United Nations climate talks move into the final two-day straight on Thursday blighted by bitter wrangling that could wreck efforts to draw up a sweeping pact to combat global warming.
As world leaders began descending on Copenhagen, wealthy nations gave the fraught negotiations a shot in the arm Wednesday by pledging billions of dollars to bankroll the climate war.
Speakers are lined up to address the summit until the small hours of the morning, including political heavyweights such as Iranian President Mahmoud Ahmadinejad, Germany's Chancellor Angela Merkel, Brazilian President Luiz Inacio Lula de Silva and French President Nicolas Sarkozy.
But as frustration mounted about the slow pace of the high-stakes talks, police used tear gas and clubs to beat back crowds of demonstrators who tried to march on the summit venue on the outskirts of the Danish capital.
Negotiators from 194 nations have been meeting for 10 days seeking to forge a strategy to head off potentially catastrophic global warming and help the most vulnerable nations but have become bogged down in wrangling between the two top polluters China and the United States and rows between rich and poor.
After a day marked by finger-pointing, Britain's climate minister Ed Miliband said he feared a deal could slip away, declaring that the talks were at a "very dangerous point."
"People can kill this process, kill the agreement with process argument," Miliband said.
Australian Prime Minister Kevin Rudd said the talks were proceeding "at a snail's pace" and played down hopes of striking a deal.
"These are very hard negotiations," he added. "This will probably be one of the largest concentrations of heads of government at any time in history, but the challenges we face are among the largest we've faced in history as well."
Chink of light
Providing a chink of light, Japan promised to stump up a whopping 1.75 trillion yen ($19.5 billion) for developing nations to fight climate change -- if a comprehensive deal is reached at Copenhagen.
It was also one of six countries -- along with Australia, Britain, France, Norway and the United States -- that said they would set up a fund to fight the loss of forests, a leading source of the rising temperatures that scientists warn will cause droughts, plagues and storms if unchecked.
"Japan as a country takes very seriously its responsibility in the international community," Environment Minister Sakihito Ozawa said as he announced the biggest financial offer yet for climate change.
Europe has already said it would give 7.2 billion euros ($10.6 billion) towards an envisioned fund worth $30 billion to help developing nations over the three years from 2010-2012.
The United States has yet to announce a contribution, although the White House has said it will offer a "fair share."
U.S. President Barack Obama has called for an "operational accord" -- essentially a political agreement with teeth that can get countries working to cut or curb their greenhouse gas emissions while a more formal and binding treaty is hammered out in 2010.
In a joint statement, the six governments also said they would collectively dedicate $3.5 billion from 2010 to 2012 in what they hoped would be just the starting point for a deforestation fund.
The announcements were intended to provide fresh momentum as delegates feared an overwhelming amount of work remained to seal a deal ahead of the summit's finale on Friday when around 120 world leaders are due in Denmark.
Lack of transparency
Developing countries, led by top polluter China, accused host Denmark of a lack of transparency by suggesting language for the agreement without full consultation.
"There's a group of countries who think they are better than us in the South, in the Third World," said Venezuelan President Hugo Chavez, who railed against "the imperial dictatorship" of the West.
The leaders of Bangladesh and Nepal pleaded for the summit to be ambitious, warning they faced some of global warming's worst ravages.
"Bangladesh's greenhouse gas contribution is negligible, but it is one of its worst victims," Prime Minister Sheikh Hasina said.
Tensions also flared outside, where police used clubs and tear gas to stop some 2,500 activists who tried to march on the tightly guarded Bella Centre.
Police said they rounded up about 260 demonstrators, some of whom clashed again with the guards of their makeshift jail in a former beer warehouse.
The summit climaxes Friday when the leaders, including U.S. President Barack Obama, try to lay out a strategy to deal with climate change after the end of 2012, when obligations run out under the landmark Kyoto Protocol.
Obama has offered to cut U.S. carbon emissions by 17 percent by 2020 over a 2005 benchmark, a figure that aligns with legislation put before Congress but is well below pledges by the European Union and Japan.