Figure 6.9.3 Change in drought statistics from the present for the CSIRO 2080s 75% scenario
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Text description of figure
The figure consists of four maps of New Zealand showing changes in various drought statistics between the present climate and the CSIRO 2080s 75% climate scenario. The first map shows the difference in PED level (in mm) for 1-in-20 year dry periods. The PED change is mostly positive except at isolated high elevation points, but is less than +50mm over most the country. The PED change reaches 100-150mm, and over 150mm at isolated individual pixels, in parts of central Otago, Coastal Canterbury, Marlborough, Hawkes Bay, Gisborne and Bay of Plenty.
The other three maps show differences in the probability of PED exceeding the specified levels of 200, 400, and 600mm, respectively. The probabilities range from 0 to 0.3.
For probability of PED exceeding 200mm, there is a weak gradient from east to west over both islands, with the higher probability in the east. The highest probability change (0.15 and above) occurs mainly in the east of the North Island.
For probability of PED exceeding 400mm, there is a stronger gradient from east to west than for the probability of PED exceeding 200mm. The highest probability change (now reaching 0.25 and above) again occurs in the east of both islands. The larger change in probability for the 400mm level than for 200mm is easily explained: in the driest eastern parts of New Zealand, the probability of PED exceeding 200mm can reach 0.9 under the current climate (Figure 2.3), and therefore cannot increase much more in future drier climates. However, the current climate probability of PED exceeding 400mm is about 0.6 in the driest eastern regions, and substantial increases are possible.
For probability of PED exceeding 600mm, the change in probability only exceeds 0.15 in Blenheim, in a narrow strip along the Canterbury coastline and in inland Otago. In the North Island, except for some small isolated regions along the east coast, the probability of PED exceeding 600mm is less than 0.05 everywhere.
