It is projected that by 2050 aircraft will account for 5% of total global warming. Aircraft currently produce about 3% of world CO2 emissions. Think 3% doesn't seem like much? If you saved 3%, you could save 30 dollars out of every thousand. Not convincing enough? In America in 2006, the total annual CO2 emission was 6,049,435 thousand metric tons – if we could decrease that by 3%, we would reach 5,867952 thousand metric tons. With the average American emitting 7.5 tons per year, that 3% reduction is as much as if 782,393 people simply stopped emitting CO2. Hopefully now you're convinced.

    Besides accounting for tons of CO2 every year, airplanes also emit nitrogen oxides, which bond with vaporized gases to create ozone. Those nitrogen emissions, along with hot air from plane engines, mix with air at high altitudes and form the long while lines often observable across the sky, called condensation trails, or contrails. There is much debate as to the role of contrails in global warming, but one thing is becoming clear. Though contrails reflect sunlight into the atmosphere during the day, it seems that at night contrails play a role in trapping escaping heat and gases within the earth's atmosphere, increasing the warming effect.

    What does this all mean to you? Though it is unreasonable to ask humanity to stop traveling by plane, it is reasonable to propone other methods of travel. If you have the time, try traveling by train or bus - modes of transportation that can move as many people as planes, but with smaller carbon footprints. Though both busses and trains use diesel fuel, which also contributes to global warming, these modes of transportation create less emissions than air travel. On average, you can calculate the kg of CO2 emitted by your travel using this simple equation:
For a bus or train: miles traveled x 0.1 = kg C02 emitted
For a plane: miles traveled x 0.29 = kg C02 emitted

    That means that travel by airplane is creates almost 3 times as much CO2 as train or bus travel. For example, let’s say you wish to travel from London to Edinburgh. The distance is about 332 miles by air, 410 miles by train. That means that if you fly to Edinburgh, you emit 96.28 kg C02. If you take the train, you emit less than half of that amount: only 41 kg C02.
   
    So next time you have the option, and a few more hours, think ground, rather than air-travel. There’s certainly more to see out the windows, like beautiful scenery, and as you recline (most likely with more legroom) you can indulge in the thought that the lovely green grass outside of your window will stay green in part because of people like you.

**RezHub wants you to know that another option when flying is offsetting the carbon that your flight produces.  Choosing to go carbon neutral is one of the gateways to responsible travel.  It's easy to do, and it's inexpensive!  We offer you the option of donating a small fee to the Conservation Fund's Go Zero program.  The Fund's focus is on planting enough trees to neutralize the carbon dioxide that your trip will create, and help clean up the mess we've already made in the atmosphere. Donating is simple CLICK HERE or follow these steps: select "Attractions," from any available destination, select "Other Services," then select "Donation to the Conservation Fund's Go Zero Program," select your desired donation, and go neutral!**


Sources:
http://news.bbc.co.uk/2/hi/science/nature/6195567.stm
http://www.climatecrisis.net/takeaction/carboncalculator/
http://mdgs.un.org/unsd/mdg/default.as
pxNature, June 15, 2006