A leading climate scientist has explained how increases in global temperatures lead to more frequent and extreme weather events, as part of the first climate class action brought by Australia's First Nations people.
With rising sea levels and other effects of climate change threatening their islands and way of life, Torres Strait Islander elders Pabai Pabai and Paul Kabai launched a Federal Court case against the federal government in October 2021.
The elders are arguing the Commonwealth owes a duty of care to Torres Strait Islanders to take reasonable steps to protect them from the harms caused by climate change.
The court held on-country hearings on Badu, Boigu and Saibai islands in June, Cairns in July and moved to Melbourne on Wednesday.
Climate scientist Professor David Karoly gave evidence on the impacts of global warming and sea level rise in the Torres Strait.
He outlined several possible scenarios for the future, depending on how much the earth's temperature rises.
Prof Karoly explained that extreme weather events become more frequent and larger with every increment of global warming.
He said his analysis had shown statistically significant increases in the frequency of temperature extremes in the Torres Strait from 1950 to 2021.
While Australia cannot address the effects of human-caused climate change alone, it can make a significant and bigger contribution than it is now, Prof Karoly said.
"Australia committing to zero emissions on its own is not sufficient to stop global warming," he said.
"But Australia is an important part of global action to reduce greenhouse gas emissions and to limit global warming."
Torres Strait Islander witnesses shared cultural and personal stories at the on-country hearings earlier this year, explaining how climate change was impacting the island way of life.
Mr Kabai told AAP that during his lifetime he had already seen the seasons change - and with them opportunities for hunting and fishing.
"We have these big inundations during monsoon season, which mean our water system, the island wells and everything is contaminated by salt," he said.
He said he has a responsibility to protect his homelands, community and culture from climate change.
"Our message to the Australian government is that we can't wait any more years for climate action," Mr Kabai said.
"If all they do is continue to talk and not listen to the scientists, our communities will disappear and we will lose everything."
Mr Pabai said if the government continues to fail his people, they will be forced to leave their homelands.
"On Boigu, the land is being eroded, our soil is being ruined by salt and the storms are becoming worse," he said.
"From the land, to the sky, to the seas - we are the people of the culture.
"If we are forced to leave our homelands, we will lose everything, our identity, our culture - everything."
Boigu and Saibai are flat, low-lying islands, about one and a half metres above sea level, meaning they are particularly vulnerable to rising seas.
Both islands are now frequently flooded by sea water, particularly during king tides, which is already affecting housing, infrastructure, cultural sites and gardens where people grow vegetables.
The court will hear from experts in climate science, health and marine biology on Thursday.
