L’Australie subit une vague de chaleur record, avec des températures dépassant les 40° dans le sud et atteignant 50° dans l’intérieur du pays. L’augmentation de la consommation électrique a par endroit provoqué l’effondrement du réseau, désorganisant les transports publics. Le sud du pays souffre d’une sécheresse marquée depuis plus d’un an. Les météorologues australiens estiment qu’elle est dûe en partie au changement climatique.

NZ Herald, 30 janvier 2009

Southeast Australia yesterday continued to bake in its worst heatwave in a century, with temperatures soaring well above 40C and reaching a furnace-like 50C in the remote interior.

As forecasters warned of another week of unrelenting heat, tens of thousands of homes and businesses in Victoria and South Australia were yesterday without power as electricity systems collapsed.

Train and bus services were hit by widespread delays and cancellations, ambulance services reported a surge in heat-related callouts, and fire services remained on high alert in extreme conditions.

In Adelaide, commuters were handed free bottles of water as buckling rails and mechanical breakdowns hit public transport.

Dozens of people have been taken to emergency wards, and health officials warned of dehydration and other possible medical problems at today’s Big Day Out concert, expected to attract more than 30,000 people despite sweltering 40C temperatures.

Firefighters contained about 20 outbreaks across the state.

Not since January 1939 - when mercury soared to a record 46.1C - has Adelaide suffered days reaching 45C. Forecasters expect the run of over-40C days to extend to six days, the longest heatwave since 1908.

Temperatures are expected to remain in the 40s until Sunday, falling only marginally to the high 30s next Monday and Tuesday.

In Victoria, Melbourne continued to endure a similar one-in-100-year heatwave, with Tuesday night barely cooling to a minimum of more than 28C after a searing 43C day.

The city had already reached 40C by lunchtime yesterday, with forecasters warning that today could again reach 43C - a record three-day run.

Across the state, temperatures climbed even higher in country towns. Train services were cancelled, paramedics treated more than 100 people for heat-related conditions, and firefighters braced for trouble with forecasts of strong, hot winds in many areas. Power failures cut supplies to more than 100,000 people, forcing authorities to call in crews from Tasmania and Queensland to help restore supplies.

But Energy Minister Peter Batchelor told Fairfax Radio that the state would be able to cope.

"The issue that has arisen is different to one of total bulk supply,’ he said. "We’ve got very intense heat pressure on our electricity distribution network causing localised problems, and we are responding to those."

And Melbourne can expect at least some relief. On Saturday a southerly change is expected to push temperatures down to the mid-30s.

Bureau of Meteorology - Drought Statement

Déficit de précipitations sur les 36 derniers mois

The rainfall deficiencies map for the 18-month period from July 2007 to December 2008 shows serious to severe deficiencies in areas across southeast Australia, western Queensland and central Australia. A small area of lowest on record is evident near Hobart. Over the 18-month period the Top End and much of eastern Queensland and northeast NSW had some benefit from above average rainfall associated with the 2007/08 La Niña. However, in southeastern Australia, central Australia and western Queensland, apart from wet November and December periods in both 2007 and 2008, rainfall was generally below to very much below average.

The Indian Ocean Dipole (IOD) is a pattern of sea surface variability across the Indian Ocean that is associated with lower than normal rainfall over central and southern Australia when it is in a positive phase (see IOD). Both 2007 and 2008 were consecutive years of sustained positive IOD, which partly explains rainfall deficits through the 18-month period in these areas. The IOD usually has its greatest impacts between June and November.

The deficiencies discussed above have occurred against a backdrop of decade-long rainfall deficits and record high temperatures that have severely stressed water supplies in the east and southwest of the country. The combination of record heat and widespread drought during the past five to ten years over large parts of southern and eastern Australia is without historical precedent and is, at least partly, a result of climate change.

BOM