Climatic Change

, Volume 121, Issue 3, pp 487-497

First online:

The long-term policy context for solar radiation management

  • Steven J. SmithAffiliated withJoint Global Change Research Institute, Pacific Northwest National Laboratory Email author 
  • , Philip J. RaschAffiliated withAtmospheric Sciences & Global Change, Pacific Northwest National Laboratory

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We examine the potential role of “solar radiation management” or “sunlight reduction methods” (SRM) in limiting future climate change, focusing on the interplay between SRM deployment and mitigation in the context of uncertainty in climate response. We use a straightforward scenario analysis to show that the policy and physical context determine the potential need, amount, and timing of SRM. SRM techniques, along with a substantial emission reduction policy, would be needed to meet stated policy goals, such as limiting climate change to 2 °C above pre-industrial levels, if the climate sensitivity is high. The SRM levels examined by current modeling studies are much higher than the levels required under an assumption of a consistent long-term policy. We introduce a degree-year metric, which quantifies the magnitude of SRM that would be needed to keep global temperatures under a given threshold.