Modeling Current and Future Climates using WorldClim and DIVA Software: Case Studies from Timor Leste and India

Abstract

To learn about spatial climate variations across a topographically nonuniform area, quantitative predictions built on top of high-resolution baseline climate models are necessary. The WorldClim program performs this task, allowing monthly rainfall and temperature baseline predictions (current conditions based on 1950–2000 averages) at a 5 km × 5 km pixel resolution to be visualized anywhere on the Earth through the DIVA mapping software. HADLEY CSIRO CCCMA and CCM3 climate predictions for the years 2020, 2050, and 2080 can be overlaid on the baseline climate. The resulting visualizations allow easy understanding of predicted rainfall and minimum and maximum temperatures across the globe, an important tool for anyone trying to understand climate-crop interactions across a nonuniform area. Indian baseline climate and projection visualizations for some years and locations are discussed. In a country as topographically variable as Timor Leste, where huge variation occurs in both rainfall and temperature across small spatial areas, this tool is especially useful. Known crop preferences for minimum and maximum temperature and rainfall thresholds can be inputted with these data to identify suitable areas for current species and cultivars, as well as suitable species and cultivar characteristics that should be focused on for future climate scenarios in specific locations. This type of information is important for research institutions, governments, and development agencies, and is also important for identifying agronomic interventions and directions for assisting local farmers to increase yields and reduce food insecurity. Timor Leste’s climate and agriculture interactions have been studied using this tool and are summarized. Results revealed that, on average, the climate in Timor Leste (East Timor) is predicted to become about 1.5°C warmer and about 10% wetter by 2050. Improved cultivars of maize, rice, cassava, sweet potato, and peanuts with increased yields have been introduced, but these will need to be augmented with better adapted cultivars and new crops and management practices specific to the changing climatic niches across the country. The hottest, low-lying areas are likely to become too hot for some species, and there will be a general upward movement of crop ranges toward the cooler, higher elevations. Coffee, the main agricultural export of the country, will likely have to shift upwards, implying massive social complications caused by land disputes and huge managerial challenges with respect to shade tree planting and ownership of the coffee plants. Temperate species currently grown at higher elevations are likely to become less common and may be phased out because of low productivity. Maize will likely be less productive at lower, hotter elevations but will respond well to higher temperatures and reduced chances of drought at middle to higher elevations. Rice yields may be affected by heat stress damage. Interventions, such as identifying and disseminating cultivars that are adapted to the predicted future conditions, are discussed. Other interventions, such as the requirements for fertilizers to boost yields; legumes to increase protein availability; and terracing and/or contour hedgerows to prevent soil erosion of steeply sloping terrain, are also identified and discussed.