| Summary: | The last millennium is defined as a "stable" climatic period with anomalies such as the Little Ice Age (LIA: ~1450 AD to 1850 AD), a period marked by low temperatures and associated with a glacier advance. Also the Medieval Climate Anomaly (MCA: ~950 AD to 1250 AD), considered as a period at least as warm as nowadays and associated with glacier retreat in the northern hemisphere. However, several studies have shown that glacial advances have occurred during the MCA period in the Baffin Land and western Greenland, in contradiction with hemispheric‑scale temperature reconstructions. In this study we propose temperature conditions for the last millennium determined from a recent study on the glacial fluctuations of the Lyngmarksbræen glacier and the application of an empirical positive degree‑day model (PDD) constrained by the outputs of the regional climate MAR atmospheric model. This simulation was conducted on the Lyngmarksbræen glacier, which shows an original succession of nested moraines dated from the last millennium. The results show that the most likely scenarios are based on air temperatures in the range of ‑1.3°C to ‑1.6°C lower during the MCA than at the end of the 20th century if we consider a variation of about ± 10% in precipitation. Sensitivity tests are then made on different parameters of the glaciological model to better constrain the uncertainty of the temperature estimations. Le dernier millénaire est défini comme une période climatique « stable » parsemée d’anomalies. La première est l’Optimum Climatique Médiéval (OCM : ~950 AD à 1250 AD), période au moins aussi chaude qu’aujourd’hui et associée à un retrait des glaciers dans l’hémisphère nord. La seconde est le Petit Âge Glaciaire (PAG : ~1450 AD à 1850 AD), marquée par des températures froides et associée à une avancée des glaciers. Cependant, plusieurs études ont montré que des avancées glaciaires s’étaient produites pendant cette période de l’OCM en Terre de Baffin et sur l’île de Disko dans l’ouest du Groenland d’une ampleur plus ...
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