Carbon emissions projection featuring possible reduction methods called “wedges”

CLOSING THE GAP—With improvements in technology, but no changes in climate or carbon policies (the so-called “business-as-usual” scenario), carbon emission levels are projected to continue to rise (orange line) far higher than required to stabilize climate change (blue) that leaves a large gap of excess emissions that cannot be reduced by a single method. Instead, several methods, often called wedges, will need to be combined to reach the target. Ocean iron represents one proposed way to draw down carbon from the air and store it in the sea. (Illustration by Jack Cook, © Woods Hole Oceanographic Institution)