Climate change and its impact on agricultural potential in the central region of Argentina between 1941 and 2010

Abstract

The productive characteristics and agricultural potential of a region are strongly related to its climate conditions, and these have changed in an unprecedented way worldwide in the last 70 years. While the warming since the late nineteenth century has been established as between 0.3 and 0.6°C, the variation of other climatic elements such as precipitation, cloudiness and evaporation, has been much less explored. Climate change and variability in the central region of Argentina between 1941 and 2010 was studied, with special emphasis on water balance information, and the impact on agricultural suitability was assessed both temporally and spatially. Time series of 7 successive decades of climatic and agroclimatic variables expressed spatially were used, with Sen's nonparametric tests to assess the rate of change, and Mann–Kendall's to establish the significance of the trend. While no major change was seen in the annual values of potential evapotranspiration (ETP), with significant rates that were positive in only 6% and negative in 2% of the territory, 57% of the territory presents an increasing total annual rainfall trend, which significantly reduced aridity. There is a general downward trend in water deficiency (Def), so that this indicator of aridity and productivity has negative rates over time (P<0.10) in 25% of the territory, with a mean value of −33mmdecade−1. The Moisture Index (IH) trend is positive in 99% and significantly positive in 42% of the region, marking wetter atmospheric conditions, especially up to the late twentieth century. Change in agricultural suitability was assessed by determining the variation of agroclimatic indicators of soybean crops at 4 sites in the production area. The results are spatially heterogeneous, with barely noticeable thermal and hydrological changes in Marcos Juárez, showing its more stable agroclimatic aptitude, but more apparent changes in Ceres and Laboulaye. While water deficit explains the low agricultural aptitude until 1970, this deficit reduced between 1971 and 2000, increasing again in the last decade analyzed. The alternation that seems to be suggested, although not completely manifest yet, may be related to the oscillation of ocean indicators: the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO).