Here are three ways you might get to Copenhagen
The number of politicians flying to a conference to tackle global warming may raise eyebrows, but there are some people choosing unusual methods to get there in order to cut down on emissions.
Plane journeys emit a fair bit of carbon per mile. So it does seem a little strange to some people that so many politicians and functionaries will be heading to the Copenhagen climate summit by air.
But the argument the politicians use is that they have so little time, they must use planes to travel.
And the organisers reject the idea of video-conferencing, saying big decisions can only be taken after discussions in person.
But assuming you have time to spare, how might you get to Copenhagen while emitting less carbon?
A special train - organised by the International Union of Railways (UIC) with support from the UN and WWF - is being laid on between Brussels and Copenhagen. The passengers will be a handful of politicians, along with numerous rail officials and environmental campaigners. The 400 people on board all have an interest in the summit, with many dedicated to advocating rail travel as a way of cutting emissions.
The German train network has its own power grid to which renewable energy is being supplied for the train
The train journey is "carbon neutral", with the UIC arranging for the amount of electricity needed to power the train to be added to the German railways' grid from renewable sources.
The Climate Express leaves Brussels Midi on Saturday at 0910 local time and arrives at 2255 local time in Copenhagen. From Brussels the train heads east through Aachen, just over the German border, to Cologne for a stop. Then it's north to Hamburg for another stop and onward to Copenhagen via Padborg. A faster journey time is possible, but the stops have been arranged to pick up more officials and campaigners and to generate publicity.
For those not invited on the Climate Express, it is possible to do the journey on scheduled trains in a quicker time. Leaving Brussels Midi at 0959 local time on Saturday, with changes in Cologne and Hamburg, you would arrive in Copenhagen at 2211 local time. Assuming you are travelling from the UK, the Eurostar goes from London St Pancras to Brussels. But in this instance, no train on Saturday morning gets you to Brussels in time. You would have to travel on Friday, which is when Eurostar is running its own version of the Climate Express for activists and journalists.
The cost of rail travel - from, for example, Manchester to Copenhagen - would be more than a flight in most circumstances.
"It is a symbolic train," says a spokesman for UIC. The specially chartered train is not as quick as some available in Europe. But as the spokesman notes: "It runs as fast as anything you have in the UK."
Of course, while the carbon emissions from a train journey might be lower than a plane, why not consider going the whole hog and get about with no emissions.
Walking is one answer.
Roz Savage has walked to Brussels in order to catch a train
That's the course that has been taken by endurance rower Roz Savage, endurance skier Alison Gannett and four other hardy souls.
In fairness, they have only walked from Big Ben to Harwich, and then from the Hook of Holland to Brussels.
"Originally I was going to walk all the way to Copenhagen, but then I was invited to join the Climate Express," says Savage.
"It's to make a statement about how strongly we feel about climate change. By far the cheapest way would have been to fly, but I didn't want to fly. It's a shame that our [rail] pricing structures are set up in such a way that people are encouraged to fly."
Covering about 15 miles a day, the walkers took six days to get to Harwich before taking the ferry.
Savage did consider taking her Brussels trip emissions down to zero by rowing across the Channel, but her boat is unavailable as she is two-thirds of the way through a journey across the Pacific.
"My boat happens to be on a small island in the middle of the Pacific. We looked at sailing but we couldn't get a sailboat in time."
She has enjoyed the long walk.
"We have been carrying these inflatable earth balls that we are getting people to sign. You see a lot more of the countryside you are travelling through. I wouldn't say it's practical for people to walk everywhere.
And if the train sounds too complicated and walking sounds a bit knackering, there is always the bus.
That's what the Climate Caravan group are doing on behalf of the Jubilee Debt Campaign. Put enough people onboard and bus emissions might be fairly modest, but in this case it's all about the choice of fuel - biodiesel.
The debt campaigners are also on their way to Copenhagen
The red bus is going all the way to Copenhagen on used chip oil. The group has obtained enough of this fuel to get them to Brussels, trusting they will be able to find a supplier there to get them the rest of the way to Copenhagen.
They left on Friday and will be at Copenhagen by Tuesday, having hit peak speeds of about 40mph. The Dover to Calais ferry will carry the bus over the waves, but the rest is all chip fat.
Biofuel is not an uncontroversial subject, with many arguments about the consequences of using vast tracts of arable land to make it. But the group say used vegetable oil - which does take some processing to burn properly - is a true low-emission fuel.
"This is because, in principle, the net emissions of biodiesel are zero - the CO2 that was absorbed by the crop during its lifecycle is emitted again on burning, so no new CO2 is put into the atmosphere. Whereas normal diesel brings fossilised carbon back into the atmosphere," says Jonathan Stevenson of the Jubilee campaign.
"But you have to subtract the emissions used to collect and refine and deliver the biodiesel. We're using locally sourced biodiesel from near Lincoln, where the bus is based, to keep its production emissions down as low as possible.
"It's really important for us that it's biodiesel from waste vegetable oil to make it as sustainable as possible. It's not a solution for the whole economy as it can only meet a fraction of the demand, but it's the greenest way for us to take the bus."
Below is a selection of your comments.
So how did Roz Savage get from the small mid-Pacific island where she left her boat?
Neil Burrows, Watford, UK
We are a group of seven students from seven different countries and five different continents and are cycling to Copenhagen over eight days. We have completed six days and have two remaining and all going well.
Christian Williams, Uppsala, Sweden
Why not hitch-hike to Copenhagen? Any car that stops for you is already on the road, and it's possible to hitch-hike the Dover-Calais ferries and travel without paying, as many types of vehicles are charged a uniform price regardless of any accompanying passengers. The carbon cost is negligible - the only extra emitted carbon would be a small amount from each car that picks you up (the cars would be slightly heavier with you in them, and burn slightly more fuel). Starting early morning in London, you could expect to be in Copenhagen the same night, or the next day at worst.
Tom Moon, Douglas, Isle of Man
The amusing thing is, and I think this demonstrates how poorly informed we all are, if the planes that brought those delegates to the conference were all full (and they probably were with all the people attending), then they will have probably been as efficient as the trains and certainly the bus in terms of energy used. Walking is the only real green option.
The walkers aren't taking into account the carbon emitted when they stay in hotels or campsites, eat food, and so on. The only sensible low-carbon way to travel long distances is by train - or that chip-fat coach.
Bob Anan, London
Why is there no mention of the daily overnight ferry from Harwich to Denmark?
David Wilson, Wokingham
This sort of gesture politics gives genuine concern for the environment a bad name. Are the Germans going to activate some special renewable power sources for the "Climate Express"? No, the rest of Germany will just get a larger proportion of non-renewable energy. And besides, modern diesel trains are more energy-efficient than electric trains anyway. And why is it OK to fuel your bus from plants which were grown recently, but not from plants which were grown millions of years ago. I am all for energy conservation and responsible use of natural resources, but while manufacturers are designing products like washing machines which last three years instead of the 15-20 years which would easily be possible, and producing yet more "must-have" electronic gadgets, this sort of thing is just a distraction.
Mark, Berkshire, UK
An alternative to the above modes of transport would be to not travel at all & use video conferencing facilities instead of all meeting in Copenhagen.
Kieron, Sundsvall, Sweden
"So it does seem a little strange to some people that so many politicians and functionaries will be heading to the Copenhagen climate summit by air." This reflects a somewhat Eurocentric view of the world. Even with time to spare, representatives from the rest of the world would find it just a little difficult to walk, catch a train or a bus to Copenhagen. Travel by ship is similarly difficult as few have the spare weeks needed to undertake the journey on a form of transport that is responsible for the same amount of global CO2 emissions as the aviation sector. Perhaps someone will suggest we use a Tardis, but then that will only get us as far as Cardiff.
Ken Owen, Canberra, Australia