How an antacid for the ocean could cool the Earth

January 03, 2025

The world’s oceans stow vast amounts of carbon dioxide. Now, a growing group of scientists and companies say they’ve found a way to increase that storage capacity by tweaking ocean water chemistry.

The technique, known as ocean alkalinity enhancement, usually involves dissolving acid-neutralizing rocks in the ocean, allowing it to absorb more carbon dioxide.

Researchers have been exploring this technology for the last five years, but over the last two months, at least a couple of start-ups have begun operation along the Atlantic and Pacific coasts. Planetary, a start-up based in Nova Scotia, removed 138 metric tons of carbon last month for Shopify and Stripe. The start-up Ebb Carbon is running a small site in Washington state that can remove up to 100 carbon metric tons per year and committed in October to remove 350,000 metric tons of carbon from the atmosphere over the next decade for Microsoft.

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