Tools for climate solutions: Developing techniques for marine carbon dioxide removal measurement, reporting and validation

Abstract

Climate change impacts and mitigation strategies will define our interaction with the oceans this century. Marine carbon sequestration could facilitate the enormous scaling necessary for gigaton-level carbon dioxide (CO2) removal: at least 10 GT/y by 2050 and 20 GT/y by 2100, required just to limit anthropogenic warming to below 2°C. Many proposed marine CO2 removal techniques involve the distributed capture of carbon, i.e., accelerating the biological carbon pump (e.g., iron ocean fertilization or artificial upwelling) or shifting the dissolution equilibrium of CO2 (e.g., ocean alkalinity enhancement). However, technology that enables rapid, inexpensive, persistent and accurate measurement and validation of drawn-down CO2 at the sequestration time- and regional ocean spatial-scales necessary to quantify carbon capture does not exist today. The accuracy and wholeness of these future techniques will be important for assigning financial value to marine CO2 removal processes in a carbon market, as well as enabling thorough evaluation of environmental impacts and a comprehensive understanding of ocean carbon dynamics. I will discuss ARPA-E’s interest in carbon sensing approaches, including passive and active acoustic techniques, which could rapidly quantify ocean carbon flux at scale and introduce powerful tools to address the challenges of mitigating climate impacts at sea.