Church bells rang out 350 times across Denmark and several other countries Sunday to encourage negotiators assembled in Copenhagen to reach a climate-change deal.
The number 350 signifies the maximum concentration of carbon dioxide, in parts per million, that the atmosphere can support without causing destructive changes in weather patterns, according to scientists.
"It's the most important number in the world," said Bill McKibben, who founded an environmental group called 350.org. "It's the line between habitability on this planet and a really, really desolate future."
The planet surpassed that concentration of carbon dioxide in 1989, and rose above 390 ppm in 2009. However, some climate scientists say the harshest effects of climate change can be avoided with a target higher than 350.
Although Sunday was a day off for delegates at the historic climate change summit, more than 40 environment ministers met for informal talks at the Danish Foreign Ministry. They discussed issues such as cuts to greenhouse gas emissions and financial aid for developing nations to help them combat climate change.
Meanwhile, local police cracked down on environmental protesters.
More than 200 people were detained on Sunday as riot police halted an unauthorized march that tried to make its way to the Copenhagen harbour, according to police spokesperson Flemming Steen Munch.
Police conducted security checks of some of the protesters, Munch said, and found bolt-cutters and gas masks during the search of a truck that led the demonstration.
The latest arrests came hours after police announced that they released most of the nearly 1,000 protesters detained Saturday during a mass climate-change demonstration.
Police said only 13 of the 968 people detained during Saturday's protest remained in custody on Sunday. Three are scheduled to appear in court to face charges of fighting with police.
Police estimated 40,000 people marched through the city to the suburban conference centre where the talks are taking place.
While the protest was largely peaceful, dozens of riot police were on hand to manage the crowd. They arrested activists who they say were near the back of the crowd of marchers when they began to vandalize buildings.
Police say windows were broken at the former stock exchange and at the Foreign Ministry.
An officer suffered minor injuries when he was hit by a rock, while a protester was injured by fireworks, Munch said.
Protest organizers criticized the arrests.
"They have arrested 1,000 people, and they only followed up on 3 of them," protest spokesperson Ida Thuesen said. "There are lots of people who haven't done anything and had no intention of doing anything."
Also on Sunday, Christian leaders from around the world held an ecumenical service devoted to climate change.
The service was led by Archbishop of Canterbury Rowan Williams at Copenhagen's Lutheran cathedral.
Archbishop Desmond Tutu of South Africa was also present, alongside religious leaders from Tuvalu, Zambia, Mexico, Greenland and Denmark.
With files from The Associated Press
