The EuroStar train service that operates between London
and Paris through the English Channel tunnel already bills itself as ten times less polluting than air travel
on the same route. Now they are aiming to be completely carbon neutral. They are aiming to reduce the carbon emissions they are directly responsible for by twenty five percent by 2012. They plan to do this by buying the electricity for their trains for greener sources, making the trains more efficient and improving their capacity utilization. On top of that after November 2007 they will buy carbon offsets
for all the emissions they can't eliminate.
[Source: Gaurdian via TreeHugger