Torres Strait Islander leaders are suing the federal government alleging it has failed to protect their communities from climate change harm.
Gadamalulgal traditional owners from the low-lying islands of Boigu and Saibai are leading a class action alleging the government breached the duty of care owed under native title and the Torres Strait Treaty.
Wadhuam Paul Kabai and Wadhuam Pabai Pabai are seeking a Federal Court order requiring the government to actively take steps to prevent harm by cutting greenhouse gas emissions.
The two men fear a global temperature rise of more than 1.5C will render their islands, about one and a half metres above sea level, uninhabitable and make Torres Strait Islander people Australia's first climate refugees.
"Our ancestors have lived on these islands for more than 65,000 years. But the government's failure to prevent the climate crisis means our islands could be flooded," Mr Kabai said.
"Becoming climate refugees means losing everything: our homes, our culture, our stories and our identity. If you take away our homelands, we don't know who we are."
Mr Pabai can't imagine being forced to leave Boigu because "this island is me and I am this island".
"If you take us away from this island then we're nothing. It's like the Stolen Generation, you take people away from their tribal land, they become nobodies," he said.
The class action was filed in the Federal Court on Tuesday as Prime Minister Scott Morrison announced Australia would adopt a target of net zero emissions by 2050.
The coalition projects an updated emission cut of between 30 and 35 per cent on 2005 levels by 2030, but won't adopt this as a target.
The court case against the government is being run by public interest law firm Phi Finney McDonald with the backing of advocacy group the Grata Fund and Dutch nonprofit the Urgenda Foundation.
"Paul and Pabai bring this action to require Australia to reduce greenhouse gas emissions to a level that will prevent Torres Strait Islanders from becoming climate refugees," principal lawyer Brett Spiegel said.
A spokesman for Environment Minister Sussan Ley said she could not comment while the matter was before the courts.
Australian Associated Press