24/02/2012 09:24 GMT | Updated 25/04/2012 06:12 BST

Cloud Height Fell Over Last Decade, Nasa Study Reports

A Nasa study has showed that the sky is falling. Or at least the clouds, anyway.

According to scientists the average height of clouds has fallen over the last decade.

The team at the University of Auckland in New Zealand looked at 10 years of cloud-level measurements from the Multi-angle Imaging Spectro-Radiometer (MISR), an instrument on the Nasa Terra satellite.

The data showed that the average global cloud height fell by around 30 to 40 meters between March 2000 to February 2010, or 1% of their normal height.

According to the study, published in the journal Geophysical Research Letters, the difference was largely a result of fewer clouds being found at high altitudes.

Lower clouds help the Earth cool itself more quickly. It is speculated the change may be a "negative feedback mechanism" counteracting some of the effect of global warming - though more study is needed before those conclusions can be confidently drawn.

"We don't know exactly what causes the cloud heights to lower," said lead researcher Roger Davies. "But it must be due to a change in the circulation patterns that give rise to cloud formation at high altitude."

"If cloud heights come back up in the next ten years we would conclude that they are not slowing climate change," said Professor Davies.

"But if they keep coming down it will be very significant. We look forward to the extension of this climate record with great interest."