Planetary-scale albedo modification

Fig 8: Examples of the global-scale inputs and modeled outputs of the simulations with HadCM3L. Regional data are also available and are being analyzed.

Fig 8: Examples of the global-scale inputs and modeled outputs of the simulations with HadCM3L. Regional data are also available and are being analyzed.

The problem:
Concerns that abatement of GHG emissions may be too slow in coming, or that the planet might experience a serious “climate surprise,” have led to renewed dialogue within the scientific community regarding potential strategies for counteracting global warming through geoengineering.  Using geoengineering is not a new idea.  However, despite years of discussion around the edges of the climate science community, little is known about the character and magnitude of the direct and indirect impacts of plausible geoengineering activities.  Nor is there any international framework for the governance of geoengineering.

The research:
In collaboration with Myles Allen and others in the project in the Physics Department at Oxford University, Morgan’s Ph.D. student, Kate Ricke, has launched an experiment to investigate the impacts of geoengineering using the HadCM3L GCM. Geoengineering activities were mimicked in the models by modifying the volcanic aerosol radiative inputs, applied as variations in stratospheric optical depth. The goal of the experiment is to examine the impacts of a transient geoengineering scheme, designed to directly counteract net long and shortwave radiative forcings associated with anthropogenic climate change (relative to pre-industrial levels of the relevant pollutants). To this end, 135 geoengineering scenarios were formulated, designed to offset the net forcings associated with long-lived greenhouse gases, tropospheric sulfur aerosols and tropospheric ozone; and spanning the uncertainties associated with these anthropogenic forcings. The scenarios and the preliminary global temperature and precipitation profiles are shown in Figure.  The output from the several thousand simulations run are being used to investigate regional temperature and hydrological impacts of these activities.  In the next phase of the experiments, we plan to:

  1. use a perturbed physics ensemble to bound uncertainties associated with the model output; and
  2. test more sophisticated geoengineering scenarios (e.g., different deployment schedules, zonal variations of geoengineering forcings, etc.).

Over the past 18 months we have organized and run two major workshops to begin to promote an international discourse on issues of global governance and CDMC investigators have participated in several other events. Under support from the proposed Center, and in collaboration with the International Risk Governance Council, and perhaps other international organizations such as ICSU, we plan to develop a comprehensive research agenda that outlines what will be needed to develop an adequate understanding of planetary-scale geoengineering, including both its direct and indirect effects, build a road-map of how the international community should proceed in developing an open and transparent approach to such research, and outline how a comprehensive international governance framework for geoengineering might best be developed.

The decision makers:

IRGC and other national and international organizations