Decreasing autumn and winter rainfall over southern Australia has been attributed to a 50-year decrease in the average intensity of storms in the region – a trend which is forecast to continue for another 50 years. In an address to the International Union of Geodesy and Geophysics conference in Melbourne, CSIRO climate scientist, Dr Jorgen Frederiksen, said these changes are due to reductions in the strength of the mid-latitude jet stream and changes in atmospheric temperatures. The jet stream comprises fast moving westerly winds in the upper atmosphere. A long, severe drought, the worst on record is being experienced in many parts of Australia. As of November 2006, the late-winter to mid-spring rainfalls had failed. The average rainfall in the state of South Australia was the lowest since 1900. Across Victoria and the Murray-Darling Basin the season was the second driest since 1900. New South Wales’ rainfall was boosted by above normal falls along the north coast of the state, however the state average rainfall for the season is the third driest since 1900. The situation has been worsened by temperatures being the highest on record since the 1950s.