SCOTTISH scientists claim to have moved a step closer to solving the mystery of why Mars became a cold, dead world instead of warm and wet like the Earth.

The team believe the Red Planet underwent reverse global warming millions of years ago which saw all carbon dioxide stripped from its atmosphere.

Without the greenhouse gas to keep heat in, as it is known to do on Earth, this led to rapid cooling and the evaporation and freezing of whatever water there was on the Martian surface.

Scientists at the Scottish Universities Environmental Research Centre, the University of Glasgow and the Natural History Museum in London came up with the theory by studying a meteorite known to have been blasted off the surface of Mars around 1300 million years ago.

Studies of the space rock, known as Lafayette, revealed it was studded with a carbon-rich mineral called siderite which is formed when chemicals in the atmosphere and earth capture carbon dioxide and trap it in a solid state by the process of carbonation.

While this process also occurs naturally on Earth, and is the focus of research into methods of permanently locking up carbon dioxide from power stations, the magnitude of the effect on Mars indicates that it has the potential to be effective on a planetary scale.

Dr Tim Tomkinson of the Scottish Universities Environmental Research Centre, Research Associate at the University of Glasgow and lead author of the paper, said "Mars once had a thick atmosphere that was rich in water and carbon dioxide, and so carbonation may help answer the mystery of why the Martian climate deteriorated around 4000 million years ago.

"This discovery is both significant in terms of the way in which scientists will study Mars in future but also to providing us with vital clues to how we can limit the accumulation of carbon dioxide in the Earth's atmosphere and so reduce climate change."