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Modelling the climate of the last millennium: What causes the differences between simulations?
Author(s) -
Goosse H.,
Crowley T. J.,
Zorita E.,
Ammann C. M.,
Renssen H.,
Driesschaert E.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl022368
Subject(s) - forcing (mathematics) , climatology , general circulation model , climate model , environmental science , climate sensitivity , climate change , climate system , atmospheric sciences , geology , oceanography
An ensemble of simulations performed with a coarse resolution 3‐D climate model driven by various combinations of external forcing is used to investigate possible causes for differences noticed in two recent simulations of the climate of the past millennium using General Circulation Models (GCMs). Our results strongly suggest that differences in sensitivity (equilibrium and transient climate response) could be responsible for temperature changes that differ by more than a factor of two between two models. In addition, the spin‐up procedure could explain some differences between the simulations during the first centuries of the second millennium. The choice of the forcing reconstruction is found to play a smaller role for the differences in the simulated climate, in the model configurations analyzed here. Furthermore, at decadal scale, internal climate variability can mask the differences associated with different forcing reconstructions.