According to Margot Gerritsen, faculty member in the Department of Energy Resources Engineering at Stanford, a Boeing 737 with 75% occupancy gives about 80 miles per gallon for each passenger (http://www.smartenergyshow.com/node/90). She further states that:
- aviation accounts for about 1/7 of transportation-related carbon emissions
- one round-trip from San Fransisco to Paris equates to about 15% of the average annual US household carbon emissions
- airline growth world-wide is about 5-6% per year (a significant cumulative increase over the coming decades)
- contrails are of interest because they lead to positive radiative forcing, however they dissipate relatively quickly
Airbus recently sponsored a global competition for new concepts in aircraft design and engineering, and has been narrowing down finalists. A group at Stanford is one of five finalists for an idea of using a "V" formation similar to migrating birds to reduce drag (up to 20% according to calculations). (http://uk.reuters.com/article/burningIssues/idUKTRE54653920090507?pageNumber=2&virtualBrandChannel=0)
I am looking forward to dramatic improvements on this front, because while I love to conserve energy, buy local, bike, etc. I have a really hard time with the idea of reducing my travel!