CO2 removal from the atmosphere (CDR), also called “negative emissions,” may or may not become a serious component of climate change policy some decades ahead. Already, integrated assessment modellers are assessing roles for negative emissions in the second half of the century. While it is early to evaluate the technological promise of the array of chemical and biological CDR options, it is arguably not too early to foster communication among those who model optimized century-scale responses to climate change, those who are scoping the opportunities and challenges associated with negative emissions, and those who are thinking about policy instruments. The purpose of this workshop is to begin these conversations.

For this workshop we will choose a reference deployment of CDR in order to provide specificity to the discussion. The reference deployment would result, over a century, in a 1 trillion tons reduction of the CO2 content of the atmosphere (an approximately 130 ppm reduction in concentration). The recently proposed linear relationship between cumulative emissions and surface temperature provides insight into this level of CO2 removal: roughly a half degree Celsius increase of long-term surface-temperature results from each trillion tons of CO2 emitted into the atmosphere. Negative emissions technologies under discussion today will be tested against the capacity to propose at least 10 percent of the reference removal.

Implications for policy will be drawn. Among the topics to be discussed are the viability, sustainability and governance of CDR technologies and implications for the optimal timing of mitigation. The integration across the interests of the participants will be fostered by keeping four questions at the front of the group throughout the workshop:

  • What can be said today about the capacity of various CDR strategies to contribute significantly to the reference deployment?
  • What are the impacts on the optimal timing of mitigation, the development of alternative mitigation technologies, and the sustainability of land and water use?
  • Under what conditions could the world, and should the world, responsibly deploy CDR at the reference scale of deployment?
  • Can we identify research strategies, priorities, and guidelines for advancing our understanding of CDR approaches and their consequences?

All the main CDR technologies will be considered, including afforestation, biomass with CCS, management of bio-stock, chemical direct air capture, enhanced weathering, and ocean fertilization. The workshop will devote very little attention to Solar Radiative Management and the removal of greenhouse gases other than CO2.

The workshop is open to a selected audience.