EGU25-10429, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-10429
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
How drought risk evolution impacts crop weather insurance loss ratio in France?
Léa Laurent1,2, Albin Ullmann1, and Thierry Castel1
Léa Laurent et al.
  • 1Biogéosciences, UMR 6282 CNRS, Université Bourgogne Europe, 6 boulevard Gabriel, 21000 Dijon, France
  • 2Group Actuarial Department, Groupama Assurances Mutuelles, 8 boulevard de Pesaro, 92000 Nanterre, France

Climate change has modified climatic hazards features and requires to reconsider agro-climatic risks. Among these, drought is one of the risks with the strongest impact on both crop production and crop weather insurance performance (Brisson et al., 2010). Understanding the effects of climate change on agro-climatic risks at regional to local scale is therefore a major challenge for the agricultural sector, specifically for insurers offering crop weather insurance policies. This work, resulting from a collaboration between an insurer and a research laboratory, focuses on the development of a drought index that well explain the evolution of crop weather insurance loss ratio. As maize is a major crop in the company's portfolio, the study focuses on this crop in particular. The aim of this work is to find the optimal set of parameters that maximizes the correlation between the drought index and the drought-related losses on crop weather insurance.

The Safran-Isba-Modcou reanalysis produced by Météo France provides spatially and temporally continuous climate data over metropolitan France of relevant interest to address this topic (Le Moigne et al., 2020; Soubeyroux et al., 2008). At the regional scale, these data allow us to quantify the evolution of climate hazards related to the water cycle from 1960 to present day. Taking into account the vulnerability of the crop of interest through the use of a simplified two reservoirs water balance model provides an opportunity to assess changes in maize water stress (Jacquart and Choisnel, 1995). The definition of a water stress threshold leads to the development of an annual drought index (Laurent et al., under review). The correlation with the crop weather insurance loss ratio due to drought is tested at various spatial scales (municipality, production basin), for different varieties, different sowing dates and different stress thresholds.

Our results indicate that climate change has affected the frequency and intensity of drought risk on maize crops in France, depending on the French production area studied. The significance of the correlation depends on maize variety, sowing date and hydric stress threshold. It seems that using drought index computed with low stress thresholds and analyzing correlations at large spatial scales gives the best results.

For non-irrigated maize area at production basin scale, our drought index can explain a significant part of drought-related losses in crop weather insurance. The results suggest that such an index may be relevant to improve the actuarial loss model of the insurer. However, further analysis is required in areas where correlations are weaker, particularly in production basins with high irrigation levels.

References:

Brisson et al., 2010. Field Crops Res. 119, 201–212. https://doi.org/10.1016/j.fcr.2010.07.012
Jacquart, Choisnel, 1995. La Météorologie 8ème série, 29–44. https://doi.org/10.4267/2042/51939
Laurent et al., under review. J. Agric. For. Meteorol.
Le Moigne et al., 2020. Geosci. Model Dev. 13, 3925–3946. https://doi.org/10.5194/gmd-13-3925-2020
Soubeyroux et al., 2008. La Météorologie 8, 40. https://doi.org/10.4267/2042/21890

How to cite: Laurent, L., Ullmann, A., and Castel, T.: How drought risk evolution impacts crop weather insurance loss ratio in France?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10429, https://doi.org/10.5194/egusphere-egu25-10429, 2025.