A Lancet medical journal report warning of the major threat to global health posed by climate change shows Australia cannot "sit back and do nothing".

Australia should take the lead in addressing climate change, say doctors following the release of a report on its potentially catastrophic risk to human health.

The Lancet medical journal report, launched on Tuesday, warns that while there are direct health impacts associated with climate change, such as more frequent and intense weather events, there are also indirect impacts such as changes in infectious disease patterns, food insecurity, involuntary migration, displacement and conflict.

Anthony Costello, the co-chairman of the commission that produced the report, said failure to address climate change could undermine the past 50 years of gains in economic development and global health.

Australian Medical Association president Brian Owler said the evidence was clear, adding: "We cannot sit back and do nothing.

"The AMA believes Australia should be showing leadership in addressing climate change and the effects it is having, and will have, on human health.

"As part of the global community, Australia must lead with ambitious targets to reduce greenhouse gas emissions."

The report's authors say the potentially catastrophic risk to human health posed by climate change has been underestimated, and that while the technologies and finance required to address the problem can be made available, global political will to implement them is lacking.

The report says there are options for policymakers that could effectively tackle climate change, and protect and promote human health, while also reducing pressures on national health budgets and delivering large cost savings.

The Climate and Health Alliance executive director, Fiona Armstrong, said the report made it clear the health benefits associated with emissions reductions are the "real low-hanging fruit in the climate policy landscape".

"Billions of dollars in savings for health budgets are available from moving to low carbon technologies and resources, with health benefits and budgetary savings available now, while climate benefits accumulate in the longer term," she said.

Royal Australasian College of Physicians president Nicholas Talley said the report reveals that climate change will disproportionately impact older people and people with existing health issues or disabilities, and disadvantaged communities in Australia.

"It highlights the urgency for action by health professionals around the country," Professor Talley said.

"It is our duty to care for the health of our community. As health professionals, we have a responsibility at a local, national and global level to address climate change."