Media release issued 5th January 1999

In 1998 Australia recorded its highest ever annual mean temperature since high-quality data records began in 1910.

The Acting Director of Meteorology, Dr. Doug Gauntlett, said today that the Australian mean temperature for 1998 was 22.54 C, 0.73 C higher than the average for the 1961 to 1990 reference period. This departure was greater than the previous highest departure of +0.69 C set in 1988.

Dr Gauntlett said Australia's mean minimum temperature departure for 1998 was greater than the mean maximum temperature departure, consistent with the pattern observed in recent decades. The mean minimum temperature of 16.20 C was 1.03 C above the 1961-1990 average, well above the previous highest departure of +0.88 C set in 1973. However, the mean maximum temperature of 28.88 C was only 0.43 C above normal, less than the highest departure of +0.85 C recorded in 1991.

Despite the new Australian record it is unlikely that many people will remember 1998 as being particularly warm. Annual mean temperature departures are small because they are averaged over all of Australia, for all of the year. Within this overall average there is a lot of variability, both in time and throughout Australia. It is the local changes in temperature that people notice, not variations in the all-Australian mean.

The largest contribution to the record Australian mean temperature came from significantly warmer than usual minimum temperatures throughout the northern half of the continent. Some southern parts were actually slightly cooler than normal during 1998.

Warmer land temperatures in 1998 were partly due to significantly above average ocean temperatures around Australia. Ocean temperatures rose during the demise of El Niņo early in the year and the subsequent transition to weak La Niņa conditions late in the year. Increased cloud cover also contributed to milder overnight temperatures and generally wetter than normal conditions through most of the country.

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

The record annual mean temperature for Australia is consistent with global trends in showing continued warming throughout this century. According to a statement released by the World Meteorological Organization on 17 December 1998, preliminary data indicates that 1998 had the highest global mean temperature in the instrumental record from 1860. Last year was the 20th consecutive year with an above average global mean temperature.

Click here to see a graph showing the variations from average temperature over Australia since 1910 or here to see a map showing the variations from average temperature over Australia during 1998. (Climatology from the high quality temperature data set from Torok and Nicholls).

For more information contact Dean Collins (03) 9669 4780, Scott Power (03) 9669 4085 or Mary Voice (03) 9669 4086.
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