LAUSR

Abstract This paper assessed the potential impacts of climate change on maize productivity in the Brazilian Northeast. To achieve this objective, bias-corrected regional downscaled scenarios from three global models for the representative emission pathways, RCP4.5 and RCP8.5, for the periods 1980–2005, 2007–2040, 2041–2070, and 2071–2099 were used as input data for a crop productivity model. Because increased temperatures are likely to shorten the crop cycle length, thus reducing productivity, we investigated the lengthening of the growing cycle as an adaptation strategy. To cope with the reduction of rainfall projected by future climate scenarios, we analyzed the potential impact of irrigation on productivity. The results showed that climate change effects would be mostly negative for maize rainfed agriculture, particularly for the worst-case scenario (RCP8.5, 2071–2099), in which losses were expected to reach more than 60%. However, productivity losses were limited to a maximum of 30% for all RCP4.5 scenarios and before 2070 for the RCP8.5 scenario. The use of maize cultivars with a longer crop cycle for rainfed agriculture was likely to increase the average productivity in all scenarios, although it came at the expense of increasing the risk of crop failure. Regarding the use of irrigation, there was an improvement in productivity for both the short- and long-cycle cultivars, although longer crop cycle cultivars had a decisive advantage, with a drop in yield of less than 20% for all RCP4.5 scenarios and for the RCP8.5 scenario until 2070 compared to the present climate. We estimated the total production and the increase in water demand based on the existing and projected irrigated areas in the region and concluded that it is possible to avoid significant losses in total maize production in the region for all scenarios, with the exception of the 2071–2099 RCP8.5 scenario. However, sustaining such levels of production requires a significant increase in water consumption (up to 140%).