The University of Washington is part of the American College & University Presidents’ Climate Commitment (ACUPCC), a pledge to measure and reduce college and university emissions that has been signed by over 650 other schools. Part of that effort involves measuring CO2 emissions from school-related air travel, and the ACUPCC provides a methodology for estimating these emissions from budget data using a figure of $0.25 per mile.
The students in my summer quarter 2009 Introduction to Environmental Economics class helped crunch the numbers to check that $0.25 per mile figure against actual UW air travel budget data, and we now have a draft paper—download it here—authored by David Corrado and Brady Voves (two students in the class), Tad Anderson (UW atmospheric sciences) and yours truly.
Our conclusion is that a more accurate estimate is $0.13 per mile, a number that is statistically indistinguishable from the most recent national estimate from the Bureau of Transportation Statistics. Using our estimate of $0.13 per mile instead of the original estimate of $0.25 per mile means that the same dollar amount takes you 87% more miles, i.e., that air travel emissions are 87% higher than previously estimated. As we note in the paper: “The ACUPCC methodology yields UW air travel emissions in 2007 of about 20,000 metric tonnes, or approximately 10% of total UW emissions of 200,000 metric tonnes. Using our methodology instead yields UW air travel emissions in 2007 of about 37,000 metric tonnes, or approximately 17% of total UW emissions of 217,000 metric tonnes.”
It’s important to note that this is preliminary work, e.g., because the data set we used only covers a fraction of total UW air travel. But it’s a good starting point, and we’d like to see this type of analysis repeated at other institutions. (Here are all the ACUPCC signatories.) It makes a great undergraduate research project, so if anybody takes it on please email me or otherwise keep me in the loop!
Update: During a discussion with ACUPCC and others, Niles Barnes of AASHE (Association for the Advancement of Sustainability in Higher Education) has referred me to this AASHE blog post (from Oct 2008) that recommends using recent ATAA figures instead of the $0.25/mile figure. These ATAA figures appear to be the same as the BTS figures we suggest in our paper, but the ATAA reference seems better because it appears to include more recent data and an extra decimal point. It seems to me that the ACUPCC should update their guidelines, and the fact that they don’t seem interested in doing so bothers me.
Update June 2010: UW is going to change the way they calculate air travel emissions, and hopefully work with ACUPCC to change their methodology also!