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We were supposed to be past this, but apparently, we’re not. The BBC is still giving unwarranted airtime to people who deny the science of climate change. Its defence – that the misleading claims were rebutted the following day by a climate scientist – is hogwash.

On Wednesday, the BBC’s flagship radio news programme Today ran a segment about the release of : a new documentary on climate change fronted by former US vice-president Al Gore, a follow-up to his Oscar-winner . Gore was arguing that climate change is extremely dangerous, and that it would be in everyone’s best interests if we stopped it by drastically reducing our greenhouse gas emissions. As they should, the presenters asked Gore some tough questions.

But later in , climate sceptic Nigel Lawson of the was invited on to the show. Lawson’s role was to provide “balance”: in other words, to argue that there is no need to take strong action to stop climate change. During the interview, Lawson was allowed to repeat , without being challenged.

For instance, global temperatures have continued rising over the last decade, according to , the and . The years 2010, 2014, 2015 and 2016 . Yet Lawson falsely claimed that: “during this past 10 years, if anything, mean global temperature, average world temperature, has slightly declined”.

In a bizarre sequel, the BBC news website ran that offered tentative support to Lawson’s claims by linking to a �鶹��ý article published in 2008. This inspired well-deserved on social media: after all, a 2008 article could hardly offer much information on the 10 years leading up to 2017, and in any case the article was arguing that warming had continued. The link has since been removed.

Yesterday morning, 11 August, the Today programme . This time they invited , a climatologist at the UK Met Office. Stott duly presented evidence that Lawson had got his facts wrong.

In summary, the Today programme had an interviewee who pushed a series of falsehoods, and the presenters failed to challenge him. But the following day they had an expert on, who did challenge the falsehoods.

This may seem like good fact-checking journalism. But really it is shoddy journalism, because it fails to understand the audience.

If you present someone with misinformation, and later debunk it, the person often carries on believing the original misinformation. Their belief may even be reinforced by the rebuttal. Psychologists call this the “”.

What’s more, even if the person accepts the debunking, the misinformation still affects their thinking: we often mistrust people who have been accused of a crime, even if they were tried and found innocent. This is the “”.

This means Lawson’s false claims will still be active in the minds of listeners, even if they heard them refuted.

It is simply not good enough for Today to allow Lawson to spout nonsense, and rebut it later. False claims must be challenged immediately. Even better, get reliable interviewees in the first place.