  Despite efforts to stabilize CO_2 concentrations, it is possible that the
climate system could respond abruptly with catastrophic consequences.
Intentional intervention in the climate system to avoid or ameliorate such
consequences has been proposed as one possible response, should such a scenario
arise. In a one-week study, the authors of this report conducted a technical
review and evaluation of proposed climate engineering concepts that might serve
as a rapid palliative response to such climate emergency scenarios.
  Because of their potential to induce a prompt (less than one year) global
cooling, this study concentrated on Shortwave Climate Engineering (SWCE)
methods for moderately reducing the amount of shortwave solar radiation
reaching the Earth. The study's main objective was to outline a decade-long
agenda of technical research that would maximally reduce the uncertainty
surrounding the benefits and risks associated with SWCE. For rigor of technical
analysis, the study focused the research agenda on one particular SWCE
concept--stratospheric aerosol injection--and in doing so developed several
conceptual frameworks and methods valuable for assessing any SWCE proposal.
