A giant white kangaroo bounced into the science books on Tuesday as part of a global experiment to measure the amount of light the Earth reflects back to the sun.

The cardboard cut-out marsupial, which measures 32 metres (105 feet) by 18 metres, was laid out in a paddock on the grounds of Monash University in the southern city of Melbourne.

"We call it our kangaroo from space because two satellites flew over (and) what they were doing was measuring the amount of light reflected from our kangaroo," Professor Patricia Vickers-Rich told AFP.

"And the point of that was to make people aware that reflected light, or lack of reflected light, has a very big effect on climate."

Scientists are concerned that the melting of the polar ice caps, happening at a faster rate than expected, is quickly robbing the earth of some of the vast white spaces which have traditionally reflected the sun's rays, she said.

"If something is white it reflects a lot of light, if something is dark it absorbs it, and that will affect the temperature of our atmosphere," Vickers-Rich said.

"If we reflect less of the sun's energy and we absorb it, then our temperatures will rise. And they are rising, there's no doubt about it."

Vickers-Rich said the white kangaroo experiment was one of 20 such tests conducted around the world by US space agency NASA to highlight changes in the amount of light reflected by the earth over the past year.

The academic, a geologist and founding director of the Monash Science Centre, said the Melbourne group was the first to make their white reflector into an animal.

"We were supposed to put out a square... and we thought, 'Well, why don't we do an animal?"

A giant koala and a massive lizard were discussed before it was decided that "everybody recognises the kangaroo".