The real answer to climate change is to leave fossil fuels in the ground

Ladies and gentlemen, I have the answer! Incredible as it might seem, I have stumbled across the single technology which will save us from runaway climate change! From the goodness of my heart, I offer it to you for free. No patents, no small print, no hidden clauses. Already this technology, a radical new kind of carbon capture and storage, is causing a stir among scientists. It is cheap, it is efficient and it can be deployed straight away. It is called ... leaving fossil fuels in the ground.

On a filthy day last week, as governments gathered in Bali to prevaricate about climate change, a group of us tried to put this policy into effect. We swarmed into the opencast coal mine being dug at Ffos-y-fran in South Wales and occupied the excavators, shutting down the works for the day. We were motivated by a fact which the wise heads in Bali have somehow missed: if fossil fuels are extracted, they will be used.

Most of the governments of the rich world now exhort their citizens to use less carbon. They encourage us to change our lightbulbs, insulate our lofts, turn our televisions off at the wall. In other words, they have a demand-side policy for tackling climate change. But as far as I can determine, not one of them has a supply-side policy. None seeks to reduce the supply of fossil fuel. So the demand-side policy will fail. Every barrel of oil and tonne of coal that comes to the surface will be burned.

Or perhaps I should say that they do have a supply-side policy: to extract as much as they can. Since 2000, the UK government has given coal firms £220m to help them open new mines or to keep existing mines working. According to the energy white paper, the government intends to "maximise economic recovery ... from remaining coal reserves".

The pit at Ffos-y-fran received planning permission after two ministers in the Westminster government jumped up and down on Rhodri Morgan, the first minister of the Welsh assembly. Stephen Timms at the department of trade and industry listed the benefits of the scheme and demanded that the application "is resolved with the minimum of further delay". His successor, Mike O'Brien, warned of dire consequences if the pit was not granted permission. The coal extracted from Ffos-y-fran alone will produce 29.5m tonnes of carbon dioxide: equivalent, according to the latest figures from the Intergovernmental Panel on Climate Change, to the sustainable emissions of 55 million people for one year.

Last year British planning authorities considered 12 new applications for opencast coal mines. They approved all but two of them. Two weeks ago, Hazel Blears, the secretary of state in charge of planning, overruled Northumberland county council to grant permission for an opencast mine at Shotton, on the grounds that the scheme - which will produce 9.3m tonnes of CO2 - is "environmentally acceptable".

The British government also has a policy of "maximising the UK's existing oil and gas reserves". To promote new production, it has granted companies a 90% discount on the licence fees they pay for prospecting the continental shelf. It hopes the prospecting companies will open a new frontier in the seas to the west of the Shetland Isles. The government also has two schemes for "forcing unworked blocks back into play". If oil companies don't use their licences to the full, it revokes them and hands them to someone else. In other words, it is prepared to be ruthlessly interventionist when promoting climate change, but not when preventing it: no minister talks of "forcing" companies to reduce their emissions. Ministers hope the industry will extract up to 28bn barrels of oil and gas from the continental shelf.

Last week the government announced a new tax break for companies working in the North Sea. The Treasury minister, Angela Eagle, explained that its purpose is "to make sure we are not leaving any oil in the ground that could be recovered". The government's climate change policy works like this: extract every last drop of fossil fuel then pray to God that no one uses it.

The same wishful thinking is applied worldwide. The International Energy Agency's new outlook report warns that "urgent action is needed" to cut carbon emissions. The action it recommends is investing $22 trillion in new energy infrastructure, most of which will be spent on extracting, transporting and burning fossil fuels.

Aha, you say, but what about carbon capture and storage? When governments use this term, they mean catching and burying the carbon dioxide produced by burning fossil fuels. It is feasible, but there are three problems. The first is that fossil fuels are being extracted and burned today, and scarcely any carbon capture schemes yet exist. The second is that the technology works only for power stations and large industrial processes: there is no plausible means of dealing with cars, planes and heating systems. The third, as Alistair Darling, then in charge of energy, admitted in the Commons in May, is that the technologies required for commercial carbon capture "might never become available". (The government is prepared to admit this when making the case, as he was, for nuclear power, but not when making it for coal).

Almost every week I receive an email from someone asking what the heck I am talking about. Don't I realise that peak oil will solve this problem for us? Fossil fuels will run out, we'll go back to living in caves and no one will need to worry about climate change again. These correspondents make the mistake of conflating conventional oil supplies with all fossil fuels. Yes, at some point the production of petroleum will peak then go into decline. I don't know when this will happen, and I urge environmentalists to remember that while we have been proved right about most things we have been consistently wrong about the dates for mineral exhaustion. But before oil peaks, demand is likely to outstrip supply and the price will soar. The result is that the oil firms will have an even greater incentive to extract the stuff.

Already, encouraged by recent prices, the pollutocrats are pouring billions into unconventional oil. Last week BP announced a huge investment in Canadian tar sands. Oil produced from tar sands creates even more carbon emissions than petroleum extraction. There's enough tar and kerogen in North America to cook the planet several times over.

If that runs out, they switch to coal, of which there is hundreds of years' supply. Sasol, the South African company founded during the apartheid period - when supplies of oil were blocked - to turn coal into liquid transport fuel, is conducting feasibility studies for new plants in India, China and the US. Neither geology nor market forces is going to save us from climate change.

When you review the plans for fossil fuel extraction, the horrible truth dawns that every carbon-cutting programme is a con. Without supply-side policies, runaway climate change is inevitable, however hard we try to cut demand. The talks in Bali will be meaningless unless they produce a programme for leaving fossil fuels in the ground.

George Monbiot