Current agro-climatic potential of Patagonia shaped by thermal and hydric patterns

Abstract

Changes in thermal and hydric patterns affect crop growth. This research is aimed to assess temporal and spatial trends of 18 climatic and agro-climatic thermal and hydric indices in the north of Argentine Patagonia (39°–44°, south latitude), to establish the current and potential suitability of this region for agriculture in a context of climate change. The period of study was 1970–2016, and it was focused on the last 20 years. Regional warming was indicated by the average increases of annual mean temperature (+ 0.2 °C decade−1), mean maximum temperature of the warm trimester (+ 0.3 °C decade−1), and extreme maximum temperature of the warmest month (+ 0.6 °C decade−1) during 1970–2016. This trend was also found in the 1996–2017 period. Mean minimum temperature of the cold trimester showed an uneven spatial and temporal trend, with increasing temperatures during 1970–2016 (+ 0.1 °C decade−1), but a negative trend (− 0.1 °C decade−1) over the last 20 years, which leads to an increasing regional trend in temperature amplitude. Negative trends in extreme minimum temperatures of April (− 0.3 °C decade−1), July and October (− 0.2 °C decade−1) imply more significant risks of cold damage for crops that exhibit sensitive phenological stages during this time. Thermal agro-climatic indices showed negative trends in winter chill (− 15.8 chill hours decade−1 considering the Weinberger method and − 20.8 chill hours decade−1 using Sharpe method) and higher accumulation of warm semester growing degree days (+ 38.8 GDD5 °C and + 32.3 GDD10 °C decade−1). Climatic and agro-climatic water indices showed that most of the region experienced decreasing water availability, mainly in the central-south and Andean subregions, showing annual precipitation trends of − 11.5 and − 31.2 mm decade−1, respectively). If these thermal and hydric trends are maintained in the future, the region will evolve into an area of greater energetic availability but with some restrictions: lower winter chill that would affect very high-chill cultivars cultivated in the warmest regions, higher risk of extreme thermal events during crucial phenological periods of specific crops, and decreasing water availability that would mainly affect dryland farming and river basin recharge.