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MELBOURNE will have twice as many days over 35 degrees and morning frosts will become a distant memory if greenhouse emissions are not curtailed, a State Government analysis shows.
Victoria is expected to warm at a slightly faster rate than the global average, especially in the north and the east.
Projections based on CSIRO figures found average temperatures statewide would rise by about 0.8 degrees by 2030. By 2070, the increase would be between 1.4 and 2.7 degrees, depending on how quickly the world acts on emissions.
If global negotiations aimed at cutting emissions are unsuccessful, the number of days over 35 degrees in Melbourne would jump from nine to 20.
The biggest shift is predicted for Mildura, where nearly one in every six days — 59 a year, up from 32 — would push the temperature into at least the high 30s.
Morning frosts in Melbourne would fall from three a year now to two in 2030 and, if little is done, none by 2070. Under the worst scenario, the number of rainy days in Melbourne would be cut by about a fifth.
In line with predictions in the Garnaut review's draft report released last week, the analysis found Victoria was likely to have more days of high fire danger, less snowfall, more frequent droughts, and rising risk of coastal erosion.
Statewide annual rainfall would drop by about 4% by 2030 and by up to 11% by 2070, with the greatest decline in winter and spring. Isolated periods of heavy rainfall were most likely in summer and autumn.
"The frequency of drought is likely to increase by between 10% and 80% in the southern half of the state," the report says.
Victoria posted its hottest year on record last year. The past 11 years have all been hotter than the long-term average.
The report says Melbourne and other cities are increasingly affected by the "urban heat island" effect: temperature rises caused by reflected heat from buildings and roads.