IMPACT OF GLOBAL WARMING ON THE ACCUMULATED CHILLING HOURS IN THE SOUTHERN REGION OF BRAZIL

Abstract

One likely consequence of global warming, which is mainly due to the anthropogenic influence (IPCC, 2007), would be the changes in the accumulated chilling hours in temperate fruit crops. Global warming might have dramatic effects in the most warmer fruit zones, e.g., the Southern Region of Brazil. Simulations were performed to assess the effect of increasing minimum air temperature by 1°C, 3°C and 5.8°C in the chilling hours, on temperate fruit crops. Data from 81 meteorological stations of Parana (Iapar), Santa Catarina (Epagri) and Rio Grande do Sul (Fepagro) States were used to develop a model to estimate the chilling hours (Ch) as a function of the average minimum air temperature from May to September (Tmin may-sep ) and the annual average of the minimum air temperature (Tmin annual ). The generated model was used into the geographical information system (GIS) to create, through regression equations, information plans of the actual average minimum temperature (May to September) and actual annual average minimum temperatures. To the information plans generated by the equations were added the temperatures of 1°C, 3°C and 5.8°C. These data were used to generate, with GIS, maps of actual and future chilling hours. If the scenario of increasing 1°C is confirmed, it will decrease the areas with higher accumulated chilling hours (ACH) and increase the areas with lower ACH. This pattern will be more pronounced with an increase of 3°C, and culminate with an increase of 5.8°C where practically all areas with ACH would disappear, with the exception of small areas on the highest places of Rio Grande do Sul and Santa Catarina States, where the maximum ACH would be 334 hours.