Enormous swaths of ocean are nutrient-poor and harbor little life. Seen from space, these areas are as blue and empty as the sky. But green, in the ocean as on land, is one of life’s signature colors.
Most of the Pacific Ocean is unremittingly blue. But Woods Hole Oceanographic Institute (WHOI) climate scientist Kris Karnauskas was readjusting the viewing frame of his satellite maps one day in October 2010 when he spotted a tiny telltale smudge of green slicing through the azure sea. The green plume trailed from one of the Gilbert Islands, a group of coral atolls straddling the equator. Karnauskas had nearly missed it because his map was usually centered on the continents, so its edge nearly bisected the Gilberts; Karnauskas only saw the green blip when he shifted the Pacific Ocean to the center of his view. The lucky move sparked an idea connecting islands, ocean currents, ...
