Mr Philip Bell complained to the Press Complaints Commission that an article published on Mail Online on 26 March 2012, headlined "Is this finally proof we're NOT causing global warming? The whole of the Earth heated up in medieval times without human CO2 emissions, says new study", was inaccurate in breach of Clause 1 (Accuracy) of the Editors' Code of Practice.

The newspaper had failed to take care not to publish inaccurate or misleading information in breach of Clause 1 (i), but had offered sufficient action to remedy the breach.

The article reported on the findings of a study conducted by scientists from Syracuse University of samples of the mineral ikaite that had been collected from the Antarctic Peninsula. The complainant, who was not connected to the research team, disputed the article's claim that the study had found that "the whole of the Earth heated up in medieval times". He said the study had focused only on one part of Antarctica and could not be relied upon as evidence of warming on a global scale during this period. He also questioned the newspaper's assertion that the results contradicted the established position of the Intergovernmental Panel on Climate Change (IPCC) that "the Medieval Warm Period was confined to Europe"; he did not accept that the IPCC had taken such a stance.

The newspaper acknowledged the position of Dr Zunli Lu, the lead author of the study, that its findings did not support the idea that the whole earth had warmed, but defended its view that a temperature rise affecting two places as distant as Europe and Antarctica was likely to affect the rest of the world. It maintained that it had clearly distinguished its editorial position in this regard from its report of the study's findings. While the newspaper did not accept a breach of the Code, on receipt of the complaint it amended the article to note Dr Lu's position that the research was not proof that the whole Earth warmed up. It subsequently offered to remove the article and publish a correction online, noting that the research related only to the Antarctic Peninsula, and that the IPCC's position was that ‘medieval warmth was heterogeneous in terms of its precise timing and regional expression'.

The complainant, a member of the public, was concerned about the reporting of a scientific paper. The Commission was able to investigate the complaint under Clause 1 (Accuracy) of the Editors' Code of Practice because relevant material - and in particular, the study on which the article had reported - was in the public domain.

Under the terms of Clause 1, "the press must take care not to publish inaccurate, misleading, or distorted information"; "a significant inaccuracy, misleading statement or distortion once recognised must be corrected promptly and with due prominence"; and "the press, whilst free to be partisan, must distinguish clearly between comment, conjecture and fact".

When reporting on scientific findings, publications must often present complex information to a general readership; this may involve an element of interpretation. In the view of the Commission, the newspaper was entitled to present to readers its position - however strongly disputed, including by the study's authors, who said that the results should not be extrapolated globally - that warming in two areas might indicate a more general pattern. It had an obligation, however, to present this claim in a manner that would not mislead readers, and that distinguished clearly between the study's findings and its own analysis.

In the event, the headline and text of the story had suggested, inaccurately, that the study had demonstrated that the warming was global. In particular, the text said the scientists had "found that contrary to the ‘consensus', the ‘Medieval Warm Period'... extended all the way down to Antarctica - which means that the Earth has already experienced global warming without the aid of human CO2 emissions". This raised a clear breach of the Code, and it was incumbent on the newspaper to correct the position publicly. In addition, the newspaper had not been able to provide material to substantiate its claims about the IPCC's public position; it was therefore also appropriate for it to clarify the position in this respect, as it could be ascertained from publicly available information.

In response to the complaint, the newspaper had offered to remove the article and publish a statement on its website, correcting the inaccuracy about the study's findings and clarifying the IPCC's stance. This was an adequate response to the complaint under the terms of Clause 1. It had been appropriate for the newspaper to delay publication of the correction pending the Commission's decision, but the correction should now be published at the next opportunity.