Copenhagen: The ear-biting 1-degree-Celsius chill did not dim the enthusiasm of the beaming Japanese campaigners handing out vegan sandwiches to the thousands pouring out of the Bella Convention Centre and heading for its modest metro station on Saturday night.

“Please, have," the Japanese said, as other groups sang, danced and staged skits. They are among more than 50,000 people who have poured into the orderly Danish capital of Copenhagen, straining its hospitality and abilities as negotiations to decide the earth’s future enter a critical second week.

Next to the Japanese, decidedly more aggressive Dutch anti-meat campaigners taunted grey-haired executives who refused to accept their leaflets. “Old men can’t read, eh?" one bear of a man hollered, flinging a leaflet at them.

Up the stairs of the metro station, it looked like a Mumbai peak-hour train station. Only, instead of dealing with the crush, the four-coach, driverless Copenhagen metro train was stalled at the station, its coaches jammed to beyond capacity, its doors refusing to close.

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Raising concern: Demonstrators march through the centre of Copenhagen during the UN Climate Change Conference on Saturday. Danish police said on Sunday they had released almost all of the nearly 1,000 protesters arrested during a weekend mass rally. Anders Debel Hansen / Reuters

In line with liberal Danish attitudes, visas have been issued to all manner of activists, NGOs, musicians and others. If the weekend was any indication, the severest test for Copenhagers—struggling with those slow-moving trains, trash, marches, and unruliness on its streets—lies ahead.

Up and down the tracks from the Bella Centre, a series of trains was stationary, and electronic indicators train timings had collapsed. “There is nothing we can do," shrugged a harassed metro employee, as she hurried to pull some people off a train.

Journeys that normally take 10 minutes lasted more than an hour. Trains lurched along, stopping frequently for signals and crowds. Copenhagers bore it all stoically, but the strains are especially evident on one-third of the population (about two million) that uses only cycles.

“Trains are packed, the streets are looking filthier and people walk on the cycling tracks," said Abastha Veenegard (24), a postgraduate student at the city university.

Cycling is the most popular form of transport after the metro in Copenhagen, where people travel 1.2 million km by cycles every day. This is the equivalent of cycling to the moon and back—twice. There are 350km of cycle tracks, each 2m wide. That’s about 60% of the total road length in Delhi.

This helps the city save 80,000 tonnes of carbon emissions every day, and the city’s 2015 goal is that 50% of travel will be on cycles. Veenegard travels more than 15km every day on her cycle, like most of her friends, young and old. Even executives and civil servants cycle. You can park cycles everywhere, even take them on the trains.

Copenhagen lives its earth ideals, and that is a strong draw for the bewildering range of people gathering here.

On Saturday, climate parties merged with pre-Christmas nights of carousing, and on Sunday, South African Nobel laureate Archbishop Desmond Tutu joined campaigners from across the world—and on the Net by many thousands—in a march to present a global petition to UN climate chief Yvo de Boer.

On Saturday, a shopping day, police asked shopkeepers in the main city centre to close down after some of at least 30,000 marchers from a “Climate Walk" broke window panes of several shops and stole drinks from a few. “They have forced us to take a day off," said grocery shop owner Andel Richel at Christianshavn in central Copenhagen.

Some participants eased themselves on the road, common in India, but a rarity in any part of Europe. The route had banners, placards, beer bottles and garbage spilled all along. Bottles and trash littered the metro and pavements through the weekend.