Assessing drought in the drylands of northeast Brazil under regional warming exceeding 4 °C

Historically, during periods of extreme drought, food security in the drylands of the semiarid region of Northeast Brazil (NEB) is under severe risk due to agricultural collapse. The drought that started in 2012 continues to highlight the vulnerability of this region, and arid conditions have been detected during the last years mainly in the central semiarid region, covering almost 2% of the NEB. Climate projections show an increase in the area under water stress condition, covering 49% and 54% of the NEB region by 2700 and 2100, respectively, with a higher likelihood with warming above 4 °C. The projections of vegetative stress conditions derived from the empirical model for Vegetation Health Index (VHI) are consistent with projections from vegetation models, where semi-desert types typical of arid conditions would replace the current semiarid bushland vegetation (“caatinga”) by 2100. Due to the impacts of the 2012–2017 drought, public policies have been implemented to reduce social and economic vulnerability for small farmers but are not enough as poor population continues to be affected. In the long term, to make the semiarid less vulnerable to drought, strengthened integrated water resources management and a proactive drought policy are needed to restructure the economy. Integrating drought monitoring and seasonal climate forecasting provides means of assessing impacts of climate variability and change, leading to disaster risk reduction through early warning. Lastly, there is an urgent need for integrated assessments because the possibility that under permanent drought conditions with warming above 4 °C, arid conditions would prevail in NEB since 2060.