2009 will be remembered for extreme bushfires, dust-storms, lingering rainfall deficiencies, areas of flooding and record-breaking heatwaves
Second warmest year for Australia
Data collected by the Bureau of Meteorology indicate that Australia's annual mean temperature for 2009 was 0.90°C above the 1961-90 average, making it the nation's second warmest year (after 2005) since high-quality records began in 1910. High temperatures were especially notable in the southeast during the second half of the year, with Australia, Victoria, South Australia and NSW all recording their warmest July-December periods on record.
Record-breaking heatwaves and high temperatures
Extreme heatwaves occurred across much of southern Australia during late January/early February resulting in a new Melbourne maximum temperature record of 46.4°C, new State maximum temperature records for Victoria (48.8°C at Hopetoun) and Tasmania (42.2°C at Scamander), and contributing to the Black Saturday bushfires. An unusual winter-time heatwave occurred during August over large parts of inland Australia and resulted in Australia's warmest August on record. A third prolonged heatwave occurred during November across central and southeast Australia, leading to a record 8 consecutive days of maximum temperatures above 35°C in Adelaide, and numerous maximum temperature records across southern and eastern Australia, especially in South Australia and New South Wales. Based on the analysis of daily (maximum and minimum) temperature data above and below set thresholds, there are clear upward trends in the number of hot events and downward trends in the number of cold events (over the period 1960 to date), consistent with the background of global warming.
Warmest decade on record
2009 ends Australia's warmest decade on record, with a decadal mean temperature anomaly of +0.48°C (above the 1961-90 average). In Australia, each decade since the 1940s has been warmer than the preceding decade. In contrast, decadal temperature variations during the first few decades of Australia's climate record do not display any specific trend. This suggests an apparent shift in Australia's climate from one characterised by natural variability to one increasingly characterised by a trend to warmer temperatures.
2009 the 5th warmest year globally
On 8 December 2009, the World Meteorological Organization (WMO) stated that 2009 is expected to be the globe's 5th warmest year on record (about 0.44°C above the 1961-90 average). A cooler-than-average global mean temperature has not been recorded since 1985, with the last decade also being the globe's warmest on record. Increasing global mean temperatures derived from instrumental measurements are consistent with other independent indicators of climate change, such as reductions in sea-ice and snow cover, and record high global sea levels.
Another drier than average year in the southeast mainland
Based on preliminary data, the overall Australian mean rainfall total for 2009 was 453 mm, slightly less than the long-term average (1961-90) of 464 mm. Above-average rainfall in January and February, especially in the northern tropics, was followed by dry conditions from March onwards, with the March-November total being the 10th lowest on record for Australia. A dry year in the southeast and southwest of mainland Australia has prolonged the multi-year meteorological drought in those regions.
During July to October 2009, serious rainfall deficiencies were experienced over large areas of Queensland and isolated parts of NSW, consistent with the development of an El Niño event during this time. The unusually dry and warm winter was associated with a series of dust-storms across eastern New South Wales and southeast Queensland in September and early October.
Despite the long dry, several short-term flood events occurred in eastern Australia in 2009, the most notable in May when daily rainfall totals exceeded previous records for the month at locations across Queensland and New South Wales. Parts of Tasmania were affected by repeated flooding during May to September. Timely rainfall across southern Australia in winter and early spring resulted in record falls in southeast Tasmania and eased water shortages for some agricultural regions and the urban water supplies of Adelaide, Canberra and Melbourne. The year ended with further flooding in parts of NSW and Queensland.
Accessing Australia's climate change datasets
The Bureau of Meteorology is responsible for collecting, managing and safeguarding Australia's climate archive. Several high-quality datasets have been developed from this archive to identify, monitor and attribute changes in the Australian climate. Extensive rehabilitation work has been undertaken on these data to ensure they have not been compromised by changes in site location, urbanisation, exposure or instrumentation over time. These high-quality data series can be accessed at: http://www.bom.gov.au/cgi-bin/climate/hqsites/site_networks.cgi