When traveling, there are tons of ways to get from point A to point B. Each travel form varies in efficiency.
A gallon of gasoline weighs 6.3 pounds (2.86 kg). As that gasoline is burned, each carbon atom combines with two oxygen atoms to form the CO2 molecule.
In the periodic table carbon is the 6th lightest elemnt and oxygen is the just a little bit heavier as the 8th lightest. This means that your gallon of gasoline goes a long way and your 6.3 gallons (2.86 kg) of gas becomes 19.6 pounds (8.9 kg) of CO2 in the atmosphere. Jet fuel is made up a bit differently and translates to 21.10 pounds of CO2 per gallon.
So, the name of the game is finding what puts the least carbon out of the tailpipe per pound of passenger. So, what ends up being most efficient?
As the bird flies, the distances from LA to New York is 2,451 Miles (3944 km). Driving is less efficient at 2,789 miles (4,499 km) as you have to drive 338 miles (543 km) more following the roads.
This means that in a car that gets 22 miles per gallon you are going to burn 127 gallons (481 litres) of fuel and emit 2,489 pounds (1129 kg) of CO2 into the air to get across the country.
On a Jet
A Jet on the other hand is going to to burn 78.45 gallons (297 litres) of jet fuel for each passenger and emit 1655.5 pounds (751 kg) of CO2 into the atmosphere.
In a Bus
So, consider taking the bus. A bus is going is going to to burn 10.7 gallons (40.5 litres) of gas for each passenger and emit 209.7 pounds (95 kg) of CO2 into the atmosphere.
Putting it all in perspective
So, for the same CO2 emitted into the atmosphere via a personal car on a trip from LA to New York, you could travel 33,104 miles (53,276 km) via bus or motor coach. That is enough to make the trip from LA to New York another 10 times or enough to go around the entire globe.
It doesn't always make sense to take the bus to every destination, but with this knowledge, you can make the world jsut a bit better. If your hotel offers a shuttle to key destinations, take it instead of driving yourself. If a National Park you are visiting offers a shuttle service, take it.
Just remember to take the bus first, then the train, then your car (if it is a diesel), then a plane and last of all take your car if it runs on gasoline.