Thursday, January 1, 2009

Melbourne's rising mercury

TEMPERATURES were almost a full degree hotter in Melbourne during 2008 compared to the long-term average, as the trend for hot and dry conditions showed no sign of abating.

The warm weather and another poor rainfall result appear to support predictions that the south-eastern corner of Australia will be among the areas most affected by climate change.

The Bureau of Meteorology said daytime temperatures were higher than average in most Victorian centres, with Melbourne showing one of the biggest jumps. Daytime maximums in the city during 2008 averaged 20.9 degrees — higher than the 20 degrees that is the bureau's accepted long-term average for Melbourne's daily maximum. The long-term average was measured between 1961 and 1990.

Temperature rises were less pronounced in the evenings, where the 2008 average minimum was 11.6 degrees and the long-term average is 11 degrees.

Bureau forecaster Geoff Feren said 2008 had continued the trend that had emerged across Victoria during the past decade.

"All you can say is it's a continuation of the trend over recent years for significantly drier than normal and also a bit warmer than normal," he said.

"Conditions were drier than normal almost everywhere in Victoria. Rainfall totals were generally between 100 millimetres and 200 millimetres below average."

Melbourne's rainfall reduction was much greater. The 447 millimetres recorded at the city gauge — almost identical to the 2007 result of 448 millimetres — was well below the long-term average of 639 millimetres.

Rainfall over Melbourne's water catchments is often higher than at the city gauge — although the figures were not available yesterday.

Yet the city result was still indicative of the dry conditions that have led Melbourne's dams to their lowest start to a year since the current network of reservoirs filled.

Dams were at 34.9 per cent of capacity yesterday, but 2009 will be the final year that Melbourne relies solely on its dams for drinking water. The controversial north-south pipeline is expected to connect Melbourne to Lake Eildon and the Goulburn River in early 2010.

The bureau is yet to finalise its assessment of national climate data for 2008, but the year appears likely to have been Australia's 15th warmest since 1910.

The bureau expects average maximum temperatures for 2008 to have been about 0.3 degrees above the long-term average.

No comments: