Satellite images show world in transformation

Jeremy Laurance
Saturday 30 March 2002 01:00 GMT
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They are images of a fragile planet – crumbling ice shelves, eroded waterways, dwindling fish stocks. The first pictures from Europe's flagship earth observation satellite, Envisat, show how coastlines shaped over millions of years are now changing in a generation.

They are images of a fragile planet – crumbling ice shelves, eroded waterways, dwindling fish stocks. The first pictures from Europe's flagship earth observation satellite, Envisat, show how coastlines shaped over millions of years are now changing in a generation.

Their beauty reminds us of what we stand to lose. The picture of the Larsen B ice shelf, which collapsed this month, shows the 3,250 sq km (1,255 sq mile) chunk has broken into thousands of small bergs and is now drifting away from Antarctica.

Other pictures beamed from the eight-ton satellite show Africa under a merciless sun, its coast defined and its interior a web of intricate tributaries, like a giant lung.

Envisat, the biggest and most expensive satellite put into orbit by Europe, was launched on an Ariane 5 rocket from Kourou in French Guiana on 28 February. Described as Europe's "green eye", it is equipped with 10 instruments to improve the accuracy of scientific measurements of the sea, land, atmosphere and ice caps for the next five years.

The instruments will measure sea surface temperatures, wind speeds and wave heights, monitor the concentrations of 25 gases in the atmosphere, detect oil pollution in the oceans and monitor the disappearance of forests. Because its radar is sophisticated enough to detect 1mm disturbances in the ground over a year, it will also be used to study earthquakes, floods and volcanoes.

Other instruments will monitor the thickness and distribution of sea ice and the ice sheets over Greenland and Antarctica. Mission controllers have spent the last month calibrating the instruments, and European Space Agency officials say everything is working. Data is sent every 100-minute orbit to the Kiruna station in Sweden.

The launch of the satellite was timed perfectly to capture the collapse of the 200m (650ft) thick Larsen B ice shelf, providing dramatic evidence of the impact of global warming in the Antarctic peninsula region.

This type of observation can help scientists understand ice dynamics and ice/climate interactions as well as ocean circulation patterns.

In a picture of the coast of west Africa, a sophisticated spectrometer was used to detect phytoplankton and chlorophyll concentrations which mark the areas where food is in abundance to attract fish. The information can be used to develop fisheries policies.

An image of the Casamance region of Senegal shows tons of sediment being washed into the sea as a result of land erosion, hastened by changes in land use.

Envisat, which cost £1.4bn, carries a solar array a third the area of a tennis court to power its instruments. Professor Alan O'Neill, who will monitor the information at Reading University, said the satellite would tell scientists how the world was coping with climatic change. "We want to give planet Earth a real health check," he said.

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