Leaders from 192 countries meeting at the UN climate change conference in Copenhagen, Denmark, began negotiations Monday towards reducing greenhouse gas emissions.
The countries will try to hammer out a deal to steer the world away from fossil fuels and other non-ecologically sound energy sources. An agreement in Copenhagen will replace the soon-to-expire Kyoto protocol.
Conference president Connie Hedegaard said the key to an agreement is finding a way to raise public and private financing for poorer countries that could be most at risk from the effects of climate change.
Hedegaard said the Copenhagen summit is one of the last chances the world has to fight climate change.
"This is our chance. If we miss it, it could take years before we got a new and better one, if ever," she said in a speech.
Scientists predict that if action is not taken soon, the consequences of climate change could be severe. Sea levels could rise, flooding low-lying cities, and extreme weather like drought could afflict the planet.
Talks started off with a hopeful mood on the heels of recent climate commitments from countries like the U.S., China, and the Commonwealth nations.
But the summit's opening video showed clips of children from around the world urging delegates to help them grow up without facing global warming.
During the first week, the conference will focus on writing a draft treaty. But no major decisions will be made until the last few days, when world leaders and environment ministers are in attendance.
Closer to the end of the summit, 110 heads of state or government will attend the conference, including Prime Minister Stephen Harper and U.S. President Barack Obama.
The conference is scheduled to end Dec. 18.
Among the major decisions to be considered is a proposed fund of $10 billion each year for the next three years for poor countries to prepare climate change strategies.
"The deal, that we invite leaders to sign up on, will be one that affects all aspects of society just as the changing climate does," said Danish Prime Minister Lars Loekke Rasmussen.
"Negotiators cannot do this alone, nor can politicians. The ultimate responsibility rests with the citizens of the world, who will ultimately bear the fatal consequences, if we fail to act."
A study released by the UN Environment Program Sunday showed current pledges to reduce greenhouse gases fall short of the requirements that scientists say are needed to stop climate change.
Environmentalists have also warned emissions commitments were dangerously short of what UN scientists have said were needed to keep average temperatures from rising more than two degrees Celsius.
Many of the larger nations have already been criticized at the meeting for not aiming higher.
Swedish Environment Minister Anders Carlgren, speaking for the European Union, said it would be "astonishing" if President Barack Obama came for the final negotiation session "to deliver just what was announced in last week's press release."
John Drexhage, a former climate change negotiator for Canada, and now with the International Institute for Sustainable Development, said that for any true deal to work, the countries will need to look at agreements in terms of their financial cost.
"One of the most important things that will come out of Copenhagen, if successful, is that it will set an international carbon price," Drexhage told CTV News Channel from Copenhagen.
"That's the only way you can make a true transition: it has got to come out in dollars and cents."
Outside the talks, climate activists drew attention to themselves with stunts -- with one man plunging feet-first into a tank with nearly 750 litres of frigid water to illustrate what rising sea levels were doing to his island nation of the Maldives. The country is only a few metres above sea level and scientists say if sea levels rise, the country could be completely submerged.
"I want people to know that this is happening," Mohamad Shinaz said as the water reached up to his chest. "We have to stop global warming."
Leah Wickham, a 24-year-old from Fiji, broke down in tears as she presented a petition she said had 10 million signatures, asking the negotiators at Copenhagen to come up with a deal to save island nations like hers.
"I'm on the front lines of climate change," she said.
Climate change officials Monday were also defending scientific research in the wake of a scandal over stolen emails from a British university.
Global warming skeptics claim the emails show scientists colluding to hide information that refute their climate change theories.
The scientists allege a smear campaign from the hackers.
"The evidence is now overwhelming" that the world needs early action to combat global warming, said Rajendra Pachauri, the head of the Intergovernmental Panel on Climate Change, a UN expert panel.
"The recent incident of stealing the emails of scientists at the University of East Anglia shows that some would go to the extent of carrying out illegal acts perhaps in an attempt to discredit the IPCC," he told the conference.
With files from The Associated Press
