Don't plan an interplanetary ski trip to Mars: the carbon dioxide ice is eroding from the frosty poles of the Red Planet, suggesting the climate is warming.

Two reports in the Dec. 7 issue of Science suggest the warming could allow water to return to the Martian surface, turning the frigid planet into a "short-sleeve environment."

Researchers also found the Martian snow is far from the powder craved by skiers. The ski conditions would be "highly non-optimal", NASA-speak for only an expert skier could tackle the ice.

Mars Orbiter

The poles are snowy but there's no snow 60 degrees north and south of the equator. Most of the snow is actually frosty dew. Snowflakes are a mere micrometre in size, too small to see.

Forecast: light icy snow and fog

The observations of Mars' carbon dioxide cycle could help scientists better understand the planet's weather and climate, and may provide information about the atmosphere and surface for future explorations.

Pictures of pits and other features on Mars' south pole were captured by a camera onboard the orbiting Mars Global Surveyor. The photos confirm the presence of solid carbon dioxide on the surface as well as in the atmosphere.

Scientists knew Mars had carbon dioxide snow when the temperatures plunge and the gas freezes out of the planet's thin atmosphere.

But the new study suggests the polar ice caps may not be so permanent after all. Instead, the glacier-like carbon dioxide ice is eroding, like a glacier melts on Earth.

Other studies have shown Mars was once awash with water, but it's thought to have disappeared or frozen.