Older voters opposed to Adani's Queensland coal mine have vowed to continue a protest in Brisbane until they're arrested.
Queensland grandmother Rae Sheridan has been arrested three times at protests demanding action on climate change.
If she has her way, it'll be four by the end of the day.
The 74-year-old is among a band of "grey power" activists who are staging a small but determined protest against Adani's proposed coal mine in outback Queensland.
They are incensed at the federal government's decision this week to approve the mine's groundwater management plan, one of the final approvals Adani needs to before it can start digging.
With deck chairs for comfort, and umbrellas for shade, the group is picketing the Brisbane headquarters of the Liberal National Party on Thursday.
And they've vowed to stay until they are arrested.
"(I'd) probably rather die in jail than in a nursing home," Ms Sheridan told AAP on Thursday.
"This issue is of such importance, because stopping Adani is a line in the sand for our relationship with coal. It has to stay in the ground ... New Zealand has done it, Australia can do it too."
Fellow protester Greg McLachlan says he was moved to take action after watching thousands of school students take to the streets across the globe, calling on governments to protect their futures.
"We should have done more, and we should be doing more," he told AAP, welling up with sadness.
"The future is their's, not ours, and we are letting them down."
Adani's Carmichael mine project is an issue because Queensland is one of the key states needed to win federal government.
It is popular in the state's central and northern regions, but could cost support among voters in inner-city seats who want more action on global warming.
Labor's environment spokesman Tony Burke says the prime minister called the election on Thursday to avoid Senate estimates hearings that would have seen the CSIRO grilled about the recent groundwater approval handed to Adani.
The hearings were promptly cancelled after Scott Morrison called the poll for May 18.
Adani's plan manage groundwater now needs state government approval so that it can start digging.
But Labor Premier Annastacia Palaszczuk's government says it won't be rushed into a decision to approve that plan, and another to manage the tiny and endangered black-throated finch.