Environmentalists have described as reckless the decision by the Australian government to grant the Indian mining company Adani the final approvals it needs to start work on a huge coalmine in Queensland.

The project, which received the green light on Thursday to commence initial construction, would open up the Galilee Basin, one of the last known untapped coal reserves on earth.

“The Australian government has just facilitated opening up a new coal basin at the same time scientists are telling us we need to stop digging up coal and burning it because it’s fuelling global warming,” said Kelly O’Shanassy, the chief executive of the Australian Conservation Foundation.

“Really it’s kind of bordering on the definition of insanity to do that, especially in Australia where we’re experiencing one of the worst droughts in our living history.”

Adani’s plan has become a lightning rod for bitter debates over climate change and the economic struggles of regional Australia.

The proposal for an open-cut coalmine in central Queensland and a rail line connecting it to the port of Abbot Point, near the Great Barrier Reef, has faced years of opposition from activists and required multiple state and federal environmental assessments.

Immediately before Australia’s federal election was called in April, the Liberal-National Coalition government rushed out a decision to approve a groundwater ecosystem management plan.

It was the final federal approval Adani required to begin initial construction such as clearing and building access roads at the site, but other environmental plans still need to be assessed before the company can begin extracting coal.

The Galilee Basin in central Queensland is one of the last known untapped coal reserves on Earth. Photograph: Andrew Quilty/PR image

﻿Adani Mining’s chief executive, Lucas Dow, said on Thursday: “Throughout the past eight years regional Queenslanders have been beside us every step of the way and we thank them for their ongoing support. We’re ready to start work on the Carmichael project and deliver the jobs these regions so badly need.”

There are still some outstanding questions about what will happen next. Adani is yet to reach a mining royalties agreement with the Queensland government and still has to obtain a licence to build and operate the rail line.

It also needs to complete scientific research work related to the groundwater and geological formations near the Carmichael site and have that assessed by the federal government before it can begin extracting coal.

The environmental movement has vowed to become more vocal in its opposition to the project and what it sees as negligence by Australia towards its international climate obligations under the Paris agreement.

Ben Pennings, a spokesman for Galilee Blockade, said the anti-Adani campaign would be reframed to adopt tactics like those seen in the Extinction Rebellion protests in the UK. Protests were being planned for cities around Australia, he said.

“A majority of Australians want the Carmichael coalmine stopped but compliant politicians have failed to represent us,” Pennings said. “Sustained non-violent tactics like strikes, boycotts, street occupations and blockades will communicate our refusal to ever allow thermal coalmining in the massive Galilee Basin.”

The decision by the Australian government to rubber-stamp the project came in the same week that Britain moved to legislate a commitment to reach net zero carbon emissions by 2050, and not long after Britain hit a milestone of two weeks without using any coal to generate electricity.

In comparison, Australia has not only paved the way for new coal projects but is also opening up gas reserves. This week the Northern Territory government gave the mining companies Santos and Origin Energy the all-clear to resume gas exploration in the Betaloo Basin.

A coal train in Queensland. Adani still needs to obtain a licence to operate a railway in the Galilee Basin. Photograph: Lisa Maree Williams/Getty Images

Scientists have said that in order to limit global heating to 2C and avoid climate catastrophe, no new fossil fuel reserves can be opened. But Australia’s energy and emissions reduction minister, Angus Taylor, has championed the industry and defended the country’s increasing greenhouse gas emissions, which have been driven by rising carbon pollution from liquefied natural gas (LNG) production for export.

Taylor has claimed that although Australia’s emissions are rising, its LNG exports are contributing to the reduction of emissions globally because they are displacing higher-emitting alternatives such as coal. Scientists have dismissed the minister’s remarks as “grossly exaggerated” and “likely wrong”.

O’Shanassy said the Australian government was not only being reckless in terms of its international obligations to reduce greenhouse emissions but also endangering the lives of its citizens by opening up the Galilee Basin. Australia, with its hot summers, bushfires and droughts, is among the countries that stand to be worst hit by climate damage.

O’Shanassy predicted that after the events of this week people would try to stop construction of the mine. “I think we will see, if our government don’t act and they keep making the problem worse, communities will rise up and this Extinction Rebellion will happen across the world and will be far greater than the very significant rebellion we just saw in the UK.”