It has taken nearly 20 years to bring the world to this pivotal moment in climate change politics.
Along the roller-coaster ride toward an international agreement, expectations have soared and plummeted dozens of times -- sometimes within a matter of days. But as nations convene today in Copenhagen for the world's largest global warming summit, one thing is new: For the first time, every major greenhouse gas polluter in the world has a promise and a plan to cut carbon.
What that change signifies still isn't clear. Few think the U.N. Framework Convention on Climate Change conference, which runs through Dec. 18, will conclude with a new international treaty. Too many countries are still sparring over major issues for that. Moreover, the nation others expect to lead the world -- the United States -- still has not passed the legislation required to cut emissions.
But analysts say the combination of last-minute pledges by the United States, India and China, building upon proposals by Europe, Japan, Norway, Brazil, Indonesia and others, may have fundamentally altered the landscape. Meanwhile, the expected arrival of President Obama and nearly 90 other world leaders toward the summit's end lends a sense of urgency never before seen in global climate talks.
"Negotiators now have the clearest signal ever from world leaders to craft solid proposals to implement rapid actions," insisted U.N. climate chief Yvo de Boer in a statement on the eve of the talks.
"Never in 17 years of climate negotiations have so many different nations made so many firm pledges together," he said. "Copenhagen is already a turning point in the international response to climate change."
The final target, said Eileen Claussen, president of the Pew Center on Global Climate Change and Strategies for the Global Environment, is crafting an agreement that will legally bind every major economy in the world to reduce greenhouse gas emissions. The new treaty, if it comes, would replace the 1997 Kyoto Protocol, which required 37 wealthy nations to cut emissions an average 5 percent below 1990 levels by 2012, but made no demands on rapidly growing economies like China's.
A 'springboard' to where?
"The real question for Copenhagen is how far it moves us toward that goal," Claussen said, adding that the summit needs to be a "springboard to a ratifiable treaty, and not just a pledging conference."
At issue over the next two weeks is whether both industrialized and developing nations can agree to collectively cut emissions far enough to avert the worst consequences of global warming.
But the fights won't be just about concentrations of carbon dioxide in the atmosphere. They will be about trade and jobs. They will be about fears industries have about the upfront costs to reducing CO2 and uncertainties about the long-term gains of clean energy.
And, to some extent, they also will be a proxy debate for how the global economy will reshape itself in the coming century, and how much responsibility emerging powerhouses like China, India and Brazil should have to shoulder as the world's economic forces shift.
The streets of Copenhagen will be a clogged climate circus -- mobs of protesters, clanging church bells, street theater and even an actual circus sponsored by local municipalities to promote nature to children. The chaos will continue inside the Bella Center conference hall, where U.N. officials are juggling accreditation applications from twice the center's 15,000-person capacity.
Environmental activists will roam the halls, giving out "angry mermaid" and "fossil of the day" awards to countries it deems to be hurting the climate talks. Skeptics will hold court, denouncing scientists for trying to quash debate on rising temperatures. Political figures from Republican California Gov. Arnold Schwarzenegger to independent New York Mayor Michael Bloomberg will tout policies. Business groups and entrepreneurs will lend the conference the flavor of a job fair, hawking everything from solar panels to straw ethanol.
The main events -- speeches from Obama and other world leaders -- will occur on Dec. 18. Obama, who originally planned to travel to Copenhagen on Dec. 9 on his way to Oslo to pick up the Nobel Peace Prize, late last week announced he would move back his trip. The move won praise from activists and other leaders who had quietly grumbled that the early arrival would have been a mere photo op.
The real issues: money and responsibility
But the real work in Copenhagen will happen behind closed doors. That's where the negotiators will be trying to resolve the three biggest problems in the debate: targets, money and responsibility.
The United States is notorious in climate circles for never having ratified the Kyoto Protocol after the Clinton administration signed it. The Senate rejected it because the agreement didn't make any demands on China or other emerging countries.
The Obama administration, led at the United Nations by State Department climate envoy Todd Stern, has been careful about making promises this time around, ever mindful of what it calls "the lessons of Kyoto." Late last month, though, Obama announced that the United States would cut emissions "in the range of" 17 percent below 2005 levels by 2020. The amount mirrors legislation that passed the U.S. House in June, but the Senate still hasn't acted.
Nevertheless, the move by the United States saw a domino effect around the world. China -- which last year eclipsed the United States as the world's leading emitter of heat-trapping gases -- and India, the world's fourth-largest emitter, also came out with targets. Both pledged to reduce carbon emissions per unit of gross domestic product, China by 40 to 45 percent and India by about 25 percent.
"Copenhagen is not Kyoto," said Ned Helme, president of the Center for Clean Air Policy. "In 12 years, a lot has changed. There's been a fundamental shift in the way developing countries are thinking about climate change."
Few think any of the targets will actually keep the concentration of carbon dioxide in the atmosphere from going above 450 parts per million, the level at which scientists believe the worst impacts of climate change can be avoided. But many believe it's a key start.
"This is the type of end-game race that we absolutely need," said Malini Mehra, founder of the Center for Social Markets think tank in India. "At least if you start talking about targets and setting them ambitiously, it means the country has set itself a pathway."
A multibillion-dollar question
Developing countries will be prodding industrialized ones to go much further. They would like to see wealthy nations slash emissions 40 percent below 1990 levels in the coming decade. But the fight over the numbers could likely be eclipsed by even bigger debates.
Money is a thorny point. Developing countries say industrialized ones cause climate change and owe poor nations dealing with the consequences money to help prevent disasters and move themselves to a low-fossil fuel economy. The Obama administration announced late last week that nations will likely offer $10 billion annually for immediate needs through 2012, though many times that figure will be expected in later years.
The United States will pay "its fair share," according to the administration's statement. State Department officials have previously said it would likely be about $1.3 billion, the amount already budgeted in the fiscal year 2010 appropriations bill for international climate funds.
That issue of money sticks in the craw of many lawmakers in the United States who bristle at the notion of climate "reparations." Others say the money is best spent at home, particularly in a time of economic crisis.
"I'm surprised the president would commit our nation to billions in new and long-term spending, particularly in a year that has seen our government rack up a record deficit, and before our economy is back on track," Sen. Lisa Murkowski (R-Alaska) said in a statement.
"I'm also disappointed that the administration has chosen to prioritize international assistance over funding that should first go to Alaska, and other places in America that badly need assistance with adaptation. My home state of Alaska literally has villages falling into the ocean -- where's the support for the people in our own country being affected by climate change?" she said.
But if some U.S. lawmakers are concerned too much money is going overseas, the islands that fear sinking into the ocean and African countries facing sweeping crop failures fear there is not enough.
"We need to develop our ability to manage climate change," Vladimir Russo, Angola's national director of environment, told E&E Friday.
The World Bank has estimated that developing countries will need between $75 billion and $100 billion annually for adaptation and mitigation. Claussen said she doesn't expect countries to come to an agreement this month about the final dollar figure, but is optimistic about finding common ground on short-term financing. With the $10 billion in immediate funding on the table, others said, poor countries are at least less likely to storm out of the talks as they did briefly at an earlier conference this year.
An overarching goal?
But the biggest issue negotiators must grapple with at this summit also is the most complex: Wshat kind of agreement is this?
If the United States has its way, the 1997 agreement will be scrapped in favor of a schedule of domestically binding commitment. That worries environmentalists, who say there must be an overarching emissions goal if the treaty is to be meaningful. And it worries developing countries that currently face no responsibilities, but that would have to agree to international commitments and, for some, maybe even funding, under the new system envisioned by the United States.
Angela Anderson, program director of the U.S. Climate Action Network, noted that nothing in the United States' position stops countries already bound to Kyoto from developing a second commitment period. Where that would leave America, though, remains unclear. "The piece that nobody is watching is what happens with the Kyoto Protocol," Anderson said.
Lost in the global chatter about an international treaty is the basic question of whether there should be one at all. At this point, most leading international figures have declared that they believe it is the best way to avert global warming. At the same time, conservative figures like James Inhofe (R-Okla.) and former Alaska Gov. Sarah Palin (R) -- along with like-minded politicians in Australia and parts of Europe -- continue to ring alarm bells that a treaty would not be in their countries' best interests.
In a Facebook post late last week, Palin urged Obama to "say no to Copenhagen," challenging him to boycott until an investigation into stolen climate science e-mails is completed. Inhofe, meanwhile, has vowed to "truth-squad" the talks by informing delegations that the U.S. Senate is not likely to pass the legislation needed to curb emissions and ultimately seal a global climate deal.
Activists who have been pushing for an international treaty, though, say they are more optimistic than they have been in a long time.
Said Keya Chatterjee, U.S. director for the World Wildlife Fund's climate change program, "If we can convince people to lay down their nuclear arms at the same time, I'm sure we can convince them to build some solar panels."