Beneath the smokestacks of the power plant that tower over Halifax harbour, Will Burt, chief ocean scientist at Planetary Technologies, leads a tour around Planetary's site.

The site — which consists of a shipping container housing an array of sensors, a mixing tank, and dozens of metres of tubes snaking in and out of the harbour — is where the company hopes it will begin to change the trajectory of climate change. 

The process uses ocean alkalinity enhancement — a way of accelerating the natural process that occurs when alkaline (or chemically basic) rock washes into the sea — to draw carbon dioxide out of the atmosphere.