14 DAY TRIAL // Australian researchers have discovered in a new study that Earth's cloud cover is dropping closer to the surface of the planet. It has been doing so for at least 10 years, and is now about one percent closer than it was a decade ago. The conclusions belong to a new study based on satellite records.
Though this may not seem like a big deal, researchers are very curious as to what effect this will have on global climate. Clouds are known to play an extremely important role in the way Earth regulates its climate, as well as in the evolution of global warming.
Investigators from the University of Auckland, in New Zealand, analyzed data collected by the Multi-angle Imaging SpectroRadiometer (MISR) instrument on the NASA Terra satellites for this study.
The datasets spanned a period of time from March 2000 to February 2010. Details of the work appear in a recent issue of the esteemed scientific journal Geophysical Research Letters. Discovering this overall trend of decreasing cloud height puzzled researchers.
A one percent decrease in average cloud heights translates into an altitude different of around 30 to 40 meters (100 to 130 feet). According to the research team, most of the difference can be accounted for by the formation of fewer high-altitude clouds, for unknown reasons.
The UA team admits that the dataset covers a very small period of time, and says that 10 years is insufficient time to establish a real trend. However, the work may have unraveled a new phenomenon, of which scientists had no idea beforehand.
According to lead researcher Roger Davies, this situation will need to be assessed more thoroughly in the future. This means that long-term monitoring of cloud cover height should be included in the standard sets of measurements being conducted on the atmosphere.
In addition, the full significance of these discoveries is only now being deciphered. Most likely, it will take a few more years until the effects of this shift become discernible in other measurements.
“We don't know exactly what causes the cloud heights to lower. But it must be due to a change in the circulation patterns that give rise to cloud formation at high altitude,” Davies says. One implication of lower cloud covers could be that more heat is reflected into space.
This could theoretically contribute to cooling the planet, and helping to mitigate global warming, at least to some extent. This evolution of the global cloud cover could represent a negative feedback mechanism through which the planet is responding to global warming.