Flying (especially on short flights) is among the least sustainable ways
to travel, to groups such as the Environmental Defense Fund.
Some airlines allow you to try to compensate for the carbon footprint
you create when flying, however, by buying what are known as carbon
offsets, or various ways to reduce greenhouse gases. Passengers on
airlines like Delta and United can calculate their carbon footprint on the
airline websites, which equate the size of a trip’s carbon footprint with a
dollar figure. They can then donate their money or miles to a carbon
reduction project such as forest conservation or renewable energy.
Airlines are not the only ones offering offsets, though. Amtrak, for
instance, has a rail calculator and allows you to offset your train trip
through Carbonfund.org.