For decades scientists have been refining methods to capture hydrogen from seawater while capturing carbon dioxide from the air and binding it in marine carbonates in the ocean. Equatic is one of a new cop of startups (Ebb Carbon, CarbonRun, and Planetary Technologies among them) who are beginning to bring this idea from the lab to the waterfront.

The idea has promise. The ocean's rich soup of carbonates naturally bind enormous amounts of CO2, drawing it from air into seawater and turning it into raw material. A lot of the carbon is incorporated into shell by plankton and shellfish, and eventually transformed into limestone and other geologic deposits.

All told, the ocean’s knack for recycling carbon makes it the largest carbon sink on the surface of the Earth, locking away more than 20 times the carbon stored in soils and plants, and more than 40 times the amount in the atmosphere.

Learning to speed up this stately natural engine of sequestration could be one of the last hopes for modern societies to veer away from climate catastrophe, now that we've blown past so many guardrails while barely tapping the brakes on our fast-growing emissions.

With this promise come some big questions. Can we learn to manage this massive new use of ocean biogeochemical capacities without disrupting marine ecosystems that feed billions of people and produce half the Earth's oxygen? Can we grow a new environmental service industry without repeating the grievous errors and injustices of past development cycles? Could variants of this same clever chemistry also help to protect fisheries and ecosystems from harmful CO2-driven ocean acidification? Or safely recycle brines from the world's proliferating desalination plants? Help offset the cost of supplying freshwater to drought- parched regions? Yield useful hydrogen and oxygen? Stay tuned.