Quantifying the role of internal variability in the temperature we expect to observe in the coming decades

Open access
Date
2020-05-12Type
- Journal Article
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Cited 30 times in
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Abstract
On short (15-year) to mid-term (30-year) time-scales how the Earth's surface temperature evolves can be dominated by internal variability as demonstrated by the global-warming pause or 'hiatus'. In this study, we use six single model initial-condition large ensembles (SMILEs) and the Coupled Model Intercomparison Project 5 (CMIP5) to visualise the role of internal variability in controlling possible observable surface temperature trends in the short-term and mid-term projections from 2019 onwards. We confirm that in the short-term, surface temperature trend projections are dominated by internal variability, with little influence of structural model differences or warming pathway. Additionally we demonstrate that this result is independent of the model-dependent estimate of the magnitude of internal variability. Indeed, and perhaps counter intuitively, in all models a lack of warming, or even a cooling trend could be observed at all individual points on the globe, even under the largest greenhouse gas emissions. The near-equivalence of all six SMILEs and CMIP5 demonstrates the robustness of this result to the choice of models used. On the mid-term time-scale, we confirm that structural model differences and scenario uncertainties play a larger role in controlling surface temperature trend projections than they did on the shorter time-scale. In addition we show that whether internal variability still dominates, or whether model uncertainties and internal variability are a similar magnitude, depends on the estimate of internal variability, which differs between the SMILEs. Finally we show that even out to thirty years large parts of the globe (or most of the globe in MPI-GE and CMIP5) could still experience no-warming due to internal variability. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000420197Publication status
publishedExternal links
Journal / series
Environmental Research LettersVolume
Pages / Article No.
Publisher
IOP PublishingSubject
internal variability; SMILEs; large ensembles; short-term projections; mid-term projections; surface temperature; model differencesFunding
174128 - Constraining dynamic and thermodynamic drivers of mid-term regional climate change projections for Northern mid-latitudes (SNF)
Related publications and datasets
Is referenced by: https://doi.org/10.3929/ethz-b-000447164
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Show all metadata
Citations
Cited 30 times in
Web of Science
Cited 32 times in
Scopus
ETH Bibliography
yes
Altmetrics