A Research Agenda
As understanding of the risks and damages of climate change has improved, almost all nations have committed to limit total global warming to less than 2°C over preindustrial levels, with an aspirational target of 1.5°C. Meeting a 2°C target is becoming exceedingly challenging; the global mean temperature has already risen about 1°C over the 20th century. Most climate and integrated assessment models project that the concentration of atmospheric carbon dioxide (CO2) would have to stop increasing (and perhaps start decreasing) by the second half of the century for there to be a reasonable chance of limiting warming and the associated dangerous climate impacts. Fossil fuel consumption, agriculture, land-use change, and cement production are the dominant anthropogenic sources of CO2 to the atmosphere. The focus of climate mitigation is to reduce energy sector emissions by 80-100%, requiring massive deployment of low-carbon technologies between now and 2050. Progress toward these targets could be made by deploying Negative Emissions Technologies (NETs), which remove carbon from the atmosphere and sequester it. Under the present conditions, where fossil CO2 is continuously added to the atmosphere, removing CO2 from the atmosphere and storing it has exactly the same impact on the atmosphere and climate as simultaneously preventing emission of an equal amount of CO2. NETs have been part of the portfolio to achieve net emissions reductions, at least since reforestation, afforestation, and soil sequestration were brought into the United Nations Framework Convention on Climate Change, albeit as mitigation options, more than two decades ago. Recent analyses found that deploying NETs may be less expensive and less disruptive than reducing some emissions, such as a substantial portion of agricultural and land-use emissions and some transportation emissions. In 2015, the National Academies published Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration, which described and initially assessed NETs and sequestration technologies. This report acknowledged the relative paucity of research on NETs and recommended development of a research agenda that covers all aspects of NETs from fundamental science to full-scale deployment. To address this need, the National Academies convened the Committee on Developing a Research Agenda for Carbon Dioxide Removal and Sequestration to assess the benefits, risks, and “sustainable scale potential” for NETs and sequestration and to define the essential components of a research and development program, including its estimated costs and potential impact (Box S.1). The full Statement of Task is presented in Box 1.3. The committee held a series of public workshops and meetings to inform its deliberations and the writing of this report.