It is now very nice that one is able to travel to any part of the world in a short time by air. However, one should take into consideration the amount of carbon dioxide (a green house gas) one would contribute to the atmosphere. Here is a site that calculate for you your carbon dioxide contribution by just inputing one's origin and destination. Go to Climate Care. All you have to do is to pick your origin and destination from a drop-down menu, fill in the box for the number of passengers, tick the radio button for one-way or return and click "Calculate my emissions". On the same site, you can also calculate carbon dioxide emission from the house by inputing the amount of electricity, gas and heating oil you use. Another section allow you to calculate the carbon dioxide emission from the car by inputing the miles/kilometre travelled per year, the type of fuel (petrol, diesel or L.P.G.) amd the vehicle fuel economy. There are also sections on offsetting your carbon emission. Interesting site you should visit.
You can also educate yourself about environmentally responsible travelling by subscribing for their newsletter (digital version) at International Ecotourism Society.
You can search for environmentally friendly hotels at Have a Green Summer or join the discussions for environmentally responsible travelling at the Google group Green Travel.