Annual Climate Report 2005

The Annual Climate Report is the Bureau of Meteorology's official historical record of the previous year's climate. It provides a national overview of temperature and rainfall during the year, and documents significant weather and climate events.

This report contains an in-depth analysis of the past year's climate, following on from the Annual Climate Statement released earlier in the year.

Australia recorded its warmest year on record in 2005. Data collected by the Bureau of Meteorology indicate that the nation's annual mean temperature for 2005 was 1.09 °C above the standard 1961–90 average, making it the warmest year since reliable, widespread temperature observations became available in 1910. The previous record of +0.84 °C was set in 1998. While these temperature departures may seem relatively small, a 1 °C increase in mean temperatures is equivalent to many southern Australian towns shifting northward by about 100 km.

A record mean temperature was set because both daytime and night-time temperatures were high: the annual mean maximum temperature was 1.21 °C above average (equal highest), while the mean minimum temperature was 0.97 °C above average (2nd highest). Temperatures were consistently above average throughout the year, but autumn was particularly warm. April had the largest Australian mean monthly temperature anomaly ever recorded, with a monthly anomaly of +2.58 °C breaking the previous record of +2.32 °C set in June 1996.

Despite some regional variations, the warm conditions in 2005 were remarkably widespread. Apart from Victoria and Tasmania, all States and the NT recorded 2005 mean temperatures among their top two warmest years on record. The only region recording a cooler than normal year was a coastal strip of WA extending from Cape Leeuwin to Carnarvon. Since 1979, all but four years have been warmer than average in Australia.

Australian temperatures have increased by approximately 0.9 °C since 1910, consistent with global warming trends. Scientific studies have linked global and Australian temperature increases to the enhanced greenhouse effect. Whilst this warming trend is expected to continue into the decades ahead, annual temperatures are influenced by numerous factors, including natural variability, so 2006 will not necessarily be warmer than 2005.

Warmer-than-normal temperatures were not confined to Australia in 2005, with many other regions reporting an exceptionally warm year. According to a preliminary estimate released by the World Meteorological Organization (WMO) on 15th December 2005, the global mean temperature for 2005 was about 0.48 °C above average, putting 2005 amongst the four warmest years globally since reliable, widespread records commenced in 1861.

In addition to being warm, the early months of 2005 were also very dry over much of Australia. The January–May period was the second driest on record. From June onwards rainfall reverted to near- to above-normal levels over much of Australia, but the lack of sustained above-normal rainfall led to the continuation of multi-year water shortages in parts of Australia, particularly in Queensland and the southeast.

In reference to the 1961–90 annual mean, most of Australia was drier than average in 2005, with substantial parts of Queensland and WA having less than 60% of the annual mean (see page 2). However, in comparison with the historical record (see page 12), large areas recorded annual totals in the 'average' range (deciles 4–7). Exceptions to this pattern occurred in Queensland and across a broad zone through central WA, where totals in deciles 1 to 3 were common, including a few small patches of driest on record.

The national-average annual rainfall in 2005 was about 407 mm, substantially below the long-term average of 472 mm and the 2004 value of 512 mm. Australia's area-averaged rainfall is calculated from a network of around 5,000 rainfall stations, most of which are staffed by volunteer observers. Observations from this network reveal that, when compared to their respective historical records, Tasmania was the wettest State in 2005, while Queensland and Western Australia were the driest.

Product Code: IDCKGCAR1.2005

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