VICTORIA will be a hotter and drier place by mid-century, with more desert and fewer temperate regions because of the impacts of global warming, new scientific analysis has found.
In a major report, Victoria's Commissioner for Environmental Sustainability, Kate Auty, warns the changes will put infrastructure and biodiversity at risk, and leave agriculture and endangered species exposed.
New climate modelling and analysis by the CSIRO and the Bureau of the Meteorology was carried out for the report using the UN Intergovernmental Panel on Climate Change's scenarios on future global greenhouse gas emissions.
The report says the best CSIRO estimates project a 1.37-degree rise in temperatures by 2050 for Victoria - potentially as high as 1.93 degrees - under a scenario of rapid economic growth and an energy mix of fossil fuels and renewables.
Under the same scenario, rainfall is projected to decline by 6 per cent by 2050, with the reduction potentially as high as 14 per cent. The highest 1 per cent of rainfall events will become more intense.
When natural variability is considered along with human-induced changes, the decline in rainfall is found to be as high as 17 per cent, but could also increase by 5 per cent under some scenarios.
As temperatures rise and rainfall declines, the types of local climate will begin to change across the state, with more areas of desert emerging and temperate regions disappearing as climatic conditions shift south.
In Mildura, the warm grassland climate is most likely to move to hot desert by 2050 under several of the emissions scenarios. In Avalon, the temperate climate is most likely to shift to persistently dry warm grassland.
In Melbourne, the increasing impact of the urban heat island effect - dense city infrastructure increasing temperatures - will create a climate class that is observably warmer than surrounding areas.
Under the hottest and driest outcomes modelled for a longer-term warming of four degrees by 2080, Melbourne would experience the same climate as Leeton, in central-west New South Wales, does now.
The report also said an analysis of daily and season fire danger indexes suggested ''serious'' and ''major'' fire seasons were becoming more common and non-significant seasons had become rarer, with bushfire impacts to worsen.
The changes would have major implications for the state's environment and infrastructure, Professor Auty's report said, requiring preparation for more intense bushfires and increased inundation of coastal areas.
Victoria's natural world will also be affected. As warming occurs and landscapes change, species may need to migrate to more suitable areas. But Victoria's fragmented natural habitat will limit migration for less-mobile species, such as those in high-altitude or southerly region, it says.
Professor Auty writes that to read the impacts of climate change on Victoria outlined in the analysis ''is to be deeply concerned. Calls have been made for 'aggressive' intervention. The situation we confront clearly warrants such a response across all tiers of government, industry sectors and the broader community.''
The report is one of three ''foundation papers'' being prepared by the commissioner's office before the release of the Victorian State of the Environment assessment due late next year.