Environmentalists across the world are to be enlisted as armchair detectives to monitor satellite images of rainforests and report any illegal logging.

The images will be frequently updated and anyone with internet access will be able to make instant comparisons with historical images and spot destruction of rainforest almost as soon as it happens.

Every four seconds an area of rainforest the size of a football pitch is cut or burnt down for timber and paper or to clear land for cattle and plantations.

Rainforest destruction accounts for 17 per cent of global greenhouse gas emissions, more than is produced by all the world’s cars, ships and aircraft. Tropical forests cover 15 per cent of the world’s land surface and have a double cooling effect, soaking up carbon dioxide from the atmosphere and maintaining high levels of evaporation from the canopy.

The armchair detectives will be able to report their findings to an international agency being created to monitor whether countries are meeting their commitments to reduce deforestation. Any state found to have broken its pledge will lose its share of a new global fund established by rich countries to pay nations for leaving their trees standing.

The fund, called Reducing Emissions from Deforestation and Forest Degradation (Redd) and worth up to $30 billion (£18 billion) a year, is due to be approved at the UN climate change summit in Copenhagen next month.

Google is helping to create the new online detective tool, which is likely to be launched next year. Philipp Schindler, from Google UK, said: “Our engineers are exploring how we might contribute to this effort by developing a global forest platform that would enable anyone in the world, including tropical nations, to monitor deforestation and draw attention to it.”

Mr Schindler was speaking yesterday at a seminar on deforestation hosted at St James’s Palace by Prince Charles and attended by leaders and ministers from several of the largest rainforest countries.

President Jagdeo of Guyana told the seminar that the cheapest way for industrialised countries to reduce carbon emissions was to pay poor countries, such as Guyana, not to fell their trees.

Contributors to the Redd fund will pay about £4 for each tonne of CO2 saved by reducing the rate of deforestation. Fitting carbon capture and storage systems to coal-fired power stations costs more than £50 for each tonne saved.

Norway announced last week that it would demonstrate how Redd could work by paying Guyana up to £150 million over five years to preserve its trees.

Guyana’s forests have been far less logged than in many tropical nations, and under the terms of the new deal with Norway, Guyana could actually be paid for increasing deforestation. The memorandum states that Norway will compensate Guyana if it does not cut down more than 0.45 per cent of its forests per year, but Guyana is currently felling trees at a far slower rate. The countries contributing to Redd are concerned that their money could disappear into the pockets of corrupt officials in poorly governed countries. There are also fears that payments will result in logging companies switching to unprotected areas, resulting in no net reduction in deforestation.

Per Frederik Pharo, of the Norwegian Government’s forest protection fund, said payments would only be made when countries could prove that they had reduced their annual rate of deforestation by an agreed amount. He said the targets would be raised every five years.

Brazil has halved its rate of deforestation in the past year but Tasso Azevedo, of Brazil’s Forest Service, warned that it could increase again unless the country received substantial sums of Redd “People have to have some income and we need a lot of cash for the community to maintain the forest,”he said.

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