Australia's record-breaking heat last summer was at least five times more likely to have occurred in a world subject to to greenhouse gas emissions from human activities than one without, a study has found.

University of Melbourne researchers drew the conclusion after examining 90 model simulations and climate observations from summers of the past 100 years.

They used nine climate models — those used by the United Nation's Intergovernmental Panel on Climate Change — to test how likely the record temperatures in Australia between December and February would be in a world with and without human-induced global warming.

They found it was very likely — with 90 per cent confidence — that summers such as that of 2012-13 were at least five times more likely to occur due to man-made climate change than in a world facing only natural variation.

The researchers also found the frequency of extremely hot summers would continue to increase due to global warming.