With 11,000 participants from all over the world, the conference is the biggest yet. And while all the delegates have come to Bali to talk about preventing global warming, the United Nations estimates that they will also emit 50,000 tons of greenhouse gases along the way. How heavy their personal carbon footprint is, though, depends a lot on how they got to Bali: by plane, train or automobile.

I started my trip to Bali as environmentally-friendly as possible with a train trip from Bonn to Frankfurt -- on an InterCity Express, one of the newest and most efficient of its kind. But this short trip couldn't make up for what came next -- a flight to Singapore on a Boeing 747 jumbo jet. From there, I took a slightly smaller plane to Denpasar Airport on Bali.

My share of the carbon emissions from the 24,500-kilometer (15,200- mile) trip was at least 5,500 tons. The various carbon calculators available on the Internet each give a slightly different verdict. Still, no matter how you look at it, the carbon footprint I made can't be overlooked.

Sparse signs of environmental awareness

The streets of Bali are jammed with cars and mopeds. Public transport is spotty at best. Like most of the participants at the conference, I took a taxi to my hotel. Indonesia does not place an environment tax on petrol -- in fact, oil is subsidized. My taxi driver said gas had gotten more expensive.

"Right now we buy the petrol for one liter 4,500 rupiah," he said. That's about 50 cents ($0.74), which means that petrol in Bali is about two-thirds cheaper than in Germany.

But there are signs on the island that the Indonesians want to help stop global warming. Energy-saving light bulbs are installed in the garden lanterns at my hotel. I can let cleaning staff know my sheets can be left unchanged with a sign on my door, but I've only seen a few of them on my hall.

Outside, United Nations Framework Convention on Climate Change (UNFCCC), the conference hosts, have provided free bikes to ride to the conference. But it is nearly 36 degrees Celsius (97 degrees Fahrenheit), humid, and I see few of the 200 available bikes on the way to the conference center in Nusa Dua.

It's supposed to be Bali's rainy season, but there's been little or no rain for the past month. Still, parts of the shores are completely under water as sea levels are rising.

Two-month train trip to Bali

The Intergovernmental Panel on Climate Change has said installing low-emissions light bulbs and energy-saving electrical devices, using better housing insulation and cutting transportation emissions as three main ways to prevent global warming.

But airline travel alone accounts for two percent of global emissions. The industry is not part of any emissions trading scheme, but delegates in Bali have been discussing whether this might change in a future climate agreement.

In a book about how people can reduce their carbon footprint, German journalist Nick Reimer calls airlines a "climate killer" because they produce three times more CO2 per person and kilometer than a train.

Riemer spent two months in trains getting from Berlin to Bali. Along the way, he witnessed the effect climate change is having on the planet.

"For me it was interesting to see that climate change is a reality," he said. "I was at the Aral Sea in Russia. The water level has dropped by 40 meters. We went to the mountains, and they didn't have enough rain. The glaciers are melting."

In the end, after traveling through Russia, China, and Central Asia, a flood and typhoon in Vietnam forced Reimer to fly to Bali. He doesn't have exact figures on the carbon emissions from his train trip, but at least his conscience isn't as burdened as mine.

Earth-friendly cars don't have to be pricey

Swiss entrepreneur Louis Palmer is another man who is walking -- or, actually, driving -- the talk. He drove his prototype Solar Taxi, a small blue and white three-wheel car pulling a trailer of solar panels behind him, all the way from Switzerland. The 13,500-kilometer trip, sponsored by the German solar producer Q-Cells, took over five months.

"I wanted to show that the technology is there, if we are only willing to use it," Palmer said. "If this car was mass-produced, it would only cost 6,000 euros. That is cheaper than any car here in Indonesia at the moment."

The Solar Taxi gets half of its energy directly from the solar panels, the other half from a battery. Palmer has an arrangement with the Swiss electrical company to take solar-powered energy off the grid. It is a huge attraction at the Bali conference, and people are lining up to take rides.

"Wherever we went, whether in Turkey or Saudi Arabia, people came out and gave us thumbs up. Everyone loves this car," said Palmer.

Certificates can offset carbon emissions

Besides a few boat trips, his carbon footprint for the trip to Bali is practically zero. He said he is even offsetting the boat trips by buying certificates that will support green technologies in developing countries like Indonesia.

Robert Turner from World Future Council, an NGO, says this is an option even the airplane passengers can take.

"Our airline has a carbon offsetting system," Turner said. "They will invest in planting new trees or in green technology projects. But it is costly. We paid 900 euros more for each airline ticket to come to Bali."

The cost of carbon, in monetary terms, is maybe the only way to really feel the impact. The UN says it will invest in so-called clean development mechanisms -- green technology in developing nations like Indonesia -- to offset the conference.

They are taking the pressure off me, in a way, so that I can walk with a light carbon footprint, even after Bali.