Seasonal climate impacts on the grape harvest date in Burgundy (France)

M Krieger,T Laepple,G Lohmann

doi:10.5194/cp-7-425-2011

Abstract

Abstract. In this study, we analyse the climatic impacts on the grape harvest date (GHD) in Burgundy (France) on interannual and decadal time scales. We affirm that the GHD is mainly influenced by the local April-to-August temperature (AAT) and provide the spatial expansion of this relationship. The spatial correlation pattern yields similar results for the instrumental and pre-instrumental period, indicating the consistency of the pre-instrumental field data with the instrumental GHD-spring/summer relationship. We find a previously undocumented second climate impact on the GHD. The winter temperature is significantly correlated with the GHD on decadal-to-multidecadal time scales and affects the GHD independently of the AAT. A multiple linear regression model, with AAT and decadal winter temperature as predictors, was found to be the best model to describe the GHD time series for the instrumental period. Stability tests of the correlations over time yield that both impacts on the GHD, AAT and decadal winter temperature, strengthen during the instrumental period. Using partial correlation analysis, we demonstrate that this is partly caused by a change in the winter–spring/summer temperature relationship. Summarising, the GHD is well suited to reconstruct interannual variations of the spring/summer temperature over large parts of Europe, even if the changing winter–spring/summer relation might affect the reconstruction in a second order. For decadal time scales, the December-to-August temperature shows the strongest relationship to the GHD and, therefore, proposes that the GHD can be used for European temperature reconstructions beyond the spring/summer season. Finally, we argue that our findings regarding the changed winter–spring/summer relation are relevant for physical and biological systems in several ways and should be analysed by other long-term proxy data and available model simulations.

Highlights

Instrumental observations of the last 50 to 100 years indicate large interannual to multidecadal climate variability (Jones and Briffa, 1992; Dima and Lohmann, 2007)
The winter temperature is significantly correlated with the grape harvest date (GHD) on decadal-to-multidecadal time scales and affects the GHD independently of the August temperature (AAT)
We focus on the seasonal dependence of the GHD in Burgundy (France) and address the following research questions: Which climate signals are recorded in the GHD? What are the seasonal spatial correlation patterns of the GHD with temperature? Are the relationships stable over time, when comparing the instrumental with the pre-instrumental period?

Summary

Introduction

Instrumental observations of the last 50 to 100 years indicate large interannual to multidecadal climate variability (Jones and Briffa, 1992; Dima and Lohmann, 2007). A promising way to assess natural climate variability on these time scales is due to early instrumental and high-resolution proxy climate data (e.g., Mann et al, 1999; Jones and Briffa, 1992; Esper et al, 2002; Rimbu et al, 2001; Lohmann et al, 2004; Luterbacher et al, 2004). When using the GHD for climate reconstructions, several caveats have to be taken into account, e.g., plant diseases or changes in viticulture techniques, varieties and wine types (Meier et al, 2007; Garcia de Cortazar-Atauri et al, 2010).

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Discussion

Conclusion