Well fling gets your washing dirty, soot got to go some where,ships are the dirties

It really isn’t that much of a difference. The plane is going to take off anyway whether or not you are on it so just go. If it upsets you that much then there are companies that will offset your air travel by planting trees. The information you are looking for is in the link below.

http://www.sightline.org/publications/enewsletters/CSNews/CS_12_04_airtravel

If the plane if 1 / 2 full and above it produces less CO2 / mile / person than a car with one person in it, for example you travelling up to collect your wife ( and then the return journey 1/2 the same again).
If she still feel guilty then plant a tree that must offset something ;o)

Actually it is pretty comparable to a car in terms of fuel consumption and therefore pollutants, about 20 miles per US gallon, or 24 per imperial gallon, per person on the flight for a jet aircraft, and 42 US (50 Imperial) gallons per mile for a turboprop aircraft which is the type your wife will be flying on that particular route, in fact it will be a Q400 that is the most modern and efficient aircraft in its class, so it will be much better than 42 miles per gallon per passenger.

Here is a web page with that info. With newer engine technologies this is getting much better.

I would say fly, save some money, some time and it will make little difference or be better than if you were to drive in terms of pollutants.

Here is the web page I got the information from.

Thanks for asking the question, I learnt something today.