“THESE days, it can be hard to imagine how Melbourne ever earned a reputation as the gloomy, rain-filled capital of the south. But, growing up in the 1970s, my memories are full of muddy ovals, local creeks in flood and catching tadpoles in puddles that lasted for months on end. How things have changed.”
This is how David Jones, head of climate analysis at the Bureau of Meteorology, began an opinion piece entitled ‘Our hot, dry future’ published by Melbourne’s The Age newspaper on October 6, 2008.
The piece continued,
“Since 1996, each successive calendar year has brought the city below-average rainfall. With 299 millimetres recorded so far this year, and with just three months to go, it seems virtually certain that this year will become the 12th in a row that has failed to get to the average of 650 millimetres. September 2008 was the driest on record in Melbourne, and the outlook for the remainder of the year suggests that below-average rainfall will continue…
“We also know that over the past 11 years Melbourne’s rainfall has been about 20% below the long-term average, and that south-east Australia as a whole has now missed out on more than a year’s worth of its normal rainfall over the duration of the event. The run-off into Melbourne’s dams has been 40% below average over this drought period compared with the longer term, while regional areas have fared even worse. And the drought hasn’t ended.”
Dr Jones goes on to blame climate change for the drought and warns there is worse to come.
I recognise that Dr Jones is an expert on predicting future climates, but I am not sure he has adequately explained the recent past climate of Melbourne.
Climate always changes and in a country like Australia climate tends to naturally cycle between periods where there is a dominance of wet La Nina conditions and then dry El Nino. The 1950s and 1960s were very wet along the entire east coast of Australia, but since 1976 the median state of the Pacific Ocean has been towards El Nino that is dry conditions. Indeed Dr Jones was a young boy when it was relatively wet while his adult life has been dominated by El Nino conditions. Of course the built environment has also changed. Melbourne is a much more affluent city now than it was 30 years ago and along with affluence comes laser levelling of sporting venues and much improved drainage and flood mitigation so ovals dry out relatively quickly, creeks are slowed and puddles in public places now a thing of the past.
But there is more to this story.
Bill Kininmonth, a meteorologist formerly with the Bureau, has made the following comment about how the recording of Melbourne’s weather has changed over the years and how the rain gauge in Melbourne’s central business district is now sheltered from the rain bearing winds of the southwest:
“Although Melbourne’s observations commenced in 1851 the location and environment have changed over that time. The earliest observations commenced at Flagstaff Hill and then they changed to the Observatory site south of the Yarra. For more than 100 years the observations have been taken from the present site on the corner of Victoria Parade and Latrobe Street. However there has been urbanisation. The site has clearly lost exposure to the cooling southerly winds and the rain gauge is sheltered from the rain bearing winds of the southwest.
“Clearly it is difficult to draw a conclusion about Melbourne’s climate and the possibility that it might be changing. The urbanisation of the site should make the record indicate a hotter and dryer climate, whether or not that has occurred. Essendon airport was a previous non-urban locality in the vicinity but that closed in the early 1970s. Tullamarine is the current site but was not open during the dry periods of the first half of the 20th century. Laverton, likewise an early site with long data has also been closed.”
I shall post more tomorrow on Melbourne’s total catchment rainfall and water storage levels in Part 2 of ‘How Melbourne’s Climate Has Changed: A reply to Dr David Jones’
Our hot, dry future, by David Jones, October 6, 200, The Age