A continual challenge for modern travelers is the task of seeing as much of the world as possible without inflicting too much environmental damage on it. The main reason this is so difficult is that there is no form of transport - with the possible exception of sailboats - which does not pollute in some way. Even riding a bike causes you to exhale a considerable amount of carbon dioxide. Traveling by plane uses a tremendous amount of fossil fuel - something which most climate scientists believe is a major contributing factor in the problem of global warming.
But that does not mean you should write off air travel as hopelessly unethical and environmentally destructive. The modern world depends on aircraft, and without the tourists they carry around the world large segments of the global economy would be in danger of collapse. Technology and humanitarian aid could not spread half as effectively as it does between continents - in short, without air travel the world would be a duller, poorer, more miserable place.
So until somebody invents a viable teleportation device we pretty much depend on flight. That means we have to look at ways of reducing or offsetting the so called carbon footprint of air travel - the amount of raw, greenhouse-causing carbon dioxide pumped into the atmosphere every time a plane flies from one place to another.
Luckily, a lot of research has recently been dedicated to finding methods of doing just that. Although some of them are controversial, they merit examination by frequent travelers who are also keen to do their bit for the good of the planet. One of the most promising avenues is the development of carbon neutral schemes. frequent fliers who sign up for such a scheme pay for the planting of trees. Because all plants soak up carbon dioxide from the atmosphere, the theory is that one can offset the amount of greenhouse gases one is responsible for releasing by planting a number of trees proportion to the amount of traveling done. trees are quite inexpensive, and - so the theory goes - it is much cheaper to pay for carbon to be "harvested" than it is to release it in the first place by booking a plane ticket.
Carbon offset schemes remain controversial, but they seem to offer a cheap, easy way of enjoying your travel without necessarily destroying your world.