What is the ecological cost of air travel and is it worth it?

Part of my family lives nearby. Another part of my family lives in another state, and the rest are scattered all over tarnation. I fly periodically to visit family. One year, I flew almost once a month. I knew that air travel was a heavy contributor to greenhouse gases, but I had a new grandchild four hundred miles away and aging parents six hundred miles the other direction. I chose to spend time with them, and that meant flying.

Because I need to visit my distant relatives regularly, and since it is unlikely I will have big blocks of time to travel by car, bus or train, it is likely I will continue to fly. To help me make decisions about how best to compensate for heavy carbon-emitting activities, I use tools like the carbon footprint calculator to assess my personal contributions to global warming. This page has good tips for reducing my footprint as well, including offsetting my air travel by avoiding cars and taking buses and trains at home, which I have been doing for several years.

Still, when you consider that most climate scientists believe we are very near the irreversible "tipping point" in global warming, air travel may be a dangerous luxury. For the past two years, conscious of the cost in CO2 emissions, I have flown less, but I miss my peeps.

People in the world of Ordinary like to visit distant relatives and friends as well. How should they get there? Are high speed trains the answer? If you nail a track across the landscape for thousands of miles this way and that, what is the cost to habitat? Can you lay the track in such a way as to account for animal needs to traverse the countryside in search of food and water, or perhaps simply to patrol their territory?

In the world of Ordinary, perhaps far less than our world today--where we crowd out wild animals to the point of extinction--trains might be a good solution. More to come on that.

Weigh in on this one, will you please?