Testing the waters: can pumping chemicals into the ocean help stop global heating?

For four days last August, a thick slick of maroon bruised the waters of the Gulf of Maine. The scene, not unlike a toxic red tide, was the result of 65,000 litres of an alkaline chemical, tagged with a red dye, that had been deliberately pumped by scientists into the ocean.

Though it sounds perverse, the event was part of a scientific experiment that could advance a technology to combat both global heating and ocean acidification. Ocean alkalinity enhancement (OAE), as the approach is called, acts like natural weathering, but on human – rather than geological – timescales.

“The ocean is already incredibly alkaline. [It holds] 38,000bn tonnes of carbon, stored as dissolved bicarbonate, or baking soda,” says Adam Subhas, the lead oceanographer of the research team who announced early results from their test at the AGU Ocean Sciences Meeting in Glasgow.

Boosting this natural alkalinity using a chemical antacid should, in theory, encourage the ocean to absorb more carbon. Over a large surface area, and in combination with sharp emissions reductions, OAE could prevent global temperatures exceeding 2C above preindustrial levels, while locally reducing ocean acidity, which is now higher than at any point in the past million years and poses a dire threat to marine life and fisheries.