Radar in space will map disappearing forests

British scientists have developed a revolutionary technique for precisely measuring the size of the world's forests by using radar systems in space.

British scientists have developed a revolutionary technique for precisely measuring the size of the world's forests by using radar systems in space.

They believe the technique will play a major role in combating global warming by accurately measuring forest density in 3D, and in mapping how quickly the world's rainforests are being denuded.

But the project, which is being funded by the European Union and the United States' Office for Naval Research, part of the US Department of Defense, could lead to international tension when it comes fully into use in 2005.

Its evidence could add to the criticism by scientists and environmental campaigners of countries such as Brazil and Indonesia over the rate of destruction of their irreplaceable rainforests.

Professor Shane Cloude, from Applied Electromagnetics, of St Andrew's, Fife, the company which has developed the technique, said: "If you could go over Brazil with a satellite without their permission, then of course they're going to be worried. There are going to be some political implications with this technology." An early version of the technology was tested on forests surrounding Lake Baikal, Siberia, from a satellite 10 kilometres high, in 1994.

Radar was also used on the space shuttle in February this year to produce detailed maps of the earth, financed by the US DoD. The British team tested a more sophisticated version this week on remnants of the ancient Caledonian forest in Glen Affric in the Highlands. The team plans further tests on much denser tropical forests, probably in the small central American state of Belize.

It is then due for its first full trial in space when the Japanese space agency launches its Alos research satellite in September 2002. If that succeeds, commercial "vegetation map" surveys are expected to begin in 2005.

Measuring the precise amount of forest cover gives scientists more data to measure climate change from the build-up of carbon dioxide. "How much carbon is stored in vegetation on the planet is the big unknown," said Professor Cloude said. "Something like this could provide a much more accurate measure of it."

The technique, being developed by scientists at Edinburgh and Stirling universities, with the British National Space Centre and National Environmental Research Centre, involves bouncing radar waves off a forest canopy.

Scientists use the returned signal to measure the size of the forest, its density and the shape of the canopy, down to a five metre resolution. From there, they can estimate the forest's volume or "biomass".

In Canada, firefighters are to test satellite-based system to help detecting and controlling forest fires, just as the fire season months of July and August approach in Western Canada.

The Remsat (Real Time Emergency Management via Satellite) system uses earth observation, navigation and telecommunications satellites to fight fires in remote areas. It can also detect the types of trees involved.

The Remsat system allows firefighters to download images of a fire from navigational satellites and add geographical information such as local topography, contours and hazards such as powerlines, as well as the best lakes where water-bombers can fill their tanks.

Eventually, fire crews will have hand-held terminals to receive the data by satellite.