In a keynote speech at Australia's Great North Conference in Darwin, the former federal environment minister urged conservation groups to work together to fight against the industry even in hard times.
One reason he put forward for the "Great North" determining Australia's future was the multiple fossil fuel developments in the region.
"Residents of the Northern Territory are essentially being climate sacrificed by territory, state and federal governments in thrall to fossil fuel companies," he said on Thursday.
The resources industry was "in effect a criminal enterprise knowingly contributing to an activity that is causing harm".
Mr Garrett said the latest climate risk assessment showed the NT and other northern regions of Australia would experience the greatest increase in temperatures, with numerous communities at high to extreme risk.
Another reason to watch the north as a determiner of the future was the failure of elected representatives to exercise duty of care over land and sea.
Land and seascapes were at risk, notably the big river systems, not just from climate impacts but from poorly considered decisions and deficient development proposals, Mr Garrett said.
National reconciliation, partly derailed by the Voice referendum, but still necessary to heal modern Australia, was another reason the region was important, the long-time advocate for Indigenous rights said.
First peoples make up a substantial proportion of the population in the north and own and control significant swathes of Country, he noted.
Defence and the growing militarisation of Australia's north was a further trend to watch, with Australia subject to the push and pull of the world's two largest economies and militaries - the US and China.
"With emerging contests over territories and markets with little public debate, the militarisation of the Top End continues apace with increased troop deployments, integrated military exercises ... and ramping up the military infrastructure."
Mr Garrett questioned whether defence planning was oriented to defence or as an expeditionary force set up for joint operations with the US.
"It's no exaggeration to say that in this lightly populated still remote neighbourhood, the future character and shape of democratic Australia will be forged."
Mr Garrett listed successes of the conservation movement in preventing harmful resource projects going ahead and urged activists at the conference to put relentless peaceful pressure on elected representatives.
"It's time to address the fact that current campaign approaches, notwithstanding occasional successes along the way are not working as well as the parlous situation requires." Â
But he said he was confident a "trusted, indefatigable climate and environment movement, with Indigenous partners and willing allies ... can make a better future happen".
