The leaders of two UK environmental charities have written to Mark Carney, the UN climate envoy and former governor of the Bank of England, to raise concerns over a blueprint for carbon offsetting that could result in billions of new carbon credits being sold around the world. Carney presented plans at the virtual Davos meeting of global business and political leaders on Wednesday evening for vast increases in the number of carbon offsets sold, aiming to expand the market from about $300m at present to between $50bn and $100bn a year. He told the conference that he “categorically rejected” criticism that offsets were greenwash. Companies buying offsets in the market would be subject to scrutiny, and must have clear plans to reach net zero, “not something written on the back of a napkin”, he said, but would need offsets to fulfil their plans. “This is bringing those companies into a formal system,” he said. “This is about maximising the use of a very limited [global] carbon budget. This is complementary [to companies taking action to reduce their own emissions] and is one piece of the puzzle. We do need this market.” Bill Gates, co-founder of Microsoft, also speaking at the event, said money from the sale of offsets could support the “bootstrapping” or rapid growth of innovations such as low-carbon cement and green aviation fuel, which must be made cheaply available if the world was to tackle the climate crisis. “All of these products, for middle income countries to buy, are going to have to come at such a small premium that they are willing to shift all their purchasing to them,” he said. The Taskforce on Scaling the Voluntary Carbon Market, launched by Carney last year, is an initiative led by the finance industry and chaired by Bill Winters, the chief executive of Standard Chartered – a bank fined more than $1bn in 2019 for money laundering. Carbon offsets, or carbon credits, are awarded to projects that reduce greenhouse gas emissions, for instance by preserving forests or restoring natural landscapes such as peatlands that store carbon, and for spreading “clean technology” such as renewable energy generation in developing countries. The credits are sold to companies, which count them towards their efforts to reach net zero emissions. Some credits come from certified international carbon trading schemes run by governments, but others are from the so-called voluntary market, which is largely unregulated. The voluntary market has been the subject of repeated scandals in which credits were awarded to projects that did not reduce carbon dioxide, or credits were not properly traceable, were mis-sold or were double counted, and cases where forests supposed to be protected were logged. Proponents of carbon markets say they form a vital source of funding for projects such as keeping forests standing or restoring degraded landscapes. Without funding from the carbon markets, it would be much harder for developing countries to resist pressure from loggers and agribusiness to exploit their remaining forests, peatlands, cerrado and other land for profit. Detractors say the markets are used as a cover by companies that wish to give the appearance of working towards net zero emissions but prefer buying cheap credits to the more difficult task of cutting their emissions. John Sauven, the executive director of Greenpeace UK, and Craig Bennett, the chief executive of the Wildlife Trusts, wrote to Carney this week to raise concerns that the taskforce’s recommendations would not close loopholes in the carbon market. “There is a danger that it becomes a large international greenwashing exercise, creating a market with low standards but high PR value,” they wrote. Sauven told the Guardian: “This initiative risks setting a terrible example ahead of the critical carbon market negotiations at the global climate summit in Glasgow later this year. [It] seems to have ignored past failures of offsetting schemes to guarantee emission cuts. At the same time, it assumes that the natural world has unlimited potential to absorb climate-wrecking emissions. It fails to acknowledge that the most important thing companies must do is to reduce their own emissions and use of fossil fuels. “For as long as these critical issues remain unaddressed, Carney’s scheme will serve as a giant get-out-of-jail-free card for polluting companies. It will undermine tighter controls in international agreements while doing little to actually tackle the climate emergency.” The Guardian has also been told of concerns among members of the taskforce about the way in which its recommendations were drawn up, with members raising objections relating to the transparency and integrity of the market that were ruled outside the scope of the report. The IIF promised last week to release a draft copy of the report, which has been repeatedly delayed. The Institute of International Finance, a body representing the finance industry, which organised the taskforce, said all taskforce members had seen the final report. However, the Guardian knows of at least two who had not. A spokesperson for the IIF told the Guardian the purpose of the initiative was to help companies meet their commitments to net zero emissions. “There is a responsibility to our firms and customers to be working toward a more sustainable future,” they said. Standard Chartered referred questions on the initiative to the IIF. Carney is the UN special envoy for climate and finance and an adviser to Boris Johnson on Cop26, the UN climate summit to be held in Glasgow in November. Carbon trading is expected to be a key subject of discussions at Cop26, because decisions on how to incorporate carbon trading under the Paris agreement were put off from the last UN climate meeting, Cop25, in Madrid in 2019.