City To Swelter Under Climate Change Predictions

Fairfax - Benjamin Preiss & Josh Gordon

Prepare for extreme heat in Melbourne. Photo: Leigh Henningham

Melburnians should prepare for more extreme heat with double the number of hot days, less rain and harsher fire conditions in coming decades, the state government has been warned.
Analysis prepared for the Andrews government paints a frightening picture of Melbourne's future climate, with transport infrastructure vulnerable to flooding and heat stress, longer and more severe bushfires and pressure on hospitals from heatwaves.
The modelling, from the CSIRO and Bureau of Meteorology, predicts climate change could have a major impact on the state's health system, economy and environment, including shorter snow seasons, food production challenges and problems with transport infrastructure.

Illustration: Matt Golding

The forecasts were prepared as the Andrews government seeks to elevate climate change as a political issue ahead of possible new laws to tackle emissions.
The predictions, based on international climate models, show that under a high emissions scenario similar to the current trend, the number of days over 35 degrees in Melbourne would more than double from an average of eight a year to 17 by 2070. Average rainfall could drop by up to 23 per cent in the most extreme case.
"Despite an overall trend of declining rainfall, more of the rain that does fall will be in increasingly extreme downpours," it said. "This is likely to lead to an increase in the incidence of flooding events, particularly in urbanised and small catchments."
The report says Melbourne has already become warmer and drier in recent decades, with sea levels up about 23 centimetres since 1880.
If the current high emissions trend continues, the report says, Melbourne's temperature could rise by as much as 2.6 degrees above the 1986 to 2005 average by 2070, with sea levels up by as much as half a metre.
"In 2050, under high emissions, the climate of Melbourne will be more like Adelaide now," the report says.
Other scenarios in the report are less dire although even under a lower emissions scenario, average temperatures would still rise by 1.5 per cent by 2070 compared to the 1986 to 2005 average.
Environment Minister Lisa Neville said Victorians were already feeling the effects of a warmer climate. She said the government was working to ensure the "right legislation" was in place to "deliver climate change action".
The economic, environmental and social ramifications of the changes are likely to be significant. The report warns future governments may need to consider moving "selected populations" in areas of extreme heat to other parts of the state. In one scenario Mildura would have 66 hot days a year.
Increased temperatures would have a major effect on Victoria's tourism sector, the projections show.
"The impacts of climate change on tourism are likely to include increased heat waves and harsher fire weather. Significant reductions in stream flows will adversely affect water-based tourism," it says.
The report finds temperatures have increased by up to 1.6 degrees in some parts of Melbourne since 1950.
Victoria's transport network would also be hit under the most extreme forecasts.
"Transport infrastructure will be increasingly exposed to periodic flooding and increased heat loading. Extremely high temperatures may also reduce the performance of the railway network, potentially leading to disruptions."
Warming seas and increased storm surges could also harm coastal ecosystems.
"Loss of biodiversity will place greater stress on the personal and economic wellbeing of communities in Greater Melbourne."
Monash University Cooperative Research Centre for Water Sensitive Cities Professor Nigel Tapper said the latest forecasts appeared consistent with international research.
While increased heat would impact Victorians' health, Dr Tapper said he was optimistic about reducing greenhouse emissions.
He said increasing vegetation in Melbourne could help to cool the city.
"If we do that we can mitigate against some of that extreme heat," he said.
The report also warned more hot days and heatwaves would exacerbate existing health risks, adding to pressure on hospitals and emergency services. "The urban heat island will add to heat stress," it said. "Vulnerable groups may need assistance to manage extreme heat, bushfires and flooding."