After spending 16 months cycling 18,000 kilometres (11,180 miles) from Brisbane to Copenhagen, Kim Nguyen is taking part in the UN climate talks with a host of eyewitness accounts of the effects of global warming from his odyssey.
"The first place that I guess I realised the severity of what we're facing already was when I was talking to farmers in East Timor, just after Australia," the 28-year-old Australian told AFP.
"They were telling me that during the last three years they had not been able to grow enough food to eat and survive because the rains that usually came at a certain time of the year were not coming. And then when they did come they came in a deluge and there were floods," Nguyen said.
On a worn map of the world that he used throughout his entire journey, Nguyen's finger traces the 22 countries he covered on his journey: East Timor, Indonesia, Malaysia, Thailand, China, Mongolia, Russia, Kazakhstan, Azerbaijan, Georgia, Turkey, then eastern and central Europe before finally reaching Denmark.
"The bike started falling apart after 6,000 kilometers so I still had 12,000 kilometres to go," Nguyen said.
"I fixed things by myself but I travelled really long distances with poor components that I eventually only could fix when I arrived in Europe," he said, explaining that he usually biked 100 kilometres a day three days in a row, then took a day off before hopping on the saddle again.
Nguyen came up with the idea for his adventure 18 months ago after a friend told him about the UN climate conference.
After seeing first-hand severe flooding in southeast Asia, the spreading of the Gobi desert in Mongolia and dried up riverbeds in northeastern China, his observations of the planet's woes pushed him to transform his adventure from a one-man affair into a joint action.
"It came out of my thoughts when I had been cycling for quite some time, thinking 'actually one guy on a bike isn't much of a big deal. Even if he's coming to Copenhagen how is that going to achieve anything'," the curly haired and bearded cyclist said.
So in each big city where he stopped, he decided to contact the local branches of environmental groups Greenpeace and Friends of the Earth - his sponsor - to help out and create a network of people who followed his journey and collected his testimony of climate change around the world.
News of his adventure began to spread, and he found himself making friends on the road near the end of his trip.
When he arrived in Copenhagen on Sunday, some 60 cyclists followed him into the city centre.
Yet Nguyen almost did not make it: three times he ended up in hospital.
The first time was due to a case of sunstroke in the Australian desert. Another time he came close to throwing in the towel near Ulan Bator, the Mongolian capital.
"My knee had hurt for more than four months. It was really painful, and I told myself 'What's the point? If I stop now, would anybody care? Probably not'," he recalled.
"I called an Australian friend but I didn't manage to get hold of him. And then I changed my mind... When he finally called me 15 minutes later, I told him I was fine," he said.
"When I arrived in Copenhagen, I was incredibly happy but also incredibly relieved. I had really been planning and doing everything to be there, my energy, my bike, my money," he said.
Twice he had to abandon his bicycle and board trains: once in China and once in Kazakhstan, both times because his visas were about to expire.
Now in Copenhagen, he has a hectic schedule: he is taking part in an alternative climate forum and he is due to meet with some of the UN climate negotiators, including the Australian delegation.
He plans to tell them that saving the planet is not a question of money.
"Mongolia is one of the poorest countries in the world, but it still manages to support people with solar energy," he said, explaining that residents there have solar panels on their tents.
"In Australia instead we build gigantic grids to link towns in the middle of the desert and connect it with a coal power station thousands of kilometres away," he lamented.
After a bit of rest, Nguyen hopes to work for a while in Europe to build up his finances - his trip cost him almost 20,000 Australian dollars (more than 18,000 US dollars, 12,000 euros) - before returning to Australia.
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