean completing a global journey approximately every thousand years. These currents directly influence climate patterns on the continents, bringing warm air to some locations and cooler winds to others. For instance, the Gulf Stream that runs along Florida’s coast moves warm air from the Caribbean along the U.S. eastern seaboard across the Atlantic Ocean towards Europe, keeping much of Northern Europe significantly warmer than other places of the same latitude. Its climate-buffering qualities extend the window of time to cut carbon emissions and minimize future climate impacts.

 

 

Despite its vastness and seemly infinite capacity to absorb human interference, the ocean’s health is deteriorating. Ocean waters hit record-high temperatures in the summer of 2022 and its acidity is increasing as a result of carbon dioxide absorption. The Laws of Physics tell us that warm water takes up more volume than cold water due to thermal expansion – occurring when heat causes water molecules to move faster and take up more space. Thermal expansion, along with melting sea ice is increasing sea levels globally, and the addition of massive amounts of freshwater from artic melt is slowing the ocean currents.  Additionally, elevated temperatures set the stage for stronger hurricanes, and warmer ocean temperatures and acidification harm corals that provide essential shelter and food for fish and other species.

 

 

Decreasing atmospheric carbon dioxide is essential for a healthier climate and ocean, and solutions that could slow and/or reverse these trends may emerge from harnessing natural systems.   An array of strategies to remove carbon from the atmosphere are undergoing trials and several new carbon sequestration technologies stem from the ocean itself.

 

 

One technique, ocean alkalinization, supports carbon removal by adding alkaline substances to seawater to increase the ocean’s capacity to absorb even more carbon dioxide. Minerals, such as olivine, or artificial substances, such as lime or some industrial byproducts, increase ocean alkalinity after undergoing a series of reactions; much like a person with heartburn (caused by excess acid) taking a Tumsâ (an alkalizing substance). When the ocean’s alkalinity is reduced, it naturally absorbs more CO₂ from the air to help restore equilibrium.

 

 

Approaches to increase ocean alkalinity include sprinkling finely ground alkaline substances over the open ocean; depositing alkaline sand or gravel on beaches or nearshore; and passing seawater through alkaline minerals inside specialized fuel cells before returning it to the sea. Ocean alkalization directly counteracts ocean acidification, helping to protect marine ecosystems, while “electrochemical weathering” uses fuel cells to produce energy and hydrogen as a byproduct. On the downside, using silicate minerals like olivine would release iron and silica, which could result in uncertain and potentially harmful impacts on marine ecosystems and ocean chemistry. Other minerals could potentially harm ocean life by accumulating in marine food chains.

 

 

Other techniques draw materials from the ocean itself. Ebb Carbon, for example, seeks locations near desalination plants, seaside power plants, aquaculture operations, salt producers, and other coastal industrial facilities to capture salty water flowing through wastewater pipes.  Its technology uses electricity generated from low-emission sources to produce hydrochloric acid and sodium hydroxide from the saltwater, which is then released at alkalinity levels compatible with the ocean. This removes acids and returns an alkaline solution, enhancing the ocean’s capacity to absorb carbon dioxide.  Ebb Carbon’s process measures and verifies the amount of carbon dioxide removed, making it a viable solution to fund using green financing. In late 2021, the company entered a $500,000 carbon removal purchase contract with Stripe Climate to remove 256 metric tons of CO2 by Sept. 1, 2024.

 

 

Captura, a company with funding from the US Department of Energy and Elon Musk’s X-Prize, extracts carbon from ocean water.  Captura, which installed its first pilot facility in Newport Beach, California in 2022, uses a patented electrodialysis process to produce a stream of pure CO₂ that can be sequestered or utilized in low-carbon products while returning alkaline water to the ocean.  Captura relies on existing offshore infrastructure like desalination plants or oil rigs for its systems. While the pilot site only takes up 1 metric ton of CO2 annually, the next-generation technology will expand to sequester 100 times that capacity.

 

 

This World Oceans Day commit to action, be it a beach cleanup, an event, or a commitment to only consume sustainable seafood. In a recent statement, UN Secretary-General Antonio Guterres stated, “It is time to realize that, to achieve the Sustainable Development Goals and the objectives of the Paris Agreement on climate change, we urgently need collective action to revitalize the ocean. That means finding a new balance in our relationship with the marine environment.”  This balance will vary among households and across communities, but, making even small changes today – like bringing bags while shopping and avoiding bottled water – help secure a brighter outlook for our shared ocean.

 

By Bridget Washburn