A GIS tool to evaluate climate change impact: functionality and case study

A Climate Change Adaptation Strategy Assessment Tool ( CCASAT) for agriculture with integrated GIS capability was described. Historical climate data from 1889 to 2008 and 12 GCMs downscaling scenarios were integrated in the tool. Daily climate change data used were based on state-of-the-art statistical downscaling methods which allow for the description of fine scale structures. Development of GIS functionality within CCASAT involves the selection of mapping projection, boundary allocation, interpolation and a graphical display of the spatial data. Several mapping projections and data interpolation were implemented in CCASAT. All interpolation methods were tested using cross validation and users can review these analyses and select the best interpolation method to plot their data. To demonstrate the GIS functionality in CCASAT, the impacts of climate change on wheat flowering in the NSW wheat belt was investigated as a case study. A non-intercepted spherical equation described well the relationship between the semi-variance in changes of annual long-term hot days (d(h), T-max >= 28 degrees C) and the lag-distance. Cross validations showed that ordinary Kriging methods were the best scheme for interpolation of this index. The results showed that the number of hot days in 2050 during the winter crop growing season (1 May-30 November) would increase by up to 28 days, while frost days (T-min <= 2 degrees(C)) would decrease by up to 29 days. Predicted changes in the winter-genotype wheat flowering dates ranged from 5 days later in the northwestern corner and 10 days earlier in south-eastern corner of the NSW wheat belt. Spring-genotype wheat flowering is projected to be earlier by up to 7 days. The delay in the winter-genotype wheat flowering date is due to the delay in the completion of vernalisation in the warmer conditions. The analysis showed that number of frost days at flowering are not projected to change dramatically in the future, however an increase in hot days during wheat flowering is projected to have serious implications. This case study demonstrates that selecting suitable genotype wheat is the key adaptation strategy for the impacts of climate change on wheat cropping. Spring wheat genotypes are likely to become predominate in future climate, while winter genotype will only be viable in areas where sufficient days of cool temperature exist for completion of vernalisation. Breeding strategies should focus on releasing early-sowing genotypes that do not require vernalisation.