This is something that I've actually thought about a lot, but hadn't ever thought to discuss on here. I travel internationally a fair amount, but recently have been feeling somewhat guilty about it for the reasons mentioned in the original post. I think this is good for putting it in perspective--I can do a lot more good by using my working life to help contribute towards lessening climate change then I can by not traveling internationally.
I feel a lot of the same guilt when I ride my motorcycle, which is one of my favorite things to do, and this really helps me feel better about that as well. Riding a vehicle that gets 45 miles a gallon is probably not having a particularly significant impact on the world as a whole.
On the other hand, I feel like this kind of thinking is part of why people don't vote, and I don't really agree with it in that situation, so I'm not sure why I agree with it here. If everyone thinks that changing what they're doing isn't going to change the world in any way, where's the incentive to move towards cleaner technology?