Media release issued 5th January 2000

The 1990s were Australia's warmest decade in the ninety years for which high-quality records are available since 1910.

The Director of Meteorology, Dr John Zillman, said today that the Australian annual mean temperature during the 1990s was, on average, 0.33°C higher than the average for the 1961 to 1990 reference period, making the 1990s the warmest decade since at least the 1910s. The next warmest decade was the 1980s with a mean temperature departure of +0.22°C. Five years during the 1990s were amongst Australia's 10 warmest years with 1998 being the warmest on record.

Annual mean temperatures often differ greatly from year-to-year in Australia, partly due to normal climate influences such as those associated with El Niño. However, decadal mean temperatures are less variable and show a rise since 1910. Australian annual mean temperatures at the end of the 20th Century are about 0.8°C higher than they were early in the century.

Australian mean temperature anomalies graph

Based on preliminary data, Dr Zillman said Australia's mean temperature for 1999 was 0.11°C above the 1961 to 1990 average, making the year the 23rd warmest on record. The 1999 Australian mean maximum temperature was equal to the long-term average while the mean minimum temperature was 0.22°C above average.

Annual mean temperatures for 1999 were generally above average throughout the country apart from in far northern Australia, the northern half of Western Australia and parts of southeast Queensland and northeast New South Wales where above normal annual rainfall totals kept temperatures cooler than average.

The Bureau of Meteorology's National Climate Centre calculates annual mean temperatures using data from about 130 non-urban observing stations throughout Australia. The temperature records at these sites have undergone strict quality control procedures and have been corrected for discontinuities caused by changes such as in instrumentation and location. Many of the sites form part of Australia's Reference Climate Station Network - a network established to monitor climate change.

Long-term temperature trends in Australia are consistent with global trends in showing warming throughout the 20th century. According to a statement released by the World Meteorological Organization on 16 December 1999, the 1990s had the highest global mean temperatures since instrumental records began in the 1860s. Preliminary data indicate that 1999 was the globe's 5th warmest year on record.

The graph above shows Australian decadal and annual mean temperature departures since 1910. Note that Australian mean temperatures prior to 1910 are insufficiently reliable for comparison due to lack of data and changes in recording instruments. The map below shows the geographical distribution of the 1999 mean temperature departures from the average for the 1961 to 1990 reference period.

Australian mean temperature anomaly map - 1999

For more information on this statement, contact the following climate meteorologists in the National Climate Centre during normal office hours from 8:45am to 5:30pm (EDT):

Dean Collins  Ph: (03) 9669 4780,  E-mail: D.Collins@bom.gov.au
Scott Power  Ph: (03) 9669 4085,  E-mail: S.Power@bom.gov.au
Paul Della-Marta  Ph: (03) 9669 4466,  E-Mail: P.Della-Marta@bom.gov.au
Mary Voice  Ph: (03) 9669 4086,  E-mail: M.Voice@bom.gov.au

This statement and other climate change information is available at: http://www.bom.gov.au/climate/change

A selection of major Australian climate events during the 1900s can be found at: http://www.bom.gov.au/climate/c20thc

WMO's statement on global temperatures during 1999 and the 1990s can be found under "Press Releases" at: http://www.wmo.ch