Building on the influential "wedge" paper by Steve Pacala and Rob Socolow, we show that stabilizing emissions is only the first step in solving climate change. Ultimately we have to stop dumping CO₂ into the atmosphere altogether. Given the recent trend of emissions, a complete phase out of emissions over the next 50 years would demand at least 19 wedges, and many more if historical rates of technology improvement falter.

As part of the Global Carbon Project's RECCAP effort, this paper describes the key differences between studies of CO₂ emissions in trade and provide a consistent set of estimates using the same definitions, modelling framework, and data. Included are new calculations of carbon physically present in traded wood, crop and livestock products.

Nations report and assume responsibility for CO₂ emissions from fossil fuels that are burned within their sovereign terrritory. But because both fossil fuels and consumer goods manufactured with fossil energy are commonly transported internationally, nations where fossil fuel resources are extracted or where the goods made with fossil energy are consumed may benefit from (and yet disclaim) emissions that occur elsewhere.

Prof. Davis is seeking outstanding graduate students and postdocs to work in the areas of energy systems analysis, land use-climate interactions, and the environmental impacts of global trade. Interested students and postdocs should contact Prof. Davis by email and describe their research interests.