Cyclones spurt water into the stratosphere, feeding global warming
April 20, 2009Scientists 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.
Source: Harvard University (news : web)
Feb 27, 2007 |
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THIS is SCIENCE?
When does your fusion reactor begin produceing power.
"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."
How did they measure the water vapour content accurately at that altitude before modern technology existed? 50yrs is not long in terms of "climate change" Shall we just say that the content was then 2/3 of present so that it appears to have increased by 50%?
If this is happening with cyclones now, it must have always have happened to the same or similar extent. The severe weather has been shown to have not increased, so there connot be this increased effect. For an increase of 50% the increase in cyclones would have to be really noticable, not even debatable. No-one could have missed it, it would have been a disaster.
"Many scientists now believe that global warming, in turn, is likely to increase the severity of tropical cyclones."
This is only a "belief" of what may possibly happen in the future.
BTW, if water vapour content has increased, something else could be causing it. It is usual to blame AGW for everything without studying other possibilities, more money in it.
Such as the increase in jetliners traveling through the stratosphere over the past half century or so. Contrails are water vapor after all.
You should take some time to study the subject before making uninformed comments.
1) Radiosonde measurements are available going back to the 30's
2)There is a period of overlap in radiosonde and satellite data, so the two datasets can be calibrated and compared.
3) Gloablly tropical storm severity and freq have increased. In the Atlantic basin the power of hurricanes (intensity over time) has increased.
4)Scientists believe that smoking causes cancer, the aids virus causes aids, etc. The use of term belief is a shorthand for having high enough confidence to make reasonable predictions about a systems future behavior. That's really the best scien cecan do, and yet we have space travel, pacemakers, weather forcasting, and iPods to show for it.
5) Just because you are unaware of them does not mean that other possibilities are not being researched. They are.
1/ local measurements
2/ locally
3/ no, they havn't
4/ don't be daft. A belief is just that, a personal acceptance that something is right or exists without solid evidence. (AGW, God?)
5/ and probably ignored because the results are inconvenient.