The finding, which threatens the entire rationale of the onshore wind farm industry, will be made by Scottish government-funded researchers who devised the standard method used by developers to calculate “carbon payback time” for wind farms on peat soils.

Thousands of Britain’s wind turbines will create more greenhouse gases than they save, according to potentially devastating scientific research to be published later this year.

Wind farms are typically built on upland sites, where peat soil is common. In Scotland alone, two thirds of all planned onshore wind development is on peatland. England and Wales also have large numbers of current or proposed peatland wind farms.

But peat is also a massive store of carbon, described as Europe’s equivalent of the tropical rainforest. Peat bogs contain and absorb carbon in the same way as trees and plants — but in much higher quantities.

British peatland stores at least 3.2 billion tons of carbon, making it by far the country’s most important carbon sink and among the most important in the world.

Wind farms, and the miles of new roads and tracks needed to service them, damage or destroy the peat and cause significant loss of carbon to the atmosphere, where it contributes to climate change.

Writing in the scientific journal Nature, the scientists, Dr Jo Smith, Dr Dali Nayak and Prof Pete Smith, of Aberdeen University, say: “We contend that wind farms on peatlands will probably not reduce emissions …we suggest that the construction of wind farms on non-degraded peats should always be avoided.”

Dr Nayak told The Telegraph: “Our full paper is not yet published, but we should definitely be worried about this. If the peatland is already degraded, there is no problem. But if it is in good condition, we should avoid it.”

Another peat scientist, Richard Lindsay of the University of East London, said: “If we are concerned about CO2, we shouldn’t be worrying first about the rainforests, we should be worrying about peatlands.

“The world’s peatlands have four times the amount of carbon than all the world’s rainforests. But they are a Cinderella habitat, completely invisible to decision- makers.”

One typical large peat site just approved in southern Scotland, the Kilgallioch wind farm, includes 43 miles of roads and tracks. Peat only retains its carbon if it is moist, but the roads and tracks block the passage of the water.

The wind industry insists that it increasingly builds “floating roads,” where rock is piled on a textile surface without disturbing the peat underneath.

But Mr Lindsay said: “Peat has less solids in it than milk. The roads inevitably sink, that then causes huge areas of peatland to dry out and the carbon is released.”

Mr Lindsay said that more than half of all British onshore wind development, current and planned, is on peat soils.

In 2011 the Scottish government’s nature protection body, Scottish Natural Heritage, said 67 per cent of planned onshore wind development in Scotland would be on peatland.

Read more from The Telegraph: http://www.telegraph.co.uk/earth/energy/windpower/9889882/Wind-farms-will-create-more-carbon-dioxide-say-scientists.html