# A review of uncertainties in global temperature projections over the twenty-first century

Author(s) Knutti, Reto, Allen, M.R., Friedlingstein, P., Gregory, J.M., Hegerl, G.C., Meehl, G.A., Meinshausen, M., Murphy, J.M., Plattner, G.-K., Raper, S.C.B., Stocker, T.F., Stott, P.A., Teng, H., Wigley, T.M.L.
Publication Type Journal Items, Publication Status: Published
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## Detailed Information

Title A review of uncertainties in global temperature projections over the twenty-first century
Author(s) Knutti, Reto
Allen, M.R.
Friedlingstein, P.
Gregory, J.M.
Hegerl, G.C.
Meehl, G.A.
Meinshausen, M.
Murphy, J.M.
Plattner, G.-K.
Raper, S.C.B.
Stocker, T.F.
Stott, P.A.
Teng, H.
Wigley, T.M.L.
Journal or Series Title Journal of Climate
Volume Number 21
Issue Number 11
Start Page 2651
End Page 2663
ISSN 0894-8755
1520-0442
Publisher American Meteorological Society
Publication Place Boston, MA
Publication Date 2008
Abstract Quantification of the uncertainties in future climate projections is crucial for the implementation of climate policies. Here a review of projections of global temperature change over the twenty-first century is provided for the six illustrative emission scenarios from the Special Report on Emissions Scenarios (SRES) that assume no policy intervention, based on the latest generation of coupled general circulation models, climate models of intermediate complexity, and simple models, and uncertainty ranges and probabilistic projections from various published methods and models are assessed. Despite substantial improvements in climate models, projections for given scenarios on average have not changed much in recent years. Recent progress has, however, increased the confidence in uncertainty estimates and now allows a better separation of the uncertainties introduced by scenarios, physical feedbacks, carbon cycle, and structural uncertainty. Projection uncertainties are now constrained by observations and therefore consistent with past observed trends and patterns. Future trends in global temperature resulting from anthropogenic forcing over the next few decades are found to be comparably well constrained. Uncertainties for projections on the century time scale, when accounting for structural and feedback uncertainties, are larger than captured in single models or methods. This is due to differences in the models, the sources of uncertainty taken into account, the type of observational constraints used, and the statistical assumptions made. It is shown that as an approximation, the relative uncertainty range for projected warming in 2100 is the same for all scenarios. Inclusion of uncertainties in carbon cycle–climate feedbacks extends the upper bound of the uncertainty range by more than the lower bound.
DOI 10.1175/2007JCLI2119.1
Additional Notes Manuscript received 27 June 2007, In final form 24 October 2007
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03731
03777
Organisational Unit(s)
NEBIS System Number 000490902
Source Database ID PP-43371
PP-46505
WOS-000256623200019
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@article{Kntt2008,
author = "Knutti, Reto and Allen, M.R. and Friedlingstein, P. and Gregory, J.M. and Hegerl, G.C. and Meehl, G.A. and Meinshausen, M. and Murphy, J.M. and Plattner, G.-K. and Raper, S.C.B. and Stocker, T.F. and Stott, P.A. and Teng, H. and Wigley, T.M.L.",
title = "{A} review of uncertainties in global temperature projections over the twenty-first century",
journal = "Journal of Climate",
year = 2008,
volume = "21",
number = "11",
pages = "2651--2663",
}


E-Citations record created: Fri, 02 Apr 2010, 00:12:55 CET