General practitioners, emergency doctors and surgeons were among those calling for fossil fuels to be phased out to protect the community from the negative effects of global warming.
Doctors for the Environment Australia said hospitals were already seeing the impacts of climate change and the government needed to prioritise the health and wellbeing of the community over the fossil fuel industry.
"The WA government must stop adding fuel to the fire, stop new gas projects and contain the escalating health crisis," GP Tim Leahy said on Friday.
The group also wants subsidies for fossil fuel companies to be axed and more investment in renewable energy.
Doctors and health professionals representing the Royal Australasian College of Surgeons, the Australian College of Rural and Remote Medicine and the Public Health Association Australia were also involved in the rally.
The Royal Australian College of General Practitioners WA said climate change was a public health emergency.
"GPs in WA and across Australia are already seeing the impacts of climate change on our patients, including from more extreme bushfires, heatwaves, droughts, and storms, which affect both physical and mental health," a spokesman said.
The groups said evidence showed the number of ambulance callouts were greater on high-heat days, with emergency departments experiencing increased patient presentations for heat-related illnesses and other associated diseases.
They said the burden this placed on the state's "ailing" health system would increase as the climate warmed.
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