Climate Dynamics

, Volume 43, Issue 1, pp 243–258

Dynamics of the coupled human–climate system resulting from closed-loop control of solar geoengineering

  • Douglas G. MacMartin
  • Ben Kravitz
  • David W. Keith
  • Andrew Jarvis
Article

DOI: 10.1007/s00382-013-1822-9

Cite this article as:
MacMartin, D.G., Kravitz, B., Keith, D.W. et al. Clim Dyn (2014) 43: 243. doi:10.1007/s00382-013-1822-9

Abstract

If solar radiation management (SRM) were ever implemented, feedback of the observed climate state might be used to adjust the radiative forcing of SRM in order to compensate for uncertainty in either the forcing or the climate response. Feedback might also compensate for unexpected changes in the system, e.g. a nonlinear change in climate sensitivity. However, in addition to the intended response to greenhouse-gas induced changes, the use of feedback would also result in a geoengineering response to natural climate variability. We use a box-diffusion dynamic model of the climate system to understand how changing the properties of the feedback control affect the emergent dynamics of this coupled human–climate system, and evaluate these predictions using the HadCM3L general circulation model. In particular, some amplification of natural variability is unavoidable; any time delay (e.g., to average out natural variability, or due to decision-making) exacerbates this amplification, with oscillatory behavior possible if there is a desire for rapid correction (high feedback gain). This is a challenge for policy as a delayed response is needed for decision making. Conversely, the need for feedback to compensate for uncertainty, combined with a desire to avoid excessive amplification of natural variability, results in a limit on how rapidly SRM could respond to changes in the observed state of the climate system.

Keywords

GeoengineeringSolar radiation managementDynamicsFeedbackControl

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Douglas G. MacMartin
    • 1
  • Ben Kravitz
    • 2
  • David W. Keith
    • 3
  • Andrew Jarvis
    • 4
  1. 1.Control and Dynamical SystemsCalifornia Institute of TechnologyPasadenaUSA
  2. 2.Atmospheric Sciences and Global Change DivisionPacific Northwest National LaboratoryRichlandUSA
  3. 3.School of Engineering and Applied Sciences and Kennedy School of GovernmentHarvard UniversityCambridgeUSA
  4. 4.Lancaster Environment CentreLancaster UniversityLancasterUK