Nav: Home

Cyclones spurt water into the stratosphere, feeding global warming

April 20, 2009

CAMBRIDGE, Mass., April 20, 2009 -- Scientists at Harvard University have found that tropical cyclones readily inject ice far into the stratosphere, possibly feeding global warming.

The finding, published in Geophysical Research Letters, provides more evidence of the intertwining of severe weather and global warming by demonstrating a mechanism by which storms could drive climate change. Many scientists now believe that global warming, in turn, is likely to increase the severity of tropical cyclones.

"Since water vapor is an important greenhouse gas, an increase of water vapor in the stratosphere would warm the Earth's surface," says David M. Romps, a research associate in Harvard's Department of Earth and Planetary Science. "Our finding that tropical cyclones are responsible for many of the clouds in the stratosphere opens up the possibility that these storms could affect global climate, in addition to the oft-mentioned possibility of climate change affecting the frequency and intensity of tropical cyclones."

Romps and co-author Zhiming Kuang, assistant professor of climate science in Harvard's Faculty of Arts and Sciences, were intrigued by earlier data suggesting that the amount of water vapor in the stratosphere has grown by roughly 50 percent over the past 50 years. Scientists are currently unsure why this increase has occurred; the Harvard researchers sought to examine the possibility that tropical cyclones might have contributed by sending a large fraction of their clouds into the stratosphere.

Using infrared satellite data gathered from 1983 to 2006, Romps and Kuang analyzed towering cloud tops associated with thousands of tropical cyclones, many of them near the Philippines, Mexico, and Central America. Their analysis demonstrated that in a cyclone, narrow plumes of miles-tall storm clouds can rise so explosively through the atmosphere that they often push into the stratosphere.

Romps and Kuang found that tropical cyclones are twice as likely as other storms to punch into the normally cloud-free stratosphere, and four times as likely to inject ice deep into the stratosphere.

"It is ... widely believed that global warming will lead to changes in the frequency and intensity of tropical cyclones," Romps and Kuang write in Geophysical Research Letters. "Therefore, the results presented here establish the possibility for a feedback between tropical cyclones and global climate."

Typically, very little water is allowed passage through the stratosphere's lower boundary, known as the tropopause. Located some 6 to 11 miles above the Earth's surface, the tropopause is the coldest part of the Earth's atmosphere, making it a barrier to the lifting of water vapor into the stratosphere: As air passes slowly through the tropopause, it gets so cold that most of its water vapor freezes out and falls away.

But if very deep clouds, such as those in a tropical cyclone that can rise through the atmosphere at speeds of up to 40 miles per hour, can punch through the tropopause too quickly for this to happen, they can deposit their ice in the warmer overlying stratosphere, where it then evaporates.

"This suggests that tropical cyclones could play an important role in setting the humidity of the stratosphere," Romps and Kuang write.
-end-
Romps and Kuang's research was funded by the Eppley Foundation and NASA.

Harvard University

Related Global Warming Articles:

A new study provides a solid evidence for global warming
The new study allows a more accurate assessment of how much heat has accumulated in the ocean (and Earth) system.
Global warming hiatus disproved -- again
UC Berkeley scientists calculated average ocean temperatures from 1999 to 2015, separately using ocean buoys and satellite data, and confirmed the uninterrupted warming trend reported by NOAA in 2015, based on that organization's recalibration of sea surface temperature recordings from ships and buoys.
Report reassesses variations in global warming
Experts at the European Centre for Medium-Range Weather Forecasts (ECMWF) have issued a new assessment of temperature trends and variations from the latest available data and analyses.
Clouds are impeding global warming... for now
Lawrence Livermore National Laboratory researchers have identified a mechanism that causes low clouds -- and their influence on Earth's energy balance -- to respond differently to global warming depending on their spatial pattern.
Global warming's next surprise: Saltier beaches
Batches of sand from a beach on the Delaware Bay are yielding insights into the powerful impact of temperature rise and evaporation along the shore that are in turn challenging long-held assumptions about what causes beach salinity to fluctuate in coastal zones that support a rich network of sea creatures and plants.
Could global warming's top culprit help crops?
A new study tries to disentangle the complex question of whether rising amounts of carbon dioxide in the air might in some cases help crops.
Evaporation for review -- and with it global warming
The process of evaporation, one of the most widespread on our planet, takes place differently than we once thought -- this has been shown by new computer simulations carried out at the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw.
Researchers reveal when global warming first appeared
Human caused climate change is increasingly apparent today through multiple lines of evidence.
1,800 years of global ocean cooling halted by global warming
Prior to the advent of human-caused global warming in the 19th century, the surface layer of Earth's oceans had undergone 1,800 years of a steady cooling trend, according to a new study in the Aug.
Global sea levels have risen 6 meters or more with just slight global warming
A new review analyzing three decades of research on the historic effects of melting polar ice sheets found that global sea levels have risen at least six meters, or about 20 feet, above present levels on multiple occasions over the past three million years.

Related Global Warming Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".