The ocean controls our climate. The ocean holds 100 times as much heat as the atmosphere and absorbs 50 times more carbon than the atmosphere. However, the ocean is changing, sometimes unexpectedly, and critical ocean-climate processes are under-observed. This leaves extreme events not well predicted, causing an increased uncertainty in global climate predictions. All climate projections, as well as the effectiveness of associated carbon reduction policies and targets, teeter on these uncertainties. This is a global economic and climate risk that we cannot afford to take.