Demonstrators rallied in eight cities across Australia on Saturday to champion the critical role science plays in our lives, and to call on the government to support more evidence-based decision making and to reinstate a Minister for Science.

"The application of science and mathematics to the world is our greatest tool, science can impose itself or run through all policy levels all areas of government," Adam Spencer, Sydney University Ambassador for mathematics and science said.

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It was the second annual March for Science and this year's rally featured speeches by a range of experts.

Vivien Thomson is a farmer and a firefighter, and one of the only women to win the Australian Fire Service Medal for distinguished service. She says science underpins all her work, not only on the farm but also fighting fires.

"I've never seen fires be so hard and so fast and harder to put out... the climate surrounding our firefighting capacity is really affecting our ability to put those fires out," she said.

"It's like the natural phenomenon are on steroids."

Experts say climate change is being felt around the world with the increasing intensity of heatwaves, floods and droughts.

As Australia experiences one of its hottest Aprils on record, demonstrators called on the government to give greater support to scientific research to tackle climate change.

"The jury is in, its indisputable human impact on the current warming climate and also the jury is in on how quickly we need to act," said Spencer.