Well, the clouds are anyway… Research published in Geophysical Research Letters by University of Auckland physicists Roger Davies and Matthew Molloy suggests that the global average cloud height declined by around 1 per cent over the last decade, or around 30 to 40 metres.
The study on cloud height has revealed a possible cooling mechanism that may be in play in the Earth’s climate. Using data from NASA’s Terra satellite which uses 9 cameras to produce stereo images of clouds from space to estimate cloud height, the scientists found that the overall trend of decreasing cloud height was mostly due to fewer clouds occurring at very high altitudes.
The 10 year record is too short to be definitive but it does suggest that something quite important might be going on due to changes in the circulation patterns such as El Niño / La Niña phenomenon in the Pacific, that give rise to cloud formation at high altitude. These changing patterns are also linked to the many rainy days we have had recently in Canberra!
(Check out this video of the changes that take place over this 10 year cycle)
Climate scientists will be factoring the changing clouds height into future climate models to have more accurate forecasts of climate change as the reducing cloud height might actually slow climate change because more heat could escape the Earth’s surface. There is chance that the clouds might return to higher altitudes over the next decade but if the clouds keep coming down, Davies says “it will be very significant”.