Quantifying uncertainty in European climate projections using combined performance-independence weighting
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Date
2019-12
Publication Type
Journal Article
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yes
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Abstract
Uncertainty in model projections of future climate change arises due to internal variability, multiple possible emission scenarios, and different model responses to anthropogenic forcing. To robustly quantify uncertainty in multi-model ensembles, inter-dependencies between models as well as a models ability to reproduce observations should be considered. Here, a model weighting approach, which accounts for both independence and performance, is applied to European temperature and precipitation projections from the CMIP5 archive. Two future periods representing mid- and end-of-century conditions driven by the high-emission scenario RCP8.5 are investigated. To inform the weighting, six diagnostics based on three observational estimates are used to also account for uncertainty in the observational record. Our findings show that weighting the ensemble can reduce the interquartile spread by more than 20% in some regions, increasing the reliability of projected changes. The mean temperature change is most notably impacted by the weighting in the Mediterranean, where it is found to be 0.35 °C higher than the unweighted mean in the end-of-century period. For precipitation the largest differences are found for Northern Europe, with a relative decrease in precipitation of 2.4% and 3.4% for the two future periods compared to the unweighted case. Based on a perfect model test, it is found that weighting the ensemble leads to an increase in the investigated skill score for temperature and precipitation while minimizing the probability of overfitting.
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published
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Journal / series
Volume
14 (12)
Pages / Article No.
124010
Publisher
IOP Publishing
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Edition / version
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Date collected
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Subject
Model weighting; Climate models; CMIP5; Europe; EUCP; Temperature; Precipitation
Organisational unit
03777 - Knutti, Reto / Knutti, Reto
09576 - Bresch, David Niklaus / Bresch, David Niklaus
Notes
Funding
776613 - European Climate Prediction System (EC)
641816 - Coordinated Research in Earth Systems and Climate: Experiments, kNowledge, Dissemination and Outreach (SBFI)
641816 - Coordinated Research in Earth Systems and Climate: Experiments, kNowledge, Dissemination and Outreach (SBFI)