The poor countries left negotiations because they are concerned that the Kyoto protocol, which aims to tackle climate change, will be abandoned. Some rich countries want a brand new climate treaty out of the Copenhagen summit to replace Kyoto.
But poor countries want to make sure the Kyoto protocol, which forces rich countries to limit their greenhouse has emissions, has a future.
Today's walkout has left the summit in limbo as ministers, including Australia's Climate Change Minister Penny Wong, frantically try to fix the problem.
"It is regrettable that we appear to have reached a gridlock on process," Senator Wong told reporters from the conference centre, adding the situation was "most unfortunate".
"(This) is not a time to play procedural games."
She did not support the developing countries' focus on the need to commit now to a future for the Kyoto protocol.
"An extension only of the Kyoto Protocol is not going to achieve the environmental outcome the world needs," Senator Wong said.
Australia does not want the Kyoto Protocol to be the only vehicle to tackle climate change because it does not include the US, nor major developing countries like China and India.
Senator Wong said that without countries like China and India on board, global efforts to tackle climate change would not work.
She said the situation at the summit was "absolutely" salvageable.
"We can resolve these issues if nations have the political will."
Senator Wong is playing a high-profile role at the UN summit, which has entered its second week and is due to finish on Friday.
Together with her Indian counterpart, she was supposed to be leading special talks to try to resolve issues around the greenhouse targets of developing countries, and around international verification of countries' emissions.
Those talks are on hold now.
There have also been complaints from some developing nations of bullying on the part of Australia, including personal calls from Prime Minister Kevin Rudd.
Ian Fry, the chief climate change negotiator for the tiny Pacific island nation of Tuvalu, said Mr Rudd had told him his position was unhelpful in securing an agreement at Copenhagen.
"Yes, we've had approaches from the prime minister of Australia to ask us to, well, to say our approach is unproductive," he told ABC television on Monday.
"Of course, we don't agree with that."
Earlier in the day, Mr Fry made an emotional plea calling for a legally binding agreement to cut carbon emissions.
"I woke up this morning crying, and that's not easy for a grown man to admit," he said. "The fate of my country rests in your hands."
Australian scientist and environmental activist Tim Flannery said part of the reason for the walkout was because of a push by Canada for commitments established under the Kyoto Protocol to be disregarded.
Because of breaches of its emissions target under the Kyoto Protocol, Canada owes about $1 billion, and will owe $1.3 billion if commitments under Kyoto continue.
"Canada and some other developed countries of course would like the Kyoto commitments to cease and then move on with a fresh slate," Prof Flannery said.
But he believes a global agreement to cut emissions can still be reached.
"To be honest, I think that the key elements are now there," he told ABC television on Monday night.
"We've seen commitment by developed countries to an accumulative 18 per cent reduction in emissions."
Prof Flannery, who is also chairman of the Copenhagen Climate Council, a collaboration between business and science, says progress has been made towards reaching an agreement.
"It's far from perfect yet but I think we're beginning to see the elements fall into place for what I'd call a good agreement."