Innovators who are working on ways to pull carbon dioxide out of the atmosphere to fight climate change are having a tough time lately.

Their biggest supporter, Microsoft, recently began telling partners that it is pausing its carbon removal purchases. To get a sense of how big of a deal this is, look at the numbers: The tech company alone has purchased approximately 80% of the contracted cumulative volume of carbon removals to date. Its retrenchment is viewed as potentially a major blow to the sector.

However, there may be a bright spot for this industry, and it comes from an unexpected source: The U.S. Environmental Protection Agency quietly decided in March to grant a research permit under the Marine Protection, Research, and Sanctuaries Act to a Houston-based carbon removal startup.

The company, Carboniferous, aims to assess the potential to durably lock up greenhouse gases by harvesting plants that took in carbon dioxide on land and sinking them to the bottom of the ocean.

This approach is often called “ocean biomass sinking,” or marine anoxic carbon storage.

Ocean biomass sinking is one of several carbon removal approaches involving the ocean known as “marine carbon dioxide removal.” Other marine approaches include adding alkaline materials that react with seawater to increase the uptake of carbon dioxide, seeding oceans with iron to stimulate the growth of phytoplankton that can take up carbon dioxide, and farming seaweed to also take up carbon dioxide and sink it.

The Intergovernmental Panel on Climate Change, which compiles research on climate change from scientists around the world, calls carbon dioxide removal “unavoidable” if the world........

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