INVITED ABSTRACT
Trade-offs between Geoengineering, Mitigation and Adaptation

NAOMI VAUGHAN (1,2), Tim Lenton (2)

(1) Tyndall Centre for Climate Change Research, UK (2) School of Environmental Sciences, University of East Anglia, UK

     Abstract Number: 660
     Last modified: May 14, 2010

Abstract
The possible application of solar radiation control strategies to counteract global warming is explored through a number of scenarios of different anthropogenic CO2 emission reduction pathways and carbon dioxide removal interventions. Using a simple Earth system model we illustrate the trade-offs between CO2 emission reduction, the use of carbon dioxide removal interventions (‘negative emissions’) and solar radiation management. These relationships are illustrated over a multi-centennial timescale, allowing sufficient time for the carbon-cycle to respond to the anthropogenic perturbation. The impacts of these trade-offs are further investigated using an Earth system model of intermediate complexity (GENIE). The anthropogenic CO2 emission scenarios (focussing on those from fossil fuel combustion) range from more to less stringent mitigation of emissions and includes the scenario assumed in our previous work on the maximum cooling potential of different geoengineering options. Results are presented in terms of transient atmospheric CO2 concentration, changes to major carbon reservoirs, and global mean temperature. Implementation of solar radiation control strategies requires an understanding of the timing and effect of terminating such an intervention, a so called ‘exit strategy’. The results illustrate a number of considerations regarding exit strategies, including the inherent commitment to either carbon dioxide removal interventions, or the length of time the solar radiation control mechanism must be maintained for. The impacts of the various trade-offs are also discussed in the context of adaptation (both planned and responsive). The results have a bearing on policy and long term planning by illustrating some of the important assumptions regarding implementation of solar radiation management. These include baseline assumptions about emission mitigation efforts, timescale of intervention maintenance and impacts on adaptation.