Academic Articles:
Unions do not have a tremendous impact on wages - see this article by Richard Freeman and Morris Kleiner.
One of the most effective ways of keeping wages high is not actually forming a union, but keeping the possibility open - this is analyzed as a "union threat" model (see this article for more details).
Higher unionization in Canada has led to higher levels of unemployment there, according to a recent study. Hence, it is important to consider the effect that union formation could have on the number of TAs and RAs hired at Columbia.
How many TAs will Columbia hire?
If graduate students vote for a union, graduate students will only be covered by union-negotiated agreements if they are working as a TA or RA for that semester. Who gets to be appointed as a TA or RA? These decisions are left up to the various academic departments, since the union does not deal with academic matters.
Two issues are readily apparent: first, having a union does not seem to fit very well in the academic context, since the decision about whether to appoint/employ someone as a TA or RA is an academic decision, not an employment one; second, Columbia has the flexibility to hire as many or as few TAs and RAs as it wants, and thus determine the composition of the union.
At a meeting recently with a graduate student in the economics department at NYU, who was on their bargaining committee, the argument was put forward that Columbia has a lot of money, and they should just give it to grad students. (As he put it, "Come on, you guys are economists - you should understand this.") It's hard to say how much money Columbia could spend on grad students, but one thing should be clear - there is no free lunch. Whenever Columbia chooses to spend more in one area, there is less funding available for others (this is what economists term opportunity cost).
Fewer TAs, and not necessarily much better funded
As pointed out above, Columbia can determine which students will be covered by collective bargaining in the event of unionization. Columbia can't do without TAs completely, though; instead, they will simply have to hire fewer of them. Personally, I am not worried about the economics department, because there is a large demand for economics TAs since economics is a big undergraduate major at Columbia. In smaller departments, however, it is likely that Columbia would fund fewer TAs. This would be a great loss for the university, and for graduate students in smaller (but no less valuable) fields.
Incidentally, as a fellow economics student pointed out to me, students in better-funded departments should not expect to have their funding increased much in the event a union is formed. Why? The GSEU plans to equalize stipends across departments. Naturally, they won't try to lower anybody's stipends - instead, they plan to raise everyone up to the same level. In principle, this sounds like a good idea - in practice, it means students in many departments will go for years with very small increases while other departments catch up. It also means that Columbia will be unable to attract the best grad students in the country since it will have to hold back on increasing funding for some departments. (GSEU claims they are not actually in favor of equalizing stipends - but they seem to be having trouble sticking to their story - see David Carpio's comments in the ninth paragraph of an article on the UAW website.)
What does GSEU think will happen to fellowships? - click here.
Postscript
I have to add that when I asked the student from NYU if the economics students in his department ever tried to analyze the issue of unionization using the tools of economics, he replied no, that they merely talked about how it would affect them as TAs and employees. This is a particularly disappointing response, since there are a wealth of insights to be gained by using the analytic framework of economics to approach this issue. For a PhD student in economics not to appreciate this is incredible.
International students might want to think twice about voting in the UAW - here's why.
For some other perspectives on unionization, see this page.
A PDF version of this page can be found here.