Climate change in the temperature and precipitation at two contrasting sites of the Argentinean wheat region

Global climate change is shifting temperature and precipitation regimes, which is modifying the environments that define wheat yield and quality. The current work characterises the changes that have occurred in the thermal and hydric environment in two contrasting sites of the wheat-growing region of Argentina, allowing comparison between sites for these changes and for how the changes are accelerating. Temperature and precipitation variables were analysed by regression and trend testing (Mann Kendall), and future projections were made based upon significant relationships. The two sites compared were in the zones around the cities of Azul in the Province of Buenos Aires and Marcos Juarez in the Province of Cordoba, located approximately 500 km apart. The climate data analysed covered the period 1931-2014 for Azul and 1952-2014 for Marcos Juarez. At both sites, temperatures increased significantly in mean and extreme values over these periods, where the rate of change accelerated during the first years of the twenty-first century. The changes observed were in general more pronounced in Marcos Juarez than in Azul. Furthermore, in Marcos Juarez, mean precipitation increased from September to December and there was a higher frequency of extremes of precipitation greater than 100 mm in September and October during the early twenty-first century. Evidence was found for temperature rise and the occurrence of extreme temperature and precipitation events occurring differently between sites, as well as for its acceleration rate in the early twenty-first century. The projected future changes made implied that wheat yield is expected to suffer losses over the coming century.