Contrails and Global Warming

by **FourthBase** » Wed Jun 14, 2006 7:29 pm

<a href="http://news.yahoo.com/s/nm/20060614/ts_nm/environment_flights_dc">news.yahoo.com/s/nm/20060...flights_dc</a> <blockquote>Quote:<hr>LONDON (Reuters) - Cutting the number of flights that take off at night could help to reduce the contribution of aviation to global warming, researchers said on Wednesday. Night flights contribute to climate change because the white streaks of condensation, or contrails, left behind by jets trap energy emitted from the Earth's surface. Daytime flights have less impact because contrails also reflect some of the sun's energy back into space which has a cooling effect. "It you wanted to minimize the contrail climate effect you might want to think about rescheduling flights," Dr Nicola Stuber of Reading University said in an interview. The researchers discovered that although only about 25 percent of flights in Britain take off between 6 p.m. and 6 a.m., they account for 60-80 percent of global warming linked with contrails. On the east coast of the United States the 36 percent of flights that take off at night account for 53 percent of the annual warming due to contrails. In southeast Asia, which had slightly fewer late flights, the percentage is about 70. "Night flights contribute disproportionately to the daily mean effect of contrails," said Stuber. Although the overall effect of contrails on climate change is small, about 3.5 percent of the potential from all human causes, the scientists warned it could gain importance as the volume of air traffic increases. Stuber and her team used a computer program to analyze flight data and atmospheric conditions to determine when contrails are most likely to form and what impact they would have on the Earth's temperature. They found that, in addition to night travel, flights during the winter months account for half of the annual warming from contrails. "So you get half of the climate warming effects from flights during one quarter of the year," said Stuber, who reported the findings in the journal Nature. Although there are fewer flights during the winter months, the conditions needed to form contrails -- the right temperature, amount of moisture in the air and aircraft altitude -- are found more often. "If you have all these conditions, you will have formation of persistent contrails. The effect of these conditions is larger than the effects of the air traffic," Stuber said.<hr></blockquote> Edited by: <A HREF=http://p216.ezboard.com/brigorousintuition.showUserPublicProfile?gid=fourthbase>FourthBase</A> at: 6/14/06 6:16 pm

by **Et in Arcadia ego** » Wed Jun 14, 2006 11:55 pm

Now, and projected persistant contrail formation in the year 2050: <img src="http://www.grida.no/climate/ipcc/aviation/images/avf3-24.jpg" style="border:0;"/> If you want to digest the science of it all, the IPCC has an extensive report on aviation's impact(radiative forcing) on the enviornment. This is precluding any suppositions of a 'spraying' program. When you examine the data, you'll see that a spraying program is hardly neccessary. The data you bring up mentions the negative impact of persistant contrails in a nocturnal scenario; they dissipate into artifical Cirrus Uncinus and block accumulated energy from the Sun during the day from espacing back into space as infrared heat at night. This was my biggest argument against 'chemtrails' being a mitigation program due to the fact that trails are easily seen during full moon evenings all through the night. The IPCC argues that persistent contrails are instigated by localized supersaturation states in the atmosphere and the occurance of persistance will not get any better than it already is. The full IPCC report is available for reading online and can be found here: http://www.grida.no/climate/ipcc/aviation/index.htm The IPCC has also published a mitigation report as well that very tightly dovetails with the Academy of Science's publication, ' Policy Implications of Greenhouse Warming: Mitigation, Adaptation, and the Science Base' that can be accessed here: http://fermat.nap.edu/catalog/1605.html#toc *hint: enlarge your text display and head over to chapter 28, 'Geoengineering'. Things become interesting by page 454: <blockquote>Quote:<hr>Page 454 (U.S. Bureau of the Census, 1988). This gives a cost of slightly more than $1 per ton-mile for freight. If a dust distribution mission requires the equivalent of a 500-mile flight (about 1.5 hours), the delivery cost for dust is $500/t, and ignoring the difference between English and metric tons, a cost of $0.50/kg of dust. If 1010 kg must be delivered each 83 days, (provided dust falls out at the same rate as soot), 5 times more than the 1987 total ton-miles will be required. The question of whether dedicated aircraft could fly longer distances at the same effective rate should be investigated. However, if the requirement is to mitigate the 1989 U.S. emissions of CO2, 500 times less dust is needed, the cost is about $10 million per year, and implementation would require about 1 percent of the ton-miles flown in 1987. If 10 percent of the ton-miles flown in 1987 were used, the system could mitigate 80 Gt CO2. These costs should probably be increased by the cost of delivered dust (say, $0.50/kg) and of delivery systems in the aircraft, but better-than-average freight rates could probably be arranged. Thus the costs appear to be about $0.0025/t CO2. Clearly, the amount of dust required could be greater by a factor of 10, and the cost would be $0.025/t CO2. This provides a cost estimate in the range of $0.003 to $0.03/t CO2. <hr></blockquote>

by **Mentalgongfu** » Thu Jun 15, 2006 1:25 am

does anyone know a meteorologist other than Scott Stevens? I have a few questions.

by **Et in Arcadia ego** » Thu Jun 15, 2006 12:45 pm

Stevens himself admitted that he does not have a meteorologist degree. He's been fired from at least one job because of that.

Contrails and Global Warming

Contrails and Global Warming

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