February 22, 2012
Falling Clouds May Combat Global Warming
In what may be a natural response to rising global temperatures, Earth's clouds fell by an average of approximately one-percent over the first decade of this century, a new study funded by NASA and completed by scientists at the University of Auckland in New Zealand has discovered.
According to a Tuesday press release from the U.S. space agency, experts at the university studied 10 years worth of global cloud-top height measurements from the Multi-angle Imaging SpectroRadiometer (MISR) instrument onboard NASA's Terra spacecraft.
That data, which covered the period between March 2000 and February 2010, uncovered "an overall trend of decreasing cloud height" with average global cloud height falling by an average of between 100 and 130 feet in 10 years' time. Fewer clouds occurring at extremely high altitudes was said to be the primary reason for the phenomenon, according to NASA.
"This is the first time we have been able to accurately measure changes in global cloud height and, while the record is too short to be definitive, it provides just a hint that something quite important might be going on," University of Auckland Professor Roger Davies, lead researcher on the project, told AP reporters Wednesday.
The university claims that consistent reductions in cloud height could potentially lead to more efficient cooling of the planet, thus reducing Earth's surface temperature and maybe even slowing down the effects of global warming. Davies said that the phenomenon may be a "negative feedback" mechanism -- a change caused by worldwide climate change that actually works to combat or counteract it.
“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 said in a statement.
NASA reported that the Terra satellite, and specifically the MISR instrument, is scheduled to continue collecting data throughout the rest of this decade, and that experts will continue to monitor the information it obtains to see whether or not the trend continues.
“If cloud heights come back up in the next ten years we would conclude that they are not slowing climate change,” said 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.”
The research has been published in the journal Geophysical Research Letters.
Image 1: This image of clouds over the southern Indian Ocean was acquired on July 23, 2007 by one of the backward (northward)-viewing cameras of the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's polar-orbiting Terra spacecraft.Image credit: NASA/JPL-Caltech
Image 2: 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
Image 3: Patterns that relate changes in cloud-top height with El NiÃ±o/ La NiÃ±a indicators. Image credit: University of Auckland/NASA JPL-Caltech
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