Climate engineering–induced changes in correlations between Earth system variables—implications for appropriate indicator selection
Climate engineering (CE) deployment would alter prevailing relationships between Earth system variables, making indicators and metrics used so far in the climate change assessment context less appropriate to assess CE measures. Achieving a comprehensive CE assessment requires a systematic and transparent reevaluation of the indicator selection process from Earth system variables. Here, we provide a first step towards such a systematic assessment of changes in correlations between Earth system variables following simulated deployment of different CE methods. We therefore analyze changes in the correlation structure of a broad set of Earth system variables for two conventional climate change scenarios without CE and with three idealized CE model experiments: (i) solar radiation management, (ii) large-scale afforestation, and (iii) ocean alkalinity enhancement. First, we investigate how the three CE scenarios alter prevailing correlations between Earth system variables when compared to an intermediate-high and a business-as-usual future climate change scenario. Second, we contrast the indicators identified for the non-CE climate change scenarios and the indicators identified when all five scenarios are considered. Finally, we use the identified indicator sets for an evaluation of the five climate change scenarios. We find that the additional indicators provide valuable information for the assessment of the CE measures, and their application hence allows for a more comprehensive and a comparative assessment of the mitigation and CE deployment scenarios.
The authors thank Wolfgang Koeve and Ulrike Loeptien for the helpful comments and discussion, as well as the participants of the Metrics Workshop of the SPP 1689 in March 2015, Hamburg, and in April 2016 in Kiel, for their thoughts on metrics and indicators.
N.M., D.P.K., W.R., M.Q., and A.O. conceived the experiment. N.M. and D.K. implemented and performed the simulations. N.M. and W.R. analyzed the data and wrote the manuscript with contributions from D.P.K., M.Q., and A.O.
This work was funded by the DFG Priority Program: Climate Engineering: Risks, Challenges, Opportunities? (SPP 1689).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
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