The former US vice president Al Gore has criticised the Morrison government for failing to increase the ambition of Australia’s 2030 emissions reduction target and warned coal workers to be deeply sceptical about “hollow words” from politicians.

Gore told a virtual conference organised by Engineers Australia on Tuesday he was glad Scott Morrison took a pledge to achieve net zero emissions by 2050 to the Cop26 summit in Glasgow, given the Intergovernmental Panel on Climate Change’s most recent assessment of the climate crisis deemed the problem a “code red for humanity”.

But he said a 2050 target “without a near-term pledge has very little meaning”.

“I was disappointed that the 2030 target was not increased,” Gore said. “I do think Australia should do more.”

Australia is the only major developed country that refused to increase its 2030 emissions reduction targets at the Cop26 in Glasgow.

In an effort to blunt sustained international criticism about his government’s lack of climate ambition, Morrison used his national statement at the Cop26 to emphasise that Australia would probably overachieve on the Abbott-era 2030 target of a cut in emissions of between 26%-28% on 2005 levels.

At the conclusion of Cop26, the Morrison government also supported language in the Glasgow communique pointing to a review of the 2030 target before the next United Nations’ led climate conference in Egypt.

But in a statement issued in Australia shortly after the Glasgow summit finished, ministers Marise Payne and Angus Taylor declared Australia’s 2030 target was “fixed” and the Coalition had no plans to ratchet up ambition.

A Cop26 spokesperson told Guardian Australia countries needed to step up their current commitments: “Over the coming year, the UK presidency will work hard to drive even greater ambition on the delivery of the Glasgow climate pact to lead the fight against climate change.”

“Through working together at the summit we have kept 1.5 alive, though this will only survive if we keep our promises and translate commitments into rapid action,” they said.

At the final Glasgow press conference, the Cop26 president Alok Sharma was asked what would happen if nations like Australia failed to update their targets.

“All countries have signed up to this and at the end of the day this is an international agreement and every country will be judged by whether or not they stuck to the commitments they’ve made,” Sharma said.

Given the international focus on 2030, and the diplomatic pressure on Australia from allies including Britain and the United States, Morrison attempted in the run up to Cop26 to secure agreement within the Coalition to increase the Abbott-era 2030 target. But that effort was vetoed by the National party.

The Nationals leader and deputy prime minister Barnaby Joyce is continuing to insist the junior Coalition partner will not support a stronger 2030 target – even though the prime minister says regularly Australia will likely cut emissions by 35% by 2030 on current projections.

“The Nationals have clearly stated that they aren’t changing the 2030 target,” Joyce told the ABC on Tuesday. “We’ve been honest and upfront about that … we’ve told you the truth about what our position is.”

But Joyce did not directly answer a question about whether the Nationals would be prepared to support a new, more ambitious, 2035 target.

A number of Liberals are urging Morrison to go to the election with a new emissions reduction target for 2035. Liberal backbencher Jason Falinski told the ABC on Tuesday afternoon he intended to keep campaigning for that landing point. “I’ll keep trying,” he said.

Falinski said he thought Morrison could have increased the 2030 target to align it with the latest projections that show Australia could achieve a 35% reduction. But he said he understood the prime minister’s arguments that changing the 2030 target would breach a commitment made to voters at the 2019 election.

The Liberal MP said the most recent government projections opened the opportunity for Australia to adopt a higher emissions reduction target for 2035.

Falinski said he hoped Morrison would take a new commitment both to the next Cop meeting in Egypt and to the Australian people at the looming federal election. “We need to go to the next election with an updated target – a new plan.”

But Joyce said Falinski and his Liberal colleague Dave Sharma – who has also championed a higher 2035 target – were “great people” who represented an affluent metropolitan constituency.

While avoiding a direct answer on 2035, Joyce contended the view of voters in Sydney were different to the “view you get in Singleton or Muswellbrook”. Joyce said Liberals and Nationals needed to represent their respective constituencies.

Joyce is continuing to insist Australia’s coal industry will continue to flourish despite the government’s own modelling pointing to a significant reduction in the coal sector by 2050.

During his contribution to the engineering summit on Tuesday, Gore warned coal sector workers to be sceptical about “hollow words” about their job security by the political class.

He said politicians spruiking the coal industry could not protect workers from automation or “from the market forces that are driving the cost of electricity from renewable sources so much lower than the cost of electricity from burning coal”.

Gore likened politicians like Joyce to King Canute telling the tides to stop.