The best option by far is to plan a plane-free route to your holiday destination. The environmental group Tourism Concern predicts that by 2015 half of the annual destruction of the ozone layer will be caused by commercial air traffic. If you feel you have no option but to take to the skies try to avoid internal flights and stopovers. Take-offs and landings release the most carbon.
You can also offset the carbon emissions of your flight - either by investing in a campaign against climate change or planting some trees. Although offsetting schemes are hugely controversial, many environmentalists argue it's better than nothing. Log on to www.futureforests.com or www.climatecare.org, which have carbon calculators to show how much your flight has cost the planet.
For short journeys cars are the least green transport. Cold engines produce up to 60 per cent more fumes than warm ones and it takes about five miles before catalytic converters begin to work. But if the car remains the only option there are a number of practical measures you can take to improve fuel economy - avoiding fast acceleration/ heavy braking, making sure your car is properly tuned and checking that the tyres are at the correct pressure for starters.
For journeys overseas, the train is something of an underused option - though the Eurostar service to Paris and Brussels has helped. In April Eurostar announced plans to make its high-speed train services 'even greener' and slash CO2 emissions by 25 per cent per traveller journey by 2012. A full train is at least twice as energy efficient - and less polluting - than a full car. However, despite the absence of direct carbon emissions the electric train is mainly powered by fossil fuels - coal and gas - so it's not an entirely eco-friendly option.
Buses and coaches
Bus and coach travel is a less greener option than train travel but far better than car. The government website www.direct.gov.uk/en/travelandtransport/index provides information on your nearest bus or coach service, the types of tickets you can buy and how to avoid a penalty fare in London, among much else. You can even find out how to hire a coach or community bus. There are also details of discounted bus and coach tickets for young people, seniors and disabled people.
Don't let the fact that Margaret Beckett is a caravanning enthusiast put you off. According to the Telegraph she described it as the 'environmentally friendly way' to holiday and she has a point.
Caravanners spend most of their holiday outdoors and eliminate the need for concrete cities of purpose built holiday resorts, instead using the existing infrastructure of roads, towns, villages and farms. But some vans are oil-leaking eco-disasters and some sites are stains on the landscape.
A variety of organisations offer guidelines on how to caravan responsibly, from national caravan clubs through to Friends of the Earth, the three main points being: choosing environmentally aware sites; thinking about how to operate, in the caravan and around the site; and ensuring that the caravan itself is as environmentally sound as possible. For more tips check out www.practicalcaravan.com/features/green.html
Most water travel is low impact - especially sailing vessels - and although it is slow and the port may be some distance away, sea travel is a worthy green option. Eco-cruises have taken off in response to a quest by both passengers and cruise operators to go off the beaten track and explore their natural surroundings more respectfully .
Remember not to overlook the cheapest form of holiday transport, your legs! Walking or cycling is the cheapest and greenest travel option by far. So consider holidaying locally. Explore walking holidays on www.ramblers.org.uk and cycle tours on www.bicyclebeano.co.uk. And even if you haven't managed to make it to your holiday destination by entirely eco-friendly means try to make it up by only walking, biking and using public transport to get around once there. Chop and change
Choosing a single best method of transport can be difficult and sometimes impossible. Consider combining different options to make the best use of each. Go on journey planner websites such as www.seat61.com, which advocates travel by train and ship. It contains comprehensive information on just about any route a traveller could desire.
The new ecoescape green travel guide helps you find the nearest rail and cycle route links to help you on your way. A bit of forward planning can ensure you adopt a convenient mix of various ethical transport for different parts of the journey.
In March 2007, Ed Gillespie set off on his round-the-world trip as a 'slow traveller'. For the most part, slow travel involves anything but flying and is the antidote to fast getaway breaks. It follows on the heels of the slow food movement, the antidote to fast food. Gillespie is cataloguing his year-long trip on www.lowcarbontravel.com. So don't let the extra time taken to ethically travel put you off. The pleasure should be in the journey not just the destination.