Elizabeth Redden's article today on study abroad and sustainability gives a good overview of the topic. For Greenback U and many other schools, the travel (mostly by air) involved in study abroad is responsible for a significant percentage of inventoried greenhouse gas emissions. Still, it's something I'd like to see campuses increase, not cut.
Why? Look back at that previous statement. "Inventoried greenhouse gas emissions." Not "total greenhouse gas emissions."
The truth of the matter is that all US colleges and universities with which I'm familiar totally ignore a large portion of their emissions when doing a greenhouse gas inventory, and for good reason. We don't, for example, count emissions from students driving from campus to the mall to shop for whatever, on the basis that this isn't a function of them being at school -- Americans of that age and that socio-economic and cultural status would be driving to the mall to shop, even if they weren't enrolled at Greenback or anywhere else. Similar arguments apply to the lifecycle emissions resulting from the food on-campus students eat. They'd be eating anyways, so those emissions aren't particularly related to their being in school.
That's the short answer to the comment by A.G. Bier. Universities (particularly signatories to the Presidents Climate Commitment) don't take a credit for lower emissions from overseas eating and transport, because we don't take a charge for US-based eating and transport -- we treat both of them as out of scope. That might not be an ideal situation, but it's the one we've got.
Still, I think overseas eating and transport (among other experiences) are big advantages of study abroad. Students (particularly traditionally-aged students) can't be expected to appreciate that other equally (or more) enjoyable lifestyles are possible if all they've ever seen is what it's like where they live. (And most students go to a college or university which is socially, culturally, and economically in tune with where they live. By no means all, but most.) Riding public transit in the US is the exception -- in many developed societies, it's the rule. Consumption of meat and frozen pre-prepared foods present just the opposite case. It's amazing the number of developed societies where families live quite happily in less than 800 sq. ft. per person.
Bier may be right -- the decreased lifestyle emissions students generate while overseas may more than offset the travel emissions they create getting there. I don't really know or care, because the impact of students having lived abroad is potentially much greater (and longer-lasting).
I do like the idea Redden discusses of having students offset, through their behavior, their travel emissions. It focuses their attention on the impacts of what they do. (Having them buy their way out of responsibility is less educational. Having the University pay for an offset and hide it in the administrative fees has no educational value at all.) Activity-based personal offsetting is an idea I'll float to our study-abroad staff folk. When I collected the data for the GHG inventory, they were troubled by the scale of emissions generated. They may well jump at a meaningful, even educational, way to solve that problem.