One third of articles in Australia’s major newspapers rejected or cast doubt on the overwhelming findings of climate science, with climate sceptic Andrew Bolt monopolising coverage of the topic in several high-circulation News Corporation titles, according to a new analysis.

A study of 602 articles in 10 newspapers by the Australian Centre for Independent Journalism found that 32% dismissed or questioned whether human activity was causing the climate to change. The articles were analysed between February and April in 2011 and again in the same period in 2012.

Significantly, newspapers based a small fraction of their coverage on peer-reviewed science, instead relying heavily on comment pieces penned by writers without a scientific background.

According to the research, the number of articles on climate science decreased in 2012 compared to the previous year, although the tone became more sharply sceptical of the established scientific position in this period.

When measured according to words allocated to an article, 31% did not accept established climate science in 2011, with this number rising to 44% in 2012.

The high levels of scepticism were driven by the editorial leanings of market-leading News Corporation titles and, in particular, its syndicated columnist Andrew Bolt, the study found.

There were 97% of comment pieces in the Herald Sun which either questioned or rejected the view of the vast majority of climate scientists – which has ironically also been measured at 97%.

Bolt, who regularly rails against the established science of climate change in print and on his Channel Ten TV show, dedicated 49% of his words in the surveyed period to climate science, writing sceptical articles for the Herald Sun, the Advertiser, NT News and the Daily Telegraph.

“Bolt describes those who support the consensus position as ‘warmists’ who are by definition driven by ideology and are unreliable,” the report states. “News Corp does not balance Bolt’s voice with climate science journalism, which leaves him as the dominant voice on climate science for many of his readers.”

The latest IPCC report, collated from findings from 800 of the leading climate scientists around the world, found there was “unequivocal” evidence that the burning of carbon-intensive fuels was the main driver of the 0.89C rise in average temperature since 1900.

Domestically, climate scientists recently rounded on an article in the Australian with the headline ‘We got it wrong on warming, says the IPCC.” The newspaper subsequently retracted some of the claims made in the piece.

In News Corporation titles, the Australian Centre for Independent Journalism study found a preference towards mentions of climate change in opinion pieces, rather than in news reporting, with more than half of words on the topic in 2012 appearing in the comment section.

“By turning climate science into a debate, skepticism occupies space in Australian non-skeptic media that might otherwise be given to articles covering climate science,” the report said.

In 2012, 45% of the articles in the two mass-selling News Corporation tabloids – the Herald Sun and the Daily Telegraph – rejected the established science of climate change, while 33% questioned it.

While just 34% of articles across all News Corporation titles acknowledged the science as valid, 85% of Fairfax titles – which include the Sydney Morning Herald and the Age – accepted the scientific position on climate change.

The divergence between the two rival newspaper companies appears to be widening, with acceptance of the science increasing in Fairfax articles between 2011 and 2012 and declining in the News Corporation tabloids.

However, both businesses largely overlooked peer-reviewed research in their coverage of climate science. Just 1% of News Corporation articles referred to peer-reviewed science, compared to 15% in Fairfax.

The report also found large geographical disparities in coverage of climate science. While the Sydney Morning Herald was most likely to prominently place stories about climate science, followed by the Australian, the West Australian and the NT News had very little news on the topic.

“Andrew Bolt is the dominant voice on climate science by a long way, although I wouldn’t personalise it on him because it’s the editors and corporate managers who give him the space in the newspaper,” Wendy Bacon, author of the report, told Guardian Australia.

“There’s an editorial decision to heavily promote him and people like Piers Akerman and Miranda Divine, who are vehemently angry with climate scientists.”

Bacon said it was an “extraordinary” situation for Australia’s largest circulation newspaper publisher to not report the position of 97% of the world’s climate scientists.

“We have one of the most concentrated media landscapes in the world,” she said.

“I think this really puts the concentration of ownership back on the agenda. This is a real political problem.”

The study is a follow-up to a similar analysis done by the Australian Centre for Independent Journalism in 2011, which found overwhelming negative coverage of the then Labor government’s handling of the carbon pricing legislation.

In response to the ACIJ study, News Corporation said in a statement:

"News Corp and its newspapers do accept the scientific consensus. There is no company edict on the line to take – editorial control rests with the editors.

“News Corp Australia’s internationally recognised environmental sustainability program One Degree has resulted in the company reducing its carbon emissions by 19% since 2006.”