Purchasing karma?

Sh. & I have just purchased plane tickets to visit my brother and his partner in British Columbia. We don’t fly very often; this will be our fourth trip in the past five years. Besides lacking the disposable income to travel more, this is in part out of an attempt to reduce our carbon footprint. When I travel to visit my co-workers in New York City, I take the train (about 10 hours), although flying would be much faster and not much more expensive. Despite these efforts, the flights we do take end up factoring significantly in our personal contribution to climate change.

Anyways, I’m not writing this to make you feel bad if you travel more than we do. I’m writing because I’m interested in purchasing carbon offsets for our flights, and would like to know if anyone has any suggestions. There are a huge variety of choices out there, each with their own method for converting dollars into carbon offsets, and if you’ve already spent some time researching these options, I’d be interested to hear which you chose and why.