What will be the consequences of the climate change on soft wheat in Normandy (France) in 2050-2100 ? Prospective impact study based on ALADIN-Climate model

France is the fifth largest producer worldwide of soft wheat. Every year over 35 million tons of wheat are harvested (average 2011-2017, data from France AgriMer) on the territory. Hence, the cereal sector occupies an important place in the French agricultural economy.

However, because of its high dependence on the atmospheric conditions, wheat production is vulnerable to climate change. Since the mid-1990s, a stagnation of yield has already been observed. According to the agronomists, the main cause is climate change. Water deficit during the production and days of scalding during the filling of the grains. By 2050-2100, these extreme events are expected in the most likely scenario (i.e. warmer springs and summers). Hence, it is of importance to know if the shortening of the plant cycle resulted from the rise in the global temperature could prevent these extreme events from happening and if other related impacts could occur.

This study illustrates 2 agricultural plains containing open fields in the Normandie area, located in the north-west part of France. In this region, wheat locally occupies more than 50% of the agricultural land. These two areas are the plain of Caen which is under the influence of an oceanic climate and the plain of Evreux where the climate is slightly more continental.

The aim of this communication if to present what the climatic conditions for the soft wheat in 2050 and 2100 would be and to compare these projected periods with the ones of the reference period (1976-2005). The reported results were obtained by the means of a simulation of  the phenology to which is grafted the occurrence of climatic hazards such as water deficit, thermal exhaustion, frost days, vernalization, low temperatures and radiation deficit. Indeed, those hazards are able to generate consequences to the agricultural yield. The climatic data are extracted from ALADIN-Climate (data from CNRS-2014) in the case of three RCP scenarii of IPSS, available on the website of Drias Les futurs du climat.

In the context of pronounced climate change, along with unchanged sowing dates by 2050 and 2100, the increase in temperatures would lead to shorten the crop cycle, and hence to a date shift in the plant phenology. Consequently, there would be a shorter overlap between the end of the crop cycle and the summer period and, usually characterized by heat waves and water stress events which are expected to occur more often. Thus high temperature triggered scalding would not be observed as much as expected and the cumulated water limitation would be also lower. However, because of this precocity, emerging consequences might be expected regarding deleterious effects of lower temperatures during meiosis, and decrease of solar radiation at the onset of stem elongation. Mild winters would also reduce the days of vernalization, limiting cold requirements during tillering. This study demonstrates the use of bioclimatic models to unravel the crop phenology modifications, expected to occur by the end of the century, under the main environmental climatic drivers.