The former Liberal leader is championing crossbench bill and argues ‘it was an emergency 30 years ago’

The former Liberal leader John Hewson has called on Scott Morrison to grant government MPs a conscience vote on a new parliamentary motion declaring a climate emergency.

Hewson, who will join MPs on Wednesday to champion the new parliamentary motion which is being pursued by the Greens and is supported by most of the lower house crossbench, told Guardian Australia there was no controversy associated with declaring a climate emergency in 2019, “because my view is it was an emergency 30 years ago”.

He said Liberal backbenchers were feeling pressure from their constituents about the Coalition’s lack of ambition on climate change, so the prime minister should allow a free vote on the motion.

Hewson argued if it had been acceptable for Tony Abbott to declare a budget emergency in the run-up to the 2013 election, Liberals in 2019 should have no issue with adopting the language in the Greens motion, because declaring a climate emergency in Australia “almost goes without saying”.

Australian natural disasters minister David Littleproud: 'I don't know if climate change is manmade' Read more

He said Australia should have adopted ambitious climate policy in the 1990s, but given that failure “we’ve left it very late in the day to get to net zero emissions by 2050”.

The British parliament declared a climate emergency in May, endorsing a parliamentary motion moved by the Labour party. Conservative MPs in the UK were told to not oppose the Labour motion.

A number of Australian councils have already declared a climate emergency, including the Wagga Wagga city council in the electorate of the deputy prime minister and Nationals leader Michael McCormack – although the Wagga motion was subsequently rescinded.

The Australian Medical Association has formally declared climate change a health emergency, pointing to “clear scientific evidence indicating severe impacts for our patients and communities now and into the future”.

The Senate late on Tuesday passed a Greens motion on the voices calling on the government to protect Australian farmers by “taking urgent action to address the climate emergency”. The Senate motion addressed drought and the elevated summer fire risk.

The proposed declaration motion for the lower house calls on the House of Representatives to declare an environment and climate emergency and to take urgent action consistent with internationally accepted science.

It notes that extreme weather events will devastate large parts of Australia and radically impact food production, water availability, public health, infrastructure, the community and the financial system; and notes that the government has acknowledged urgent action is required to address climate change.

The proposal is being advanced by the lower house Green MP, Adam Bandt, and would seconded by the independent member for Warringah, Zali Steggall. The motion is supported by independents Helen Haines and Andrew Wilkie and the Centre Alliance member for Mayo, Rebekha Sharkie.

The Greens are yet to canvass Labor on whether they will support the motion. The former Labor leader, Bill Shorten, went close to declaring a climate emergency during the May election campaign, declaring in a speech during the final week: “We will take [the climate change] emergency seriously, and we will not just leave it to other countries or to the next generation”.

While senior Labor figures insist Labor will stay the course on climate change during this term, this week the shadow climate change minister, Mark Butler, said Labor needs to review all of its election policies, including the ones he developed in the climate and energy portfolio.

“Nothing should be excluded or treated as sacrosanct,” Butler said on Monday. “The area I had responsibility for – climate change and energy – must be part of that thorough examination, as should all of our taxation policies and the spending commitments they were directed at funding.”

Butler declared that after a federal election where Labor had its “backside handed to [it] by Fozzie Bear and Kermit the Frog – it’s time for some serious reflection”.

Activity in support of the motion comes as new research has found Australians are increasingly concerned about droughts and floods, extinctions and water shortages associated with climate change, and most people think all levels of government aren’t doing enough to combat the effects of global warming.

Authorities have warned that early spring bushfires in Queensland may go on for weeks. Firefighters on Tuesday were battling more than 50 fires in New South Wales. The overall fire danger index has increased for most of southern Australia over the past 40 years and the Bushfire and Natural Hazards Cooperative Research Centre says the trend is expected to continue.

But Australia’s minister responsible for drought and natural disasters, David Littleproud, told Guardian Australia on Tuesday while the climate is changing, he doesn’t “know if climate change is manmade”.