Cautious optimism that a new climate deal can be reached in Copenhagen was the overriding theme of the discussions on board the Climate Express, a symbolic train journey which carried more than 400 COP 15 delegates, civil society representatives and media from Brussels to Copenhagen on Saturday.
"We've had a lot of very hopeful signals in the past week or so," UNEP's Executive Director, Achim Steiner, told the passengers during the closing on-board debate.
"The number of world leaders now planning to attend the climate talks is one such signal, but the responsibility to hold the leaders to account and to continue to apply intense pressure sits with civil society," Mr Steiner said.
UNEP partnered with the International Union of Railways, WWF and the British Council to plan the Climate Express journey, which featured a novel, on-board climate change conference as the electric train made its ways to the COP host city via Germany.
Speaking on board, the head of WWF, Jim Leape, said a new climate change deal was possible.
"I think Copenhagen presents the best political opportunity we've ever had to address the most important issue of our generation," Mr Leape said. "A new deal is in our grasp but we've got to make sure Heads of Government hear the demand for action from their constituents."
The debates and presentations during the 13-hour journey ranged from the latest climate science and a briefing on the UN-REDD programme to a screening of the acclaimed climate change film, The Age of Stupid, introduced by its director, Franny Armstrong.
"Getting the right deal at Copenhagen is obviously the world's number one priority, but we've also got to prove that a low carbon future is possible and, if this eco-train trip is anything to go by, that future is going to be good fun," Ms Armstrong said.
Also on board the Climate Express was Solar Impulse chairman and co-founder, Dr Bertrand Piccard, fresh from conducting a runway test of the world's first solar-powered aeroplane two days earlier, on Thursday, 3 December. The plane has the wing span of a traditional jumbo jet, weighs the same as a car and is designed to fly between sunsets.
During a briefing on the train, Dr Piccard highlighted the need to make climate change solutions profitable.
"Getting rid of our dependence on oil is a mission greater than going to the moon, but it won't happen unless we can show that we can make it profitable to fight climate change," he said.