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| Titel |
Historical and idealized climate model experiments: an intercomparison of Earth system models of intermediate complexity |
| VerfasserIn |
M. Eby, A. J. Weaver, K. Alexander, K. Zickfeld, A. Abe-Ouchi, A. A. Cimatoribus, E. Crespin, S. S. Drijfhout, N. R. Edwards, A. V. Eliseev, G. Feulner, T. Fichefet, C. E. Forest, H. Goosse, P. B. Holden, F. Joos, M. Kawamiya, D. Kicklighter, H. Kienert, K. Matsumoto, I. I. Mokhov, E. Monier, S. M. Olsen, J. O. P. Pedersen, M. Perrette, G. Philippon-Berthier, A. Ridgwell, A. Schlosser, T. Schneider von Deimling, G. Shaffer, R. S. Smith, R. Spahni, A. P. Sokolov, M. Steinacher, K. Tachiiri, K. Tokos, M. Yoshimori, N. Zeng, F. Zhao |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 3 ; Nr. 9, no. 3 (2013-05-16), S.1111-1140 |
| Datensatznummer |
250018056
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| Publikation (Nr.) |
 copernicus.org/cp-9-1111-2013.pdf |
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| Zusammenfassung |
| Both historical and idealized climate model experiments are performed with a
variety of Earth system models of intermediate complexity (EMICs) as part of
a community contribution to the Intergovernmental Panel on Climate Change
Fifth Assessment Report. Historical simulations start at 850 CE and continue
through to 2005. The standard simulations include changes in forcing from
solar luminosity, Earth's orbital configuration, CO2, additional
greenhouse gases, land use, and sulphate and volcanic aerosols. In spite of
very different modelled pre-industrial global surface air temperatures,
overall 20th century trends in surface air temperature and carbon uptake are
reasonably well simulated when compared to observed trends. Land carbon
fluxes show much more variation between models than ocean carbon fluxes, and
recent land fluxes appear to be slightly underestimated. It is possible that
recent modelled climate trends or climate–carbon feedbacks are overestimated
resulting in too much land carbon loss or that carbon uptake due to CO2
and/or nitrogen fertilization is underestimated. Several one thousand year
long, idealized, 2 × and 4 × CO2 experiments are used
to quantify standard model characteristics, including transient and
equilibrium climate sensitivities, and climate–carbon feedbacks. The values
from EMICs generally fall within the range given by general circulation
models. Seven additional historical simulations, each including a single
specified forcing, are used to assess the contributions of different climate
forcings to the overall climate and carbon cycle response. The response of
surface air temperature is the linear sum of the individual forcings, while
the carbon cycle response shows a non-linear interaction between land-use
change and CO2 forcings for some models. Finally, the preindustrial
portions of the last millennium simulations are used to assess historical
model carbon-climate feedbacks. Given the specified forcing, there is a
tendency for the EMICs to underestimate the drop in surface air temperature
and CO2 between the Medieval Climate Anomaly and the Little Ice Age
estimated from palaeoclimate reconstructions. This in turn could be a result
of unforced variability within the climate system, uncertainty in the
reconstructions of temperature and CO2, errors in the reconstructions of
forcing used to drive the models, or the incomplete representation of certain
processes within the models. Given the forcing datasets used in this study,
the models calculate significant land-use emissions over the pre-industrial
period. This implies that land-use emissions might need to be taken into
account, when making estimates of climate–carbon feedbacks from
palaeoclimate reconstructions. |
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