Special Colloquium

Atmospheric carbon dioxide removal (CDR) technologies are increasingly being considered as potentially useful tools to combat climate change. For specific carbon dioxide management targets to be achieved, large-scale CDR strategies may be needed, even with aggressive efforts to reduce carbon dioxide emissions in the coming decades. The American Physical Society's Panel on Public Affairs recently released a report that breaks down the physical requirements necessary for large-scale implementation of CDR technologies, demonstrating the challenges inherent to incorporating CDR into any carbon dioxide management portfolio. I will provide a technical overview of new and current CDR approaches and evaluate their fundamental physical constraints. Based on this I will discuss several recommendations for the U.S. federal government and industry. These include ensuring that the potential for CDR does not compromise ongoing actions to reduce carbon emissions. While large-scale CDR technologies require a lot of energy and material resources, they might be needed in combination with emission reduction strategies to achieve specific climate goals. Research and development on CDR should be selectively pursued, despite the many challenges. These include under appreciated potential radiative impacts of CDR approaches that modify large land or ocean areas.