The wave of global offshore decommissioning expenditure (decommex) is rising. Hundreds of offshore facilities have already ceased production but are yet to be decommissioned. By 2030, total decommex will exceed US$15 billion a year (based on our Lens data). Between 2021 and 2050 we estimate US$400 billion will need to be spent. And an accelerated energy transition could turn the wave into a tsunami.