Kyoto Protocol comes into force

After years of delays, the Kyoto Protocol on curbing human emissions of heat-trapping gases by 2012 took effect at midnight EST amid muted celebrations including a ceremony in the ancient Japanese city of Kyoto where the pact was signed in 1997.

"Climate change is a global problem. It requires a concerted global response," U.N. Secretary-General Kofi Annan said in pre-recorded remarks to be aired in Kyoto.

"I call on the world community to be bold, to adhere to the Kyoto Protocol, and to act quickly in taking the next steps. There is no time to lose," he said.

Environmental group Greenpeace flew a hot air balloon over Kyoto, emblazoned with the message: "New dawn for the climate." It said it held other celebrations from Bonn to Bangalore.

Supporters of the 141-nation pact say it is a first step to slow global warming. Climate experts fear temperature increases could lead to rising sea levels, extreme weather patterns and wipe out thousands of animal and plant species by 2100.

But the United States pulled out in 2001, saying Kyoto was too costly, based on unreliable science and unfairly excluded big developing nations India, China and Brazil, which account for a third of the world's population.

Among major developed nations, only Australia has joined the United States in refusing to cap emissions of gases like carbon dioxide emitted mainly by burning fossil fuels in cars, factories and power plants.

"Climate change is happening already...but we know Kyoto is only a first step," European Environment Commissioner Stavros Dimas said.

He called Kyoto a cause for "sober celebration," noting that the World Health Organization believed climate change was already killing 150,000 people a year.

In Sydney, ice sculptures of kangaroos and koalas melted during a protest by green groups over Australia's refusal to ratify the pact.

In China, home to 1.3 billion people and one of the world's fastest-growing economies, a man dressed as a gloomy looking polar bear took to Beijing's streets as part of Greenpeace China's campaign to explain the impact of climate change.

And a US conservation group, the Center for Biological Diversity, urged Washington to list the polar bear as an endangered species, saying the Arctic icecap was likely to melt in summertime by 2100.

The Kyoto pact is the first legally binding plan to tackle climate change. It requires developed nations to cut emissions of greenhouse gases, mainly carbon dioxide, by 5.2 percent below 1990 levels by 2008-12.

Its fate beyond 2012 is unclear because of Washington's decision to stay out of the plan President Bush has called fatally flawed. His administration once denounced it as "an unrealistic and ever-tightening regulatory straitjacket."

The United States accounts for almost a quarter of greenhouse gas emissions.