Chicken Licken was right, the sky really is falling. Nasa
satellite data has shown that the Earth's cloud tops have been
lowering over the last decade. Cloud-top height fell one percent
on average between March 2000 and February 2010, according to
measurements from the multi-angle imaging spectroradiometer
mounted on Nasa's Terra satellite. That one percent means a
reduction of 30 to 40 metres in the average height of clouds,
during the 00s. While the short record means it's difficult to
draw any strong conclusions from the data, it does hint towards
a longer-term trend. Roger Davies, the lead researcher on the
project, warns that it's something that should be monitored in
the coming decades to determine how significant it is for global
temperatures. If there is indeed a consistent reduction in cloud
height, and this isn't just natural variability, then Earth
would begin cooling to space more efficiently, reducing the
surface temperatures and slowing the effects of climate change.
"We don't know exactly what