A letter in newscientist also addressed this issue, but I'm afraid it's still bad news for contrails:
"Cirrus-like cloud (2 April, p 16)<http://www.newscientist.com/article/dn20304-contrails-warm-the-world-more-than-aviation-emissions.html> that originates as aircraft contrails can be expected to have two effects: trapping heat from the ground, and reflecting solar energy back into space. It would help if the model described evaluated the net global warming effect. *London, UK* *The editor writes:* Ulrike Burkhardt, whose results we reported, says her model does include both. She emphasised the trapping effect because it is larger." On 6 April 2011 09:47, John Nissen <[email protected]> wrote: > Hi John > > I am at the EGU in Vienna, accessing internet for first time. Ive just > read article in New Scientist April 2 issue suggesting contrails have > warming effect but there's no mention of the albedo effect so I don't trust > it at all. However we had a session on geoengineering, with a new UK > project has considered TiOx particles rather than sulphates in > stratosphere. A major benefit is that you can engineer the size of > particle. With any particle there is ozone issue, but TiO seems good from > many aspects. Alan Gidean from Leeds was there and he had poster on cloud > brightening which he is very keen on. I think we need both methods as belts > and braces approach to avert major catastrophe from permafrost methane, the > subject of my oral presentation today. > > Cheers, > > John > > > > On Thu, Mar 31, 2011 at 10:06 AM, John Gorman <[email protected]>wrote: > >> My idea for stratosheric aerosol generated from aircraft fuel (1) came >> from reading papers showing the warming during the three day period after >> 9-11 when there were no contrails over the US. >> >> That was long before I had heard the word geoengineering or about >> volcanoes, SO2, Alan Robock or Paul Crutzen. -or this group! >> >> I later heard that there were other papers suggesting that contrails >> caused warming. I put some effort into trying to work out which was correct >> but eventually gave up , concluding that there were equal numbers of papers >> suggesting that contrails caused warming or cooling. I very much doubt that >> this has added more than one bit of paper to one side of the balance. >> >> There was even a paper suggeting that commercial flights should be limited >> to 20,000 feet. I cant remember why. >> >> john gorman >> >> (1) www.naturaljointmobility.info/grantproposal09.htm >> >> >> >> ----- Original Message ----- From: "John Nissen" <[email protected]> >> To: "Geoengineering" <[email protected]> >> Sent: Wednesday, March 30, 2011 11:04 PM >> Subject: [geo] Contrails bad? >> >> >> >> >>> http://planetark.org/wen/61626 >>> >>> John >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "geoengineering" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/geoengineering?hl=en. >>> >>> >>> >> > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
