The giant kelp (Macrocystis pyrifera) is the fastest-growing plant in the world, living mostly on the Pacific coast, off the shores of California and British Co

The giant kelp (Macrocystis pyrifera) is the fastest-growing plant in the world, living mostly on the Pacific coast, off the shores of California and British Columbia. It had economic value at one point, so kelp farming was a major industry in the early 20th century. Though, I suspect if CO2 is all that matters, simple algae is easier to manage than large plants. Sadly, the natural kelp forests are in really bad shape. I haven't seen the stats on giant kelp, but the bull kelp forests have been practically been wiped off the map by sea urchins and warming waters over the past decade or two. The natural kelp forests probably didn't provide much in terms of CO2 absorption, as dead plant matter would decay quickly in the ocean, but it's been a huge loss for aquatic wildlife.