Will Boris Johnson please listen to his own father, rather than Jeremy Corbyn’s climate sceptic brother, on the subject of climate change? It may go against the prime minister’s instincts, but it is the best hope for Britain to live up to its responsibilities in a crucial year for our species.

Johnson cannot do this on his own. That much was clear this week during the shambolic London launch of the COP 26 UN climate summit, which will take place in Glasgow in November. This will be the most important international conference in five years and as host the UK will play a leading role in deciding whether it ends in success or failure.

The event was overshadowed by the sacking of the UK’s COP 26 president Claire O’Neill, who responded with a scathing takedown of a premier who she described as “not getting” climate change, failing to devote sufficient resources to summit preparations, and being fundamentally untrustworthy.

The firing was not all bad news. O’Neill lacked the political heft and diplomatic skill needed to forge a global consensus on this most divisive of issues. If a more senior politician is appointed in her place, it would show the UK is taking preparations more seriously. The fact that the prime minister is fronting the launch demonstrates an investment of political capital that is commensurate with the challenge.

He also said many of the right things, most concretely by confirming the UK’s commitment to go net-zero on carbon emissions by 2050. “Of course it’s expensive, of course it’s difficult, it will require thought and change and action, people will say it’s impossible and it can’t be done, and my message to you all this morning is that they are wrong,” he declared. “I hope it will be a defining year of action for our country, and indeed for our planet, on tackling climate change but also on protecting the natural world.”

But can he be trusted and can he deliver? On that question, almost all the evidence – from parliamentary voting records and donations from climate sceptics to his newspaper columns and performance as mayor – says no.

Although Johnson has repeatedly called for reduced emissions, he scored zero out of 100 in the Guardian’s climate scorecards last year based on his rejection of actions that would achieve this in five key parliamentary votes. This includes opposition to onshore wind subsidies, emissions-based vehicle taxes and carbon capture and storage.

He was also shown to have declared donations of £5,000 from Michael Hintze and £25,000 from Terence Mordaunt (via First Corporate Shipping), who fund the climate science sceptic Global Warming Policy Foundation.

The Conservative party says the Guardian cherry-picked votes and failed to recognise Johnson’s support for the net zero emissions target. The Guardian stands by its methodology, which can be read here.

Other broader data sources confirm the prime minister’s woeful record on parliament. The parliamentary watchdog They Work for You notes that Johnson has “almost always voted against measures to prevent climate change” with one vote in favour, eight against and six absences (the latter largely due to his period as mayor of London).

The gulf between words and deeds was also evident when Johnson was foreign minister, when he oversaw a 60% cut in the UK’s team of climate attaches across the world from 165 to 65, just as the UK was supposed to be delivering the Paris agreement. He then tried to hush up what happened, according to the former chief scientist David King, who claimed Johnson also ignored his advice to be more publicly supportive of climate change and misled the public about King’s agreement to chair an inquiry into building an airport in the Thames estuary.

While mayor of London, his record was mixed. On the positive side, he initiated a trial of fully electric buses, raised diesel charges, improved cycling networks and encouraged tree planting and zero-emission taxis. But he also held back a report on the impact of air pollution on deprived schools and curtailed a western extension of the congestion charge zone, which could have reduced traffic and improved air quality.

His most famous green boast was that he would lie down in front of bulldozers to prevent a third runway being built at Heathrow airport. But was absent during the 2018 vote on this issue, and strongly supported his own pet airport project – a four-runway mega-terminal in the Thames estuary that never got off the ground.

Johnson’s newspaper columns provide copious proof that he does not “get” climate change. In 2012, he described wind farms as “white satanic mills”, supported shale gas fracking and urged readers to “ignore doom merchants” who warn of the dangers of emissions.

On three occasions, he blithely – and completely wrongly – claimed global heating was primarily caused by solar activity. “Whatever is happening to the weather at the moment, it is nothing to do with the conventional doctrine of climate change,” he wrote in 2015, citing the debunked claims of the climate sceptic Piers Corbyn – the brother of the Labour leader Jeremy Corbyn. He was scoring points against a political opponent by dismissing the consensus view among scientists that the climate crisis is driven by human activity.

The prime minister’s father, Stanley Johnson, is, by contrast, a committed environmentalist who has campaigned for faster action on climate change. At an Extinction Rebellion demonstration last year he declared himself proud to wear the badge of “non cooperative crusties”, which was the criticism levelled by his son at protesters. His influence is apparent in Boris Johnson’s endorsement of various wildlife campaigns, which he presents in colonial fashion as the fault of other nations. A quick glance at his backlist of articles reveals attacks on Japan for whaling, China for the slaughter of pangolins, and a belief that African elephants and cheetahs need to be saved by the UK.

On the basis of his diplomatic clumsiness, poor grasp of science and voting record, Johnson appears to be the worst man for the job of making COP 26 a success. But, beyond his dad, there are two other reasons to hope that he might yet turn the pig’s ear of preparations into a silk purse of an event. If the democrat in him – and, perhaps more importantly in his adviser, Dominic Cummings – decides strong climate action is the will of the electorate (as polls overwhelmingly suggest), then he could demonstrate this by pushing it through with the same determination as Brexit. And if the patriot in him makes up his mind to make the UK a global leader in solving the greatest challenge of our age, then he will recognise the need to appoint a strong candidate to replace O’Neill.

In this week’s speech, he alluded to this in an encouraging recognition of the UK’s responsibility to decarbonise. “I think it’s quite proper that we should, we were the first, after all, to industrialise. Look at historic emissions of the UK, we have a responsibility to our planet to lead in this way and to do this,” he said.

Sadly it seems more likely, given his own history and his squabbles with Nicola Sturgeon over the hosting arrangements, that Johnson will put political partisanship first and bow to pressure from the US to downplay climate concerns in return for a trade deal, and from his donors and supporters to weaken EU environmental standards so the UK economy is more competitive after Brexit.

Father will not approve. But Corbyn’s brother, at least, will have reason to smile.

• This article was amended on 11 February 2020. A previous version said that, as Mayor of London, Boris Johnson had electrified the city’s bus fleet; it now clarifies that he initiated a trial of fully electric buses.