The document, titled The Right Way and introduced at the Conservative conference in Birmingham, was used by party leader Kemi Badenoch to justify the decision to scrap the UK's target of reaching net zero emissions by 2050, a commitment originally made under Theresa May. In a chapter on net zero, the document claimed that the Climate Change Committee (CCC) had estimated the cost of its net zero route at £957bn.
However, the actual figure from the CCC's Sixth Carbon Budget totals £478bn — half of what the Conservative document stated. The error appears to have occurred because the spreadsheet used by the Conservatives included both the individual column totals and the row showing overall sums, effectively doubling the number.
A spokesperson for the Climate Change Committee said: "We don't recognise this number. The committee has previously offered to meet with Ms Badenoch and talk her through our advice. That offer is, of course, still open."
The CCC's most recent analysis puts the expected cost of achieving net zero by 2050 at about £110bn over 30 years, roughly £4bn a year or 0.2% of GDP.
The erroneous figure appears to have been copied without independent verification. It had previously been published in a report by the Institute of Economic Affairs, a right-leaning thinktank, and in an article in The Spectator.
Badenoch, in a foreword to the 100-page document, noted that "as an engineer", she is used to correctly diagnosing issues so they can be addressed. The document is modelled on The Right Approach, a policy blueprint produced by Margaret Thatcher's Conservative Party in 1976.