Thorne, Peter, Outten, Stephen, Bethke, Ingo and Seland, Oyvand (2015) Investigating the recent apparent hiatus in surface temperature increases: 2. Comparison of model ensembles to observational estimates. The Journal of Geophysical Research: Atmosphere, 120 (17). pp. 8597-8620. ISSN 2156-2202
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Abstract
To assess published hypotheses surrounding the recent slowdown in surface warming (hiatus),
we compare five available global observational surface temperature estimates to two 30-member ensembles
from the Norwegian Earth System Model (NorESM). Model ensembles are initialized in 1980 from the transient
historical runs and driven with forcings used in the CMIP5 experiments and updated forcings based upon
current observational understanding, described in Part 1. The ensembles’ surface temperature trends are
statistically indistinguishable over 1998–2012 despite differences in the prescribed forcings. There is thus
no evidence that forcing errors play a significant role in explaining the hiatus according to NorESM. The
observations fall either toward the lower portion of the ensembles or, for some observational estimates and
regions, outside. The exception is the Arctic where the observations fall toward the upper ensemble bounds.
Observational data set choices can make a large difference to findings of consistency or otherwise. Those
NorESM ensemble members that exhibit Nino3.4 Sea Surface Temperature (SST) trends similar to observed
also exhibit comparable tropical and to some extent globalmean trends, supporting a role for El Nino Southern
Oscillation in explaining the hiatus. Several ensemble members capture the marked seasonality observed in
Northern Hemispheremidlatitude trends, with cooling in the wintertime and warming in the remaining seasons.
Overall, we find that we cannot falsify NorESM as being capable of explaining the observed hiatus behavior.
Importantly, this is not equivalent to concluding NorESM could simultaneously capture all important facets of
the hiatus. Similar experiments with further, distinct, Earth System Models are required to verify our findings.
Item Type: | Article |
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Keywords: | hiatus; surface temperature increases; model ensembles to observational estimates; |
Academic Unit: | Faculty of Social Sciences > Geography Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS |
Item ID: | 6468 |
Identification Number: | 10.1002/2014JD022805 |
Depositing User: | Peter Thorne |
Date Deposited: | 16 Oct 2015 14:08 |
Journal or Publication Title: | The Journal of Geophysical Research: Atmosphere |
Publisher: | American Geophysical Union (AGU |
Refereed: | Yes |
Related URLs: | |
URI: | https://mu.eprints-hosting.org/id/eprint/6468 |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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