Roberts is the son of Ieuan Roberts, a coal miner, later a coal mine manager and then Queensland's chief inspector of mines. His childhood home (in India) was staffed with servants, and as a child, Roberts built a miniature coalmine in the yard of his home.
Roberts graduated from the University of Queensland with a degree in mining engineering. He also has an MBA from the University of Chicago. An Australian court found that Roberts had wrongly sought a $30,000 tax deduction for the costs of the MBA.
In 1977, Roberts began work as a coalface miner. During this time, until 1979, he worked in this role at five different mines across Australia before becoming a mining engineer. Thereafter, he worked as an engineer and general manager for various companies such as Peabody Coal Company, Consolidation Coal Company and Atlantic Richfield, though he had not held paid employment for eight years prior to his election in 2016.
From 1982-88 Roberts worked as a manager for Coal & Allied at West Wallsend, New South Wales. The mine proved to be unprofitable due to its location, leading to its sale in 1988, at which time Roberts took a redundancy package. After completing an MBA, Roberts was appointed general manager at the Gordonstone coal mine mine in Queensland, the largest underground mine in Australia. Roberts left the role three years later. According to Roberts he resigned due to a lack of support during an industrial dispute, but others have suggested that he was let go after cost overruns at the mine.
That was the end of Roberts' mining career. With his wife, in 1994 he started a management consultancy, Catalyst For Corporate Performance, and became involved in Eastern and alternative self-help techniques including meditation.
Roberts served as chairman of the board of the Brisbane Montessori School from 1999 until 2003 and served voluntarily on the advisory board (as a parent representative member) of the International Montessori Council from 2000 until 2008.
Roberts' major interest and activity since ending his mining career is the denial of climate change. The catalyst was the 2006 film, An Inconvenient Truth on television.
Since 2006, Roberts has been a full-time political activist, speaking at rallies against the Labor Government’s carbon tax, working for the climate change denying Galileo Movement, and sending hundreds of emails to political, scientific and media figures on the topic. He also met politicians, had universities launch academic inquiries into climate scientists and sent legal letters demanding the resignation of government ministers.
Roberts was elected to the Australian Senate in 2016.
Roberts promotes climate conspiracy theories, and does not accept the scientific consensus on climate change. He is the leader of the Galileo Movement, established in 2011. A 2011 Scientific American article on the group stated that it "recycles many of the same straw man arguments and distortions about the science that other groups have previously employed".
Roberts travelled to the US to attend the Heartland Institute’s climate skeptics conference in New York in 2008, co-sponsored by the Institute of Public Affairs. His views were supported by Alan Jones, who is the patron of the Galileo Movement and interviewed Roberts on his breakfast program.
Roberts is a prolific letter writer. He writes to politicians, government agencies, universities and scientists. The topic of these letters is mostly formal complaints regarding allegations of corruption in climate science. He keeps an archive of his letters and replies at his website.
Climate scientists have universally repudiated Roberts's views on climate, saying that "of course he is wrong" (David Karoly), that he has "broke[n] the first law of thermodynamics" (Roger Jones, IPCC author), and that he has failed to understand high school science (Matthew England).
Roberts frequently states that NASA has falsified climate data to exaggerate warming in the Arctic. In November 2016, Gavin Schmidt, director of NASA's Goddard Institute for Space Studies, told Roberts he was "mistaken" to assert NASA had removed data to hide Arctic warming in the 1940s. Schmidt stated that the data was freely available online and that Roberts should check it himself, adding that he was surprised that Roberts was in fact a senator, and that his allegation of inappropriate temperature data adjustment is "the definition of denial".
Roberts' specific objection related to charts from Icelandic stations at Vestmannaeyjar and Teigarhorn, where temperatures from the 1930s and 1940s were adjusted down, removing the apparent warming recorded at that time. However a senior Icelandic meteorologist with a specialty in historical climatology emailed Roberts that the temperature adjustments, which were made because of a daytime bias and relocation of one of the stations, were "quite sound ... absolutely necessary and well founded".
Roberts authored a 300,000-word essay called CSIROh! (a play on the acronym CSIRO) that, according to a report in The Australian newspaper, claimed global warming is UN-inspired hoax to introduce an “antihuman” socialist New World Order, aided by bankers and politicians. The essay was described as “conspiracist rubbish” by climate scientist David Karoly and “utterly stupid” by conservative commentator Andrew Bolt.
The CSIROh! document contained an attack on the environment editor of one of Australia's major newspapers, Ben Cubby of The Sydney Morning Herald. In it, Roberts charged that Cubby had failed to report on corruption of climate science, was ignorant of science, and that his articles were dishonest, inaccurate and spread corruption of climate science, inter alia. Roberts sent a copy of CSIROh! to Cubby and demanded a response. Cubby responded by commenting that the essay was "littered with errors of all kinds: a mish-mash of muddled conjecture, impossible leaps of logic, fundamental misunderstandings of the scientific method, misread and misquoted research that has been poorly cited, internal contradictions, confused dates, spelling mistakes, and strangled grammar. It is, in all respects, a dud."
In 2016, Roberts requested a briefing from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) on scientific evidence of human-caused global warming. The briefing was delivered in September 2016, after which Roberts said he would consider the CSIRO's evidence, but also accused the CSIRO of pushing the “de-industrialisation” of Australia, and added that policies to mitigate climate change were "anti-human".
On 6 November 2016 Roberts delivered his response to the briefing, presenting a 42-page report titled "On Climate, CSIRO Lacks Empirical Proof", co-authored by Timothy Ball and Tony Heller.
The report by Roberts and his co-authors included the spurious claim that sea level was not rising. They said that carbon dioxide in Earth's atmosphere "is not and cannot be affected by human production" and cannot affect atmospheric temperatures, denying the greenhouse effect. Their report misrepresented the work of the Intergovernmental Panel on Climate Change, alleged that international banks profit from climate change, and said that Under-Secretary-General of the United Nations Maurice Strong "was remarkably successful in gaining control of weather agencies". It said that "Misrepresentation of science and climate is a form of control over people’s minds" and that "schools today subtly teach people what to think".
Roberts demanded that the Australian government set up an independent inquiry into the CSIRO and Bureau of Meteorology. He also demanded that Australia reject the Paris Agreement and leave the United Nations.
The CSIRO subsequently issued a statement that "CSIRO stands behind its peer-reviewed science on environment, climate and climate change".
In a clash between Roberts and physicist Brian Cox on the live television talk show Q&A on ABC TV broadcast 15 August 2016, Roberts claimed that engineer and blogger Steven Goddard (a pseudonym of Tony Heller) had shown the NASA temperature data for the 1930s were "warmer than recent decades". In The Guardian's assessment, Roberts was referring to a debunked conspiracy theory that claimed 1934 was hotter than 1998. Cox then asked if NASA, the Australian Academy of Science, and the Met Office in the UK were all collaborating to manipulate global temperature data, to which Roberts asked if he was being accused of claiming they were all collaborating, to which Cox responded: "What, they've all manipulated it in the same way and accidentally got to the same answer? Is that what you're saying?"
Malcolm Roberts is an advocate for freedom of speech, having called for the repeal of section 18C of the Racial Discrimination Act 1975, which makes it an offence to publicly "offend, insult, humiliate or intimidate" another person because of their race. He believes the law was passed to "nobble" Andrew Bolt, a journalist who was taken to court by a person who was insulted by an article he wrote in The Herald Sun, ordered to pay their legal costs, apologise and not publish the article again.
On ABC TV, Roberts said "You can call me short, you can call me fat... Whatever you want to call me, the only person who decides whether I'm upset is me".
Malcolm Roberts supports the reestablishment of the Office of the Australian Building and Construction Commissioner, which would have powers to fight union corruption in the construction industry, because he believes that its existence would promote freedom. He has stated that "we want to protect union members rather than the union bosses," and criticised the CFMEU for its impact upon small businesses.
Since being elected to the parliament Roberts and One Nation has voted with the government on a number of welfare cuts.
Roberts has frequently used a style of writing and terminology linked to the sovereign citizen movement, created by David Wynn Miller. This movement sees governments as illegitimate and attempts to assert the rights of individuals to ignore laws and taxes. Members of this movement aspire to exist outside both the social and legal bounds of society, and use colons and hyphens to evade what they claim is government enslavement via grammar.
In 2011, Roberts wrote an affidavit to then Prime Minister Julia Gillard — addressing her as "The Woman, Julia-Eileen: Gillard., acting as The Honourable JULIA EILEEN GILLARD" — demanding that she sign a contract exempting him from paying the carbon tax and compensation of up to $280,000 if she didn’t provide him with disclosure on 28 points, including evidence that "the Commonwealth of Australia CIK# 000805157 is not a corporation registered on the United States of America securities exchange". Roberts signed himself as "Malcolm-Ieuan: Roberts., the living soul". Roberts has used this form of sovereign citizen address before, namely in a list of acknowledgements he wrote in 2013.
Roberts stated in 2016 that he did not identify as a "sovereign citizen".
Roberts believes that the United Nations is a threat to the Australian way of life: "Australian values and way of life are also at risk from insidious institutions such as the unelected swill that is the United Nations. Australia must leave the UN. We need an OzExit." He states that the UN is "destroying Australia’s sovereignty through deals such as Agenda 21".
In 135-page document titled “Why? Motives Driving Climate Fraud”, Roberts states that international bankers (the Rothschilds, Goldman Sachs, the Rockefellers and the Warburg family) are surreptitiously trying to gain global control through environmentalism. Roberts' document cites the work of Eustace Mullins, an American anti-Semite and Holocaust denier who claimed that international banks and the US Federal Reserve were part of a Jewish conspiracy to introduce global socialism.
Roberts rejects the assertion that he is an anti-Semite, noting that two of the founders of the Galileo Movement were Jewish, and stated that "I respect and admire the Jews".
Roberts commented on the 2016 US presidential election by stating that "the only safe space for Hillary to occupy is a prison cell", and that he'd "settle for [her] going to Guantanamo, along with other terrorists". Roberts stated that his party, Pauline Hanson's One Nation, had hired former Trump economic adviser, Darren Brady Nelson.
Roberts celebrated the victory of president-elect Donald Trump by displaying a Gadsden flag at Parliament. He stated that the result supported his belief that people shouldn't serve the government, but the government should serve the people.