Cultivation of upland cotton in the rainfed system in Northeastern Brazil in the climate change scenario

The main objective of the study was to analyse the impact of climate change on upland cotton (Gossypium hirsutum L. latifolium Hutch) grown in Northeastern Brazil from estimates of the availability of land suitable for rainfed agriculture. This information, based on scenarios of increased temperature and rainfall variability of the Intergovernmental Panel on Climate Change (IPCC), was used in a model of inter-regional water balance. The data series used in the study were climatological daily rainfall of more than 30 years, crop coefficients, evapotranspiration potential and cycle length. The scenarios named A, B and C were related to increases in average air temperature of 1.5, 3.0 and 5.0 degrees C, respectively. In addition, these scenarios were associated with the precipitation fluctuations of +/- 10, +/- 25 and +/- 40%. The Index Satisfaction of Water Requirements for crop (ISNA), defined as the ratio between the maximum evapotranspiration and actual evapotranspiration (ETa/ETm), was used as a criterion in defining areas favorable for cotton cultivation. The results obtained suggest that the climate change scenarios should lead to reduction in areas favorable for upland cotton in the entire northeast region of Brazil.