"What it's good at is spotting changes over time," he told BBC News Online.

Meris can observe how plankton spread through the Earth's oceans, providing a valuable insight into the way the seas act as a counterweight to global warming by storing carbon dioxide.

Meris' field of view means that it can provide an almost daily view of any given point on Earth.

Its host satellite, Envisat, was launched on an Ariane 5 in 2002. The satellite is the biggest and most expensive Earth-observation spacecraft ever built by Europe.

BBC NEWS | Science/Nature | Satellite shows dramatic Aral loss: "Along the way much of their water is taken for the irrigation of thirsty cotton crops.
Large scale irrigation began in the 1960s and has led to the Aral losing half its area and three-quarters of its volume"