Lawson’s claim that global temperatures are not rising went unchallenged, breaching guidelines on accuracy and impartiality

The BBC has apologised for an interview with the climate change denier Lord Lawson after admitting it had breached its own editorial guidelines for allowing him to claim that global temperatures have not risen in the past decade.

BBC Radio 4’s flagship news programme Today ran the item in August in which Lawson, interviewed by presenter Justin Webb, made the claim. The last three years have in fact seen successive global heat records broken.

The Today programme rejected initial complaints from listeners, arguing that Lawson’s stance was “reflected by the current US administration” and that offering space to “dissenting voices” was an important aspect of impartiality.

However, some listeners escalated their complaint and, in a letter seen by the Guardian, the BBC’s executive complaints unit now accepts the interview breached its guidelines on accuracy and impartiality.

The complaint centred on two statements by Lawson: that the UN’s Intergovernmental Panel on Climate Change “has confirmed that there has been no increase in extreme weather events” and “according to the official figures, during this past 10 years, if anything, mean global temperature, average world temperature, has slightly declined”.

The BBC complaints unit accepted that these statements “were, at the least, contestable and should have been challenged”. In fact the Global Warming Policy Forum itself, the campaign group chaired by Lawson, acknowledged on 13 Augustthat the temperature data he was referring to was “erroneous” and not official. Senior scientists also declared that Lawson’s statement about extreme weather was wrong.

It is not the first time the Today programme has been censured by the BBC complaints unit for an interview with Lawson. A broadcast in February 2014 was judged to have “given undue weight to Lord Lawson’s views, and had conveyed a misleading impression of the scientific evidence on the matter”.

“I really thought the climate change debate had finished and that these voices of the very rich and well connected had lost relevance in the whole argument,” said Dr Tim Thornton, a recently retired GP from Yorkshire who made one of the complaints. “It’s fine that they don’t like the idea of climate change but they are on a par with flat-earthers.”

Thornton highlighted the claim that global temperatures had not risen: “Even a sixth-former would be able to tell you that wasn’t so. So the BBCinterviewer, if they are talking about climate change, should have done a little bit of homework.”

In his letter to Thornton, Colin Tregear, the BBC complaints director, said: “I hope you’ll accept my apologies, on behalf of the BBC, for the breach of editorial standards you identified.”

Bob Ward, the policy director of the Grantham research institute on climate change at the London School of Economics, welcomed the upholding of the complaint but said: “There needs to be a shift in BBC policy so that these news programmes value due accuracy as much as due impartiality.

“As well as taking account of the rights of marginal voices like Lord Lawson to be heard, the BBC should also take account of the harm that its audiences can experience from the broadcast of inaccurate information,” said Ward. “His inaccurate assertion that there has been no change in extreme weather was harmful to the programme’s listeners because they may have been misled into believing that they do not need to take precautions against the increasing risk of heatwaves and flooding from heavy rainfall in the UK.”

Lawson did not respond to the Guardian’s request for comment.

Neither the Global Warming Policy Forum or its charitable arm, the Global Warming Policy Foundation, disclose the source of their funding. On their websites, the groups state: “In order to make clear its complete independence, it does not accept gifts from either energy companies or anyone with a significant interest in an energy company.”

The programme in August featuring the interview with Lawson also included an interview with Al Gore, the former US vice-president and climate campaigner, who discussed his new film An Inconvenient Sequel: Truth to Power, and another interview with the director Fisher Stevens, who made Before the Flood, also about climate change, starring Leonardo DiCaprio.

The BBC complaints team told Thornton that “the BBC accepts there is broad scientific agreement on climate change” and that “the global climate is changing and the change is predominantly manmade”. The complaints unit said a 2011 review by the BBC Trust had made clear “the requirement to avoid the impression a minority view stands on the same footing as the views of climate scientists”.

Simon Bullock of Friends of the Earth said: “It was a real choke-on-cornflakes interview, with Lord Lawson’s misleading climate denial views given undue weight and passing unchallenged. After this ruling hopefully the BBC will now move the climate debate on to how to stop our planet warming, not denying that it is happening.”