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| Titel |
A lower and more constrained estimate of climate sensitivity using updated observations and detailed radiative forcing time series |
| VerfasserIn |
R. B. Skeie, T. Berntsen, M. Aldrin, M. Holden, G. Myhre |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2190-4979
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| Digitales Dokument |
URL |
| Erschienen |
In: Earth System Dynamics ; 5, no. 1 ; Nr. 5, no. 1 (2014-03-25), S.139-175 |
| Datensatznummer |
250115299
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| Publikation (Nr.) |
 copernicus.org/esd-5-139-2014.pdf |
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| Zusammenfassung |
| Equilibrium climate sensitivity (ECS) is constrained
based on observed near-surface temperature change, changes in ocean heat
content (OHC) and detailed radiative forcing (RF) time series from
pre-industrial times to 2010 for all main anthropogenic and natural forcing
mechanism. The RF time series are linked to the observations of OHC and
temperature change through an energy balance model (EBM) and a stochastic
model, using a Bayesian approach to estimate the ECS and other unknown
parameters from the data. For the net anthropogenic RF the posterior mean in
2010 is 2.0 Wm−2, with a 90% credible interval (C.I.) of 1.3 to
2.8 Wm−2, excluding present-day total aerosol effects
(direct + indirect) stronger than −1.7 Wm−2. The posterior mean
of the ECS is 1.8 °C, with 90% C.I. ranging from 0.9 to
3.2 °C, which is tighter than most previously published estimates. We
find that using three OHC data sets simultaneously and data for global mean
temperature and OHC up to 2010 substantially narrows the range in ECS
compared to using less updated data and only one OHC data set. Using only one
OHC set and data up to 2000 can produce comparable results as previously
published estimates using observations in the 20th century, including the
heavy tail in the probability function. The analyses show a significant
contribution of internal variability on a multi-decadal scale to the global
mean temperature change. If we do not explicitly account for long-term
internal variability, the 90% C.I. is 40% narrower than in the main
analysis and the mean ECS becomes slightly lower, which demonstrates that the
uncertainty in ECS may be severely underestimated if the method is too
simple. In addition to the uncertainties represented through the estimated
probability density functions, there may be uncertainties due to limitations
in the treatment of the temporal development in RF and structural
uncertainties in the EBM. |
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