Scientists say new research proves the Indian Ocean has significantly warmed and there will be less rain across southern Australia.

The CSIRO research has found a rise of 2 degrees Celsius in the Indian Ocean over the past 40 years.  It confirms long-held beliefs of general warming but for the first time in exact detail.  The researchers say the temperature change cannot be explained by natural variability and is linked to the heating up of the atmosphere.

Chief researcher Dr Gael Alory says the rising temperature of ocean currents means fewer storms along the Australian coast.  "There will be less rainfall on the continent," he said.  "The rainfall will move more south to just the ocean and that means less rainfall."  He says Western Australia's south-west will be hardest hit by the change in climate.

The research was carried out by following the trade routes of ships and measuring temperatures down to 800 metres.