The chancellor and prime minister have promoted gas as a clean option for powering the UK.
But a draft report for the United Nation’s third panel on climate change says gas cannot provide a long-term solution to stabilising climate change.
Gas is only worthwhile if it is used to substitute a dirty coal plant – and then only for a short period, it says.
Instead the world should be trebling or quadrupling the share of renewables for electricity, the authors say.
The report will offer ammunition to the Department for Energy and Climate Change, which has fought attempts from the Treasury to switch more of the UK’s energy sources to gas with the projected “shale gas revolution”.
The UK hopes to emulate the success of the US, where shale gas has slashed energy prices and stimulated manufacturing.
However, the draft report backs the position taken by the Environment Agency chairman, Chris Smith, who has told the prime minister the UK could only expand the role of gas in power generation if power stations were fitted with carbon-capture equipment to suck carbon dioxide from exhaust gases and store them in underground rocks.
The UK is currently committed to trialling this technology in a gas power station in Peterhead.
But the technology is so far untried at scale. It also adds to the cost of gas burning and reduces the efficiency of power stations.
The UN report draws an implicit difference between a nation like the US, which has seen a huge fall in emissions by switching from coal to gas, and a country like the UK, which enjoyed its “dash for gas” in the 1980s and has since passed the Climate Change Act, requiring an 80% emissions cut across the UK by 2050.
Some Conservatives want the act to be repealed and it is not yet clear whether the party’s election manifesto will reflect their views.
Labour and the Liberal Democrats back the act.
One senior Conservative told me many of his backbench colleagues were heavily influenced by the Mail on Sunday’s campaign to define climate change as a con trick.
Elsewhere, the UN’s draft report spells bad news for coal-exporting countries.
It warns that their exports are likely to be hit as the world turns its back on the fuel.
This paragraph may prove contentious as governments discuss the final draft.