ENASA satellite finds Earth's clouds are getting lower

(PhysOrg.com) -- Earth's clouds got a little lower -- about one percent on average -- during the first decade of this century, finds a new NASA-funded university study based on NASA satellite data. The results have potential implications for future global climate.

Data from NASA's MISR instrument on NASA's Terra spacecraft show that global average cloud height declined by about 1 percent over the decade from 2000 to 2010, or around 100 to 130 feet (30 to 40 meters).Image credit: University of Auckland/NASA JPL-Caltech

Lead researcher Roger Davies said that while the record is too short to be definitive, it provides a hint that something quite important might be going on. Longer-term monitoring will be required to determine the significance of the observation for global temperatures.

A consistent reduction in cloud height would allow Earth to cool to space more efficiently, reducing the surface temperature of the planet and potentially slowing the effects of global warming. This may represent a "negative feedback" mechanism - a change caused by global warming that works to counteract it. "We don't know exactly what causes the cloud heights to lower," says Davies. "But it must be due to a change in the circulation patterns that give rise to cloud formation at high altitude."

Patterns that relate changes in cloud-top height with El Niño/ La Niña indicators. Image credit: University of Auckland/NASA JPL-Caltech