The company I work for uses high quality carbon offsets to reach carbon neutrality for all business activities, including business travel by employees. Of course, this isn't scalable, so it doesn't
really absolve me. But the travel I do is also not
really optional. I just personally don't think it's necessary or helpful. Doesn't mean I don't have to do it when I'm called upon to do so.
The other thing I do is live a fairly carbon efficient lifestyle. I travel much less than other folks in my income bracket, and I live in the most carbon efficient city in the U.S. I take mass transit to work and don't own a car. There is of course more that I could do, but if I zero out my usage it will make precisely no difference to the outcome. So I also vote with my dollars and my actual votes for political candidates who will push in the right direction on this issue.
But more than anything, I think if I'm honest, I don't justify it. I just do it. These scales cannot be balanced -- the human mind cannot encompass actions whose harms are so incrementally minor and diffuse, but corporately so major and severe. Our social heuristic engine is not equipped to process it, and mine isn't an exception.