When the climate changes, one of the first sectors affected is agriculture.
When studying the readings of Météo France for 60 years, the Regional Observatory for Climate and Air Energy observes that in Auvergne-Rhône-Alpes the average temperatures have increased (around + 2.2 ° C), very hot days are more moreover, snow and frost are rarer. .
>> + 2.2 ° C on average for 60 years for the climate of Auvergne-Rhône-Alpes
So slowly but surely, the impacts of this climate change can also be read about the nature of crops, agricultural yield, the impact of droughts, the use of irrigation, the harvest schedule …
Photographic Progress / Richard MOUILLAUD
Grâce aux relevés de l’Institut Français de la Vigne (IFV) sur 200 parcelles de vigne (cépage Gamay) in Beaujolais, l’Observatoire régional climat air energy fait the constat d’une evolution des dates d’apparition des différents stades phénologiques de the vineyard. These stages of maturity always seem to occur earlier in the season.
On average, during the period 1971-1990, flowering was observed on June 10. Twenty years later, between 1991-2010, it occurs on average 13 days before, that is, on May 28. The same happens with this time of year, called veraison, when the grape swells and changes from green to bright red for black grapes, to translucent yellow for white grapes. From August 6 for the first period, the veraison went to July 24 on average for the second.
The Regional Observatory of Climate, Air and Energy correlates these dates with the temperature curve. To conclude that “for the years 1990, 2003, 2005, 2009 and 2015 the accumulated temperatures from March to July are higher than in previous years. It corresponds to years in which the phenological stages, in particular flowering, appear earlier ”.
On the contrary, “for the years 1980 and 1996, the accumulated temperatures from March to July are lower than in previous years. This corresponds to years in which the phenological stages appear later ”.
With earlier grape maturity, it is also the date of the harvest ban that changes on the calendar. In Beaujolais, 30 years ago rather around September 14, rather on average September 4 during the period 1990-2019.
Same observation in other French vineyards
Regarding the harvest, the National Office on the Effects of Global Warming (ONERC) noted a gap of 18 days for 40 years in the ten-year averages. In the Saint-Emilion vineyard, the vintages began to settle in early 1988. Champagne has gained 20 days in 20 years.
Studies between Rhône also corroborate this phenomenon in their Tavel and Châteauneuf-du-Pape reference plots for the Côtes-du-Rhône. In 2020, Saint-Péray opened the harvest ban on August 18.
The precocity of the vine in Beaujolais is also due, in addition to the influence of global warming, to the drop in yield imposed since the 90s to improve quality. But also to human appreciations. It is still the winegrowers who decide when the harvest is optimal in terms of maturity and health of the vines!
Photographic progress / Pierre AUGROS
Less frost for fruit trees
The precocity of flowering is common to all fruit trees. While the National Office on the Effects of Global Warming (ONERC) closely monitors apple and pear trees, the Regional Observatory of Climate Energy and Air monitors apricot trees. And the conclusions are similar.
In a context of increasing winter temperatures in our region, there are fewer days of frost.
But the risk persists for fruit trees that experience an earlier flowering date, which consequently leads the plant to a period of risk in terms of exposure to frost and therefore of consequences at harvest.
In its monitoring of apricot trees, the Regional Observatory of Climate and Air Energy first indicates a great variability between years. And the places. At its stations in Aubenas and Annonay (Ardèche), for example, the evolution of the climatic impact on apricot cultivation is slow. However, according to surveys further east in Montélimar (Drôme), apricot buds have been frozen less frequently since the 1980s (an average of -3 days of risk of frost at this stage per year). Same observation at the time of the flower petals falling and at the berry stage (- 5 days). In flowering, it is – 4 days.
Warming temperatures in Auvergne-Rhône-Alpes is also having an impact on livestock, forests, water resources …
Finally, among the consequences, is an increase in the exposure of the population to natural risks. The regional territory is particularly subject to the risks of floods, shrinkage-swelling of clay and forest fires. More than 90% of the municipalities of Auvergne-Rhône-Alpes are affected by at least one of these types of risk.